Jaundice

Jaundice. Therapeutic endoscopic intervention, including sphincterotomy, can remove the CBD stone and may be curative when done prior to cholecystectomy (keeping in mind that up to 5% of patients may be recurrent primary CBD stone formers), but it has associated morbidity of up to 10% because of the risk of iatrogenic pancreatitis [53,72]. ERCP is limited in the evaluation of patients with previous gastroenteric anastomoses, as it is technically difficult to advance the endoscope into the biliopancreatic limb of the anastomosis. ERCP also remains the standard procedure for stent placement in cases of obstructive jaundice. When deployed for distal CBD strictures, stenting via ERCP is successful in more than 90% of cases [115]. For diagnostic yield from ERCP-guided FNA of biopsies of solid pancreatic neoplasms, ERCP demonstrated sensitivity between 57.1% (for pancreatic body/tail neoplasms) and 82.4% (for pancreatic head neoplasms) [116]. In patients with suspected sclerosing cholangitis or biliary stricture, ERCP should be performed with caution, as suppurative cholangitis may be induced by endoscopic catheter manipulation of an obstructed biliary system [53]. MRCP findings may guide directed approaches, such as ERCP, with brushing, percutaneous transhepatic biliary stenting, or reconstructive surgery [34,51-53,62,63]. Jaundice Studies from the gastroenterology literature show that ERCP has equivalent or greater sensitivity for tumor detection (provided the tumor is in the pancreatic head/duodenum or CBD), with superior sensitivity particularly for ampullary carcinoma, but it does not provide staging information for operability [76]. Tissue diagnosis can be obtained by endoscopically directed brushing or guided US with FNA [71,76,78,117,118]; however, results of brush cytology for biliary strictures from pancreatic malignancies are inferior (46% sensitive) relative to biliary malignancies (68%) [119].


Jaundice

Jaundice. In patients with suspected malignant biliary obstruction and negative or equivocal CT or MRI examinations, ERCP with EUS may provide an imaging and cytologic diagnosis (FNA) [78,120]. As an interventional procedure, ERCP has risk of between 4% (111 of 2,769) to 5.2% (872 of 16,855) for major complications (pancreatitis, cholangitis, hemorrhage, and perforation), with a 0.4% (11 of 2,769) mortality risk [69,70]. These factors need to be weighed against the potential benefits of ERCP [53,68,71,72]. The main indication for ERCP remains management of CBD stones, which can be cleared in 80% to 95% of cases [71,73]. ERCP also remains the standard procedure for stent placement in cases of obstructive jaundice. When deployed for distal CBD strictures, stenting via ERCP is successful in more than 90% of cases [115]. For diagnostic yield from ERCP-guided FNA of biopsies of solid pancreatic neoplasms, ERCP demonstrated sensitivity between 57.1% (for pancreatic body/tail neoplasms) and 82.4% (for pancreatic head neoplasms) [116]. Endoscopic or percutaneous transhepatic biliary drainage is appropriate for patients who are not candidates for surgery and may even be useful in operative candidates for whom there is a delay to definitive surgical resection. Standard ERCP is sufficient in 90% to 95% of patients who require biliary decompression. Factors that contribute to ERCP failure include gastric outlet or duodenal obstruction that is due to tumor invasion, or altered anatomy from diverticula or prior surgery. Percutaneous transhepatic cholangiography as well as EUS-guided biliary drainage are both effective for biliary decompression [117]. US Abdomen Endoscopic EUS is an invasive procedure that is typically performed by gastroenterologists or general surgeons in an interventional suite or operating room under general anesthesia and requires advancing an endoscope equipped with an US probe into the duodenum, with sonographic images obtained of the pancreaticobiliary tree.


Jaundice

Jaundice. EUS may be performed with a concomitant FNA or biopsy. EUS offers high-resolution sonographic imaging of the head of the pancreas/distal CBD, and as such can be used to detect small distal biliary ductal calculi, can locally stage pancreatic or periampullary neoplasms, and can guide FNA or biopsy [76-80]. EUS is limited by its narrow field of view and therefore cannot detect pathology outside of its imaging field of view (ie, cannot see pathology beyond the region to which the sonographic probe is physically adjacent) [81,82]. Complications from EUS have been reported in up to 6.3% of patients (most commonly postprocedural pancreatitis) [83]. The sensitivity, specificity, and accuracies of EUS with FNA biopsy for solid pancreatic tumor are 90.8%, 96.5%, and 91%, respectively [79,84,85]. Variant 3: Jaundice. Suspected medical, metabolic, or functional etiologies based on initial imaging, clinical condition, or laboratory values. No suspected mechanical obstruction. Patients with unconjugated hyperbilirubinemia (nonobstructive) jaundice most commonly have diffuse hepatocellular disease (eg, cirrhosis, hepatitis), inability of the liver to handle a bilirubin load (eg, hemolytic anemia), or a bilirubin metabolism deficiency (eg, Gilbert disease [1], Crigler-Najjar syndrome, etc). Differentiating between these nonobstructive etiologies of jaundice is typically done through analysis of characteristic history and physical examination findings, as well as diagnostic laboratory profiles. If imaging is performed in these settings, it will confirm the absence of a mechanical obstruction and may point to an alternate etiology for the elevated bilirubin levels (eg, features of liver cirrhosis) [32]. Therefore, the largest role of imaging in unconjugated hyperbilirubinemia is in excluding other potential diagnoses. Jaundice US Abdomen In the initial setting of jaundice with a laboratory and clinical picture suggestive of a lack of biliary obstruction, US is usually performed as the initial evaluation [32].


Jaundice

Jaundice. US can confirm the absence of a mechanical obstruction, with specificities ranging between 71% to 97% [20-25]. US images may suggest an alternate etiology for the elevated bilirubin (such as cirrhosis), with US having an overall sensitivity of 65% to 95%, with a positive predictive value of 98% for the detection of cirrhosis [15-19]. The most accurate finding on sonography in liver cirrhosis is a nodular surface, which is more sensitive on the undersurface of the liver than the superior surface (86% versus 53%) [15]. If the US is negative, the American College of Gastroenterology recommends additional laboratory testing assessing for liver failure, ultimately suggesting a liver biopsy [32]. MRI Abdomen MRI with MRCP may be of additional value in the setting of a negative US and clinical workup inconclusive for the etiology of the bilirubin elevation, particularly if there is concern for potential primary sclerosing cholangitis or primary biliary cirrhosis [32,105]. Proceeding directly to liver biopsy may run the risk of a false-negative biopsy, as the early disease process is patchy in the initial stages of primary sclerosing cholangitis or primary biliary cirrhosis; these diseases are nonglobal in their initial manifestations. Therefore, MRCP may help better detect pathology in these situations [121-123]. MRI may be useful when there is questionable hepatic parenchymal disease based on laboratory findings, as these modalities may show changes of early fibrosis (particularly if MR elastography is used), cirrhosis, or general hepatic inflammation [124]. Although there are not many data comparing contrast-enhanced MRI with noncontrast MRI in the setting of a nonobstructive jaundice, there are data showing that contrast administration improves the sensitivity for the detection of acute cholangitis and the detection of primary sclerosing cholangitis [125,126].


