Pretreatment Detection Surveillance and Staging of Prostate Cancer. CT Chest, Abdomen, and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT chest, abdomen, and pelvis without and with IV contrast because obtaining CT with both techniques does not provide additional benefit in terms of detecting nodal and distant metastases. CT Chest, Abdomen, and Pelvis Without IV Contrast CT chest, abdomen, and pelvis without IV contrast for nodal staging is generally useful in intermediate-risk patients because the a priori risk of nodal disease exceeds 10% [20]. However, it should be recognized that without using IV contrast there is a possibility of less optimal detection of metastases to visceral organs. FDG-PET/CT Whole Body Because prostate cancer and metastases from it are generally not FDG-avid unlike most other malignancies, FDG- PET/CT may not be beneficial as part of staging clinically established intermediate-risk prostate cancer. FDG-PET/MRI Skull Base to Mid-Thigh Because prostate cancer and metastases from it are generally not FDG-avid unlike most other malignancies, FDG- PET/MRI may not be beneficial as part of staging clinically established intermediate-risk prostate cancer. Fluciclovine PET/CT Skull Base to Mid-Thigh Although fluciclovine PET/CT is primarily used in the recurrent setting, it can also be considered in the pretreatment assessment of prostate cancer based on its ability to better detect nodal and distant metastases than CT and bone scan [98,102-105]. The specificity of fluciclovine PET/CT is high (0.98, 95% CI: 0.88-1.00) [98], and in a study of 57 patients, it demonstrated higher sensitivity for detecting nodal metastases (55.3% versus 33.3%) and was able to identify 12.3% (7/57) additional patients with distant metastasis when compared to conventional imaging (bone scan and CT) in patients with intermediate- and high-risk disease [106].


Pretreatment Detection Surveillance and Staging of Prostate Cancer. Fluciclovine PET/MRI Skull Base to Mid-Thigh Fluciclovine PET/MRI is less commonly used than fluciclovine PET/CT but shares similar principles and can be considered in the pretreatment assessment of prostate cancer based on its ability to better detect nodal and distant metastases than CT and bone scan [102,105]. The specificity of fluciclovine PET/CT is high (0.98, 95% CI: 0.88- 1.00) [98], and in a study of 57 patients, it demonstrated a higher sensitivity for detecting nodal metastases (55.3% versus 33.3%) and was able to identify 12.3% (7/57) additional patients with distant metastasis when compared with conventional imaging (bone scan and CT) in patients with intermediate- and high-risk disease [106]. Although no specific study deals with only patients with intermediate-risk disease, it is notable that in a study of 28 patients with high-risk disease, the sensitivity and specificity of fluciclovine PET/MRI for detecting nodal metastases was 40% and 100%, respectively [105]. Also, fluciclovine PET/MRI has been shown to potentially improve characterization of the primary tumor compared with PET/CT [103]. Pretreatment Detection of Prostate Cancer MRI Abdomen and Pelvis Without and With IV Contrast The literature indicates that MRI abdomen and pelvis without and with IV contrast may be used in intermediate- risk patients for 1) nodal and distant metastasis staging in addition to 2) assessment of the local extent of primary tumor [109-112]. This can be supported by the fact that a priori risk of nodal disease (most of which are in the pelvis and some up to the retroperitoneum) exceeds 10% [20].


Pretreatment Detection Surveillance and Staging of Prostate Cancer. In addition, because a majority of the distant metastases occur (at least in the pretreatment setting) in the axial skeleton and it is rare to harbor isolated bone metastases without simultaneously harboring metastases in the pelvic and lumbosacral vertebral bones, MRI abdomen and pelvis is usually sufficient to detect the presence of bone metastasis at the patient level [113]. MRI Abdomen and Pelvis Without IV Contrast Because the main purpose for imaging the abdomen and pelvis would be to identify nodal and distant metastases, MRI abdomen and pelvis without IV contrast is a viable option as an alternative to that using IV contrast [109-113]. However, it should be recognized that without using IV contrast there is the possibility of less optimal detection of metastases to visceral organs. MRI Whole Body Without IV Contrast Because the main purpose for imaging the whole body would be to identify nodal and distant metastases, MRI whole body without IV contrast is a viable option as an alternative to that using IV contrast [49,96,108-112,114- 117]. However, it should be recognized that without using IV contrast there is the possibility of less optimal detection of metastases to visceral organs. Pretreatment Detection of Prostate Cancer PSMA PET/CT Skull Base to Mid-Thigh The literature indicates PSMA PET/CT is useful in patients with intermediate- and high-risk disease. PSMA PET, which can be used with CT or MRI (PET/CT and PET/MRI, respectively), is one of the newer imaging modalities, which has been primarily investigated in the setting of biochemical recurrence and biochemical failure, where, because of its superior capability to detect recurrent disease, has shown to substantially change management [118].


Pretreatment Detection Surveillance and Staging of Prostate Cancer. Nevertheless, many recent studies have shown its potential to detect metastatic disease in patients with intermediate- and high-risk prostate cancer undergoing pretreatment assessment, and it has recently received approval from the FDA for both recurrent and primary staging settings [117,119-121]. PSMA PET/CT examination has higher diagnostic performance for prostate cancer compared to fluciclovine PET/CT, which was able to identify additional patients with distant metastasis when compared to conventional imaging (bone scan and CT) in patients with intermediate- and high-risk disease. In a study of 130 patients with intermediate- and high-risk patients, PSMA PET demonstrated superior sensitivity and a similar specificity to morphological imaging alone (CT or MRI) [121]: 68.3% and 99.1%, respectively, for PSMA PET and 27.3% and 97.1%, respectively, for morphological imaging. Additionally, PSMA PET, especially when combined with MRI, can potentially improve detection and characterization (eg, assessment of local extent) of the primary tumor, by using different types of PSMA-targeted radiotracers, compared with multiparametric MRI alone or clinical nomograms [19,122,123]. TRUS Prostate TRUS is unlikely to provide useful incremental information in patients with an established diagnosis of intermediate-risk prostate cancer and so it is not beneficial. TRUS-Guided Biopsy Prostate Active surveillance may be beneficial in carefully selected patients with intermediate-risk prostate cancer [109- 111]. In that setting, some form of serial TRUS-guided biopsy would be useful as part of the monitoring regimen. Choline PET/CT Skull Base to Mid-Thigh Although choline PET/CT is primarily used in the recurrent setting, it can also be considered in the pretreatment assessment of prostate cancer based on its ability to better detect nodal and distant metastases than CT and bone scan.


Pretreatment Detection Surveillance and Staging of Prostate Cancer. In patients with intermediate- and high-risk prostate cancer, choline PET/CT has shown to identify more nodal and distant metastatic lesions than conventional imaging [96,98-100]. For example, in a study of 48 patients, choline PET/CT showed a higher sensitivity (46.2% versus 69.2%) with an identical specificity (92.3%) for detecting nodal metastases [99]. In another multicenter study of 269 patients, choline PET/CT was shown to identify more nodal and distant metastatic lesions than conventional imaging, which led to a change in therapeutic indication in approximately 70% of patients [100]. Choline PET/MRI Skull Base to Mid-Thigh Choline PET/MRI is less commonly used than choline PET/CT but can be considered in the pretreatment assessment of prostate cancer based on the same principles that it better detects nodal and distant metastases than CT and bone scan [96,98-100]. For example, in a study of 48 patients with intermediate- and high-risk disease, choline PET/CT showed a higher sensitivity (46.2% versus 69.2%) with an identical specificity (92.3%) for detecting nodal metastases [99]. In a prospective study of 58 patients with high-risk disease, which specifically assessed choline PET/MRI, it was superior to CT and bone scan for detecting distant metastases (100% versus 63.6%, respectively) [101]. Pretreatment Detection of Prostate Cancer CT Abdomen and Pelvis With IV Contrast CT abdomen and pelvis with IV contrast for nodal staging is generally useful in high-risk patients because a priori risk of nodal disease exceeds 10% [20]. CT Abdomen and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT abdomen and pelvis without and with IV contrast because obtaining CT with both techniques does not provide additional benefit in terms of detecting nodal and distant metastases.


Pretreatment Detection Surveillance and Staging of Prostate Cancer. CT Abdomen and Pelvis Without IV Contrast CT abdomen and pelvis without IV contrast for nodal staging is generally useful in high-risk patients because a priori risk of nodal disease exceeds 10% [20]. However, it should be recognized that without using IV contrast there is the possibility of less optimal detection of metastases to visceral organs. CT Chest, Abdomen, and Pelvis With IV Contrast CT chest, abdomen, and pelvis with IV contrast for nodal staging is generally useful in high-risk patients because a priori risk of nodal disease exceeds 10% [20]. CT Chest, Abdomen, and Pelvis Without and With IV Contrast There is limited evidence to support the use of CT chest, abdomen, and pelvis without and with IV contrast because obtaining CT with both techniques does not provide additional benefit in terms of detecting nodal and distant metastases. CT Chest, Abdomen, and Pelvis Without IV Contrast CT chest, abdomen, and pelvis without IV contrast for nodal staging is generally useful in high-risk patients because a priori risk of nodal disease exceeds 10% [20]. However, it should be recognized that without using IV contrast there is the possibility of less optimal detection of metastases to visceral organs. FDG-PET/CT Whole Body Because prostate cancer and metastases from it are generally not FDG-avid unlike most other malignancies, FDG- PET/CT may not be beneficial as part of staging clinically established high-risk prostate cancer. FDG-PET/MRI Skull Base to Mid-Thigh Because prostate cancer and metastases from it are generally not FDG-avid unlike most other malignancies, FDG- PET/MRI may not be beneficial as part of staging clinically established high-risk prostate cancer.


