Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization Variant 2: Indeterminate, greater than 1 cm liver lesion on initial imaging with CT (noncontrast or single- phase) or noncontrast MRI. Normal liver. No suspicion or evidence of extrahepatic malignancy or underlying liver disease. CT Abdomen Contrast-enhanced CT correctly differentiates between malignant and benign lesions in 74% to 95% of lesions [9,10]. For patients with incidental liver lesions, multiphase contrast-enhanced CT has 91% to 95% accuracy for diagnosis of hemangioma, 85% to 93% accuracy for the diagnosis of FNH, and 96% to 99% accuracy for diagnosis of HCC [10,12]. CT of the abdomen with and without IV contrast is not recommended for this clinical scenario because there is no added value for unenhanced images. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT in this clinical scenario. DOTATATE PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of Ga-68-DOTATATE PET/CT in this clinical scenario. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen There is no relevant literature to support the use of In-111 somatostatin receptor scan with SPECT or SPECT/CT in this clinical scenario. Image-Guided Biopsy Liver Percutaneous image-guided biopsy may be necessary to establish the diagnosis, particularly when the imaging features on a CT or MRI examination indicate possibility of malignancy. In some liver lesions, such as lymphoma, histopathologic analysis is the only technique that can make a definitive diagnosis [20]. Various techniques exist for guidance of the biopsy, and US and CT are the most commonly utilized modalities for biopsy guidance. When a biopsy is performed to diagnose or rule out malignancy in indeterminate lesions, the overall technical success rate under grayscale US guidance is 74%, which can be increased to 100% under CEUS guidance [21,22].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. The percentage of tumor cells in the biopsy sample is greater with a higher number of collected biopsy samples [23]. Furthermore, for lesions not seen on grayscale US, the success rate for CEUS-guided biopsy can be as high as 88% to 96% [24,25]. US fusion with CT or MRI, can be used for percutaneous biopsy of lesions with poor sonographic conspicuity, with a 96% technical success rate [25]. Lesions that are isointense on CT can also present a challenge for CT-guided biopsy; however, use of anatomic landmarks or IV contrast can achieve accuracy of 96% to 98% [26]. Image-guided biopsies carry a risk of postbiopsy bleeding, which may be as high as 9% to 12%, particularly with hypervascular lesions [27,28]. In addition, a very small risk of needle-track seeding exists. RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario. US Abdomen Diagnostic accuracy of grayscale US is 41% to 68% for specific diagnosis and 86% for differentiation between malignant and benign lesions [9,29]. US can be helpful in some cases due to its ability to characterize a lesion as a Liver Lesion-Initial Characterization cyst. Doppler evaluation of flow is an integral part of the clinical grayscale US examination. However, none of the reviewed studies specifically compared performance of US examinations with and without the addition of Doppler. US Abdomen with Contrast In a small retrospective study of solid indeterminate lesions detected on contrast-enhanced CT in patients without parenchymal liver disease, addition of CEUS improves diagnostic accuracy from 43% to 49% to 89% to 92% [39]. CEUS is able to provide correct diagnosis in 89% of cases and can distinguish between benign and malignant lesions in 97% of cases [9].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. In noncirrhotic patients, the hypoechoic pattern in portal and sinusoidal phase (rapid wash-out) or the markedly hypoechoic or anechoic pattern in sinusoidal phase (marked late wash-out) showed a sensitivity, specificity, and accuracy of 97%, 100%, and 98%, respectively, for the diagnosis of malignancy [37]. Variant 3: Indeterminate, greater than 1 cm liver lesion on initial imaging with US. Known history of an extrahepatic malignancy. CT Abdomen In patients with a history of primary malignancy, contrast-enhanced CT can differentiate between metastases and benign lesions with 74% accuracy [40]. Specifically, in patients with a history of colon cancer, lesion characterization on contrast-enhanced CT is correct in 77% of cases [41]. When metastases are suspected based on US, the sensitivity and specificity of contrast-enhanced CT for detection of metastases are 88% and 17%, respectively [42]. In patients with hypervascular liver metastases, addition of noncontrast CT can improve the confidence level for lesion characterization by 4% to 15%; however, it does not change the diagnostic accuracy [43]. The addition of noncontrast CT can increase sensitivity for breast cancer metastases by 5% to 23% but does not improve sensitivity for melanoma metastases [44]. Sensitivity of noncontrast CT alone is 61% to 100% for breast cancer metastases, 62% to 100% for melanoma metastases, and 17% to 88% for NET metastases [44]. In comparison, contrast- enhanced CT has sensitivity of 77% to 95% for breast cancer metastases, 86% to 100% for melanoma metastases, and 44% to 77% for NET metastases [44,45]. FDG-PET/CT Skull Base to Mid-Thigh In patients with a history of primary malignancy, FDG-PET/CT can differentiate between malignant and benign lesions with an accuracy of 75% [40].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. When metastases are suspected based on US, the sensitivity and specificity of PET/CT in the detection of hepatic metastases is 97% and 75%, respectively, which is higher, compared with contrast-enhanced CT alone with sensitivity and specificity of 88% and 17%, respectively [42]. DOTATATE PET/CT Skull Base to Mid-Thigh In patients with primary NET, Ga-68-DOTATATE PET/CT demonstrates sensitivity of 80% to 100% and of specificity 82% to 100% [8]. Specifically, Ga-68-DOTATATE PET/CT is more sensitive than FDG-PET/CT, with sensitivities of 72% to 100% versus 54% to 78%, respectively [8]. Ga-68-DOTATATE PET/CT is not used in assessment metastases from primary cancers other than NET. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen Sensitivity of In-111 somatostatin receptor scan with SPECT or SPECT/CT varies depending on the specific histologic type of the primary NET. For example, detection rates are >75% in small-cell-lung cancer and carcinoid metastases and 40% to 75% in insulinoma and medullary thyroid cancers [46]. Image-Guided Biopsy Liver Percutaneous image-guided biopsy may be necessary to establish the diagnosis, particularly when the imaging features on a CT or MRI examination indicate a possibility of malignancy. In some liver lesions, such as lymphoma, histopathologic analysis is the only technique that can make a definitive diagnosis [20]. Various techniques exist Liver Lesion-Initial Characterization for guidance of the biopsy, where US and CT are the most commonly utilized modalities for biopsy guidance. When a biopsy is performed to diagnose or rule out malignancy in indeterminate lesions, the overall technical success rate under grayscale US guidance is 74%, which can be increased to 100% under CEUS guidance [21,22]. The percentage of tumor cells in the biopsy sample is greater with a higher number of collected biopsy samples [23].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Furthermore, for lesions not seen on grayscale US, the success rate for CEUS-guided biopsy can be as high as 88% to 96% [24,25]. US fusion with CT or MRI can be used for percutaneous biopsy of lesions with poor sonographic conspicuity with a 96% technical success rate [25]. Lesions which are isointense on CT can also present a challenge for CT-guided biopsy; however, use of anatomic landmarks or IV contrast can achieve accuracy of 96% to 98% [26]. Image-guided biopsies carry a risk of postbiopsy bleeding, which may be as high as 9% to 12%, particularly with hypervascular lesions [27,28]. In addition, a very small risk of needle-track seeding exists. RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario. US Abdomen with Contrast Depending on the appearance of the lesion on the initial US, CEUS may be performed for lesion characterization. CEUS can differentiate between malignant and benign lesions in 90% of lesions [48]. Diagnostic accuracy of CEUS for metastases is 83% compared with 76% for MRI with extracellular contrast agent [35]. In noncirrhotic patients, the hypoechoic pattern in portal and sinusoidal phase (rapid wash-out) or the markedly hypoechoic or anechoic pattern in sinusoidal phase (marked late wash-out) showed a sensitivity, specificity, and accuracy of 97%, 100%, and 98%, respectively, for the diagnosis of malignancy [37]. Variant 4: Indeterminate, greater than 1 cm liver lesion on initial imaging with CT (noncontrast or single- phase) or noncontrast MRI. Known history of an extrahepatic malignancy. CT Abdomen In patients with a history of primary malignancy, contrast-enhanced CT can differentiate between metastases and benign lesions with 74% accuracy [40].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Specifically, in patients with a history of colon cancer, lesion characterization on contrast-enhanced CT is correct in 77% of cases [41]. In patients with hypervascular liver metastases, adding a noncontrast CT phase to a contrast-enhanced CT examination can improve the confidence level for lesion characterization by 4% to 15%; however, it does not change the diagnostic accuracy [43]. The addition of noncontrast CT can increase sensitivity for breast cancer metastases by 5% to 23% but does not improve sensitivity for melanoma metastases [44]. Sensitivity of noncontrast CT alone is 61% to 100% for breast cancer metastases, 62% to 100% for melanoma metastases, and 17% to 88% for NET metastases [44]. In comparison, contrast-enhanced CT has a sensitivity of 77% to 95% for breast cancer metastases, 86% to 100% for melanoma metastases, and 44% to 82% for NET metastases [44,45]. FDG-PET/CT Skull Base to Mid-Thigh In patients with a history of primary malignancy, FDG-PET/CT can differentiate between malignant and benign lesions with an accuracy of 75% [40]. In patients with a history of primary cancer and indeterminate lesions found by either CT or MRI, FDG-PET/CT has an accuracy of 75% with a high sensitivity of 96% and a limited specificity of 33% [40]. The sensitivity and specificity of FDG-PET/CT in the detection of hepatic metastases is 97% and 75%, respectively, which is higher compared with contrast-enhanced CT alone (which as a sensitivity and specificity of 88% and 17%, respectively) [42]. DOTATATE PET/CT Skull Base to Mid-Thigh In patients with primary NET, Ga-68-DOTATATE PET/CT demonstrates sensitivity of 80% to 100% and specificity of 82% to 100% [8]. Specifically, Ga-68-DOTATATE PET/CT is more sensitive than FDG-PET/CT, with sensitivities of 72% to 100% versus 54% to 78%, respectively [8]. Liver Lesion-Initial Characterization