Jaundice

Jaundice. Although less sensitive than contrast-enhanced MRI, a noncontrast MRI (including MRCP) may be of use for this variant, as there are imaging findings seen on both C+ MRCP and C- MRCP. For example, both studies are useful in the assessment of subtle regions of peripheral biliary dilatation within the liver (seen in early manifestations of primary sclerosing cholangitis), in the detection of hepatolithiasis (which can occur secondary to surgical reconstructions and in the setting of recurrent pyogenic cholangitis), volume redistribution of the liver/inferior surface nodularity (seen in cirrhosis from varying underlying etiologies), detection of regions of peripheral fibrosis or other morphologic/signal abnormalities that can be associated with jaundice, and in unsuspected intra- or extrahepatic biliary strictures (from surgery or infectious etiologies) [127]. If there is concern for a previously unsuspected underlying hepatocellular disease, MRI shows a moderately high accuracy in detection of cirrhosis; a study comparing CT, MRI, and US (compared with explant livers resected for hepatocellular carcinoma at the time of transplant) found that CT had an accuracy of 67%, MRI an accuracy of 70.3%, and US an accuracy of 64% [44] for the detection of underlying cirrhosis. MRI is not very sensitive or specific for the diagnosis of acute hepatitis; however, several studies have found a significant relationship between the apparent diffusion coefficient and inflammation scores (ie, livers in the setting of acute hepatitis may have high signal on high b-value diffusion-weighted images) [128,129]. When imaging does not yield a cause for jaundice (ie, there is no biliary obstruction and no parenchymal process to explain jaundice), liver dysfunction or an infiltrative process must be excluded, and liver biopsy will be the most effective next step in diagnosis [12,32].


Jaundice

Jaundice. CT Abdomen MDCT may be useful in the setting of nonobstructive jaundice when there is questionable hepatic parenchymal disease based on laboratory findings, as these modalities may show changes of early fibrosis, cirrhosis, or general hepatic inflammation [124]. When imaging does not yield a cause for jaundice (ie, there is no biliary obstruction and no parenchymal process to explain jaundice), liver dysfunction or an infiltrative process must be excluded, and liver biopsy will be the most effective next step in diagnosis [12,32]. ERCP There is limited to no role for ERCP in the setting of nonobstructive jaundice. US Abdomen Endoscopic There is limited to no role for EUS in the setting of nonobstructive jaundice. Jaundice Summary of Recommendations Variant 1: US abdomen, CT abdomen with IV contrast, or MRI abdomen without and with IV contrast with MRCP is usually appropriate for the initial imaging of jaundice with no known predisposing conditions. These procedures are equivalent alternatives. Variant 2: CT abdomen with IV contrast, MRI abdomen without and with IV contrast with MRCP, MRI abdomen without IV contrast with MRCP, or US abdomen is usually appropriate for jaundice when initial imaging is suggestive of mechanical obstruction based on initial imaging, clinical condition, or laboratory values. These procedures are equivalent alternatives. Variant 3: MRI abdomen without and with IV contrast with MRCP, CT abdomen with IV contrast, or US abdomen is usually appropriate for jaundice when mechanical obstruction is not suspected in the setting of suspected medical, metabolic, or functional etiologies based on initial imaging, clinical condition, or laboratory values. These procedures are equivalent alternatives. 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.


Breast Implant Evaluation

Breast Implant Evaluation.  Introduction/Background Breast implants are routinely placed for augmentation and reconstruction and have been available for more than 50 years. A large variety of implants are commercially available, including saline, silicone (including form-stable varieties also known as gummy bear implants), double lumen varieties using both saline and silicone, and polyacrylamide gel. Saline-filled breast implants are inflated to the desired size with sterile isotonic saline, and silicone gel-filled breast implants contain a fixed volume of silicone gel, although silicone gel viscosity differs among implants and manufacturers [1]. aPenn State Health Hershey Medical Center, Hershey, Pennsylvania. bPanel Chair, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida. cPanel Vice-Chair, University of Cincinnati, Cincinnati, Ohio. dVirtua Willingboro Hospital, Willingboro, New Jersey; American College of Surgeons. eBoston University Schools of Medicine and Public Health, Boston, Massachusetts, Primary care physician. fUniversity of Connecticut School of Medicine, Farmington, Connecticut; American Society of Plastic Surgeons. gMemorial Sloan Kettering Cancer Center, New York, New York. hUniversity of Michigan, Ann Arbor, Michigan. iSt. Bernards Healthcare, Jonesboro, Arkansas. jUMass Memorial Medical Center/UMass Chan Medical School, Worcester, Massachusetts. kHarvard Medical School, Boston, Massachusetts; American Geriatrics Society. lCentral Oregon Radiology Associates, Bend, Oregon. mHoag Family Cancer Institute, Newport Beach, California and University of Southern California, Los Angeles, California; Commission on Nuclear Medicine and Molecular Imaging. nSpecialty Chair, Boston University School of Medicine, Boston, Massachusetts. Reprint requests to: publications@acr.org Breast Implant Evaluation