Pretreatment Detection Surveillance and Staging of Prostate Cancer. Fluciclovine PET/CT Skull Base to Mid-Thigh Although fluciclovine PET/CT is primarily used in the recurrent setting, it can also be considered in the pretreatment assessment of prostate cancer based on its ability to better detect nodal and distant metastases than CT and bone scan [98,102]. The specificity of fluciclovine PET/CT is high (0.98, 95% CI: 0.88-1.00) [98], and in a study of 57 patients, it demonstrated a higher sensitivity for detecting nodal metastases (55.3% versus 33.3%) and was able to identify 12.3% (7/57) additional patients with distant metastasis when compared with conventional imaging (bone scan and CT) in patients with intermediate- and high-risk disease [106]. Fluciclovine PET/MRI Skull Base to Mid-Thigh Fluciclovine PET/MRI is less commonly used than fluciclovine PET/CT but shares similar principles and can be considered in the pretreatment assessment of prostate cancer based on its ability to better detect nodal and distant metastases than CT and bone scan [102,105]. The specificity of fluciclovine PET/CT is high (0.98, 95% CI: 0.88- 1.00) [98], and in a study of 57 patients, it demonstrated a higher sensitivity for detecting nodal metastases (55.3% versus 33.3%) and was able to identify 12.3% (7/57) additional patients with distant metastasis when compared with conventional imaging (bone scan and CT) in patients with intermediate- and high-risk disease [106]. In a study of 28 patients with high-risk disease who underwent fluciclovine PET/MRI, the sensitivity and specificity for detecting nodal metastases was 40% and 100%, respectively [105]. Pretreatment Detection of Prostate Cancer MRI Abdomen and Pelvis Without and With IV Contrast The literature indicates MRI abdomen and pelvis may be used in high-risk patients for 1) nodal and distant metastasis staging in addition to 2) assessment of the local extent of primary tumor [109-112].


Pretreatment Detection Surveillance and Staging of Prostate Cancer. This can be supported by the fact that a priori risk of nodal disease (most of which are in the pelvis and some up to the retroperitoneum) exceeds 10% [20]. In addition, because a majority of the distant metastases occur (at least in the pretreatment setting) in the axial skeleton and it is rare to harbor isolated bone metastases without simultaneously harboring metastases in the pelvic and lumbosacral vertebral bones, MRI abdomen and pelvis is usually sufficient to detect the presence of bone metastasis at the patient level [113]. MRI Abdomen and Pelvis Without IV Contrast Because the main purpose for imaging the abdomen and pelvis would be to identify nodal and distant metastases, MRI abdomen and pelvis without IV contrast is a viable option as an alternative to using IV contrast [20,109-113]. However, it should be recognized that without using IV contrast there is possibility of less optimal detection of metastases to visceral organs. MRI Pelvis Without and With IV Contrast In addition to standard local and nodal staging, multiparametric MRI may be helpful in the management of high- risk prostate cancer by identifying more extensive disease that may merit supplementary extended androgen deprivation therapy, localizing dominant disease for focal therapy, guiding surgical planning, or changing management plan from surgery to radiation [49,114,115]. MRI Pelvis Without IV Contrast In addition to standard local and nodal staging, multiparametric MRI without IV contrast may be a viable option as an alternative to using IV contrast in the management of high-risk prostate cancer [49,114,115]. Although the same principles and controversies regarding the use of IV contrast persists, many of these scenarios are less dependent on the potential advantages of IV contrast. MRI-Targeted Biopsy Prostate Most patients with high-risk disease require definitive therapy, and targeted biopsy is unlikely to significantly alter management.


Pretreatment Detection Surveillance and Staging of Prostate Cancer. MRI Whole Body Without and With IV Contrast The literature indicates that MRI whole body can be used to assess the nodal and distant metastatic state in patients with intermediate- and high-risk prostate cancer prior to treatment [96,108,117]. In a prospective study of 56 intermediate- and high-risk patients, whole body MRI was more accurate than bone scan and similar to choline PET/CT for detecting nodal and distant metastases [96]. In a prospective study of 36 high-risk patients, whole body MRI was concordant with PSMA PET/CT for determining nonregional nodal metastases in 72.2% and for distant metastases in 86.1% of the patients [117]. In addition to standard local, nodal, and distant metastasis staging, multiparametric MRI of the prostate may be added in the whole body MRI protocol, providing additional information to assist management of high-risk prostate cancer by identifying more extensive disease that may merit supplementary extended androgen deprivation therapy, localizing dominant disease for focal therapy, guiding surgical planning, or changing management plan from surgery to radiation [49,114,115]. MRI Whole Body Without IV Contrast Because the main purpose for imaging the whole body would be to identify nodal and distant metastases, MRI whole body without IV contrast is a viable option as an alternative to using IV contrast [49,96,108,114,115,117]. However, it should be recognized that without using IV contrast there is the possibility of less optimal detection of metastases to visceral organs. PSMA PET/CT Skull Base to Mid-Thigh PSMA PET, which can be used either with CT or MRI (PET/CT and PET/MRI, respectively) has shown its potential to detect metastatic disease in patients with high-risk prostate cancer undergoing pretreatment assessment [117,119- 121].


Routine Chest Imaging

Routine Chest Imaging.  Historically, routine chest radiography served as a method of screening a general population for disease. Early use of routine chest imaging was used to identify tuberculosis in asymptomatic individuals for public health and safety measures [2]. However, as the overall rates of undiagnosed tuberculosis have decreased, its usefulness is now being questioned [2]. More recent studies have shown that routine imaging in an otherwise healthy and asymptomatic population has a low diagnostic yield [3,4]. Preprocedural routine imaging has also been used for detection of subclinical disease, such as malignant neoplasms, emphysema, or cardiovascular disease, that could be associated with perioperative complications [2]. Multiple studies have shown that routine imaging studies in the preoperative setting have no significant impact on the decision to operate [5] and usually do not yield information that is not available by clinical history or physical examination [6]. However, there are no randomized control trials to show whether routine chest imaging improves outcomes. This document reviews the use of routine chest imaging performed on adult patients for evaluation on hospital admission, preoperative preparation, and asymptomatic outpatient follow-up and evaluation. Special Imaging Considerations Chest radiography can be performed as a 2-view or a single-view imaging study. A 2-view (posterior-anterior and lateral views) chest radiograph requires that a patient is able to stand and appropriately position their arms to be out of the field of view. Alternatively, a single-view chest radiograph using anterior-posterior technique (also refered to as portable technique) can be performed in a patient who is not ambulatory or unable to tolerate positioning of a posterior-anterior radiograph. However, anterior-posterior/portable technique is associated with lower image quality, distortion of normal structures (eg, magnification of the cardiac silhouette), and higher rates of artifactual findings [7].


Routine Chest Imaging

Routine Chest Imaging. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. OR Discussion of Procedures by Variant Variant 1: Routine chest imaging for hospital admission. No clinical concern for cardiopulmonary disease. Initial Imaging. CT Chest With IV Contrast There is no relevant literature to support the use of CT chest with intravenous (IV) contrast as routine imaging for hospital admission. CT Chest Without and With IV Contrast There is no relevant literature to support the use of CT chest without and with IV contrast as routine imaging for hospital admission. CT Chest Without IV Contrast CT chest is known to have a higher sensitivity than chest radiography for the detection of pulmonary infections and malignancies. Millor et al [9] performed a retrospective review of 6,516 adult patients who underwent a self-referred whole-body CT (including a CT chest without IV contrast), performed in the absence of specific symptoms and no history of malignancy. The authors found that the incidence of abnormal whole-body CT findings increased with age and found a higher rate of abnormal findings in men. Although most findings were benign, there was a 1.47% rate of primary neoplasm detection, the majority of which were found before metastatic spread.


Routine Chest Imaging

Routine Chest Imaging. The authors suggested that the early detection of these abnormalities (eg, before metastatic spread of malignancy) allows for earlier intervention and sometimes curative treatment. A number of incidental and relatively common cardiac abnormalities can be detected on routine CT chest without IV contrast [9,10]. These include pericardial, myocardial, coronary, aortic, and valvular abnormalities. CTA Chest With IV Contrast There is no relevant literature to support the use of CTA chest with IV contrast as routine imaging for hospital admission. CTA Chest Without and With IV Contrast There is no relevant literature to support the use of CTA chest without and with IV contrast as routine imaging for hospital admission. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT for routine initial chest imaging on hospital admission in the absence of cardiopulmonary disease. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of MRI chest without and with IV contrast for routine chest imaging on hospital admission in the absence of cardiopulmonary disease. Routine Chest Imaging MRI Chest Without IV Contrast There is no relevant literature to support the use of MRI chest without IV contrast as routine imaging for hospital admission in the absence of cardiopulmonary disease. Radiography Chest Chest radiography is a commonly ordered study on hospital admission. In a retrospective study by Shimoni et al [11] of 238 patient records and interviews with treating physicians, the investigators found that routine admission chest radiography yielded minimal benefit in patients without respiratory symptoms. In addition, routine admission chest radiography was also associated with false-positive findings, leading to inappropriate hospitalization and unnecessary antibiotic therapy.


Routine Chest Imaging

Routine Chest Imaging. The authors concluded that admission chest radiography was not warranted in patients without respiratory symptoms but could be considered in patients with an uncertain diagnosis who may present atypically, such as older patients, patients who are immunocompromised, or who cannot communicate symptoms with multiple comorbidities and uncertain diagnosis on admission. Malnik et al [12] conducted a retrospective investigation of medical records and found that a very small number of admission chest radiographs altered patient management if there was no clinical indication or abnormal physical examination finding. The authors concluded that a routine admission radiograph only altered management if there was a clinical indication for performance or abnormal physical examination findings in the thorax. Variant 2: Routine preoperative chest imaging for noncardiothoracic surgery. No history of chronic cardiopulmonary disease or cardiothoracic surgery. Initial imaging. CT Chest With IV Contrast Patients undergoing evaluation for abdominal solid organ transplant (eg, liver or kidney) are known to have higher rates of intrathoracic diseases, including coronary artery disease, pleural effusions, pulmonary hypertension, and hepatopulmonary syndrome, which may not be clinically apparent [13,14]. Currently, the American Association for the Study of Liver Diseases recommends screening of liver transplant candidates for hepatopulmonary syndrome. This is initially done by pulse oximetry, although CT chest with IV contrast may be pursued to exclude other causes of pulmonary disease [15]. CT Chest Without and With IV Contrast There is no relevant literature to support the use of CT chest without and with IV contrast for routine preoperative evaluation of patients without cardiopulmonary disease undergoing noncardiothoracic surgery.