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen Sensitivity of a In-111 somatostatin receptor scan with SPECT or SPECT/CT varies depending on the specific histologic type of the primary NET. For example, detection rates are >75% in small-cell-lung cancer and carcinoid metastases and 40% to 75% in insulinoma and medullary thyroid cancers [46]. MRI Abdomen In patients with a history of primary malignancy, noncontrast MRI can differentiate between malignant and benign lesions with accuracy of 71% [47]. The accuracy increases by between 83% and 91% with the addition of dynamic postcontrast sequences and further increases to 94% with addition of HBP [47,48]. In patients with a history of colon cancer, the lesion characterization on contrast-enhanced MRI is correct in 89% of cases [41]. In patients with suspected colorectal liver metastases, the combination of gadoxetate-enhanced MRI and DWI shows significantly higher accuracy (90% to 93%) for the preoperative detection of small colorectal liver metastases than DWI alone [49]. In patients with known primary cancer, ADC values can help to distinguish between metastasis and benign solid hepatic lesions [50]. Image-Guided Biopsy Liver Percutaneous image-guided biopsy may be necessary to establish the diagnosis, particularly when the imaging features on a CT or MRI examination indicate possibility of malignancy. In patients with a history of primary malignancy, 91% of biopsies are positive for malignancy, 5% of which can be different from the primary cancer [51]. Up to 6% of biopsies in patients with primary malignancy are nondiagnostic [51]. In some liver lesions, such as lymphoma, histopathologic analysis is the only technique that can make a definitive diagnosis [20]. Various techniques exist for guidance of the biopsy, and US and CT are the most commonly utilized modalities for biopsy guidance.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. When a biopsy is performed to diagnose or rule out malignancy in indeterminate lesions, the overall technical success rate under grayscale US guidance is 74%, which can be increased to 100% under CEUS guidance [21,22]. The percentage of tumor cells in the biopsy sample is greater with a higher number of collected biopsy samples [23]. Furthermore, for lesions not seen on grayscale US, the success rate for CEUS-guided biopsy can be as high as 88% to 96% [24,25]. US fusion with CT or MRI, can be used for percutaneous biopsy of lesions with poor sonographic conspicuity, with a 96% technical success rate [25]. Lesions that are isointense on CT can also present a challenge for CT-guided biopsy; however, use of anatomic landmarks or IV contrast can achieve an accuracy of 96% to 98% [26]. The image-guided biopsies carry a risk of postbiopsy bleeding that may be as high as 9% to 12%, particularly with hypervascular lesions [27,28]. In addition, a small risk of needle-track seeding exists. In patients with HCC, the rate of seeding is 0.1% to 0.7% [52-54]. RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario. US Abdomen Grayscale US is able to provide correct diagnosis in 68% of liver lesions [9]. For differentiation between malignant and benign lesions, US is correct in 86% of cases [9]. US Abdomen with Contrast In noncirrhotic patients, the hypoechoic pattern in portal and sinusoidal phase (rapid wash-out) or the markedly hypoechoic or anechoic pattern in sinusoidal phase (marked late wash-out) showed a sensitivity, specificity, and accuracy of 97%, 100%, and 98%, respectively, for the diagnosis of malignancy [37].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. In a small retrospective study of patients with primary pancreatic adenocarcinoma, CT and CEUS have similar sensitivities for detection of metastases (73% versus 80%, respectively) [2]. However, CEUS is able to more accurately differentiate between an incidental benign lesion (eg, cysts, vascular shunts) from metastases, resulting in fewer false-positive diagnoses and therefore higher PPV (60% versus 92%) [2]. The accuracy of CEUS for diagnosis of metastases is 76% [35]. Liver Lesion-Initial Characterization Variant 5: Incidental liver lesion, greater than 1 cm on US, noncontrast or single-phase CT, or noncontrast MRI. Known chronic liver disease. Evaluation of liver lesions detected in a patient with chronic liver disease should be performed based on the algorithm set forth by the most recent version of LI-RADS [6,55]. CT Abdomen The sensitivity of a dual-phase contrast-enhanced CT for diagnosing a small HCC (<2 cm) is 53% [56]. In patients with chronic liver disease, triple-phase contrast-enhanced CT correctly characterizes lesions in 49% to 68% of cases and has a sensitivity of 61% to 73% for lesion detection [57]. Delayed phase wash-out on CT is important in HCC diagnosis [58]. For 1- to 2-cm lesions in patients with cirrhosis detected on screening US, the addition of noncontrast CT to dynamic postcontrast phases (CT without and with IV contrast) does not increase sensitivity or accuracy for HCC [59]. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT has a limited role in characterization of liver lesions in patients with parenchymal liver disease [6]. Once the diagnosis of HCC is established, tumor FDG activity may predict microvascular invasion [60]. DOTATATE PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of Ga-68-DOTATATE PET/CT in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen There is no relevant literature to support the use of In-111 somatostatin receptor scan with SPECT or SPECT/CT in this clinical scenario. MRI with extracellular agents has a sensitivity of 78% to 83% and specificity of 100% [35,61]. Addition of HBP improves sensitivity and accuracy for nodules <2 cm [62]. The sensitivity of MRI with gadoxetate for diagnosing a small HCC (<2 cm) is 76% to 97% [56,63]. Addition of HBP improves detection of HCC and differentiation between HCC and dysplastic nodules [64,65]. Furthermore, addition of HBP improves sensitivity and accuracy for diagnosis of HCC, compared with the dynamic images alone [66,67]. Gadoxetate-enhanced MRI allows for correct characterization of liver lesions in 87% to 91% of cases [63]. However, the HBP on gadoxetate-enhanced MRI can be limited in the setting of poor liver function, and transient hepatic enhancement differences can cause artifacts in the HBP in cirrhotic patients [68,69]. In patients with chronic liver disease, the mean ADC values in benign solid lesions are higher than those in malignant lesions [70]. In small (<3 cm) lesions, presence of high signal intensity on both T2-weighted imaging and DWI helps differentiate atypical HCCs from dysplastic nodules, with the resultant sensitivity of 80%, specificity of 100%, PPV of 100%, and NPV of 78.3% [71]. For lesions <3 cm in patients with cirrhosis, the sensitivity and accuracy to differentiate the dysplastic nodule from HCC are 46% to 82% and 57% to 75%, respectively [72,73]. The addition of DWI to dynamic sequences improved its ability to distinguish between HCC and dysplastic nodules compared with dynamic sequences alone, with a resultant accuracy of 93% and sensitivity of 97% [73].


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Image-Guided Biopsy Liver Biopsy plays a minor role in establishing the diagnosis of HCC because the imaging criteria of LI-RADS category 5 (definite HCC) can establish such diagnosis with nearly 100% specificity and PPV [6,74]. Biopsy may be necessary if the imaging features of the lesion do not meet the criteria for LI-RADS 5 (definite HCC) category or for molecular analysis to determine clinical trial eligibility or to guide treatment [74]. Overall risk of bleeding for image-guided biopsy can be as high as 12% [27]. An additional risk in biopsy of HCC is a risk of needle-tract seeding, with track seeding incidence being 2.7% overall and 0.1% to 0.9% per year [52-54,75]. RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario. Liver Lesion-Initial Characterization US Abdomen with Contrast For indeterminate liver lesions detected on US, CEUS can provide definitive diagnosis in 77% to 93% of cases and can distinguish between benign and malignant lesions in 89% to 96% of cases [31,32]. The sensitivity of CEUS for diagnosing a small HCC (<2 cm) is 68% compared with 53% for contrast-enhanced CT and 77% for gadolinium- ethoxybenzyl-diethylenetriamine pentaacetic acid MRI in the same study [56]. Diagnostic accuracy of CEUS for HCC is 79% [35]. On CEUS, HCC typically shows a global arterial hyperenhancement and a delayed contrast wash-out, whereas intrahepatic cholangiocarcinoma shows an initial contrast enhancement primarily at the tumor periphery followed by an early portal-venous contrast wash-out in the tumor center [78]. CEUS can accurately differentiate between intrahepatic cholangiocarcinoma and HCC [79]. CT of the abdomen with and without IV contrast is not recommended for this clinical scenario because there is no added value for unenhanced images.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. FDG-PET/CT Skull Base to Mid-Thigh In patients with a history of primary malignancy, FDG-PET/CT may be indicated to evaluate for presence of metastases beyond the liver. Current literature does not support the use of FGD-PET/CT specifically to characterize subcentimeter liver lesions due to its limited sensitivity for lesions <1 cm. DOTATATE PET/CT Skull Base to Mid-Thigh Ga-68-DOTATATE PET/CT is sensitive for detection of metastases in patients with primary NET; however, there is no relevant literature on assessment of subcentimeter liver lesions. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen In patients with a history of primary NET, In-111 somatostatin receptor scan with SPECT or SPECT/CT can detect liver metastases; however, there is no relevant literature to support the use of this procedure in characterization of subcentimeter liver lesions. MRI Abdomen On MRI with gadoxetate, the combination of HBP and DWI has the highest accuracy for detection of subcentimeter liver lesions [15]. ADC values can help differentiate benign versus malignant subcentimeter liver lesions with 92% to 93% accuracy [84]. There is no relevant literature that has assessed the performance of MRI without IV contrast specifically for this clinical scenario. Therefore, the committee recommendations on the use of MRI without IV contrast are based primarily on expert opinion. In some cases, MRI without IV contrast may be appropriate as it can differentiate between small cysts and solid lesions. Image-Guided Biopsy Liver Tissue sampling may be necessary to establish the definitive diagnosis in patients with a history of primary malignancy and indeterminate subcentimeter liver lesions. However, the role of percutaneous biopsy is limited in the evaluation of subcentimeter liver lesions because such lesions are typically difficult to target under image guidance. Furthermore, there is no relevant literature to assess performance of percutaneous biopsy techniques for subcentimeter liver lesions.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Lesion-Initial Characterization RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario. US Abdomen with Contrast Compared with a baseline grayscale US, CEUS can detect 6.5 times more subcentimeter metastases [9]. For indeterminate liver lesions discovered on grayscale US, CEUS reached a specific diagnosis in 83% of cases and distinguished benign versus malignant in 90% of cases [30]. For the benign diagnoses, CEUS correctly characterized 89% of areas of focal fat, 90% of hemangiomas, 87% of complex cysts, 78% of hepatic adenomas, 90% of FNHs, 86% of abscesses, and 60% of hematomas [30]. CEUS correctly characterized 86% of metastases [30]. Variant 7: Indeterminate, less than 1 cm liver lesion on initial imaging with CT (noncontrast or single-phase) or noncontrast MRI. Known history of an extrahepatic malignancy. CT Abdomen Subcentimeter liver lesions in patients with primary malignancy are seen on contrast-enhanced CT in 13% of patients, and of these, 12% are metastases [82]. Among patients with a history of colorectal and breast cancers, small hepatic lesions were metastatic in 14% and 22% of cases, respectively [82]. Subcentimeter liver lesions in women with breast cancer can be found in 29%, and if no obvious liver metastases are present, 93% to 97% of these subcentimeter liver lesions are benign [85]. CT of the abdomen with and without IV contrast is not recommended for this clinical scenario because there is no added value for unenhanced images. FDG-PET/CT Skull Base to Mid-Thigh In patients with a history of primary malignancy, FDG-PET/CT may be indicated to evaluate for the presence of metastases beyond the liver.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. There is no relevant literature to support the use of FDG-PET/CT specifically to characterize subcentimeter liver lesions due to its limited sensitivity for lesions <1 cm. DOTATATE PET/CT Skull Base to Mid-Thigh Ga-68-DOTATATE PET/CT is sensitive for detection of metastases in patients with primary NET; however, there is no relevant literature on assessment of subcentimeter liver lesions. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen In patients with a history of primary NET, In-111 somatostatin receptor scan with SPECT or SPECT/CT can detect liver metastases; however, there is no relevant literature on assessment of subcentimeter liver lesions. MRI Abdomen For subcentimeter liver lesions detected on CT, the sensitivity, specificity, PPV, and NPV for differentiation of benign from malignant lesions for contrast-enhanced MRI are 83%, 98%, 92%, and 94%, respectively [86]. In patients with a history of colon cancer, MRI has a sensitivity of 60% for detection of subcentimeter metastases [87]. There is no relevant literature that has assessed the performance of MRI without IV contrast specifically for this clinical scenario. Therefore, the committee recommendations on the use of MRI without IV contrast are based primarily on expert opinion. Image-Guided Biopsy Liver Tissue sampling may be necessary to establish the definitive diagnosis in patients with a history of primary malignancy and indeterminate subcentimeter liver lesions. However, the role of percutaneous biopsy is limited in the evaluation of subcentimeter liver lesions because such lesions are typically difficult to target under image guidance. Furthermore, published data are not available to assess performance of percutaneous biopsy techniques for subcentimeter liver lesions. RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario.