Breast Implant Evaluation

Breast Implant Evaluation. with delayed (>1 year after surgery) peri-implant effusion around a textured implant or surrounding scar capsule, usually occurring 8 to 10 years following implantation with a breast implant for either cosmetic or reconstructive indications [8-10]. Imaging options for implant evaluation include mammography, digital breast tomosynthesis (DBT), US, or MRI. However, saline implant rupture is usually clinically apparent, with diagnosis made by physical examination. Special Imaging Considerations PET/CT: For confirmed cases of BIA-ALCL, a PET scan is often beneficial for demonstrating capsular masses or chest wall involvement and is the preferred test to evaluate for systemic spread to regional or distant lymph nodes and/or organ involvement [11]. Active BIA-ALCL is positive on a PET scan [11]. On PET, BIA-ALCL demonstrates moderate fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) uptake in associated effusion or as a moderate-high focal uptake relating to masses located at the external implant fibrous capsule [12]. In addition, locally advanced disease demonstrates increased uptake beyond the capsule and is evident in involved lymph nodes [12]. FDG-PET is therefore useful for local staging as well as for disease surveillance [12]. There are; however, clinically important nuances with the use of PET/CT for evaluating BIA-ALCL. The metabolic component of PET/CT does not allow determination of whether a peri-implant effusion is benign or lymphoma related, because the cell density within the fluid is too low for an effective positron signal to be detected (ie, PET/CT does not allow distinction of benign from malignant effusions); this can result in a false-negative PET interpretation [13]. Inflammatory activity is normally observed surrounding a breast implant capsule (owing to FDG uptake by activated macrophages and granulation tissue), which can lead to a false-positive PET interpretation and confound peri- implant mass component assessment [13].


Breast Implant Evaluation

Breast Implant Evaluation. A false-positive interpretation can occur owing to FDG uptake by local- regional lymphadenopathy reactive to the in situ breast implant (at the draining axillary and internal mammary stations) [13]. A key clinical indication for PET/CT in BIA-ALCL is cervical, thoracic, abdominal, and pelvic staging for detection of distant disease, particularly in the context of mass-forming BIA-ALCL before (potentially curative) surgical resection [13]. Breast Implant Evaluation MRI Breast Without and With IV Contrast There is no role for MRI without and with intravenous (IV) contrast for implant evaluation in asymptomatic patients with saline implants [16]. The saline from the implant is resorbed by the body without significant sequelae or secondary findings in the breast. MRI Breast Without IV Contrast There is no role for MRI without IV contrast for implant evaluation in asymptomatic patients with saline implants [16]. The saline from the implant is resorbed by the body without significant sequelae or secondary findings in the breast. US Breast There is no role for US for implant evaluation in asymptomatic patients with saline implants. The saline from the implant is resorbed by the body without significant sequelae or secondary findings in the breast. Variant 2: Adult younger than 30 years of age. Female or transfeminine. Evaluation of saline breast implants. Clinical examination equivocal for implant rupture. Initial imaging. Digital Breast Tomosynthesis Diagnostic Rupture of saline implants is usually clinically evident because the saline is resorbed by the body over a period of days and the patient experiences a change in breast size and shape [16,17]. Although DBT may be useful in patients with suspected saline implant rupture and equivocal clinical findings, DBT is typically not performed as the initial imaging study in patients <30 years of age.


Breast Implant Evaluation

Breast Implant Evaluation. Mammography Diagnostic Rupture of saline implants is usually clinically evident because the saline is resorbed by the body over a period of days and the patient experiences a change in breast size and shape [16,17]. Although diagnostic mammography may be useful in patients with suspected saline implant rupture and equivocal clinical findings, diagnostic mammography is typically not performed as the initial imaging study in patients <30 years of age. MRI Breast Without and With IV Contrast There is no role for MRI without and with IV contrast in the evaluation of saline implants [16]. MRI Breast Without IV Contrast There is no role for MRI without IV contrast in the evaluation of saline implants [16]. US Breast In cases of saline implant rupture, the collapsed implant shell is visible by US, and for patients <30 years of age, an US is helpful as the initial examination. If a patient is uncertain which type of implant is in place, the implant type can be determined at US by examining the implant at its margin and witnessing the effect the implant has on surrounding normal tissue [18]. Because the speed of sound through silicone (997 m/sec) is slower than that through soft tissues and saline (1,540 m/sec), it will take longer for sound waves to travel through a silicone implant compared with through a saline-filled implant, causing a step-off appearance in silicone implants, which is not seen in saline implants [18]. Variant 3: Adult 30 to 39 years of age. Female or transfeminine. Evaluation of saline breast implants. Clinical examination equivocal for implant rupture. Initial imaging. Digital Breast Tomosynthesis Diagnostic For patients 30 to 39 years of age, DBT may be complementary to US. Rupture of saline implants is usually clinically evident because the saline is resorbed by the body over a period of days and the patient experiences a change in breast size and shape [16,17]. However, DBT may be useful in patients with suspected saline implant rupture and equivocal clinical findings.


Breast Implant Evaluation

Breast Implant Evaluation. Findings on DBT are diagnostic, in which a collapsed implant shell is visible. Mammography Diagnostic For patients 30 to 39 years of age, diagnostic mammography may be complementary to US. Rupture of saline implants is usually clinically evident because the saline is resorbed by the body over a period of days and the patient experiences a change in breast size and shape [16,17]. However, diagnostic mammography may be useful in patients with suspected saline implant rupture and equivocal clinical findings. Findings on mammography are diagnostic, in which a collapsed implant shell is visible. Breast Implant Evaluation MRI Breast Without and With IV Contrast There is no role for MRI without and with IV contrast in the evaluation of saline implants [16]. MRI Breast Without IV Contrast There is no role for MRI without IV contrast in the evaluation of saline implants [16]. US Breast For patients 30 to 39 years of age, US may be complementary to diagnostic mammography or diagnostic DBT. In cases of saline implant rupture, the collapsed implant shell is visible by US. If a patient is uncertain which type of implant is in place, the implant type can be determined at US by examining the implant at its margin and witnessing the effect the implant has on surrounding normal tissue [18]. Because the speed of sound through silicone (997 m/sec) is slower than that through soft tissues and saline (1,540 m/sec), it will take longer for sound waves to travel through a silicone implant compared with through a saline-filled implant, causing a step-off appearance in silicone implants, which is not seen in saline implants [18]. MRI Breast Without and With IV Contrast There is no role for MRI without and with IV contrast in evaluation of saline implants [16]. MRI Breast Without IV Contrast There is no role for MRI without IV contrast in the evaluation of saline implants [16]. Breast Implant Evaluation time, such as the appearance of undulations, which potentially indicate a problem with implant integrity [18].