Routine Chest Imaging

Routine Chest Imaging. CT Chest Without IV Contrast Patients undergoing evaluation for abdominal solid organ transplant (eg, liver or kidney) are known to have higher rates of intrathoracic diseases, including coronary artery disease, pleural effusions, pulmonary hypertension, and hepatopulmonary syndrome, which may not be clinically apparent [13,14]. Currently, the American Association for the Study of Liver Diseases recommends screening of liver transplant candidates for hepatopulmonary syndrome. This is initially done by pulse oximetry, although CT chest without IV contrast may be pursued to exclude other causes of pulmonary disease [15]. CTA Chest With IV Contrast There is no relevant literature to support the use of CTA chest with IV contrast for routine preoperative evaluation of patients without cardiopulmonary disease undergoing noncardiothoracic surgery. CTA Chest Without and With IV Contrast There is no relevant literature to support the use of CTA chest without and with IV contrast for routine preoperative evaluation of patients without cardiopulmonary disease undergoing noncardiothoracic surgery. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT for routine preoperative evaluation of patients without cardiopulmonary disease undergoing noncardiothoracic surgery. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of MRI chest without and with IV contrast for routine preoperative evaluation of patients without cardiopulmonary disease undergoing noncardiothoracic surgery. MRI Chest Without IV Contrast There is no relevant literature to support the use of MRI chest without IV contrast for routine preoperative evaluation of patients without cardiopulmonary disease undergoing noncardiothoracic surgery. Routine Chest Imaging Radiography Chest Multiple guidelines for preoperative chest radiography have been published, largely advocating against the use of routine preoperative chest radiographs for elective surgery [16].


Routine Chest Imaging

Routine Chest Imaging. This is based on multiple studies that have shown minimal benefit from the routine use of chest radiography before surgery. Joo et al [17] conducted a systematic literature review to investigate the value of screening chest radiographs before surgery. They found that the diagnostic yield of preoperative chest radiographs in patients <50 years of age is low and are generally not recommended in patients <70 years of age. Most radiologic abnormalities found on preoperative imaging were chronic diseases and did not affect management or outcome [17]. A large retrospective study in 1983 found that preoperative chest radiographs in low-risk patients were unnecessary with only 0.3% of chest radiographs finding a relevant finding [6]; furthermore, these abnormalities were not associated with any perioperative complications or need for additional interventions. However, radiographic abnormalities were more common in patients with known risk factors based on clinical history and examination. The authors contended that clinical evaluation could appropriately predict which patients should undergo preoperative chest radiography and argued against the use of chest radiography for routine preoperative evaluation [6]. A meta-analysis by Archer et al [18] found that unsuspected radiologic findings on routine preoperative chest radiography were rare, occurring in only 1.3% of cases; these rare findings resulted in a change in management in only 0.1% of cases. Gagner et al [19] performed a retrospective review of 1,000 patients who underwent a preoperative chest radiograph and found that 7.4% of studies were abnormal. Abnormal chest radiographs were more common in older individuals than in younger individuals (30% of patients >50 years of age versus 3% in patients <50 years of age), and there were no changes in clinical outcomes due to chest radiographic findings.


Routine Chest Imaging

Routine Chest Imaging. A large, multicenter study found that preoperative radiographs performed in patients undergoing noncardiothoracic surgery rarely influenced the decision to undergo surgery [5]; in fact, 25.7% of cases proceeded to surgery before the radiology report was even available [5]. The authors also found wide variability in the use of preoperative chest radiography between different surgical departments, despite clinical risk factors for cardiopulmonary disease. Patients undergoing evaluation for abdominal solid organ transplant (eg, liver or kidney) are known to have higher rates of intrathoracic diseases, including coronary artery disease, pleural effusions, pulmonary hypertension, and hepatopulmonary syndrome, which may not be clinically apparent [13,14]. In a study of 341 patients being evaluated for liver transplantation, Bozbas et al [20] determined that 48% of patients had an abnormal chest radiograph. Other studies have shown that increasing severity of liver disease correlates to the degree of abnormality on chest radiography [14]. Currently, the American Association for the Study of Liver Diseases recommends screening of liver transplant candidates for hepatopulmonary syndrome. This is initially done by pulse oximetry, although chest radiography may be pursued to exclude other causes of pulmonary disease [15]. Variant 3: Routine preoperative chest imaging for noncardiothoracic surgery. History of chronic cardiopulmonary disease or cardiothoracic surgery. Initial imaging. CT Chest With IV Contrast Patients undergoing evaluation for abdominal solid organ transplant (eg, liver or kidney) are known to have higher rates of intrathoracic diseases, including coronary artery disease, pleural effusions, pulmonary hypertension, and hepatopulmonary syndrome, which may not be clinically apparent [13,14]. Currently, the American Association for the Study of Liver Diseases recommends screening of liver transplant candidates for hepatopulmonary syndrome.


Routine Chest Imaging

Routine Chest Imaging. This is initially done by pulse oximetry, although CT chest with IV contrast may be pursued to exclude other causes of pulmonary disease [15]. CT Chest Without and With IV Contrast There is no relevant literature to support the use of CT chest without and with IV contrast for routine preoperative evaluation of patients with chronic cardiopulmonary disease undergoing noncardiothoracic surgery. CT Chest Without IV Contrast Patients undergoing evaluation for abdominal solid organ transplant (eg, liver or kidney) are known to have higher rates of intrathoracic diseases, including coronary artery disease, pleural effusions, pulmonary hypertension, and hepatopulmonary syndrome, which may not be clinically apparent [13,14]. Currently, the American Association for the Study of Liver Diseases recommends screening of liver transplant candidates for hepatopulmonary syndrome. Routine Chest Imaging This is initially done by pulse oximetry, although CT chest without IV contrast may be pursued to exclude other causes of pulmonary disease [15]. CTA Chest With IV Contrast There is no relevant literature to support the use of CTA chest with IV contrast for routine preoperative evaluation of patients with chronic cardiopulmonary disease undergoing noncardiothoracic surgery. CTA Chest Without and With IV Contrast There is no relevant literature to support the use of CTA chest without and with IV contrast for routine preoperative evaluation of patients with chronic cardiopulmonary disease undergoing noncardiothoracic surgery. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT for routine preoperative evaluation of patients with chronic cardiopulmonary disease undergoing noncardiothoracic surgery. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of MRI chest without and with IV contrast for routine preoperative evaluation of patients with chronic cardiopulmonary disease undergoing noncardiothoracic surgery.


Routine Chest Imaging

Routine Chest Imaging. MRI Chest Without IV Contrast There is no relevant literature to support the use of MRI chest without IV contrast for routine preoperative evaluation of patients with chronic cardiopulmonary disease undergoing noncardiothoracic surgery. Radiography Chest In a retrospective cohort study of patients with known cardiothoracic disease, abnormal chest radiographic findings were a common finding [21]. However, a review of preoperative chest radiographs in a general population (performed before a variety of different types of surgeries) found that only 5% of studies had an impact on anesthetic management [22]. The authors suggested that discontinuing the use of routine preoperative chest radiographs did not result in any adverse effects on patient care. A study of 240 patients with known vascular disease investigated the role of preprocedural chest radiographs before peripheral or coronary angiography. Although nearly half of preprocedural chest radiographs had at least one abnormality, no procedures were postponed or canceled because of the radiographic findings [23]. Given these findings, multiple societal guidelines have been published, largely recommending against the use of routine preoperative chest radiography for patients with known cardiovascular disease. The European Society of Anaesthesia does not recommend routine preoperative chest radiography for elective noncardiac surgery because it rarely changes perioperative course [24]. A practice advisory by the American Society of Anesthesiologists Task Force acknowledged that radiographic abnormalities are higher in older patients and those with stable cardiothoracic disease but did not recommend routine chest radiography in the preanesthesia evaluation of these patients [25]. Evidence generally suggests that most preoperative abnormalities may be predicted by clinical evaluation, although chest radiography may be helpful in patients with known chronic disease or patients >50 years of age [26].


Routine Chest Imaging

Routine Chest Imaging. One exception is patients with cardiac implantable electronic devices (implanted cardioverter-defibrillators and pacemakers), in whom certain procedures and surgical instruments can be associated with electromagnetic interference (eg, extracorporeal shock wave lithotripsy, radiofrequency ablation, electrocautery) [27]. In the setting of known cardiovascular disease and implanted electronic device, preoperative/preprocedural chest radiograph may be useful for identification of the device type as well as identification of device location [27-29] because these device-related factors may direct selection of surgical instruments or surgical approach. Patients undergoing evaluation for abdominal solid organ transplant (eg, liver or kidney) are known to have higher rates of intrathoracic diseases including coronary artery disease, pleural effusions, pulmonary hypertension, and hepatopulmonary syndrome, which may not be clinically apparent [13,14]. In a study of 341 patients being evaluated for liver transplantation, Bozbas et al [20] determined that 48% of patients had an abnormal chest radiograph. Other studies have shown that increasing severity of liver disease correlates to degree of abnormality on chest radiography [14]. Currently, the American Association for the Study of Liver Diseases recommends screening of liver transplant candidates for hepatopulmonary syndrome. This is initially done by pulse oximetry, although chest radiography may be pursued to exclude other causes of pulmonary disease [15]. Routine Chest Imaging Variant 4: Routine chest imaging. History of chronic cardiopulmonary disease with stable clinical findings. Surveillance chest imaging. CT Chest With IV Contrast There is no relevant literature to support the use of CT chest with IV contrast for surveillance of patients with unspecified chronic, stable cardiopulmonary disease.