Liver Lesion Initial Characterization

Liver Lesion Initial Characterization. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario. Liver Lesion-Initial Characterization US Abdomen In patients with a history of primary malignancy and indeterminate, subcentimeter focal liver lesions on CT, grayscale US is able to prove cystic nature of the lesion in 67% of cases [88]. US Abdomen with Contrast In patients with a history of primary malignancy and indeterminate, subcentimeter focal liver lesions on CT that were proven to be noncystic on grayscale US, CEUS correctly characterizes 95% of lesions overall, and 98% of metastases [88]. Compared with a baseline dual-phase contrast-enhanced CT, CEUS can detect 6.5 times more subcentimeter metastases [9]. CT of the abdomen with and without IV contrast is not recommended for this clinical scenario because there is no added value for unenhanced images. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT in this clinical scenario. DOTATATE PET/CT Skull Base to Mid-Thigh There is no relevant literature to support the use of Ga-68-DOTATATE PET/CT in this clinical scenario. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen There is no relevant literature to support the use of In-111 somatostatin receptor scan with SPECT or SPECT/CT in this clinical scenario. There is no relevant literature that has assessed the performance of MRI without IV contrast specifically for this clinical scenario. Therefore, the committee recommendations on the use of MRI without IV contrast are based primarily on expert opinion. RBC Scan Abdomen and Pelvis There is no relevant literature to support the use of a Tc-99m RBC scan in this clinical scenario. Liver Spleen Scan There is no relevant literature to support the use of a Tc-99m sulfur colloid scan in this clinical scenario. Liver Lesion-Initial Characterization Liver Lesion-Initial Characterization


Urinary Tract Infection Child

Urinary Tract Infection Child.  Cystitis is a UTI limited to the bladder. Cystitis typically presents with localized symptoms of frequency, urgency, fever, and dysuria. Cystitis in the absence of pyelonephritis is usually not associated with long-term sequelae [4]. Acute pyelonephritis is infection of one or both kidneys. Pyelonephritis typically presents with systemic symptoms such as high fever, malaise, vomiting, abdominal or flank pain, and tenderness [2-5]. Pyelonephritis is diagnosed in children on the basis of the presence of pyuria and/or bacteriuria, fever, flank pain, or tenderness. Between 50% and 64% of children who have a febrile UTI are found to have defects on renal cortical scintigraphy indicating acute pyelonephritis [7]. Pyelonephritis can cause renal scarring, which is the most severe long-term sequela of UTI and can lead to accelerated nephrosclerosis, leading to hypertension and chronic renal failure [2-5]. The reported incidence of scarring in children after pyelonephritis varies widely in the literature. A systematic review showed that 15% (95% confidence interval, 11%-18%) of children had evidence of renal scarring after the first episode of UTI [7]. With the increased use of prenatal ultrasound (US), it was determined that many of the scars that had been attributed to pyelonephritis actually occur in utero and represent renal dysplasia [2-5]. Contrary to earlier studies suggesting that renal scarring secondary to pyelonephritis is the most common cause of chronic renal disease in children, it is now evident that the long-term risk is low [2-5]. The role of imaging is to guide treatment by identifying patients who are at high risk to develop recurrent UTIs or renal scarring. However, identification of children at risk is relevant only if there is effective treatment. Current management strategy to prevent UTIs and renal scarring is based on prophylactic antibiotics and selective surgical correction of vesicoureteral reflux (VUR).


Urinary Tract Infection Child

Urinary Tract Infection Child. UTI in a neonate or young infant requires special consideration. The prevalence of UTI in term neonates and young infants varies from 0.1% to 1%, with a predominance in the first 2 months of life in neonates and young infants AMAB [8-11]. The presentation of UTI is generally nonspecific, with symptoms similar to neonatal sepsis, and not all children will have fever. Concomitant bacteremia is common with UTI and was observed ranging from 4% to 36.4% [5,8-11]. Neonates with UTI have a high incidence of urinary anomalies; the most common is VUR [8,10- 12]. Reprint requests to: publications@acr.org Urinary Tract Infection-Child tract UTI, or 1 episode of UTI with acute pyelonephritis/upper tract UTI plus 1 or more episodes of UTI with cystitis/lower tract UTI, or 3 or more episodes of UTI with cystitis/lower tract UTI [13]. Upper tract refers to the kidneys and ureters, and lower tract is distal to the ureters. Special Imaging Considerations Voiding urosonography (VUS) is a safe and accurate method to evaluate for VUR. The bladder is filled with a solution containing microbubbles that appear echogenic by US. CT urography (CTU) is an imaging study that is tailored to improve visualization of both the upper and lower urinary tracts. There is variability in the specific parameters, but it usually involves unenhanced images followed by intravenous (IV) contrast-enhanced images, including nephrographic and excretory phases acquired at least 5 minutes after contrast injection. Alternatively, a split-bolus technique uses an initial loading dose of IV contrast and then obtains a combined nephrographic-excretory phase after a second IV contrast dose; some sites include arterial phase. CTU should use thin-slice acquisition. Reconstruction methods commonly include maximum intensity projection or 3-D volume rendering. For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast.


Urinary Tract Infection Child

Urinary Tract Infection Child. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the nonenhanced and excretory phases. MR urography (MRU) is also tailored to improve imaging of the urinary system. Unenhanced MRU relies upon heavily T2-weighted imaging of the intrinsic high signal intensity from urine for evaluation of the urinary tract. IV contrast is administered to provide additional information regarding obstruction, urothelial thickening, focal lesions, and stones. A contrast-enhanced T1-weighted series should include corticomedullary, nephrographic, and excretory phase. Thin-slice acquisition and multiplanar imaging should be obtained. For the purposes of this document, we make a distinction between MRU and MRI abdomen and pelvis without and with IV contrast. MRI abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases, and without heavily T2-weighted images of the urinary tract. OR Discussion of Procedures by Variant Variant 1: Child assigned male at birth (AMAB). Younger than 2 months of age. First febrile urinary tract infection with appropriate response to medical management. Initial imaging. CT Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis with IV contrast in the evaluation of a child AMAB <2 months of age for the initial imaging of a first febrile UTI. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without and with IV contrast in the evaluation of a child AMAB <2 months of age for the initial imaging of a first febrile UTI.