Breast Implant Evaluation

Breast Implant Evaluation. Frank bulges or herniations represent areas of weakening of the fibrous capsule and potential weak points of the elastomer shell [18]. An implant that becomes more rounded in appearance may signify the presence of capsular contracture rather than implying a problem with implant integrity. Calcifications along the fibrous capsule, thought to arise as a consequence of a chronic inflammatory response, are more frequently encountered in older implants that have been in place for multiple years. Capsular calcifications correlate with implant age, but calcifications alone do not necessarily imply capsular contracture or implant rupture. Although insensitive for identifying intracapsular rupture, DBT is useful in detecting extracapsular silicone. When silicone escapes the confines of the fibrous capsule and enters the surrounding breast parenchyma, DBT can often reveal the high-density free silicone. In the absence of a prior history of implant rupture or revision, the presence of silicone outside the expected contour of the implant signifies extracapsular rupture and, by extension, intracapsular rupture [18,20]. MRI Breast Without and With IV Contrast There is no relevant literature to support the use of MRI without and with IV contrast in the evaluation of asymptomatic silicone implants less than 5 years after implant placement. MRI Breast Without IV Contrast There is no relevant literature to support the use of MRI without IV contrast in the evaluation of asymptomatic silicone implants less than 5 years after implant placement. Note that in the updated FDA recommendations for asymptomatic patients with silicone implants, the first US or MRI should be performed at 5 to 6 years postoperatively, then every 2 to 3 years thereafter [1]. US Breast There is no relevant literature to support the role of US breast in the evaluation of an asymptomatic patient with silicone implants that have been in place less than 5 years.


Breast Implant Evaluation

Breast Implant Evaluation. Note that in the updated FDA recommendations for asymptomatic patients with silicone implants, the first US or MRI should be performed at 5 to 6 years postoperatively, then every 2 to 3 years thereafter [1]. Breast Implant Evaluation Breast Implant Evaluation MRI Breast Without and With IV Contrast There is no relevant literature to support the use of MRI without and with IV contrast in the evaluation of asymptomatic silicone implants. MRI Breast Without IV Contrast MRI without IV contrast is helpful for imaging silicone implants. The FDA updated guidance recommends that for asymptomatic patients, the first US or MRI should be performed at 5 to 6 years postoperatively, then every 2 to 3 years thereafter [1]. T1- and T2-weighted, short tau inversion recovery, and silicone-suppressed sequences allow for optimal imaging of implant integrity [16]. There is currently no consensus on whether ruptured implants require surgery in asymptomatic patients, and the benefits of screening for implant rupture are controversial. Some authors [21] have advocated a patient-centered approach with shared decision making between the patient and surgeon rather than generalized recommendations for all patients with silicone implants. Most studies focused on symptomatic women, in whom the expected prevalence of rupture would be higher than among asymptomatic women. In addition, numerous studies evaluating the rupture rate of more modern implants have shown this rate to be low [22-25]. Studies of asymptomatic women have reported sensitivities and specificities of 64% and 77% [26], accuracy of 94% [27], sensitivity of 89%, specificity of 97%, accuracy of 92%, positive predictive value (PPV) of 99%, and negative predictive value (NPV) of 79% [28]. US Breast In the updated FDA recommendations, for asymptomatic patients with silicone implants, the first US or MRI should be performed at 5 to 6 years postoperatively, then every 2 to 3 years thereafter [1]. Variant 7: Adult younger than 30 years of age.


Breast Implant Evaluation

Breast Implant Evaluation. Female or transfeminine. Evaluation of silicone breast implants. Suspected implant complication. Initial imaging. Digital Breast Tomosynthesis Diagnostic In symptomatic patients with silicone breast implants, an MRI is recommended by the FDA to evaluate for rupture [1]. DBT is typically not performed as the initial imaging study in patients under the age of 30. Extracapsular silicone implant ruptures, although only a minority of all implant ruptures, frequently present with palpable findings or other symptoms. The diagnosis of silicone implant rupture can be challenging, however, with clinical examination known to be unreliable [19]. DBT can identify extracapsular silicone [20,29,31,35], which presents as high-density material outside the confines of the implant shell. In patients without prior explantation of silicone implants, this is diagnostic of extracapsular rupture. However, in patients who have had prior silicone implants, this Breast Implant Evaluation may represent residual silicone rather than rupture of the new implants, and comparison with priors is critical. Intracapsular silicone implant rupture is frequently asymptomatic and may not be reliably diagnosed with DBT. Mammography Diagnostic In symptomatic patients with silicone breast implants, an MRI is recommended by the FDA to evaluate for rupture [1]. Diagnostic mammography is typically not performed as the initial imaging study in patients under the age of 30. Extracapsular silicone implant ruptures, although only a minority of all implant ruptures, frequently present with palpable findings or other symptoms. The diagnosis of silicone implant rupture can be challenging, with clinical examination known to be unreliable [19]. In cases of extracapsular silicone implant rupture, the diagnosis is often made with mammography in which high-density silicone is seen outside the implant contour. Mammography does not detect intracapsular silicone implant rupture.


Breast Implant Evaluation

Breast Implant Evaluation. Both standard craniocaudal and mediolateral oblique and implant-displaced views should be obtained. Mammography can identify extracapsular silicone [20,29,31,35], which presents as high-density material outside the confines of the implant shell. In patients without prior explantation of silicone implants, this is diagnostic of extracapsular rupture. However, in patients who have had prior silicone implants, this may represent residual silicone rather than rupture of the new implants, and comparison with priors is critical. MRI Breast Without and With IV Contrast There is no relevant literature to support the use of MRI without and with IV contrast in the evaluation of symptomatic silicone implants. Breast Implant Evaluation In patients without prior explantation of silicone implants, this finding is diagnostic of extracapsular rupture. However, in patients who have had prior silicone implants, this may represent residual silicone rather than rupture of the new implants. Variant 8: Adult 30 to 39 years of age. Female or transfeminine. Evaluation of silicone breast implants. Suspected implant complication. Initial imaging. Digital Breast Tomosynthesis Diagnostic In symptomatic patients with silicone breast implants, an MRI is recommended by the FDA to evaluate for rupture [1]. However, DBT can identify extracapsular silicone. Extracapsular silicone implant ruptures, although only a minority of all implant ruptures, frequently present with palpable findings or other symptoms. The diagnosis of silicone implant rupture can be challenging, with clinical examination known to be unreliable [19]. In cases of extracapsular silicone implant rupture, the diagnosis is often made with DBT in which high-density silicone is seen outside the implant contour. DBT does not detect intracapsular silicone implant rupture. Both standard craniocaudal and mediolateral oblique and implant-displaced views should be obtained.