Imaging of Possible Tuberculosis

Imaging of Possible Tuberculosis.  Introduction/Background Pulmonary tuberculosis (TB) predominantly results from the transmission of aerosolized mycobacterium TB to susceptible hosts [1]. In the vast majority of cases, this results in subclinical disease with the immune system isolating the organism. In this setting, a person has latent TB and does not pose a risk to the community at large. The development of active infection within 1 year following exposure is termed primary TB and is classically described as a lobar pneumonia and/or mediastinal and hilar adenopathy. This pattern is most often seen in children and severely immunocompromised individuals. If active infection develops later than 1 year after initial exposure, it is considered to be reactivation TB, often presenting with apical posterior upper-lobe or superior- segment lower-lobe fibrocavitary disease and endobronchial spread through the airways. With modern molecular techniques it has been shown that radiographic patterns of primary and reactivation TB overlap, and thus the preferred terminology for TB infection is active TB [2]. The important public health issue is that both primary and reactivation TB present a risk of exposing the general population to TB infection. A high level of suspicion should be maintained in immunocompromised hosts, particularly those with AIDS, as imaging manifestations may not fit a classic primary or reactivation pattern; instead, these patients may present with mediastinal lymphadenopathy alone or a deceptively normal chest radiograph. Overview of Imaging Modalities Chest radiograph The chest radiograph is usually the first study performed in patients suspected of having TB. Although frontal and lateral radiographs are often performed in this setting, it has been shown that the lateral radiograph does not improve the detection of findings related to TB [3].


Imaging of Possible Tuberculosis

Imaging of Possible Tuberculosis. In those with signs or symptoms of disease, the radiographic pattern of upper-lobe or superior-segment lower-lobe fibrocavitary disease in the appropriate clinical setting is sufficient to warrant respiratory isolation and sputum culture for definitive diagnosis. Using radiographs in combination with clinical evaluation results in a high sensitivity for the diagnosis but a relatively low specificity for both latent [4] and active TB [5]. In addition, radiographs may reveal ancillary findings of TB such as pleural effusion or spondylitis. For immunocompromised hosts, particularly those with a low CD4 count, computed tomography (CT) should be considered. 1Principal Author and Panel Chair, Medical University of South Carolina, Charleston, South Carolina. 2Panel Vice-chair, National Jewish Health, Denver, Colorado. 3Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. 4University of Texas MD Anderson Cancer Center, Houston, Texas. 5Mayo Clinic, Rochester, Minnesota. 6Mayo Clinic, Phoenix, Arizona. 7Vanderbilt University Medical Center, Nashville, Tennessee, American College of Chest Physicians. 8Mayo Clinic, Jacksonville, Florida. 9Columbia University Medical Center New York and Temple University Health System, Philadelphia, Pennsylvania. 10Specialty Chair, University of Florida College of Medicine, Gainesville, Florida. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org Imaging of Possible Tuberculosis Magnetic resonance imaging Only 1 study has been performed evaluating magnetic resonance imaging (MRI) for suspected TB.


Imaging of Possible Tuberculosis

Imaging of Possible Tuberculosis. In this study the accuracy of MRI was similar to CT in describing findings related to culture-positive patients [12]. Inferential data regarding the value of MRI can also be derived from its role in cystic fibrosis and the observation in other settings that MRI correlates well with CT for parenchymal findings including bronchiectasis, cavitation, and tree- in-bud nodules [13]. Although MRI is technically feasible and described in the literature, MRI has not been specifically evaluated as a primary imaging modality for patients with suspected or proven TB. Nuclear scintigraphy Several nuclear radiopharmaceuticals have been employed for the purpose of evaluating possible TB, particularly for differentiating active from inactive tuberculomas and distinguishing tuberculomas from neoplasms. In small studies, Tc-99m methoxyisobutylisonitrile has shown higher activity over background in active tuberculomas compared with inactive tuberculomas [14,15]. Similarly, metabolic activity measured by fluorine-18-2-fluoro-2- deoxy-D-glucose positron emission tomography (FDG-PET) is higher in active tuberculomas. Dual-time-point FDG-PET imaging (1 and 2 hours postinjection) can also help differentiate active tuberculomas from neoplasms, owing to the longer retention of FDG in benign lesions [16]. Gallium 67 has been used to follow patients for disease activity and correlates with the number of organisms on sputum smears [17]. Evidence for the use of nuclear imaging to diagnose active TB is limited to either small single-site studies or several small studies, and the impact on clinical practice and patient care at this time is minimal. Discussion of the Imaging Modalities by Variant Variant 1: Suspect active tuberculosis. The initial suspicion of active TB should be made based on clinical symptoms and demographics.


Imaging of Possible Tuberculosis

Imaging of Possible Tuberculosis. Those at particular risk include those in close contact with patients having active TB, spending time in a TB-endemic country, or working/spending time in sites where TB is more prevalent, such as prisons, homeless shelters, and long-term care facilities. Those who are immunocompromised are at particular risk. Included in this category are also individuals with a newly positive purified protein derivative (PPD) skin test or a positive interferon-gamma release assay (IGRA) and who have symptoms that could be related to active TB. Clinical symptoms of active TB may include unexplained weight loss, night sweats, fever, prolonged cough, hemoptysis, and fatigue. Chest radiography Identified individuals should undergo chest radiography as the initial test. Chest radiographs have been shown to have a high sensitivity for detecting manifestations of active TB [5]. Chest radiography has a high sensitivity but relatively poor specificity owing to the overlap of findings with nontuberculous pulmonary infection. The yield of chest radiographs in high-risk patients ranges from 1% to 7%, although it is not clear how many of these cases would have been suspected based on clinical symptoms alone [18,19]. In particular, lobar pneumonia with associated hilar and/or mediastinal adenopathy or cavitary air space disease involving the apical posterior segments of the upper lobe or superior segment of the lower lobe should raise particular concern [20]. When a chest radiograph confirms the clinical suspicion of active TB, it is sufficient to warrant respiratory isolation pending sputum cultures. However, in patients who are immunocompromised, particularly those with AIDS and very low CD4 counts, chest radiographs may be deceptively normal. Magnetic resonance imaging MRI is a reasonable consideration for use in select patients for whom there is a desire to avoid ionizing radiation. Variant 2: Newly positive PPD or IGRA OR positive PPD or IGRA with unknown prior status. No clinical symptoms.


Imaging of Possible Tuberculosis

Imaging of Possible Tuberculosis. Chest radiography One key principal of PPD testing is application in those at high risk for developing latent TB infection. This may include those who work in settings where contact with active TB is possible and those coming from regions where Imaging of Possible Tuberculosis TB is endemic. Although screening of low-risk individuals is discouraged, it is recommended for those whose future activity will place them at high risk for exposure or reactivation. The rationale behind performing chest radiography following a positive PPD is to distinguish latent TB from active TB, as these are managed differently. However, in patients without clinical symptoms the yield of radiographs for active TB (that would change management) is negligible [21]. Furthermore, parenchymal findings of latent TB are relatively poor predictors of future reactivation. If a chest radiograph is performed, a frontal view is sufficient [3]. Computed tomography CT should be reserved for the rare case in which a chest radiograph may be equivocal for active TB and cases for which knowledge of latent TB abnormalities may inform future care, such as patients undergoing solid organ transplantation and biologic therapy for rheumatologic disease [4,11]. Magnetic resonance imaging Like CT, there is a very limited role for MRI, although it may be considered when cross-sectional imaging is deemed necessary in a patient for whom there is a desire to avoid ionizing radiation. Variant 3: PPD not available. Placement in group home or skilled nursing facility. No clinical symptoms. Chest radiography Low-risk screening also frequently occurs in patients being transferred to correctional institutions, group homes, and skilled nursing facilities. Because of time constraints related to placing and interpreting a PPD, chest radiography has emerged as a surrogate measure.