Urinary Tract Infection Child

Urinary Tract Infection Child. CT Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without IV contrast in the evaluation of a child AMAB <2 months of age for the initial imaging of a first febrile UTI. CTU Without and With IV Contrast There is no relevant literature to support the use of CTU in the evaluation of a child AMAB <2 months of age for the initial imaging of a first febrile UTI. Urinary Tract Infection-Child DMSA Renal Scan A Tc-99m dimercaptosuccinic acid (DMSA) scan can be done for the initial imaging, close to the time of febrile UTI to evaluate for the presence of pyelonephritis. If the DMSA scan is normal, voiding cystourethrography (VCUG) may be avoided in >50% of individuals [14]. Tc-99m DMSA has a good image quality and is a desirable agent for renal cortical scintigraphy, especially in small infants, in patients with poorly functioning kidneys, and when other studies have identified dilated uropathy or high-grade VUR [15]. The UK National Institute for Health and Care Excellence (NICE) guidelines do not recommend DMSA for infants <6 months of age with first febrile UTI who respond well to treatment within 48 hours [16]. Fluoroscopy Voiding Cystourethrography Literature on VCUG has mixed recommendations. Fluoroscopic VCUG has been shown to detect VUR in newborn children AMAB even if US is normal [8-11]. A finding of VUR, especially high-grade VUR, may lead to a change in management [9]. VUR is more commonly detected in children AMAB compared with children AFAB [17]. In addition, one of the primary concerns in young infants AMAB is diagnosing posterior urethral valves [9]. The NICE guidelines do not recommend VCUG for infants AMAB <6 months of age with first febrile UTI who respond well to treatment within 48 hours. If there is poor urine flow or if there is a family history of VUR, VCUG may be helpful if there is an abnormal kidney US study [16]. Others advocate performing routine VCUG studies in all newborns AMAB [9].


Urinary Tract Infection Child

Urinary Tract Infection Child. Furthermore, recent data have shown that in children <3 months of age with first febrile UTI, the presence of E coli in urine, and normal renal and bladder US, VCUG can be safely avoided [18]. MRI Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis with IV contrast in the evaluation of a child AMAB <2 months of age for the initial imaging of a first febrile UTI. MRI Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis without IV contrast in the evaluation of a child AMAB <2 months of age for the initial imaging of a first febrile UTI. MRU Without and With IV Contrast There is no relevant literature to support the use of MRU in the evaluation of a child AMAB <2 months of age for the initial imaging of a first febrile UTI. Nuclear Medicine Cystography There is no relevant literature to support the use of nuclear medicine cystography in the evaluation of a child AMAB <2 months of age for the initial imaging of a first febrile UTI. There is good correlation between nuclear medicine cystography and VCUG for the detection of reflux [19]. The nuclear cystogram does not allow for urethral assessment in a infant AMAB [20]. US Kidneys and Bladder In a child AMAB <2 months of age, there is increased incidence of sepsis and renal anomalies associated with UTIs and increased rate of hospitalization. Therefore, the potential benefit of imaging in children <2 months of age is greater than in older children. However, there is less convincing evidence for the benefit of imaging based on outcome [8-11,21]. Hydronephrosis is the most frequent abnormality, found in 45% of neonates with UTI [9]. Postnatal US prior to 2 months of age is typically performed even if the prenatal US was normal.


Urinary Tract Infection Child

Urinary Tract Infection Child. The NICE guidelines for UTI recommend US in evaluation of UTI in children <6 months of age within 6 weeks of the UTI if typical infection or during the acute infection if an atypical infection [16]. In the study by Goldman et al [9] on newborn AMAB with UTI, 8 of 12 children with abnormal postnatal US had a normal intrauterine US; 1 patient had posterior urethral valves, and 4 patients had grades III and IV VUR. The main limitations of US are the detection of pyelonephritis, scarring, and VUR. In a study by Chang et al [22] for evaluation of young infants (<3 months of age) with bacteremic UTI, US kidneys and bladder and fluoroscopic VCUG abnormalities were common, and the authors did not refer to any special imaging considerations for bacteremia in imaging decisions for otherwise well- appearing young infants with UTI. US has a high specificity (97.2%) for the detection of findings suggestive of VUR in children after the first UTI [23]. Sensitivity of US for the detection of findings suggestive of high-grade VUR is markedly improved when uroepithelial thickening is considered [24]. The main limitation of US is the low sensitivity (76.5%) for detecting VUR and renal scarring [25-31]. Voiding Urosonography VUS is an alternative to VCUG for the evaluation of VUR in children, with a comparable sensitivity and specificity ranging from 80% to 100% and 77.5% to 98%, respectively [32-39]. The diagnostic accuracy of VUS compared Variant 2: Child assigned female at birth (AFAB). First febrile urinary tract infection with appropriate response to medical management. Initial imaging. CT Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis with IV contrast in the evaluation of a child AFAB <2 months of age for the initial imaging of a first febrile UTI.


Urinary Tract Infection Child

Urinary Tract Infection Child. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without and with IV contrast in the evaluation of a child AFAB <2 months of age for the initial imaging of a first febrile UTI. CT Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without IV contrast in the evaluation of a child AFAB <2 months of age for the initial imaging of a first febrile UTI. CTU Without and With IV Contrast There is no relevant literature to support the use of CTU in the evaluation of a child AFAB <2 months of age for the initial imaging of a first febrile UTI. DMSA Renal Scan A Tc-99m DMSA scan can be done for initial imaging, close to the time of febrile UTI, to evaluate for the presence of pyelonephritis. This top-down approach has been suggested in literature. If the DMSA scan is normal, VCUG may be avoided in more than 50% of individuals [14]. Tc-99m DMSA has a good image quality and is a desirable agent for renal cortical scintigraphy, especially in small infants, in patients with poorly functioning kidneys, and when other studies have identified dilated uropathy or high-grade VUR [15]. The NICE guidelines do not recommend DMSA for infants <6 months of age with first febrile UTI who respond well to treatment within 48 hours, but they do recommend DMSA for atypical or recurrent UTI [16]. Fluoroscopy Voiding Cystourethrography A finding of VUR, especially high-grade VUR, may lead to a change in management [9]. The NICE guidelines do not recommend VCUG for infants AFAB <6 months of age with first febrile UTI who respond well to treatment within 48 hours. Furthermore, recent data has shown that in children <3 months of age with first febrile UTI, the presence of E coli in urine, and normal renal and bladder US, VCUG can be safely avoided [18].


Urinary Tract Infection Child

Urinary Tract Infection Child. In patients AFAB, there is usually less of a need for detailed anatomic evaluation of the urethra, and radionuclide cystography can be performed as an alternative to VCUG [42]. However, fluoroscopic VCUG may still be a useful study to perform based on consensus opinion derived from common practice. MRI Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis with IV contrast in the evaluation of a child AFAB <2 months of age for the initial imaging of a first febrile UTI. MRI Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis without IV contrast in the evaluation of a child AFAB <2 months of age for the initial imaging of a first febrile UTI. MRU Without and With IV Contrast There is no relevant literature to support the use of MRU in the evaluation of a child AFAB <2 months of age for the initial imaging of a first febrile UTI. Nuclear Medicine Cystography There is good correlation between nuclear medicine cystography and VCUG for the detection of reflux [19]. For more information, please see the fluoroscopic VCUG section. In patients AFAB, there is usually less of a need for detailed anatomic evaluation of the urethra, and radionuclide cystography can be performed instead of VCUG [42]. Urinary Tract Infection-Child The literature in this patient population is evolving with a focus on other modalities such as VUS and fluoroscopy VCUG. It should be noted that the primary evidence supporting use of nuclear cystography is generally older than that of other modalities. US Kidneys and Bladder In patients AFAB <2 months of age, there is an increased incidence of sepsis and renal anomalies associated with UTIs and an increased rate of hospitalization. Therefore, the potential benefit in children <2 months of age is greater than in older children. However, there is less convincing evidence for the benefit of imaging based on outcome [8- 11,21].


Urinary Tract Infection Child

Urinary Tract Infection Child. Hydronephrosis is the most frequent abnormality, found in 45% of neonates with UTI [9]. Postnatal US prior to 2 months of age is typically performed even if the prenatal US was normal. The NICE guidelines for UTI recommend US in evaluation of UTI in children <6 months of age within 6 weeks of the UTI if typical infection or during the acute infection if an atypical infection [16]. As discussed earlier, the main limitations of US are the detection of pyelonephritis, scarring, and VUR. In a study by Chang et al [22] for evaluation of young infants (<3 months of age) with bacteremic UTI, US kidneys and bladder and fluoroscopic VCUG abnormalities were common, and the authors did not refer to any special imaging considerations for bacteremia in imaging decisions for otherwise well-appearing young infants with UTI. Sensitivity of US for the detection of high-grade VUR is markedly improved when uroepithelial thickening is considered [24]. The main limitation of US is the low sensitivity (76.5%) for detecting VUR and renal scarring [25-31]. Variant 3: Child. 2 months to 6 years of age. First febrile urinary tract infection with appropriate response to medical management. Initial imaging. Prospective studies in children between the ages of 2 months and 6 years with UTIs were done to evaluate the effect of therapy [6,43,44]. There is limited evidence to support routine imaging of uncomplicated UTIs, and optimal imaging is controversial [2,5,43,45]. Currently there are 2 main methods for evaluating children with UTIs: the bottom-up approach [2], which focuses on detection of VUR, and the top-down approach [2,5,16], which focuses on the diagnosis of acute pyelonephritis and renal scarring [2,5]. DMSA followed by cystourethrography if DMSA renal scan suggests pyelonephritis is the top-down approach. The potential benefit of this approach is a decrease in the number of cystourethrography studies.


Urinary Tract Infection Child

Urinary Tract Infection Child. CT Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis with IV contrast in the evaluation of a child 2 months to 6 years of age for the initial imaging of a first febrile UTI. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without and with IV contrast in the evaluation of a child 2 months to 6 years of age for the initial imaging of a first febrile UTI. CT Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without IV contrast in the evaluation of a child 2 months to 6 years of age for the initial imaging of a first febrile UTI. CTU Without and With IV Contrast There is no relevant literature to support the use of CTU in the evaluation of a child 2 months to 6 years of age for the initial imaging of a first febrile UTI. DMSA Renal Scan Tc-99m DMSA is a sensitive (90%) and specific (95%) test for detecting pyelonephritis [46]. The NICE guidelines do not suggest DMSA renal scan if the patient responds well to treatment within 48 hours. A delayed DMSA renal scan (4-6 months) to evaluate for renal scarring in high-risk patients with atypical or recurrent UTI is recommended Urinary Tract Infection-Child [16]. Evidence of acute pyelonephritis is detected by DMSA in children with UTIs in approximately 50% to 80% of cases [47-52]. However, short-term studies have demonstrated that many of these abnormalities resolve over time, irrespective of whether a prophylactic antibiotic was used [53-55]. This suggests little benefit in using renal cortical scintigraphy after the first episode of UTI [5]. Furthermore, the high incidence of pyelonephritis identified on DMSA suggests that performing DMSA will not change the need to perform VCUG in many patients.