Breast Implant Evaluation

Breast Implant Evaluation. DBT will identify extracapsular silicone, which presents as high-density material outside the confines of the implant shell. In patients without prior explantation of silicone implants, this is diagnostic of extracapsular rupture. However, in patients who have had prior silicone implants, this may represent residual silicone rather than rupture of the new implants, and comparison with priors is critical. Breast Implant Evaluation Mammography Diagnostic In symptomatic patients with silicone breast implants, an MRI is recommended by the FDA to evaluate for rupture [1]. However, diagnostic mammography can identify extracapsular silicone. Extracapsular silicone implant ruptures, although only a minority of all implant ruptures, frequently present with palpable findings or other symptoms. The diagnosis of silicone implant rupture can be challenging, with clinical examination known to be unreliable [19]. In cases of extracapsular silicone implant rupture, the diagnosis is often made with mammography in which high-density silicone is seen outside the implant contour. Mammography does not detect intracapsular silicone implant rupture. Both standard craniocaudal and mediolateral oblique and implant-displaced views should be obtained. Mammography can identify extracapsular silicone [20,29,31,35], which presents as high-density material outside the confines of the implant shell. In patients without prior explantation of silicone implants, this is diagnostic of extracapsular rupture. However, in patients who have had prior silicone implants, this may represent residual silicone rather than rupture of the new implants, and comparison with priors is critical. MRI Breast Without and With IV Contrast There is no relevant literature to support the use of MRI without and with IV contrast in the evaluation of symptomatic silicone implants. Breast Implant Evaluation Variant 9: Adult age 40 years or older. Female or transfeminine. Evaluation of silicone breast implants. Suspected implant complication.


Breast Implant Evaluation

Breast Implant Evaluation. Initial imaging. Digital Breast Tomosynthesis Diagnostic In symptomatic patients with silicone breast implants, an MRI is recommended by the FDA to evaluate for rupture [1]. However, DBT can identify extracapsular silicone. DBT can be useful in the evaluation of suspected extracapsular silicone implant rupture, which frequently presents with palpable findings or other symptoms. The diagnosis of silicone implant rupture can be challenging, with clinical examination known to be unreliable [19]. In cases of extracapsular silicone implant rupture, the diagnosis is often made with DBT in which high-density silicone is seen outside the implant contour. DBT does not detect intracapsular silicone implant rupture. Both standard craniocaudal and mediolateral oblique and implant-displaced views should be obtained. DBT can identify extracapsular silicone [20,29-31,35], which presents as high-density material outside the confines of the implant shell. In patients without prior explantation of silicone implants, this finding is diagnostic of extracapsular rupture. However, in patients who have had prior silicone implants, this may represent residual silicone rather than rupture of the new implants, and comparison with priors is critical. Breast Implant Evaluation Mammography Diagnostic In symptomatic patients with silicone breast implants, an MRI is recommended by the FDA to evaluate for rupture [1]. However, diagnostic mammography can identify extracapsular silicone. Diagnostic mammography can be useful in the evaluation of suspected extracapsular silicone implant rupture, which frequently presents with palpable findings or other symptoms. The diagnosis of silicone implant rupture can be challenging, with clinical examination known to be unreliable [19]. In cases of extracapsular silicone implant rupture, the diagnosis is often made with mammography in which high-density silicone is seen outside the implant contour. Mammography does not detect intracapsular silicone implant rupture.


Breast Implant Evaluation

Breast Implant Evaluation. Both standard craniocaudal and mediolateral oblique and implant-displaced views should be obtained. Mammography can identify extracapsular silicone [20,29-31,35], which presents as high- density material outside the confines of the implant shell. In patients without prior explantation of silicone implants, this finding is diagnostic of extracapsular rupture. However, in patients who have had prior silicone implants, this may represent residual silicone rather than rupture of the new implants, and comparison with priors is critical. MRI Breast Without and With IV Contrast There is no relevant literature to support the use of MRI without and with IV contrast in the evaluation of symptomatic silicone implants. US Breast In symptomatic patients with silicone breast implants, an MRI is recommended by the FDA to evaluate for rupture [1]. However, US can identify extracapsular silicone. Extracapsular rupture is disruption of both the polymer and fibrous capsules with leak of silicone into the breast tissue. Rupture of silicone implants, however, may be asymptomatic, especially if the rupture is intracapsular (contained by the fibrous shell formed by the body around the implant). If the rupture is extracapsular, patients may present with palpable masses or changes in breast contour. Diagnosis of extracapsular rupture of silicone implants is often made with mammography and/or US, in which high- density silicone is identified outside the confines of the implant shell. The rate of implant ruptures increases with time, and most of them do not cause any clinical symptoms. Once an implant ruptures, free silicone can migrate. Most frequently, free silicone infiltrates the adjacent breast tissues and sometimes can mimic breast cancer. US can Breast Implant Evaluation Variant 10: Adult younger than 30 years of age. Female or transfeminine. Evaluation of unexplained axillary adenopathy. Silicone breast implants (current or prior). Initial imaging.


Breast Implant Evaluation

Breast Implant Evaluation. Digital Breast Tomosynthesis Diagnostic DBT is typically not performed as the initial imaging study in patients under the age of 30. DBT may be useful as a complementary imaging modality to evaluate unexplained axillary adenopathy in patients <30 years of age when suspicious sonographic findings are identified. Silicone within low axillary nodes may also be seen on DBT. Mammography Diagnostic Diagnostic mammography is typically not performed as the initial imaging study in patients under the age of 30. Diagnostic mammography may be useful as a complementary imaging modality to evaluate for unexplained axillary adenopathy in patients <30 years of age when suspicious sonographic findings are identified. Silicone within low axillary nodes may also be seen on diagnostic mammography. MRI Breast Without and With IV Contrast There is no relevant literature to support MRI without and with IV contrast as the initial imaging study in this setting. However, it is needed if biopsy shows axillary metastatic disease from a mammographically and sonographically occult primary breast carcinoma. MRI Breast Without IV Contrast There is no relevant literature to support MRI without IV contrast in evaluation of unexplained axillary adenopathy in patients <30 years of age because its primary function would be to identify silicone in the lymph nodes as an explanation for the adenopathy. Breast Implant Evaluation Variant 11: Adult 30 to 39 years of age. Female or transfeminine. Evaluation of unexplained axillary adenopathy. Silicone breast implants (current or prior). Initial imaging. Digital Breast Tomosynthesis Diagnostic DBT may help to evaluate unexplained axillary adenopathy in patients 30 to 39 years of age. Silicone within low axillary nodes may be seen on DBT. When DBT is performed, axillary US is complementary and may be performed at the same time. Mammography Diagnostic Diagnostic mammography may help to evaluate unexplained axillary adenopathy in patients 30 to 39 years of age.