Imaging of Possible Tuberculosis

Imaging of Possible Tuberculosis. A meta-analysis of homeless populations suggests that using chest radiography as a screening measure is sufficient and can lead in some cases to a decline in the incidence of TB over time [19]. This study, however, did not compare chest radiography screening to other screening strategies in terms of efficacy. Screening procedures vary from one prison site to another. There does not appear to be a large discrepancy in TB incidence regardless of screening technique (symptom survey, PPD, or chest radiograph) [22]. There is no evidence regarding the performance of routine radiography in low-risk patients who did not receive other TB screening before transfer to a group home or nursing facility. Computed tomography CT should be reserved for the rare case in which a chest radiograph is equivocal for active TB and more definitive testing such as sputum culture is impractical. Magnetic resonance imaging Like CT, there is a very limited role for MRI, although it might be considered when cross-sectional imaging is deemed necessary in a patient for whom there is a desire to avoid ionizing radiation. Summary of Recommendations Chest radiography is the first recommended test in patients with suspected tuberculosis. Chest radiography is generally appropriate for patients with new evidence of exposure or at high risk for development of tuberculosis, although it may be of low yield in patients who have no clinical symptoms. Chest CT is appropriate when tuberculosis is suspected and radiography is nonrevealing or nondiagnostic. Although there are references that report on studies with design limitations, 11 well-designed or good-quality studies provide good evidence. Relative Radiation Level Information Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs.  Introduction/Background Infections of the musculoskeletal system are a leading cause of pain, disability, and health care encounters. Because of the rise of an aging population, diabetes and obesity, and orthopedic surgeries, the incidence of musculoskeletal infections are also increasing. The overall infection rate following orthopedic hardware placement is estimated to be approximately 5%, and the overall mortality rate associated with necrotizing fasciitis (NF) is >10% [1]. Musculoskeletal infections may have bone and soft tissue involvement and often need imaging using a multimodality approach [2]. The nonspecific signs and symptoms of musculoskeletal infections can make their diagnosis particularly challenging. Predisposing conditions inflammatory arthritis, diabetes, immunosuppression, drug and alcohol abuse, surgery, burns, extremes of body habitus, and poor socioeconomic status can further add to the difficulty of diagnosing musculoskeletal infections both clinically and with imaging [3]. Placement of orthopedic hardware can make imaging diagnosis challenging because of metal artifact, especially on CT and MRI. Imaging plays a critical role in the diagnosis and treatment of musculoskeletal infections. When imaging is appropriately used, proper characterization of bone and soft tissue infections often guides clinical management. Even when infection is clinically apparent, imaging often provides additional information including the extent of infection into deeper tissues, presence of abscesses, joint involvement, and vascular complications. These assessments are central to medical, surgical, and image-guided treatments [4]. OR Discussion of Procedures by Variant Variant 1: Suspected osteomyelitis or septic arthritis or soft tissue infection (excluding spine and diabetic foot). Initial imaging.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. For osteomyelitis, the body regions covered are ankle, chest, elbow, femur, foot, forearm, hand, hip, humerus, knee, pelvis, shoulder, tibia/fibula, wrist. For septic arthritis, the body regions covered are ankle, elbow, hip, knee, shoulder, wrist. aUniversity of Virginia, Charlottesville, Virginia. bResearch Author, University of Virginia Health Center, Charlottesville, Virginia. cPanel Chair, Mayo Clinic, Jacksonville, Florida. dPanel Vice-Chair, Wake Forest University School of Medicine, Winston Salem, North Carolina. eThe Johns Hopkins University School of Medicine, Baltimore, Maryland. fMallinckrodt Institute of Radiology Washington University School of Medicine, Saint Louis, Missouri. gAventura Hospital, Aventura, Florida and Nova Southeastern University, Fort Lauderdale, Florida. hMoffitt Cancer Center and University of South Florida Morsani College of Medicine, Tampa, Florida; MSK-RADS (Bone) Committee. iUniversity of Virginia, Charlottesville, Virginia, Primary care physician. jDiagnostic Imaging Associates, Chesterfield, Missouri. kMayo Clinic Florida, Jacksonville, Florida. lSUNY Downstate Health Sciences University, Brooklyn, New York. mMayo Clinic, Jacksonville, Florida; Commission on Nuclear Medicine and Molecular Imaging. nSpecialty Chair, University of Kentucky, Lexington, Kentucky. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org Suspected Osteomyelitis, Septic Arthritis For soft tissue infection, the body regions covered are abdomen, neck, ankle, chest, elbow, thigh, foot, forearm, hand, hip, arm, knee, pelvis, shoulder, leg, wrist.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. 3-Phase Bone Scan Area of Interest There is insufficient evidence to support the use of a 3-phase bone scan area of interest for the initial evaluation of osteomyelitis, septic arthritis, or soft tissue infections. CT Area of Interest There is insufficient evidence to the support the use of CT area of interest for the initial evaluation of osteomyelitis, septic arthritis, or soft tissue infections. MRI Area of Interest There is insufficient evidence to support the use of MRI area of interest for the initial evaluation of osteomyelitis, septic arthritis, or soft tissue infections. Radiography Area of Interest The literature indicates that radiographs should be used for the initial evaluation of musculoskeletal infections, including osteomyelitis, septic arthritis, and soft tissue infection. Erosions and periosteal reaction are common findings in acute osteomyelitis, whereas bone sclerosis is commonly associated with chronic osteomyelitis. In early acute osteomyelitis (<14 days), radiographs may be normal or show only mild soft tissue swelling [5]. Soft tissue swelling, joint effusion, ulcers, effacement of fat planes, gas, and foreign bodies may indicate soft tissue infections or septic arthritis [2]. Many radiographic findings are not specific for infection, and a differential diagnosis may include tumors, trauma, arthritides, metabolic conditions, cardiovascular etiologies, and venous insufficiency or thrombosis. However, obtaining the initial radiograph provides an excellent overview of the anatomic area of interest and can exclude fractures and tumors as the cause of swelling or pain. Radiographs also help with the interpretation of future imaging studies such as CT, MRI, ultrasound (US), and nuclear medicine scans [6]. US Area of Interest There is insufficient evidence to support the use of US area of interest for the initial evaluation of osteomyelitis, septic arthritis, or soft tissue infections.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. Variant 2: Suspected septic arthritis or soft tissue infection. Initial radiographs normal or with findings suggestive of joint effusion or soft tissue swelling. Next imaging study. For septic arthritis, the body regions covered are ankle, elbow, hip, knee, shoulder, wrist. For soft tissue infection, the body regions covered are abdomen, neck, ankle, chest, elbow, thigh, foot, forearm, hand, hip, arm, knee, pelvis, shoulder, leg, wrist. 3-Phase Bone Scan Area of Interest Radionuclide imaging, which includes 3-phase bone scan, is of limited use for the diagnosis of septic arthritis and soft tissue infection [7]. On 3-phase bone scans, early images may show increased activity with hyperperfusion and hyperemia on flow and blood pool phases. Delayed images may be normal or have increased activity limited to the articular surfaces, in the case of a septic joint [7]. Compared with US, CT, and MRI, bone scan has poor spatial resolution and lacks specificity [4]. However, bone scan can be useful for the evaluation of multifocal infections. Image-Guided Aspiration Area of Interest In many cases, imaging cannot distinguish infected from noninfected joints or fluid collections, and aspiration and culture are needed for diagnosis [8,9]. Culture allows for identification of the infectious organism, which directly affects treatment. Although imaging may delay performing the aspiration, preaspiration imaging with US, CT, or MRI can be essential for planning for a safe aspiration [8]. Image-guided aspiration is ideal because proper, accurate needle placement is confirmed with fluoroscopy, US, CT, and rarely MRI. Also, image guidance significantly reduces vascular complications and injury to nerves. Using image guidance, needle trajectory and placement can be planned to reduce the risk of contaminating normal adjacent tissues [10].


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. CT Area of Interest CT allows for the evaluation of various soft tissue compartments and may help differentiate cellulitis, myositis, tenosynovitis, abscess, and septic arthritis [11]. CT with intravenous (IV) contrast can assess soft tissue and the extent of infection, which can guide aspiration or surgical debridement. Contrast-enhanced CT can also improve Suspected Osteomyelitis, Septic Arthritis the detection of synovitis, inflammation, fistulas, abscesses, and vascular complications [4]. CT is also the most sensitive modality for detecting soft tissue gas. Although CT is not sensitive at detecting early bone marrow changes, it can show early periosteal reaction and bone erosions, adjacent soft tissue infection, or septic arthritis. MRI Area of Interest MRI allows for the evaluation of musculoskeletal soft tissue infections because of its high sensitivity to fluid and inflammation in bones, joints, muscles, tendons, and other soft tissues [2,6,12]. Because of its excellent spatial and contrast resolution, MRI is excellent at detecting and evaluating the extent of both superficial and deep soft tissue infections [13]. MRI can also exclude soft tissue infection, if edema or fluid signal representing inflammation, joint effusion, or abscess are not present [2,6]. Contrast-enhanced MRI further increases the diagnostic sensitivity for abscesses, fistulas, and vascular complications. Detection of inflammation of joints, bursa, tendons, and muscles is also improved with contrast-enhanced MRI. Compared to CT, soft tissue gas is not as well visualized on MRI. Although MRI often provides imaging for preoperative planning, MRI is not commonly used for image-guided aspiration or drainage. US Area of Interest US is useful for detecting fluid, including joint effusions, abscesses, and infected tendon sheaths.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. US-guided aspirations of soft tissue fluid collections and joint effusions is becoming increasingly common [14]. With the use of color Doppler, vascularity and hyperemia can be assessed without the administration of IV contrast. If needed, US can examine the contralateral side for comparison or extend the area of imaging of suspected infection. Absence of a fluid essentially excludes the diagnosis of septic arthritis, tenosynovitis, and abscess. Gaspari et al [14] reported that US correctly diagnosed an abscess in 29 out of 30 patients and no abscess in 30 of 35 patients with an alternative diagnosis. In comparison, CT correctly diagnosed 23 out of the same 30 patients with abscess and correctly diagnosed 32 of the 35 patients without an abscess. They reported the overall sensitivity and specificity of US for the diagnosis of an abscess as 96.7% and 85.7%, respectively, whereas CT had 76.7% sensitivity and 91.4% for specificity. They concluded that both CT and US are accurate for diagnosing superficial abscesses. US can evaluate the internal characteristics of the abscess cavity, such as necrosis or debris, and associated pathology like foreign bodies, fistulas, and vascular injury. For deeper soft tissue structures and the evaluation of adjacent bone involvement, US is limited compared with MRI and CT. Variant 3: Suspected osteomyelitis. Initial radiographs normal or with findings suggestive of osteomyelitis. Next imaging study. For osteomyelitis, the body regions covered are ankle, chest, elbow, femur, foot, forearm, hand, hip, humerus, knee, pelvis, shoulder, tibia/fibula, wrist. 3-Phase Bone Scan and WBC Scan and Sulfur Colloid Scan Area of Interest These 3 scans are ordered in progression to increase the accuracy of diagnosing osteomyelitis.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. If the 3-phase bone scan is positive with increased activity, also obtaining a white blood cell (WBC) scan and Tc-99m sulfur colloid scan may increase specificity for the evaluation of acute osteomyelitis. Addition of sulfur colloid scan may be considered if results remain equivocal following a WBC and 3-phase bone scans. In cases in which radiotracer uptake is increased on WBC scan and 3-phase bone scans, sulfur colloid imaging will show no corresponding radiotracer uptake in cases of osteomyelitis [15,16]. 3-Phase Bone Scan and WBC Scan Area of Interest In patients with low pretest probability of infection who have a positive 3-phase bone scan, the addition of WBC scan may increase specificity for infection, particularly in the setting of recent surgery or fracture at the suspected site of infection [17]. 3-Phase Bone Scan Area of Interest A 3-phase bone scan can be used to rule out osteomyelitis. However, a positive 3-phase bone scan is nonspecific. A meta-analysis performed by Wang et al [17] showed specificity of only 45% for diagnosis of osteomyelitis, whereas sensitivity was 83%. A 3-phase bone scan is most accurate in the diagnosis of osteomyelitis when bone is not affected by other underlying condition such as osteoarthritis, recent fracture, or recent hardware implantation [18]. Addition of single-photon emission CT (SPECT)/CT may be helpful in localization of acute osteomyelitis [19]. Suspected Osteomyelitis, Septic Arthritis CT Area of Interest CT is insensitive in evaluation of acute osteomyelitis. IV contrast administration is helpful for assessing soft tissue involvement. CT may be most useful in characterizing osseous changes from chronic osteomyelitis including detection of sequestrum. Although the use of IV contrast does not improve diagnostic sensitivity for acute osteomyelitis, it may be helpful in the identification of soft tissue infection such as abscess formation [11].