Urinary Tract Infection Child

Urinary Tract Infection Child. There is conflicting evidence on the sensitivity of renal cortical scintigraphy and the top-down approach in the detection of sequela of VUR [45,56,57]. In a randomized controlled study comparing oral versus IV antibiotic administration, 308 patients who had Tc-99m DMSA were evaluated. The sensitivity of this top-down approach for VUR detection was 70%, with specificity of 42% [45]. A meta-analysis on the use of DMSA in acute UTI yielded a sensitivity and specificity of 79% and 53%, respectively, for grades 3 to 5 VUR. There was marked statistical heterogeneity between the studies. The authors concluded that acute-phase DMSA renal scanning is not useful as a replacement for VCUG in the evaluation of young children with a first febrile UTI [56]. Fluoroscopy Voiding Cystourethrography The Randomized Intervention for Children With Vesicoureteral Reflux study, which enrolled 607 children, 2 months to 6 years of age with any grade of VUR, demonstrated that 2 years of prophylactic antibiotics in children with VUR decreased the incidence of recurrent UTIs by half (number needed to treat for 2 years was 8) [58]. Patients with high-grade VUR (grades III and IV) are more likely to have recurrent UTIs and scarring [7,43,50,58-61] and may benefit even more from prophylactic antibiotics. The Swedish study randomly assigned 203 children, 12 to 23 months of age, with dilated (grade III or IV) VUR and demonstrated benefit only in patients AFAB who received either prophylactic antibiotics or endoscopic treatment in decreasing recurrent UTI (number needed to treat for 2 years, 2.5 and 3, respectively) [62]. Patients AFAB who received antimicrobial prophylaxis had the lowest incidence of renal scarring (number needed to treat for 2 years was 5) [62]. The NICE guidelines do not recommend VCUG for patients from 6 months to 3 years of age with first febrile UTI who respond well to treatment within 48 hours and have a normal renal and bladder US study, normal urine flow, and no family history of VUR.


Urinary Tract Infection Child

Urinary Tract Infection Child. However, VCUG is recommended for patients with a family history of VUR [16]. The NICE guidelines do not recommend VCUG for patients >3 years of age with first febrile UTI. The AAP guidelines suggest that VCUG should not be performed routinely after the first febrile UTI for patients 2 to 24 months of age but that VCUG is indicated if the renal and bladder US reveals hydronephrosis, scarring, or other findings that would suggest either high-grade VUR or obstructive uropathy. Furthermore, VCUG may be indicated in other atypical or complex clinical circumstances [41]. MRI Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis with IV contrast in the evaluation of a child 2 months to 6 years of age for the initial imaging of a first febrile UTI. MRI Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis without IV contrast in the evaluation of a child 2 months to 6 years of age for the initial imaging of a first febrile UTI. MRU Without and With IV Contrast There is no relevant literature to support the use of MRU in the evaluation of a child 2 months to 6 years of age for the initial imaging of a first febrile UTI. Nuclear Medicine Cystography Good correlation has been shown between nuclear medicine cystography and VCUG for the detection of VUR [19]. Unlike in children AMAB, detailed urethral assessment in children AFAB is less necessary, so radionuclide cystography can be performed as an alternative for VCUG in patients AFAB [42,48]. A finding of VUR, especially high-grade VUR, may lead to a change in management [9]. Nuclear medicine cystography may reveal VUR despite a normal VCUG in children with recurrent febrile UTI [63]. For more information, please see the fluoroscopic VCUG section. US Kidneys and Bladder The main benefit of US is for the detection of underlying congenital renal anomalies [1,16].


Urinary Tract Infection Child

Urinary Tract Infection Child. The potential harm of using US as the only imaging for UTI is the poor sensitivity for VUR and pyelonephritis/scarring [25-30,64]. There are limited data showing inconsistent results on the sensitivity of US in the detection of dilated VUR [65,66]. Grayscale US identifies approximately 25% of the patients with acute pyelonephritis and approximately 40% of the patients with chronic parenchymal scarring [29,31,67-72]. Urinary Tract Infection-Child In a retrospective study of 2,259 children <5 years of age, sensitivity of US was related to criteria for the definition of a normal study. With the use of the most relaxed criteria (25% abnormal), US had a sensitivity of 28% (specificity of 77%), and with the most stringent criteria (4% abnormal), US had a sensitivity of 5% (specificity of 97%) [31]. Assuming a 40% prevalence of VUR and a 20% recurrent rate of UTIs in 100 children who have US, up to 11 children will have positive US studies that will be followed by a VCUG study, of which 8 will be positive for VUR. Two years of a prophylactic antibiotic will decrease recurrent UTIs from up to 2 children to 1 child. This means that 1 child will benefit from US and an additional 3 children that may benefit from prophylactic antibiotic will not be treated. In addition, with the increased use of prenatal US screening, the yield of detection of unknown renal abnormalities in children with UTIs has decreased [73]. A few studies with small series of children suggest good correlation between power Doppler and Tc-99m DMSA for pyelonephritis [74,75]. Other studies, however, demonstrated low sensitivity for pyelonephritis and low prediction for development of renal scarring [49,76,77]. Therefore, the use of power Doppler as a replacement for DMSA is not useful [26,49,76]. The NICE guidelines for UTI do not recommend US in evaluation of UTI in children >6 months of age if typical infection [16]. The AAP guidelines recommend US for children with a febrile UTI from ages 2 to 24 months [41].


Urinary Tract Infection Child

Urinary Tract Infection Child. Variant 4: Child. Older than 6 years of age. First febrile urinary tract infection with appropriate response to medical management. Initial imaging. The incidence of new-onset UTI in children >6 years of age is low and often associated with behavioral abnormalities, dysfunctional elimination syndrome, or initiation of sexual intercourse in adolescents [78,79]. Patients AFAB are affected more often than patients AMAB [78]. The likelihood of detection of a previously unknown underlying renal anomaly is low [79]. There is no evidence to support any routine imaging in the first UTI in this group of patients. CT Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis with IV contrast in the evaluation of a child >6 years of age for the initial imaging of a first febrile UTI with appropriate response to medical management. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without and with IV contrast in the evaluation of a child >6 years of age for the initial imaging of a first febrile UTI with appropriate response to medical management. CT Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without IV contrast in the evaluation of a child >6 years of age for the initial imaging of a first febrile UTI with appropriate response to medical management. CTU Without and With IV Contrast There is no relevant literature to support the use of CTU in the evaluation of a child >6 years of age for the initial imaging of a first febrile UTI with appropriate response to medical management. DMSA Renal Scan The NICE guidelines do not recommend DMSA renal scan for patients >6 years of age with first febrile UTI [16]. Fluoroscopy Voiding Cystourethrography The NICE guidelines do not recommend VCUG for patients >6 years of age with first febrile UTI [16]. Urinary Tract Infection-Child


Urinary Tract Infection Child

Urinary Tract Infection Child. MRI Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis with IV contrast in the evaluation of a child >6 years of age for the initial imaging of a first febrile UTI with appropriate response to medical management. MRI Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis without IV contrast in the evaluation of a child >6 years of age for the initial imaging of a first febrile UTI with appropriate response to medical management. MRU Without and With IV Contrast There is no relevant literature to support the use of MRU in the evaluation of a child >6 years of age for the initial imaging of a first febrile UTI with appropriate response to medical management. Nuclear Medicine Cystography The NICE guidelines do not recommend cystography for patients >6 years of age with first febrile UTI [16]. Voiding Urosonography The NICE guidelines do not recommend VUS for patients >6 years of age with first febrile UTI [16]. However, VUS may be a useful study to perform based on consensus opinion. Variant 5: Child. Atypical or recurrent febrile urinary tract infections. Initial imaging. CT Abdomen and Pelvis With IV Contrast An IV contrast-enhanced CT scan can be performed selectively when there is suspicion for complications, such as renal abscess or xanthogranulomatous pyelonephritis [80-83]. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without and with IV contrast in the evaluation of a child with atypical or recurrent febrile UTI for the initial imaging. CT Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without IV contrast in the evaluation of a child with atypical or recurrent febrile UTI for initial imaging.


Urinary Tract Infection Child

Urinary Tract Infection Child. CTU Without and With IV Contrast There is no relevant literature to support the use of CTU in the evaluation of a child with atypical or recurrent febrile UTI for initial imaging. DMSA Renal Scan A DMSA renal scan may have limited benefit in patients with VUR and atypical, complicated, or recurrent UTIs. A normal DMSA scan in patients with recurrent infections may exclude high-grade reflux on VCUG and thus direct toward antibiotic treatment without the need for invasive VCUG. The NICE guidelines recommend DMSA renal scan 4 to 6 months after atypical or recurrent infection (<3 years) and for recurrent infection (>3 years) in children [83]. The literature in this patient population is evolving with a focus on other modalities such as VUS and fluoroscopy VCUG. It should be noted that the primary evidence supporting use of DMSA renal scan is generally older than that of other modalities. Fluoroscopy Voiding Cystourethrography Children with recurrent UTIs have an increased prevalence of VUR [43]. Based on multiple studies in a pooled cohort of infants after first UTI and recurrent UTI, the frequency of VUR increases from 35% to 74%, with increased risk for renal scarring with each UTI [1]. A finding of VUR without dilatation of urinary tract may lead to antibiotic prevention treatment, and a finding of dilated VUR may lead to endoscopic or surgical treatment. VCUG is routinely performed for children <6 months of age with atypical UTI and from 6 months to 3 years of age with atypical UTI and abnormalities on renal and bladder US, poor urine flow, or family history of VUR as per the NICE guidelines Urinary Tract Infection-Child [83]. VCUG is not recommended by NICE guidelines for children >3 years of age with UTI, even if atypical or recurrent UTI [16]. The AAP guidelines suggest VCUG for children 2 to 24 months of age after the second febrile UTI and after the first for patients with abnormalities on renal and bladder US [41].