Breast Implant Evaluation

Breast Implant Evaluation. Silicone within low axillary nodes may be seen on mammography and DBT. When mammography is performed, axillary US is complementary and may be performed at the same time. MRI Breast Without and With IV Contrast There is no relevant literature to support MRI without and with IV contrast in this setting as the initial imaging study in this setting. However, it is needed if biopsy shows axillary metastatic disease from a mammographically and sonographically occult primary breast carcinoma. MRI Breast Without IV Contrast MRI without IV contrast is of limited value in evaluation of unexplained axillary adenopathy in patients 30 to 39 years of age because its primary function would be to identify silicone in the lymph nodes as an explanation for the adenopathy. MRI Breast Without and With IV Contrast MRI without and with IV contrast may not be ideal in this setting. However, it is needed if biopsy shows axillary metastatic disease from a mammographically and sonographically occult primary breast carcinoma. Breast Implant Evaluation Variant 13: Adult of any age. Female or transfeminine. Suspected breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) (delayed seroma, swelling, mass, pain, but no erythema, warmth, or skin changes that would raise concern for inflammatory breast cancer or mastitis). Breast implant of any type. Initial imaging. Digital Breast Tomosynthesis Diagnostic If the patient is >40 years of age, DBT may be considered. DBT has a low sensitivity and specificity for BIA-ALCL, but it may be used to assess for any potential mimics or masses and other diagnoses including in situ and invasive primary breast malignancy [11,40]. In cases of BIA-ALCL, the capsule may be thickened and the membrane contour may be disrupted [11]. In general, DBT findings include nonspecific capsular thickening, circumferential asymmetry around the implant, or irregular mass [13]. DBT may detect a change in implant appearance related to a new fluid collection or an associated mass.


Breast Implant Evaluation

Breast Implant Evaluation. Distinguishing between fluid and solid tissue typically requires US. One meta-analysis [11] reported a sensitivity of 73% and a specificity of 50% for mammography in the detection of an abnormality. Mammography Diagnostic If the patient is >40 years of age, mammography may be considered. Mammography has a low sensitivity and specificity for BIA-ALCL, but it may be used to assess for any potential mimics or masses and other diagnoses including in situ and invasive primary breast malignancy [11,40]. In cases of BIA-ALCL, the capsule may be thickened and the membrane contour may be disrupted [11]. In general, diagnostic mammography findings include nonspecific capsular thickening, circumferential asymmetry around the implant, or irregular mass [13]. Diagnostic mammography may detect a change in implant appearance related to a new fluid collection or an associated mass. Distinguishing between fluid and solid tissue typically requires US. One meta-analysis [11] reported a sensitivity of 73% and a specificity of 50% for mammography in detection of an abnormality. MRI Breast Without and With IV Contrast MRI without and with IV contrast is the second imaging test of choice and may be needed when US yields indeterminate results [9,41,42]. MRI has reported sensitivity of 82% for the detection of effusion and 50% for detection of a mass, with corresponding specificities of 33% and 93%, respectively [11]. MRI breast can be considered if US is equivocal or nondiagnostic. MRI findings include peri-implant tissue edema and effusion, as well as peri-implant mass lesions, including small volume mass components not detected with US [41,42]. The principal MRI signs seen in the Rotili et al [41] study included liquid-serous effusion, peri-implant and capsule related masses, enhancement of the capsule, irregular thickness of the capsule, and subcutaneous nodules of local recurrence of ALCL after capsulectomy.


Breast Implant Evaluation

Breast Implant Evaluation. MRI Breast Without IV Contrast MRI without IV contrast may identify a fluid collection associated with the implant but is of limited value in the detection of an associated mass. US provides an easier means to assess for effusion and has the added benefit of guiding aspiration for cytologic diagnosis. MRI breast without IV contrast may serve to evaluate for the presence of implant rupture when there is a silicone implant [13]. US Breast Initial workup may include US evaluation for fluid collection, breast masses, and enlarged regional lymph nodes (axillary, supraclavicular, and internal mammary) [8,11,43]. Other symptoms can include breast enlargement, skin rash, capsular contracture, and lymphadenopathy [8]. Early recognition is critical, however, as diagnosis can often Breast Implant Evaluation be made from cytological analysis of the fluid, and patients with disease limited to the implant capsule have a much better prognosis than those with an associated mass or systemic disease [8,11,44-48]. US will frequently identify a fluid collection or mass if present and provides image guidance for diagnostic aspiration of the fluid for cytology or core biopsy of a mass lesion [4]. In cases in which a mass (or masses) is present, it most commonly appears as an oval, hypoechoic, and well-circumscribed solid mass, without hypervascularity, although a complex-cystic mass has also been observed [13]. Adrada et al [11] reported an 84% sensitivity for detection of effusion and a 46% sensitivity for detection of a mass, with a corresponding specificity of 75% and 100%, respectively. Periprosthetic effusions should undergo fine needle aspiration, and any suspicious mass should undergo tissue biopsy; specimens should be sent for cytology [4,8]. Ideally, a minimum of 50 mL of fluid should be sent to the laboratory with a specific request to evaluate for BIA-ALCL [8].


Renal Transplant Dysfunction

Renal Transplant Dysfunction.  Introduction/Background Renal transplantation is the preferred treatment method in patients with end-stage renal failure. Compared with maintenance dialysis, most patients who receive a successful transplant experience an improved quality of life and a significant reduction in mortality [1]. According to the Organ Procurement and Transplantation Network of the U.S. Health Resources and Services Administration, over 375,000 renal transplants have been performed in the United States since 1988 [2]. In 2014 alone, 17,108 renal transplants were performed, of which 11,570 were from deceased donors and 5538 were from living donors. Unfortunately, there remains a huge imbalance between organ availability and demand. Although the number of candidates on the waiting list has increased, the total number of renal transplants performed in the United States has not increased significantly in the last decade. When a renal transplant is performed, every effort is made to address allograft dysfunction by management of immunosuppression and transplant complications. Five-year survival rates for the graft in renal transplant patients range from 72% to 99%, with the best rates seen in patients receiving kidneys from living donors. Although the timing of intrinsic renal dysfunction may aid in narrowing the differential diagnosis, there is significant overlap between the various etiologies. In the immediate postoperative period (<1 week), the most common etiology of intrinsic dysfunction is acute tubular necrosis (ATN). ATN is seen in the immediate post- transplant period in a high percentage of cadaver grafts but occurs infrequently in living related donors. Acute rejection occurs from 1 week to 1 month after transplantation. Fortunately, acute rejection is an uncommon occurrence in current practice [3].