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. There is no added benefit in performing multiphase CT imaging before and after IV contrast administration in the evaluation of infection. MRI Area of Interest MRI is highly accurate for detection of acute osteomyelitis. Noncontrast MRI has high sensitivity and specificity in the diagnosis of osteomyelitis. MRI is sensitive at depicting marrow signal changes of acute osteomyelitis. Additionally MRI provides excellent evaluation of the adjacent soft tissues including abscess or fistulas [13,23-26]. The use of IV contrast does not improve diagnosis of peripheral osteomyelitis; however, its use may improve the evaluation of soft tissue infections [27]. US Area of Interest US is of limited benefit in the diagnosis of osteomyelitis. Although findings such as juxtacortical fluid collections and fistulous tracts may be seen, these findings are not specific for osteomyelitis [28]. WBC Scan and Sulfur Colloid Scan Area of Interest A sulfur colloid scan is often performed when WBC scan results are equivocal. If osteomyelitis is present, a sulfur colloid scan will show no radiotracer activity in areas of WBC scan activity. WBC scan combined with marrow imaging has been reported up to 90% accurate in diagnosing osteomyelitis [18]. Disadvantages include low spatial resolution [15,16]. WBC Scan Area of Interest A WBC scan has been reported to have variable sensitivity and specificity when performed alone in the evaluation of osteomyelitis [17]. The addition of SPECT/CT has been suggested to increase the accuracy of WBC scan for the diagnosis of osteomyelitis. When a WBC scan is positive on planar images, SPECT/CT can be performed for more accurate localization of infection [15,21]. Variant 4: Suspected osteomyelitis or soft tissue infection with implanted extra-articular surgical hardware.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. Initial radiographs normal or with findings suggestive of osteomyelitis or soft tissue infection with implanted extra-articular surgical hardware. Next imaging study. For osteomyelitis and soft tissue infection, the body regions covered are ankle, elbow, hip, knee, shoulder, wrist. 3-Phase Bone Scan and WBC Scan and Sulfur Colloid Scan Area of Interest There is insufficient evidence to support the use of 3-phase bone scan, WBC scan, and sulfur colloid scan for the evaluation of infection of extra-articular surgical hardware in the absence of known fluid collection or abscess. 3-Phase Bone Scan and WBC Scan Area of Interest A 3-phase bone scan has low specificity for infection in the setting of trauma or recent surgery. A WBC scan should be considered in patients with a low suspicion of infection who have positive findings on 3-phase bone scan [21]. 3-Phase Bone Scan Area of Interest A meta-analysis by Wang et al [17] found that a 3-phase bone scan had sensitivity of 83% but specificity of <50%. In the setting of prior surgery or trauma, the specificity of 3-phase bone scan is likely even lower because osseous remodeling will result in radiotracer uptake [21]. Although studies have shown that SPECT/CT aids in anatomic localization of infection, findings often remain equivocal [19]. Suspected Osteomyelitis, Septic Arthritis There is insufficient evidence to support the use of image-guided aspiration for evaluation of infection of extra- articular surgical hardware in the absence of known fluid collection or abscess. CT Area of Interest CT is useful in the evaluation of postsurgical complications including hardware fracture, periprosthetic osteolysis, and fracture nonunion [29]. Osseous changes of osteomyelitis can be visualized with CT, although these findings are often nonspecific, particularly if there has been recent trauma or surgery.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. CT can be helpful in identifying fluid collections adjacent to bone or surgical hardware that can be targeted for further investigation with percutaneous or surgical drainage. CT may also be useful in the detection of necrotic osseous fragments or sequestra that supply a nidus for chronic infection [21]. IV contrast should be considered because this may allow for better definition of fluid collections or fistulous communication to orthopedic implants [22]. FDG-PET/CT Area of Interest A systematic review by Govaert et al [21] found that FDG-PET/CT has specificity for posttraumatic osteomyelitis ranging from 76% to 100% and sensitivity ranging from 83% to 100%. However, in the acute setting, inflammation due to fracture or recent surgery may decrease accuracy. A retrospective review by Hartmann et al [30] demonstrated sensitivity of 100% and specificity ranging from 88% to 93%. This study included patients with orthopedic implants and joint replacements. This small study of 33 patients also suggested that FDG-PET was most specific when evaluating infection in the axial skeleton. Wenter et al [22] retrospectively reviewed PET imaging performed in 215 patients for suspected osteomyelitis or implant associated infection and reported sensitivity of 88% and specificity of 76%. Their results also showed no significant decrease in accuracy in patients with orthopedic implants. MRI Area of Interest MRI is useful for the evaluation of osteomyelitis or soft tissue infection in the setting of extra-articular surgical hardware. MRI allows for characterization of both bone marrow signal and adjacent soft tissues. Recent advances in metal artifact reduction techniques have improved orthopedic hardware imaging, particularly in the appendicular skeleton [31]. In the setting of posttraumatic osteomyelitis, MRI can be used to determine the degree of osseous and soft tissue involvement.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. However, caution must be used in the recent postoperative or posttrauma period because bone marrow and soft tissue edema may persist and mimic infection [21]. IV contrast administration is preferred to help evaluate the soft tissues [27,32]. US Area of Interest US may be used in detection of soft tissue abnormalities such as abscess or fistulous tracts. However, assessment of the underlying bone is typically limited with US findings of osteomyelitis either not visualized or nonspecific [28,33]. WBC Scan and Sulfur Colloid Scan Area of Interest Combining a sulfur colloid scan with a WBC scan may reduce false positive results from normal WBC accumulation in bone marrow adjacent to orthopedic hardware. No studies were found that specifically investigated accuracy of combined WBC scan and sulfur colloid scan in diagnosing osteomyelitis associated with extra-articular hardware. Because sulfur colloid is a bone marrow imaging technique, there is no added benefit for assessment of soft tissue infection associated with orthopedic hardware. The addition of SPECT/CT hybrid imaging may increase ability to localize infection in cases with orthopedic hardware. WBC Scan Area of Interest A systematic review by Govaert et al [21] found that a WBC scan for posttraumatic osteomyelitis had sensitivity ranging from 50% to 100% and specificity ranging from 40% to 97%. The addition of SPECT/CT hybrid imaging may increase ability to localize infection in cases with orthopedic hardware. Variant 5: Suspected septic arthritis with arthroplasty or other implanted intra-articular surgical hardware. Initial radiographs normal or with findings suggestive of septic arthritis with arthroplasty or other implanted intra-articular surgical hardware. Next imaging study. For septic arthritis, the body regions covered are ankle, elbow, hip, knee, shoulder, wrist.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. 3-Phase Bone Scan and WBC Scan and Sulfur Colloid Scan Area of Interest There is insufficient evidence to support the use of 3-phase bone scan, WBC scan, and sulfur colloid scan for evaluation of suspected septic arthritis. Suspected Osteomyelitis, Septic Arthritis 3-Phase Bone Scan and WBC Scan Area of Interest While the literature does not support routine use of 3-phase bone scan and WBC scan for suspected periprosthetic infection, WBC may be performed following a positive bone scan to assess for infection. A 3-phase bone scan can be positive for multiple reasons in the post arthroplasty setting. Trevail et al [34] suggested the addition of WBC scan following a positive arthroplasty is up to 99% specific for infection and 80% sensitive. 3-Phase Bone Scan Area of Interest Bone scintigraphy alone has high sensitivity and low specificity in the evaluation of suspected periprosthetic joint infection [35,36]. A negative 3-phase bone scan suggests low probability of periprosthetic infection [34,37]. Image-Guided Aspiration Area of Interest The use of image-guided joint aspiration is supported to evaluate suspected septic arthritis. Depending on the joint, image guidance may be used to access the joint and confirm intra-articular needle positioning in the event of dry tap. Joint aspiration may be performed under fluoroscopy, US, or, less commonly, CT. The decision of imaging modality should be based on operator expertise and comfort because no modality has been proven superior to others. Laboratory analysis should include cultures, Gram stain, and cell count with differential [31,38,39]. CT Area of Interest CT can be used to evaluate hardware complications including osteolysis adjacent to implanted hardware. The use of metal artifact reduction techniques can improve the detection of joint effusion, soft tissue abscess, and periostitis.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. CT is also helpful in identifying necrotic bone fragments or sequestra in the setting of chronic osteomyelitis [21,31]. Although IV contrast is not helpful for assessment of osteomyelitis, the addition of IV contrast may aid in the detection of synovial thickening or soft tissue abscesses [11]. FDG-PET/CT Area of Interest A meta-analysis by Verberne et al [36] showed that there was considerable heterogeneity in the literature regarding the diagnostic criteria for prosthetic joint infection. The authors suggested that radiotracer accumulation around prosthetic head, neck, and distal tip may persist for up to 2 years following implantation, thus limiting evaluation of septic arthritis. Although there seems to be promise for FDG-PET/CT in the evaluation of prosthetic joint infection, the specificity of PET/CT in the diagnosis of septic arthritis remains uncertain because of a lack of clearly defined diagnostic criteria [40]. MRI Area of Interest Although MRI is susceptible to metallic artifact as a result of indwelling hardware, metal reduction sequences have mitigated this as a limitation. MRI is useful at detection of osseous changes of osteomyelitis with high sensitivity and specificity. MRI findings of synovial enhancement, joint effusion, and T1 hypointense bone marrow signal changes have a high correlation with infection [41]. MRI also provides evaluation of adjacent soft tissues including tendons and muscles that may offer an alternative diagnosis to infection in patients with pain following arthroplasty [42]. MRI is accurate for localization of soft tissue fluid collections that may be targeted for aspiration or surgical drainage. One disadvantage of MRI is that bone marrow signal abnormalities may persist for months following injury or surgery. [21]. IV contrast administration should be considered because this can assist in differentiating abscess from phlegmon [32,43].