Urinary Tract Infection Child

Urinary Tract Infection Child. MRI Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis with IV contrast in the evaluation of a child with atypical or recurrent febrile UTI for initial imaging. MRI Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis without IV contrast in the evaluation of a child with atypical or recurrent febrile UTI for initial imaging. MRU Without and With IV Contrast There is no relevant literature to support the use of MRU in the evaluation of a child with atypical or recurrent febrile UTI for initial imaging. Nuclear Medicine Cystography There is good correlation between nuclear medicine cystography and VCUG for the detection of reflux [19]. For more information, please see the fluoroscopic VCUG section. The literature in this patient population is evolving with a focus on other modalities such as VUS and fluoroscopy VCUG. It should be noted that the primary evidence supporting use of nuclear cystography is generally older than that of other modalities. US Kidneys and Bladder In children with atypical, recurrent, or complicated UTI, the main benefit of US is the detection of underlying abnormalities, calculi, or complications such as a renal or perirenal abscess [82,84]. The potential harm of using US as the only imaging for UTI is the poor sensitivity for VUR and pyelonephritis/scarring [25-30,64]. There are limited data showing inconsistent results on the sensitivity of US in the detection of dilated VUR [65,66]. Grayscale US identifies approximately 25% of the patients with acute pyelonephritis and approximately 40% of the patients with chronic parenchymal scarring [29,31,67-72]. In a retrospective study of 2,259 children <5 years of age, sensitivity was related to criteria for the definition of a normal study.


Urinary Tract Infection Child

Urinary Tract Infection Child. With the use of the most relaxed criteria (25% abnormal), US had a sensitivity of 28% (specificity of 77%), and with the most stringent criteria (4% abnormal), US had a sensitivity of 5% (specificity of 97%) [31]. Assuming a 40% prevalence of VUR and a 20% recurrent rate of UTIs in 100 children who have US, up to 11 children will have positive US studies that will be followed by a VCUG study, of which 8 will be positive for VUR. Two years of a prophylactic antibiotic will decrease recurrent UTIs from up to 2 children to 1 child. This means that 1 child will benefit from the US study and an additional 3 children that may benefit from prophylactic antibiotic will not be treated. In addition, with the increased use of prenatal US screening, the yield of detection of unknown renal abnormalities in children with UTIs has decreased [73]. Few studies with small series of children suggest good correlation between power Doppler US and Tc-99m DMSA findings of pyelonephritis [74,75]. Other studies; however, demonstrated a low sensitivity for pyelonephritis and a low prediction for development of renal scarring [49,76,77]. Therefore, the use of power Doppler US as a replacement for nuclear medicine cystography is not useful [26,49,76]. The NICE guidelines for UTI recommend US if the infection is atypical for all ages or recurrent [16]. The AAP guidelines recommend US for children with a febrile UTI from ages 2 to 24 months [41]. Urinary Tract Infection-Child Variant 6: Child. Established vesicoureteral reflux. Follow-up imaging. CT Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis with IV contrast in the evaluation of a child with established VUR for follow-up imaging. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without and with IV contrast in the evaluation of a child with established VUR for follow-up imaging.


Urinary Tract Infection Child

Urinary Tract Infection Child. CT Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of CT abdomen and pelvis without IV contrast in the evaluation of a child with established VUR for follow-up imaging. CTU Without and With IV Contrast There is no relevant literature to support the use of CTU in the evaluation of a child with established VUR for follow-up imaging. DMSA Renal Scan Approximately one-fifth of children may have renal damage after UTI, with significant risk for deterioration [85]. DMSA may be considered for follow-up of children with VUR to detect new renal scarring, especially after a febrile UTI or when renal US is abnormal [61]. Fluoroscopy Voiding Cystourethrography VCUG is recommended by the American Urological Association between 12 and 24 months after UTI with longer intervals between follow-up studies in patients in whom evidence supports lower rates of spontaneous resolution (ie, those with higher grades of VUR [grades III-V], bladder/bowel dysfunction, and older age) [61]. MRI Abdomen and Pelvis With IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis with IV contrast in the evaluation of a child with established VUR for follow-up imaging. MRI Abdomen and Pelvis Without IV Contrast There is no relevant literature to support the use of MRI abdomen and pelvis without IV contrast in the evaluation of a child with established VUR for follow-up imaging. MRU Without and With IV Contrast MRU has been suggested as a safer alternative to scintigraphy in children with VUR, particularly those who require follow-up imaging [86,87]. This is pertinent for follow-up imaging of VUR causing renal scarring.


Diffuse Lung Disease

Diffuse Lung Disease.  Some of the DLDs, such as idiopathic pulmonary fibrosis, demonstrate episodes of acute exacerbation or acute deterioration as a result of the intrinsic DLD itself. These episodes typically manifest with a 1 to 2 month prodrome of worsening dyspnea or cough and progressive lung disease [11-16]. The development of acute exacerbations is not rare and has significant impact on mortality [17]. Clinically, these episodes frequently overlap with other causes of respiratory illness, such as infection, pulmonary embolism, heart failure, or malignancy. These other causes of acute clinical decline are outside the scope of this work and are best addressed in other ACR Appropriateness Criteria documents. 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 Diffuse Lung Disease evaluation of DLD distribution [23-26]. In this document, statements regarding the appropriateness of non-contrast CT include the use of such HRCT sequences based on the suspected DLD and clinical questions. FDG-PET/CT Skull Base to Mid-Thigh There is limited research supporting the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT in some DLDs, which does not currently support the use of FDG-PET/CT for initial imaging. FDG-PET/CT may have a secondary role for evaluation of some DLDs because of increased FDG activity that correlates with disease severity and prognosis. A majority of relevant studies focus on sarcoidosis and a minority on fibrotic DLD including idiopathic pulmonary fibrosis [85-105]. MRI Chest There is limited research supporting the use of MRI in DLDs, which does not currently support the use of MRI for initial imaging.


Diffuse Lung Disease

Diffuse Lung Disease. Small studies have shown adequate concordance of MRI findings with CT in established cases of DLD utilizing a variety of specialized MRI sequences. Some MRI sequences in the setting of DLD may provide additional functional information such as tissue characterization, gas transfer efficiency, and lung elasticity [106- 118]. Diffuse Lung Disease chest radiograph at time of initial diagnosis of DLD may assist with diagnosis of these other conditions via radiograph on follow-up. FDG-PET/CT Skull Base to Mid-Thigh There is limited research supporting the use of FDG-PET/CT in some DLDs, which does not currently support FDG-PET/CT for imaging of acute exacerbation or acute deterioration of DLD. MRI Chest There is limited research supporting the use of MRI in some DLDs, none of which currently supports the use of MRI for imaging of acute exacerbation or acute deterioration of DLD. FDG-PET/CT Skull Base to Mid-Thigh There is limited research supporting the use of FDG-PET/CT in DLDs. In sarcoidosis, FDG-PET/CT can be used as a marker of disease extent and severity, and it can assist in follow-up and monitoring of treatment response [86,87,89,92,93,95,96,98-100]. Research supporting the use of FDG-PET/CT is more limited in other DLDs but has been evaluated in some studies of lung fibrosis [90,91,102]. Diffuse Lung Disease MRI Chest There is limited research supporting the use of MRI in DLD, none of which currently supports the use of MRI for follow-up imaging. Small studies have shown adequate concordance of MRI findings with CT in established cases of DLD utilizing a variety of specialized MRI sequences. Some MRI sequences in the setting of DLD may provide additional functional information such as tissue characterization, gas transfer efficiency, and lung elasticity. [106- 118]. Radiography Chest There is no research supporting the use of chest radiography over CT for follow-up imaging of confirmed DLD without acute clinical deterioration.


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus.  Introduction/Background The Centers for Disease Control and Prevention National Diabetes Statistics Report of 2017 states that 30.3 million people in the United States have diabetes (9.4% of the population) [1]. Diabetes-related foot complications, such as soft-tissue infection, osteomyelitis, and neuropathic osteoarthropathy, account for up to 20% of all diabetic-related North American hospital admissions, with up to $1.5 billion spent annually in the United States on diabetic foot ulcer care [2]. Neuropathic changes in the foot are present in about 1% of diabetics [3]. Neuropathic osteoarthropathy is a progressive process affecting the bones, joints, and soft tissue of the foot and ankle. Delay in the diagnosis may lead to derangement of the bony architecture of the foot, deformity, recurrent foot ulcerations, cellulitis, osteomyelitis, and amputation [4]. Discussion of Procedures by Variant Variant 1: Suspected osteomyelitis of the foot in patients with diabetes mellitus. Initial imaging. Radiography Foot Radiographs are useful as the initial screening examination. They evaluate anatomic detail and previous surgeries and are useful to evaluate for other causes of pain, such as radiopaque foreign body, soft-tissue gas, fracture, degenerative changes, neuropathic arthropathy, or tumor. Radiographs are insensitive in the detection of early stages of acute osteomyelitis [11]. Soft-tissue swelling and obscuration of the fat planes will precede osseous changes [12]. Osseous changes may take 10 to 12 days to develop in adults [13]. Early bony changes of osseous infection include periosteal reaction, lytic bone destruction, endosteal scalloping, osteopenia, loss of trabecular architecture, and new bone apposition [13]. CT Foot There is no relevant literature to support the use of CT with or without intravenous (IV) contrast as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot.


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. 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 Suspected Osteomyelitis of the Foot MRI Foot There is no relevant literature to support the use of MRI with or without IV contrast as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot. FDG-PET/CT Whole Body There is no relevant literature to support the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot. WBC Scan and Sulfur Colloid Scan Foot There is no relevant literature to support the use of a dual isotope WBC with sulfur colloid scan as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot. WBC Scan Foot There is no relevant literature to support the use of In-111 WBC scan as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot. 3-phase Bone Scan and WBC Scan and Sulfur Colloid Scan Foot There is no relevant literature to support the use of combined imaging with 3-phase bone scan and In-111 WBC scan and Tc-99m sulfur colloid scan as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot. 3-phase Bone Scan and WBC Scan Foot There is no relevant literature to support the use of a 3-phase bone scan with In-111 WBC as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot.