Renal Transplant Dysfunction

Renal Transplant Dysfunction. Although the introduction of calcineurin inhibitors (cyclosporine and tacrolimus) has dramatically reduced the rate of acute allograft rejection, these drugs are nephrotoxic at supratherapeutic levels [4]. Toxicity is most common in the second or third month after transplantation, when the drugs are being titrated [5]. Chronic rejection is the most common cause of late graft dysfunction and presents at least 3 months following transplantation. Like intrinsic renal dysfunction, vascular complications and peri-transplant collections are most often encountered during specific postoperative time periods. Renal artery thrombosis (RAT) and renal vein thrombosis (RVT) usually occur in the first week after transplantation. They are usually the result of technical surgical difficulties and/or clotting disorders [6]. Renal artery stenosis (RAS) is the most common vascular complication, with an incidence of 1% to 2% [6,7]. Although it can occur at any time, RAS usually presents between 3 months and 24 months following transplantation. Peri-graft collections occur in up to 50% of patients following transplantation [8]. Seromas and hematomas generally occur in the first week following surgery. Abscesses and urinomas usually occur 1 to 3 weeks after transplantation. Lymphoceles typically present 1 to 2 months after transplantation [9]. Radiology plays a critical role in the diagnosis and management of renal transplant dysfunction. Ultrasound (US) is the modality of choice to evaluate renal transplants early in the postoperative period, in the post-transplant period, and also for long-term follow-up. US is also used to guide diagnostic and therapeutic interventions, such as biopsy, nephrostomy placement, and fluid aspiration. Radionuclide imaging is a modality capable of assessing 1Principal Author, George Washington University Hospital, Washington, District of Columbia. 2Panel Vice-chair, Northwestern University, Chicago, Illinois. 3Rhode Island Hospital, Providence, Rhode Island.


Renal Transplant Dysfunction

Renal Transplant Dysfunction. 4Albert Einstein College of Medicine, Bronx, New York, Society of Nuclear Medicine and Molecular Imaging. 5University of Rochester Medical Center, Rochester, New York. 6University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, American Society of Nephrology. 7University of Washington, Seattle, Washington, American Urological Association. 8Scottsdale Medical Imaging, Scottsdale, Arizona. 9University of Utah, Salt Lake City, Utah. 10University of Pittsburgh, Pittsburgh, Pennsylvania. 11UT Southwestern Medical Center, Dallas, Texas. 12Duke University Medical Center, Durham, North Carolina, American Urological Association. 13Cleveland Clinic, Cleveland, Ohio. 14The University of Mississippi Medical Center, Jackson, Mississippi. 15University of California San Francisco School of Medicine, San Francisco, California. 16Oakland University William Beaumont School of Medicine, Troy, Michigan. 17University of Maryland School of Medicine, Baltimore, Maryland. 18Specialty Chair, Cleveland Clinic, Cleveland, Ohio. 19Panel Chair, University of Alabama at Birmingham, Birmingham, Alabama. Reprint requests to: publications@acr.org Renal Transplant Dysfunction graft function both qualitatively and quantitatively [10]. Computed tomography (CT) and magnetic resonance imaging (MRI) can provide information about structural abnormalities like arterial stenosis and arterial or venous thrombosis. Angiography is used for treatment of complications like RAS, pseudoaneurysm (PSA), and arteriovenous fistula (AVF). Ultrasound Since renal transplants typically are located anteriorly in the pelvis, they are usually readily examined with US. US is routinely used to evaluate the transplant within the first 24 hours after transplantation and also serves as the first-line evaluation method following the onset of transplant dysfunction.


Renal Transplant Dysfunction

Renal Transplant Dysfunction. Grayscale images are obtained to evaluate for transplant size, echotexture, hydronephrosis, peri-transplant fluid collections, and masses and to measure renal cortical thickness. Color Doppler images evaluate the patency and direction of flow in transplant arteries and veins. Spectral analysis of vascular waveforms and velocities can provide information about a range of pathologies, including RAS and RVT. Advantages of US over CT include portability, no radiation exposure, and the lack of need for potentially nephrotoxic iodinated contrast agents. US is fast and real time, particularly when compared to MRI. Vascular evaluation with US instead of MRI can avoid the risk of nephrogenic systemic fibrosis (NSF) from gadolinium-based contrast agents. A relative limitation of US in comparison to CT or MRI is its operator dependence. Grayscale US abnormalities in dysfunctional renal transplants include a reduction in corticomedullary differentiation, reduction in renal sinus echogenicity, increased and reduced renal parenchymal echoes, and increased cortical echogenicity. Unfortunately, these findings are of limited value as the features are nonspecific and generally occur well after the onset of transplant dysfunction. Renal segmental or intralobar artery resistive indices (RI), measured by duplex Doppler US, are often used as a nonspecific parameter for allograft dysfunction. Although RI values differ between normal and abnormal allografts, studies have suggested that the RI is neither sensitive nor specific in identifying the cause of functional transplant dysfunction [11,12]. Using RI >0.90 in 145 examinations of 81 patients, Rifkin et al [13] found a sensitivity of 13%, a specificity of 100%, a positive predictive value (PPV) of 100%, and a negative predictive value (NPV) of 66% in making the diagnosis of acute rejection with duplex Doppler US.


Renal Transplant Dysfunction

Renal Transplant Dysfunction. Genkins et al [14] found a sensitivity of 9%, a specificity of 91%, a PPV of 29%, and an NPV of 70% using an RI cutoff of 0.90 for the diagnosis of allograft rejection. Previous studies have shown that renal arterial RI is useful in predicting graft survival [15], especially when using a lower RI cutoff of 0.8. Radermacher et al [15], using a cutoff of 0.80 at 3 months after transplantation, found that 47% of patients with RI >0.80 developed chronic allograft nephropathy (CAN), compared to 9% of patients with RI <0.80. McArthur et al [16] found that both RI and pulsatility index measured between week 1 and 3 months significantly correlated with the 1-year estimated glomerular filtration rate. Although an RI >0.80 was initially thought to correlate with allograft dysfunction, a recent study by Naesens et al [17] raises doubt on this theory. Their single-center prospective study analyzed RI at the time of protocol- specified renal allograft biopsies in addition to patients with graft dysfunction. Patients with RI >0.80 did have 4.12 times higher mortality at 24 months than those <0.80, but their need for dialysis did not differ. The RI was significantly higher at the time of biopsy performed in patients with graft dysfunction, but changes in the RI did not reflect changes in histologic features when biopsies were performed at protocol-specific time points. The authors surmised that these changes did not reflect an underlying intrarenal disease process but were related to patient age and central hemodynamic factors. This complex interaction of coexisting factors in renal transplants makes the interpretation of Doppler parameters difficult. Despite this recent study, US with Doppler imaging remains the first-line imaging in the early post-transplantation period as it establishes a baseline for future comparisons.