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. US Area of Interest US may be useful for the detection of synovial thickening or joint effusion. However these are not specific to septic arthritis. US limitations include difficulty imaging deeper structures, deep larger joints (such as the shoulder or hip), an inability to evaluate metal implants, and a lack of sensitivity and specificity to findings such as fistulous tracts, subperiosteal fluid collections, and periosteal thickening [28,33]. WBC Scan and Sulfur Colloid Scan Area of Interest The addition of a sulfur colloid scan is useful in cases in which results are equivocal for septic loosening or osteomyelitis because leukocytes may accumulate in marrow adjacent to orthopedic implants [36,44]. However, the addition of a sulfur colloid bone marrow scan to a WBC scan does not increase the accuracy for detection of septic arthritis. The addition of SPECT/CT is recommended in positive studies to aid in the differentiation of soft tissue infection from osteomyelitis. WBC Scan Area of Interest Systematic reviews by Verberne et al [36] and Van der Bruggen et al [45] both describe significant variability in specificity and sensitivity of WBC scan ability to diagnosis infection of orthopedic implants. This is likely due to Suspected Osteomyelitis, Septic Arthritis variability in scanning technique and criteria used for diagnosis of prosthetic related infection. In a study of 215 patients, Trevail et al [34] reported that a WBC scan had a sensitivity of 80% and a specificity >99%. The addition of SPECT/CT is recommended in positive studies to aid in the differentiation of soft tissue infection from osteomyelitis. Variant 6: Suspected soft tissue infection. History of puncture wound with possible retained foreign body. Radiographs normal. Next imaging study.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. For soft tissue infection, the body regions covered are abdomen, neck, ankle, chest, elbow, thigh, foot, forearm, hand, hip, arm, knee, pelvis, shoulder, leg, wrist. In patients with puncture wounds, one of the main goals of imaging is to determine the presence or absence of a retained foreign body. Around the foreign body and puncture wound, soft tissue granulomatous reaction occurs and a superimposed soft tissue infection can develop including cellulitis, abscess, myositis, septic arthritis, or sinus tract. Foreign bodies are either radiodense or radiolucent. Metal, stone, and graphite are radiodense and are detected on radiographs. However, plastic, rubber, and wood are not visible or radiolucent. Glass and ceramic are not always seen on radiographs. CT can evaluate for the complications of foreign body infections such as cellulitis, muscle/fascial edema, abscesses, sinus tracts, and vascular or tendon injuries. Vascular injuries or pseudoaneurysms are best evaluated with the administration of IV contrast. However, soft tissue changes associated with foreign bodies, such as peripheral edema, hyperemia, and inflammation, may require a more sensitive modality such as MRI or US. CT can detect bone changes related to foreign bodies including osseous destruction, sclerosis, periosteal reaction, or intraosseous abscess [46,47]. Although CT can detect foreign bodies embedded in bone, CT is not as sensitive as MRI for detecting bone marrow edema. MRI Area of Interest On MRI, foreign bodies are usually low signal on all sequences and demonstrate morphology that is not anatomic (ie, linear or polygonal shape). MRI is the most sensitive modality for evaluating the soft tissue and osseous changes of infection; however, it is not sensitive or specific for detecting foreign bodies. Especially if the foreign bodies are small, many may be missed.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. Because of the granulomatous, inflammatory response to foreign bodies within soft tissues, surrounding fluid signal, edema, peripheral enhancement is a dominant pattern on MRI, which can be used to help localize foreign bodies. MRI with IV contrast can also assess complications of foreign bodies in soft tissues and bone, including cellulitis, fasciitis, abscesses, sinus tracts, osteomyelitis, and vascular or tendon injuries. Compared with US and CT, MRI has a lower sensitivity and inferior spatial resolution for detection of foreign bodies. Radiodense foreign bodies are better visualized on radiography [46]. Metallic foreign bodies and air produce susceptibility artifact, which can limit MRI quality. With metallic objects and MRI, there is a potential for severe soft tissue heating and motion of the foreign body because of the magnetic field. The severity of this risk is dependent on the ferromagnetic properties and location of the metallic foreign body, how long the foreign body has been in place, and the strength of the MRI unit [47]. Therefore, radiographic screening for metallic foreign bodies is recommended before MRI. US Area of Interest If a foreign body is not visualized on radiographs, US can be used for further evaluation especially in the acute, emergency setting [46,47]. US has a reported sensitivity of 95% for the detection of foreign bodies [48]. Tantray et al [48] reported out of 120 patients that went to surgery for foreign body exploration, US visualized foreign bodies in 114 patients. Among the 6 patients with negative US, only 1 patient had a foreign body on surgery. In addition, US can further characterize foreign body morphology, depth, and location in relation to adjacent structures like Suspected Osteomyelitis, Septic Arthritis vessels, bone, joints, tendons, or nerves. Furthermore, US can provide image guidance for removal of the foreign bodies.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. US can show the complications of foreign body infections such as cellulitis, myositis, abscesses, sinus tracts, and vascular or tendon injuries [47]. All foreign bodies are hyperechoic on US with some degree of posterior acoustic shadowing. A rim of hyperechogenicity may surround the foreign body with increased inflammation and vascularity on color Doppler. This can develop within 24 hours, and it is thought to represent soft tissue granulomatous reaction [47]. Although most superficial foreign bodies are visible on US, deeper locations (>4 cm from the skin) are more difficult to detect on US [46]. It is also difficult to visualize foreign bodies if there is air in the adjacent soft tissues, especially deeper and smaller foreign bodies. US cannot detect foreign bodies within bone. Variant 7: Suspected soft tissue infection. Initial radiographs show soft tissue gas (without puncture wound) or are normal with high clinical suspicion of necrotizing fasciitis. Next imaging study. For soft tissue infection, the body regions covered are abdomen, neck, ankle, chest, elbow, thigh, foot, forearm, hand, hip, arm, knee, pelvis, shoulder, leg, wrist. NF is a rare, rapidly progressive soft tissue infection, which is often difficult to treat and requires surgical intervention with a high mortality rate ranging from 29% to 80% [2,49]. A polymicrobial infection composed of both aerobic and anaerobic organisms is typically seen. The infection causes necrosis by microvascular occlusion along the fascial tissues beginning at the superficial fascia along the subcutaneous soft tissues and then progressing into the deeper fascial layers between muscle planes and compartments [49]. In addition to the clinical findings of NF, laboratory evaluation can be helpful.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. A scoring system named Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) is often used, which takes into consideration WBC, hemoglobin, blood chemistry values, and C-reactive protein [50]. Although NF is primarily diagnosed clinically, imaging findings can be critical to support the diagnosis, to aid in surgical planning, and to map disease extent and involvement. However, obtaining imaging studies, such as MRI, should not delay appropriate surgical treatment in patients who are severely ill and unstable [49]. CT Area of Interest The CT findings in NF correlate with the pathophysiology of the infection causing soft tissue inflammation and liquefactive necrosis. Skin thickening, inflammatory subcutaneous fat stranding, and fluid or gas in the superficial or deep fascial planes are the typical CT findings [49,51,52]. In a study evaluating 20 surgically proven cases of NF, Wysoki et al [53] reported that CT demonstrated subcutaneous fat stranding and fascial fluid or thickening in 80%, soft tissue gas in 55%, and abscesses in 35% of cases. Tso et al [52] concluded that although the overall sensitivity of CT in diagnosing NF is 80%, the specificity is low because similar findings may be present in non- NF, cellulitis, pyomyositis, bursitis, and other soft tissue infections. Compared with radiography, US, and MRI, CT is the most sensitive modality for detection of soft tissue gas [51,52,54]. Fernando et al [54] reported in a meta-analysis of 23 studies that the visualization of soft tissue gas on radiographs had a sensitivity of 49% and a specificity of 94% for the diagnosis of NF. Soft tissue gas on CT was associated with a sensitivity of 89% and a specificity of 93% for diagnosing NF. Gas within fascial planes and fluid collections is an important finding and can be a CT hallmark of NF; however, the absence of soft tissue gas does not exclude NF [2,49,51,52].


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. Early in the disease process, especially NF infections with more aerobic organisms, and in diabetic patients, soft tissue gas may not be present or detectable by CT [52]. In the Fernando et al meta-analysis of NF studies, most CT examinations were performed without IV contrast or the type of CT examination was not specified [52,54]. The evaluation of the use of contrast-enhanced imaging in the medical literature is limited [2]. Carbonetti et al [51] performed a retrospective study investigating 36 selected patients who had contrast-enhanced CT imaging performed and concern for NF or other severe soft tissue infection, which included confirmed patients with NF (10 surgically proven patients), non-NF (2 patients), cellulitis (10 patients), soft tissue abscess (7 patients), myositis (5 patients), and gas gangrene (2 patients). This study concluded that CT findings of fascial fluid and thickening and lack of enhancement of the fascia after CT with IV contrast administration were both highly associated with NF. The Carbonetti et al study reported that more patients with surgically proven NF had absence of fascial enhancement compared with those with other musculoskeletal infections, suggesting that the absence of fascial enhancement was specific for NF [55]. Contrast-enhanced CT imaging also improves the assessment for abscess, tissue necrosis, and vascular complications [6,52]. However, noncontrast CT is highly accurate for detection of NF [2,49,52,54]. Suspected Osteomyelitis, Septic Arthritis MRI Area of Interest MRI is the modality of choice for detecting superficial or deep fascial fluid or edema [2,49,50,52,56,57]. MRI can recognize small amounts of fluid or edema in the fascia, potentially allowing for earlier diagnosis [54,56].