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. 3-phase Bone Scan Foot There is no relevant literature to support the use of a 3-phase bone scan as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot. US Foot There is no relevant literature to support the use of ultrasound (US) as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot. 3-phase Bone Scan and WBC Scan with SPECT or SPECT/CT foot There is no relevant literature to support the use of single-photon emission computed tomography (SPECT/CT) as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot. Variant 2: Soft-tissue swelling without ulcer. Suspected osteomyelitis or early neuropathic arthropathy changes of the foot in patients with diabetes mellitus. Additional imaging following radiographs. The likelihood of developing osteomyelitis without an associated wound or ulceration is extremely low. Almost all osteomyelitis and soft-tissue abscesses of the diabetic foot represent areas of contiguous infection from adjacent skin ulcerations and not hematogenous seeding [14]. Any imaging modality performed for this variant should be able to identify soft-tissue infections, tumors and abscesses, early neuropathic arthropathy, or subtle fractures not revealed on initial radiographs. Diabetic foot osteomyelitis and neuroarthropathy can be difficult to differentiate clinically. The early diagnosis of neuropathic disease prior to the development of radiographic change is important, as these patients will be treated with altered footwear and orthotics to prevent the progression to deformity. US Foot US is of limited benefit in the detection of adult osteomyelitis because of its inability to penetrate the cortex of the bone. The role of US in the diabetic foot includes detection of subperiosteal and soft-tissue abscesses, tenosynovitis, joint effusions, and radiolucent foreign bodies.


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. US is insensitive to the marrow edema and trabecular microfractures present in neuropathic foot. CT Foot CT is able to image large anatomic regions rapidly with multiplanar reconstruction capability. CT with or without IV contrast demonstrates the features of acute osteomyelitis, such as periosteal reaction, endosteal scalloping, and lytic bone destruction, more clearly and in more detail than on radiographs but is less sensitive than MRI and nuclear medicine studies for detecting early intramedullary changes of acute osteomyelitis [15]. Features of chronic osteomyelitis (sequestra, involucrum, cloaca, sinus tracts) are well depicted on CT with or without IV contrast. CT with or without IV contrast may be superior to MRI for the findings of sequestra, foreign bodies, and Suspected Osteomyelitis of the Foot soft-tissue gas [16]. CT with or without IV contrast is more sensitive than radiographs to osseous changes allowing earlier detection of neuropathic arthropathy changes of debris, fragmentation, disruption, and dislocation [3,17]. When metal is present in or near the area of interest, there is significant loss of image resolution that is due to a beam-hardening artifact [13]. Dual-energy CT may be useful for metal artifact reduction if available. With high-resolution multiplanar imaging, CT is able to delineate the anatomic extent of soft-tissue infections. Contrast is preferred for the evaluation of soft-tissue infection and delineation of fluid collections [16]. MRI Foot MRI with or without enhancement demonstrates excellent soft-tissue contrast and sensitivity to marrow abnormalities [18,19] with high-resolution detail in multiple anatomic planes. The likelihood of osteomyelitis without an associated wound or ulceration is extremely low.


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. MRI with or without enhancement is a good modality to identify other potential sources of pain in this variant, such as soft-tissue infections, tumors and abscesses, early neuropathic arthropathy, or subtle fractures. Normal marrow signal reliably excludes osteomyelitis [20]. Positive cases of osteomyelitis demonstrate decreased T1-weighted bone marrow signal and increased signal on fluid-sensitive sequences [21,22]. Some authors suggest increased T2-weighted bone marrow signal may represent early osteomyelitis or be a predictor of later development of osteomyelitis, even in the setting of a normal T1-weighted signal [2]. MRI with or without enhancement is often the modality of choice in this variant because of its high sensitivity for osteomyelitis [23-25]. MRI with or without IV contrast can detect the earliest findings of neuropathic arthropathy, such as marrow edema and trabecular microfractures [17,26]. A negative MRI indicates that acute neuropathic arthropathy is unlikely [27]. MRI may be limited by artifact secondary to orthopedic hardware. 3-phase Bone Scan Foot The 3-phase bone scan is sensitive but not specific in differentiating osteomyelitis from a neuropathic foot since both processes cause increased osteoblastic activity [30]. Pathologies with high bone turnover, such as fracture, neuroarthropathy, malignancy, or recent surgery, may result in a positive scan in the absence of infection. A negative bone scan excludes infection with a high degree of certainty [31]. Nuclear medicine modalities are useful in cases where infection is multifocal or when the infection is associated with orthopedic hardware or chronic bone alterations from trauma or surgery.


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. 3-phase Bone Scan and WBC Scan Foot The combined bone scan and labeled leukocyte scan (In-111 or Tc-99m) markedly improves specificity in the nonmarrow-containing skeleton when there has been previous surgery, radiographs are abnormal, or when any other cause for bone remodeling is present [32]. It can be useful for distinguishing true WBC accumulation secondary to osteomyelitis from nonspecific WBC uptake that is seen in neuropathic joint [32,33]. Planar scintigraphic imaging modalities alone have relatively low spatial resolution and lack anatomic specificity. Nuclear medicine modalities are useful in cases where infection is multifocal or when the infection is associated with orthopedic hardware or chronic bone alterations from trauma or surgery. WBC Scan Foot Labeled leukocyte imaging is advantageous for imaging acute infection in immunocompetent patients with intact chemotaxis. The modality is most useful for identifying neutrophil-mediated inflammatory processes, such as bacterial infections, because the majority of leukocytes labeled are neutrophils, and it is less useful in illnesses in which the predominant cellular response is other than neutrophilic, such as tuberculosis. Chronicity of infection and nonspecific inflammation may lead to inconsistent results, and a recent onset neuropathic joint may yield false-positive results [34,35]. Planar scintigraphic imaging modalities have relatively low spatial resolution and lack of anatomic specificity. Nuclear medicine modalities are useful in cases where infection is multifocal or when the infection is associated with orthopedic hardware or chronic bone alterations from trauma or surgery. Suspected Osteomyelitis of the Foot WBC Scan and Sulfur Colloid Scan Foot Combined labeled leukocyte and sulfur colloid bone marrow imaging is most useful when increased labeled leukocyte activity is secondary to altered bone marrow distribution, such as around joint prosthesis [36].


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. Labeled leukocytes and sulfur colloid normally accumulate in bone marrow, and discordant labeled white cell activity without corresponding sulfur colloid uptake indicates infection [37]. Planar scintigraphy imaging modalities alone have relatively low spatial resolution and lack anatomic specificity. Nuclear medicine modalities are useful in cases where infection is multifocal or when the infection is associated with orthopedic hardware or chronic bone alterations from trauma or surgery. 3-phase Bone Scan and WBC Scan and Sulfur Colloid Scan Foot Combined labeled leukocyte and sulfur colloid bone marrow imaging is most useful when increased labeled leukocyte activity is secondary to altered bone marrow distribution, such as around joint prostheses [36]. In evaluating arthroplasties, positive bone scan and WBC uptake with no uptake on the bone marrow scan is considered positive for infection [38]. This modality may be helpful when significant metal hardware is present that would impair MRI or CT imaging. Planar scintigraphic imaging modalities have relatively low spatial resolution and lack anatomic specificity. Nuclear medicine modalities are useful in cases where infection is multifocal or when the infection is associated with orthopedic hardware or chronic bone alterations from trauma or surgery. FDG-PET/CT Whole Body FDG-PET/CT has potentially an important role in diagnosing deep soft-tissue infection and osteomyelitis and in differentiating neuropathic arthropathy [39,40]. The high resolution of FDG-PET/CT offers an advantage over single-photon emitting tracers, particularly when evaluating precise localization of radiotracer accumulation in bones of the distal forefoot, where the majority of diabetic foot infections occur [41]. Fused FDG-PET/CT allows correct differentiation between osteomyelitis and soft-tissue infection [42,43].


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. FDG-PET/CT can be used in the evaluation of patients with metal implants that would compromise the accuracy of MRI or CT [40]. Prior studies have demonstrated high accuracy in the detection of osteomyelitis in cases complicated by prior surgery, trauma, and the presence of orthopedic hardware [44-46]. 3-phase Bone Scan and WBC Scan with SPECT or SPECT/CT Foot Planar scintigraphic imaging modalities have relatively low spatial resolution and lack anatomic specificity. SPECT/CT fused imaging improves the diagnostic accuracy mainly because of accurate anatomic localization [47-50]. Dual isotope SPECT/CT is reported to be more accurate than bone scan SPECT/CT or WBC-SPECT/CT alone [51]. Variant 3: Soft-tissue swelling with ulcer. Suspected osteomyelitis of the foot in patients with diabetes mellitus with or without neuropathic arthropathy. Additional imaging following radiographs. Imaging plays a central role in characterizing soft-tissue and osseous infections in the diabetic foot by identifying the location, evaluating the extent of involvement, and detecting complications, such as soft-tissue abscesses or sinus tracts. The infected ulcer may progress to soft-tissue abscess, sinus tract, infected tendon sheath, osteomyelitis, or septic arthritis [29]. If an ulcer with a positive probe-to-bone test is present, the risk of osteomyelitis is 12% to 66% [52-54]. The role of any imaging modality in these patients is to confirm the presence of soft-tissue or osseous infection and determine the anatomic extent for treatment planning. US Foot US demonstrates limited benefit in the detection of adult osteomyelitis because of its inability to penetrate the cortex of the bone. The role of US in the diabetic foot includes detecting subperiosteal and soft-tissue abscesses, tenosynovitis, joint effusions, and radiolucent foreign bodies. US is insensitive to the marrow edema and trabecular microfractures present in neuropathic foot.


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. CT Foot CT is able to image large anatomic regions rapidly with multiplanar capability. CT with or without IV contrast demonstrates the features of acute osteomyelitis, such as periosteal reaction, endosteal scalloping, and lytic bone destruction, more clearly and in more detail than on radiographs, but is less sensitive than MRI and nuclear medicine studies for detecting early intramedullary changes of acute osteomyelitis [15]. Features of chronic osteomyelitis (sequestra, involucrum, cloaca, sinus tracts) are well depicted on CT with or without IV contrast. CT with or without IV contrast may be superior to MRI for the findings of sequestra, foreign bodies, and soft- tissue gas [16]. CT with or without IV contrast is more sensitive than radiographs to osseous changes, allowing Suspected Osteomyelitis of the Foot earlier detection of neuropathic arthropathy changes of debris, fragmentation, disruption, and dislocation [3,17]. When metal is present in or near the area of interest, there is significant loss of image resolution that is due to a beam-hardening artifact [13]. Dual-energy CT may be useful for metal artifact reduction if available. With high- resolution multiplanar imaging, CT is able to delineate the anatomic extent of soft-tissue infections. Contrast is preferred for the evaluation of soft-tissue infection and delineation of fluid collections [16]. MRI Foot MRI with or without enhancement is the favored modality in this variant and has demonstrated high sensitivity (90%) and specificity (83%) for early osteomyelitis in a large meta-analysis [23]. MRI with or without enhancement demonstrates excellent soft-tissue contrast and sensitivity to marrow abnormalities [18,19] with high-resolution detail in multiple anatomic planes. Normal marrow signal reliably excludes osteomyelitis [20]. Positive cases of osteomyelitis demonstrate decreased T1-weighted bone marrow signal and increased signal on fluid-sensitive sequences [21,22].


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. Some authors suggest increased T2-weighted bone marrow signal may represent early osteomyelitis or be a predictor of later development of osteomyelitis, even in the setting of a normal T1-weighted signal [2]. The high resolution can delineate the anatomic extent of osteomyelitis and assist in surgical planning [29]. MRI with or without IV contrast can detect the earliest findings of neuropathic arthropathy, such as marrow edema and trabecular microfractures [17,26]. A negative MRI indicates that acute neuropathic arthropathy is unlikely [27]. MRI may be limited by artifact secondary to orthopedic hardware. 3-phase Bone Scan Foot The 3-phase bone scan is sensitive but not specific in differentiating osteomyelitis from a neuropathic foot since both processes cause increased osteoblastic activity [30]. Pathologies with high bone turnover, such as fracture, neuroarthropathy, malignancy, or recent surgery, may result in a positive scan in the absence of infection. A negative bone scan excludes infection with a high degree of certainty [31]. Nuclear medicine modalities are useful in cases where infection is multifocal or when the infection is associated with orthopedic hardware or chronic bone alterations from trauma or surgery. In the setting of deep soft-tissue ulceration, positive uptake in the adjacent bone is highly suggestive of osteomyelitis. 3-phase Bone Scan and WBC Scan Foot The combined bone scan and labeled leukocyte scan (In-111 or Tc-99m) markedly improves specificity in the nonmarrow-containing skeleton when there has been previous surgery, radiographs are abnormal, or when any other cause for bone remodeling is present [32]. It can be useful for distinguishing true WBC accumulation secondary to osteomyelitis from nonspecific WBC uptake that is seen in neuropathic joint [32,33]. Planar scintigraphic imaging modalities alone have relatively low spatial resolution and lack anatomic specificity.


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. Nuclear medicine modalities are useful in cases where infection is multifocal or when the infection is associated with orthopedic hardware or chronic bone alterations from trauma or surgery. WBC Scan Foot Labeled leukocyte imaging is advantageous for imaging acute infection in immunocompetent patients with intact chemotaxis. The modality is most useful for identifying neutrophil-mediated inflammatory processes, such as bacterial infections, because the majority of leukocytes labeled are neutrophils, and it is less useful in illnesses in which the predominant cellular response is other than neutrophilic, such as tuberculosis. Chronicity of infection and nonspecific inflammation may lead to inconsistent results, and a recent onset neuropathic joint may yield false-positive results [34,35]. Planar scintigraphic imaging modalities have relatively low spatial resolution and lack of anatomic specificity. Nuclear medicine modalities are useful in cases where infection is multifocal or when the infection is associated with orthopedic hardware or chronic bone alterations from trauma or surgery. WBC Scan and Sulfur Colloid Scan Foot Combined labeled leukocyte and sulfur colloid bone marrow imaging is most useful when increased labeled leukocyte activity is secondary to altered bone marrow distribution, such as around joint prosthesis [36]. Labeled Suspected Osteomyelitis of the Foot leukocytes and sulfur colloid normally accumulate in bone marrow, and discordant labeled white cell activity without corresponding sulfur colloid uptake indicates infection image [37]. Planar scintigraphic imaging modalities alone have relatively low spatial resolution and lack anatomic specificity. Nuclear medicine modalities are useful in cases where infection is multifocal or when the infection is associated with orthopedic hardware or chronic bone alterations from trauma or surgery.


Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus. 3-phase Bone Scan and WBC Scan and Sulfur Colloid Scan Foot Combined labeled leukocyte and sulfur colloid bone marrow imaging is most useful when increased labeled leukocyte activity is secondary to altered bone marrow distribution, such as around joint prostheses [36]. In evaluating arthroplasties, positive bone scan and WBC uptake with no uptake on the bone marrow scan is considered positive for infection [38]. This modality may be helpful when significant metal hardware is present that would impair MRI or CT imaging. Planar scintigraphic imaging modalities have relatively low spatial resolution and lack anatomic specificity. Nuclear medicine modalities are useful in cases where infection is multifocal or when the infection is associated with orthopedic hardware or chronic bone alterations from trauma or surgery. FDG-PET/CT Whole Body FDG-PET/CT has potentially an important role in diagnosing deep soft-tissue infection and osteomyelitis and differentiating neuropathic arthropathy [39,40]. The high resolution of FDG-PET/CT offers an advantage over single-photon emitting tracers, particularly when evaluating precise localization of radiotracer accumulation in bones of the distal forefoot, where the majority of diabetic foot infections occur [41]. Fused FDG-PET/CT allows correct differentiation between osteomyelitis and soft-tissue infection [42,43]. FDG-PET/CT can be used in the evaluation of patients with metal implants that would compromise the accuracy of MRI or CT [40]. Previous studies have demonstrated high accuracy in the detection of osteomyelitis in cases complicated by prior surgery, trauma, and the presence of orthopedic hardware [44-46]. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.


Adrenal Mass Evaluation

Adrenal Mass Evaluation.  Introduction/Background An adrenal incidentaloma is an unsuspected asymptomatic mass, usually detected on a radiologic study that was obtained for purposes unrelated to adrenal disease [1,2]. The prevalence of incidentally discovered adrenal masses ranges from 4% to 10% on radiological studies, depending on patient age, and from 1% to 8.7% in autopsy specimens [3]. The majority of incidentalomas are benign and most are nonhyperfunctioning adenomas. The prevalence of adenomas in the general population ranges from 1% to 2% [4], although autopsy studies have shown rates as high as 6.6% to 8.7%, depending on the age distribution of the patients. The risk of primary adrenocortical carcinoma in the general population is quite small, on the order of 0.06%; however, among patients with known adrenal masses, the risk is reported to be as high as 4.7% [4]. Other adrenal malignancies, such as angiosarcoma, lymphoma, and pheochromocytoma, are rare in the general population. Many other criteria are involved in the assessment of incidental adrenal masses, including size, growth or stability, and endocrine function. Size is an important variable in predicting malignancy of an incidentally discovered adrenal mass. Smaller lesions are usually benign [11]; therefore, incidental adrenal masses with <1 cm short axis measurement do not generally require further evaluation because of the overwhelming likelihood that these lesions are benign [12]. Conversely, larger lesions have a greater likelihood of being malignant. In addition, interval growth of adrenal masses has also been advocated as a potential indicator of malignancy. If prior imaging is available, and a lesion has been stable for 1 year or more, it can generally be considered benign [12,13]. Even though incidentally discovered adrenal masses are by definition asymptomatic, a proportion will show subclinical function. Current guidelines from the Association of Clinical Endocrinologist and American Association aCleveland Clinic, Cleveland, Ohio.


Adrenal Mass Evaluation

Adrenal Mass Evaluation. bCleveland Clinic, Cleveland, Ohio. cPanel Chair, Northwestern University, Chicago, Illinois. dPanel Vice-Chair, UT Southwestern Medical Center, Dallas, Texas. eUniversity of Rochester Medical Center, Rochester, New York. fThe University of Texas MD Anderson Cancer Center, Houston, Texas. gUniversity of Washington, Seattle, Washington; American Urological Association. hDuke University Medical Center, Durham, North Carolina. iEmory University School of Medicine, Atlanta, Georgia. jThomas Jefferson University Hospital, Philadelphia, Pennsylvania. kBrigham & Women's Hospital, Boston, Massachusetts. lCleveland Clinic, Cleveland, Ohio. mMedical University of South Carolina, Charleston, South Carolina; American Urological Association. nUniversity of Alabama at Birmingham, Birmingham, Alabama. oUniversity of California San Francisco School of Medicine, San Francisco, California. pJohns Hopkins University School of Medicine, Washington, District of Columbia. qUniversity of Maryland School of Medicine, Baltimore, Maryland. rRhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, Rhode Island. sSpecialty Chair, University of Alabama at Birmingham, Birmingham, Alabama. 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 Adrenal Mass Evaluation of Endocrine Surgeons recommend biochemical evaluation of all adrenal incidentalomas to exclude presence of hyperfunctioning lesion [14]. Special Imaging Considerations Adrenal CT A dedicated adrenal CT protocol consists of unenhanced thin-section images through the upper abdomen with axial and coronal reformatted images.