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. MRI has the highest reported sensitivity of 93% for the diagnosis of NF because of this detection of fluid signal on T2 fat suppressed or short tau inversion recovery (STIR) sequences [49,52]. Furthermore, the absence of fluid signal along the fascia essentially excludes the diagnosis of NF [2,52,56,57]. However, MRI findings of superficial and deep fascial fluid or edema are not specific for NF and can be seen in other soft tissue infections, such as severe cellulitis and non-NF. If the MRI is negative or with nonspecific findings and there is high clinical suspicion of NF, appropriate surgical treatment should be planned [49]. Also, in stable yet nonimproving patients, obtaining follow- up MRI can be of benefit to assess for progression of necrosis or fascial fluid and edema [49]. Although CT is more sensitive for detecting soft tissue gas, it can be seen as low punctate or curvilinear signal on all MRI sequences (T1-weighted, T2-weighted, STIR) and can be detected with high sensitivity with gradient echo sequences because of blooming artifact and susceptibility artifact. The presence of soft tissue gas is highly associated with NF; however, the absence of soft tissue gas on MRI should not exclude the diagnosis of NF and may be seen in late stages of NF [50,52,56]. Although some degree of fascial thickening, indistinctness of fascial planes, and fluid accumulation can be seen on CT, the MRI high signal intensity appearance of fascial fluid and edema on T2 fat suppression/STIR sequences is far superior for the detection of NF [56]. Yoon et al [50] also compared 2 parameters for diagnosing NF: utilization of the LRINEC score only and when both MRI findings and the LRINEC scores where applied to the diagnostic scenario. When the LRINEC score was used alone, the sensitivity, specificity, positive predictive value, and negative predictive value were 57%, 84%, 77%, and 67%, respectively.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. Integrating both MRI findings and LRINEC scoring produced values of 77%, 84%, 82%, and 79%, respectively. They concluded that MRI findings improved the overall sensitivity of diagnosing NF. There are varying reports regarding the amount of fascial enhancement present based on the stage of necrosis [49,52]. Similar to CT, the assessment of fascial enhancement is controversial. Based upon studies in the MRI literature from >20 years ago, NF fascial enhancement patterns following IV contrast administration are variable with nonenhancement, mixed, and enhancement patterns all reported in the medical literature [2,58]. The presence of fascial enhancement is attributed to increased capillary permeability and IV contrast extravasation. In contrast, the absence of fascial enhancement is attributed to necrosis and microvascular occlusion [2,49,52,58]. In the later stages of NF, focal or diffuse nonenhancement of the fascia may be seen because of necrosis, which can be helpful to differentiate from non-NF [50,52,57]. In general, contrast-enhanced MRI aids in the identification of abscess and areas of necrosis, extent of infection, and delineation of vascular involvement, which can be beneficial in NF [2,49,52]. However, noncontrast MRI is still an important examination with the highest reported sensitivities to detect soft tissue findings of fascial edema/fluid signal and can detect the known imaging findings of NF to include deep fascial/intermuscular edema, soft tissue gas, and fluid collections [2,49,50,52,56,57]. US Area of Interest US findings of NF include soft tissue gas, subcutaneous fat edema, and irregular thickening and fluid along superficial and deep fascial planes [52,57,59,60]. A unique benefit to US is the ability to compare the contralateral extremity or other regions of normal tissue.


Suspected Osteomyelitis Septic Arthritis or Soft Tissue Infection Excluding Spine and Diabetic Foot PCAs. Also, US can evaluate for deep venous thrombosis, provide image guidance for fluid aspiration, use color Doppler, and assess for foreign bodies [52,59]. The US appearance of soft tissue gas is typically an echogenic region or foci along the superficial and/or deep fascia with some degree of incomplete posterior acoustic shadowing. The presence of gas causes the posterior acoustic shadowing, and the changes in echotexture does impede sound penetration which can limit visualization of deeper structures [57]. For NF, this may cause US to have a limited role for the evaluation of the deeper intermuscular fascia especially in larger body habitus patients [52,57]. The subcutaneous fat can be thickened and demonstrate overall increased echogenicity due to fat edema and inflammatory change. Also, the fat lobules can form a cobblestone appearance due to the thickening of subcutaneous fat septa [52,57,59,60]. Although these findings are not specific for NF and Suspected Osteomyelitis, Septic Arthritis can be seen in cellulitis or anasarca, finding irregular thickened fascia and abnormal fluid collections in deeper muscle fascia can help differentiate NF [52,60]. Consistent throughout the US literature is the importance of the detection of fluid accumulation and thickened deep intermuscular fascia for diagnosing NF [52,59-62]. The overall sensitivity of US for the diagnosis of NF varies from 42% to 88%, with a specificity of 70% to 94% [52,59,60]. These variations may be due to the amount of deep fascial thickening and fluid accumulation. There is limited evidence regarding the role of US in the diagnosis of NF [52,57,59,60]. Because CT and MRI are more sensitive modalities for visualizing fluid and fascial thickening, a negative US should not exclude the diagnosis of NF [61].


Dysphagia

Dysphagia.  Dysphagia affects up to 22% of adults in the primary care setting and is more common in older adults [3,4]. Adults over 65 years of age account for up to two-thirds of all people with dysphagia [3]. Although the aging process is associated with neuromuscular changes, aging itself does not typically cause clinically significant dysphagia. Aging is associated with an increased prevalence of neuromuscular and degenerative disorders that can cause dysphagia; therefore, the presence of dysphagia should prompt evaluation [3,5]. It is also important to recognize that a person may have an asymptomatic swallowing disorder. In one study of 2,000 patients evaluated with videofluoroscopic examinations, 51% of patients were found to aspirate; however, of those who were aspirated, 55% demonstrated silent aspiration with an absent protective cough reflex [6]. Reprint requests to: publications@acr.org Pharynx Dynamic and Static Imaging Biphasic examination of the pharynx is performed by acquiring static and dynamic images of the pharynx. Double-contrast and single-contrast images of the pharynx and videofluoroscopy of swallowing are obtained. Pharyngeal function, structure, and motility are also assessed. The structural evaluation of the pharynx is superior to that obtained with a modified barium swallow because fluoroscopic spot images are obtained. Therapeutic maneuvers are not typically performed or assessed in this examination. Biphasic Esophagram A biphasic fluoroscopic evaluation of the esophagus includes single- and double-contrast techniques, including full-column, mucosal relief, and double-contrast views of the esophagus [11]. Esophageal function and motility are evaluated at fluoroscopy. Double-contrast technique provides more mucosal detail compared with the single- contrast technique. However, patient cooperation and mobility are required.


Dysphagia

Dysphagia. Single-Contrast Esophagram A single-contrast esophagram or barium swallow includes full-column distension, mucosal relief views, and fluoroscopic observation of esophageal motility. Single-contrast studies are well suited for elderly, debilitated, obese, and postoperative patients as well as patients who are unable to fully cooperate with the biphasic examination. A single-contrast esophagram may be performed with barium or water-soluble contrast. Discussion of Procedures by Variant Variant 1: Oropharyngeal dysphagia with an attributable cause. Initial imaging. An accurate medical and surgical history from the patient or medical record is helpful to determine the appropriate test to optimally assess the patient. Typical functional and neurologic causes of oropharyngeal dysphagia include recent stroke, worsening dementia, myasthenia gravis, or amyotrophic lateral sclerosis. Many patients with oropharyngeal dysphagia can subjectively localize a sensation of blockage or discomfort in the throat. Patients with oropharyngeal dysphagia typically complain of food sticking in the throat or of a globus sensation with a lump in the throat. Other symptoms of oropharyngeal dysfunction include coughing or choking during swallowing (due to laryngeal penetration or aspiration), a nasal-quality voice or nasal regurgitation (due to soft palate insufficiency), food dribbling from the mouth, and difficulty initiating swallow or chewing (due to an abnormal oral phase of swallowing). It is also important to recognize that abnormalities of the mid or distal esophagus or even the gastric cardia may cause referred dysphagia to the upper chest or pharynx, whereas abnormalities of the pharynx rarely cause referred dysphagia to the lower chest [6]. Therefore, the esophagus and cardia should be evaluated in patients with pharyngeal symptoms, particularly if no abnormalities are found in the pharynx to explain these symptoms [12].


Dysphagia

Dysphagia. Fluoroscopy Pharynx Dynamic and Static Imaging The evaluation of the pharynx with dynamic and static imaging evaluates swallowing function similar to the modified barium swallow. However, this examination typically does not involve a variety of barium consistencies, does not include an evaluation of therapeutic options, and does not evaluate the thoracic esophagus and gastric cardia. Static images aid in evaluation for structural abnormalities of the pharynx. CT Neck and Chest CT is usually not indicated in this clinical scenario because it does not assess oropharyngeal function. Esophageal Transit Nuclear Medicine Scan Scintigraphy is usually not indicated in this clinical scenario because it does not assess the oropharynx. Variant 2: Unexplained oropharyngeal dysphagia. Initial imaging. Patients with unexplained oropharyngeal dysphagia may need a more detailed barium study to determine the cause. Also, because abnormalities of the distal esophagus or gastric cardia can cause referred sensation of dysphagia in the upper chest or pharynx, the esophagus and gastric cardia should be evaluated in patients with pharyngeal symptoms, and a combined radiologic examination of the oral cavity, pharynx, esophagus, and gastric cardia is appropriate for patients with unexplained pharyngeal dysphagia. In patients with unexplained oropharyngeal dysphagia, the combination of videofluoroscopy and static images of the pharynx with an examination of the esophagus has a higher diagnostic value than either videofluoroscopy (such as a modified barium swallow) or static images (such as a biphasic or single-contrast esophagram) alone [17]. If a study is performed using solely static imaging, a biphasic study is preferable to a single-contrast barium swallow because of its superior depiction of mucosal processes. Fluoroscopy Single-Contrast Esophagram Double-contrast technique provides more superior mucosal detail compared with the single-contrast technique.


Dysphagia

Dysphagia. However, patient cooperation and mobility are required and single-contrast technique may be better suited for those patients who are unable to fully cooperate with the biphasic examination, such as elderly, debilitated, and obese patients. Fluoroscopy Barium Swallow Modified A modified barium swallow examination may be of benefit in this setting, particularly if structural abnormalities have been excluded by direct endoscopic visualization. In a study by Madhavan et al [19], a videofluoroscopic Dysphagia modified barium swallow identified a cause for dysphagia in 76% of patients. Localization of the videofluoroscopic finding to the site of the patients symptoms was accurate in 75% of cases when the finding was structural versus 18% when the finding was physiologic [19]. CT Neck and Chest CT is usually not indicated in this clinical scenario as initial imaging because it does not assess oropharyngeal and esophageal mucosa and motility. CT may be helpful in the subsequent evaluation of patients if initial studies are not revealing. Esophageal Transit Nuclear Medicine Scan Nuclear scintigraphy could be used to assess for motility abnormalities or gastroesophageal reflux; however, it is not a substitute for examinations that evaluate the function and structure of the pharynx. Variant 3: Retrosternal dysphagia in immunocompetent patients. Initial imaging. Patients with retrosternal dysphagia experience a sensation of blockage or discomfort at any level between the thoracic inlet and the xiphoid process. Because retrosternal dysphagia can be caused by esophageal motility disorders or by structural abnormalities of the esophagus or cardia (ie, esophagitis, rings, strictures, or tumors), a biphasic esophagram is the preferable imaging procedure. Fluoroscopy Biphasic Esophagram The biphasic esophagram permits detection of both structural and functional abnormalities of the esophagus. Structural lesions include esophagitis, strictures, rings, and carcinoma.