Renal Transplant Dysfunction

Renal Transplant Dysfunction. Doppler US is a first-line noninvasive tool in the evaluation of suspected RAS and uses a combination of direct insonation of the anastomosis and main renal artery in addition to indirect intrarenal waveform morphology. Peak systolic velocity (PSV) in the renal artery is commonly used as the parameter to assess for the presence of RAS on US. Cutoff values of 200 to 300 cm/s have been proposed in various studies [18,19], but the lower limit suffers from low specificity, leading to unnecessary angiography procedures [20]. As in native kidneys, a tardus parvus waveform (small peak amplitude with delayed upstroke) can be seen within the transplanted kidney downstream to the stenosis. This morphologic waveform change is reflected quantitatively by the acceleration time (AT). De Morais et al [21] reported a sensitivity of 90% to 96.8% and a specificity of 87.5% to 70% using various PSV thresholds in the main renal artery and a sensitivity of 100% and specificity of 96.7% using an AT of 0.09 or less as normal. Another parameter that can be used is the renal artery to iliac artery ratio, which has been shown to The US appearance of RAT is striking, with complete absence of flow in the renal vessels on color flow and spectral analysis. Power Doppler imaging may be helpful because of its capability to detect low flow. However, it is important to remember that the absence of arterial flow within the kidney can also be seen in patients with hyperacute rejection and RVT [23]. Absence of renal venous flow and renal enlargement are classically seen in patients with RVT. Reversal of flow in the renal artery in diastole is often found in association with RVT [24]; however, this represents only approximately 10% of cases of reversed diastolic flow. Reversal of flow is seen more commonly in rejection or ATN and occasionally with nephrosclerosis [25].


Renal Transplant Dysfunction

Renal Transplant Dysfunction. Postoperative fluid collections like abscess, hematoma, lymphocele, and urinoma can be identified on US, but it cannot reliably differentiate between them. Sometimes an US examination may not demonstrate the extent of the collection and a noncontrast CT may be required. If large, these collections can lead to hydronephrosis; compression of the renal vein, leading to RVT; or compression of femoral vessels, leading to lower-extremity swelling or deep venous thrombosis. Large hematomas may lead to Page kidney. The time frame in which the collection is discovered has some prognostic ability since urinomas, hematomas, and abscesses occur in the early postoperative period, whereas lymphoceles occur weeks to months after surgery. Lymphoceles more often have septa than other collections, and hematomas tend to have higher echogenicity. In order to differentiate these entities, aspiration is usually required, and this is commonly performed with US guidance. Hydronephrosis can also be easily identified with US; however, it should be interpreted in correlation with biochemical data since reflux can give a similar appearance as well [27]. Urine leak may appear as a fluid collection on US, but an isotope scan would be more helpful [23]. Leaks are definitively diagnosed by aspiration of the collection with measurement of creatinine. Since ATN and acute rejection cannot be diagnosed with US and serum creatinine is insensitive for detecting early graft pathology, US-guided biopsy is the standard method for the diagnosis of rejection and evaluation of immunosuppression. The complication rate from renal transplant biopsies is low, with a reported rate of 0.4% to 1% graft loss in approximately 2500 biopsies [28]. Contrast-enhanced US (CEUS) has been used by some investigators to evaluate graft perfusion both in large arteries and within the cortex. Schwenger et al [29] found that patients with CAN had significantly lower blood flow values quantified by CEUS compared to patients without CAN.


Renal Transplant Dysfunction

Renal Transplant Dysfunction. In a small series, CEUS was found to be helpful in differentiating the underlying causes of delayed graft dysfunction [30]. CEUS can confirm transplant RAS and also aids in the assessment of the degree of stenosis [31]. Currently, CEUS has not received approval by the U.S. Food and Drug Administration. US-based elastography is another tool that may aid in the noninvasive assessment of CAN. The parenchymal stiffness measured by the transient elastography technique correlates with underlying histologic interstitial fibrosis [32]. Unfortunately, kidney stiffness is not just related to the degree of fibrosis but is also related to functional and mechanical parameters [33]. Although this new tool has promise, further validation is needed in clinical practice. Computed Tomography and Computed Tomography Angiography The utilization of CT of the abdomen and pelvis with contrast should be considered in conjunction with the risks of nephrotoxicity from iodinated contrast [34]. It may be beneficial in evaluating renal masses, perinephric fluid collections, and post-transplant lymphoproliferative disease. Renal Transplant Dysfunction In patients with suspected vascular complications (RAS, RVT, PSA, AVF), CTA can provide a detailed anatomic depiction prior to undergoing percutaneous angiography. Data about the usefulness of CT in evaluating transplant vascular complications are limited. Helck et al [35] found abnormalities on CT in 42% of cases when US was unremarkable. These included renal infarction, renal vein stenosis, and AVF. Rountas et al [36], in their study of native kidney vasculature, found that CTA and MRA have comparable negative predictive accuracy in evaluating suspected RAS. They found that CTA had 94% sensitivity, 93% specificity, 71% PPV, and 99% NPV. A small series by Gaddikeri et al [37] that compared CTA and MRA in the assessment of transplant RAS also demonstrated little difference between the modalities.


Renal Transplant Dysfunction

Renal Transplant Dysfunction. CTA, however, has the drawback of potential postcontrast acute kidney injury and radiation exposure in addition to insensitivity to mild RAS [38]. A noncontrast CT of the abdomen and pelvis may be helpful in patients with suspected hemorrhage or in the evaluation for nephrolithiasis in the transplant kidney. It also may be useful to define the extent of a peri- transplant fluid collection or in patients who cannot receive intravenous contrast. Magnetic Resonance Imaging and Magnetic Resonance Angiography MRI is being increasingly used as a second-line imaging modality for the evaluation of kidney transplants. Like a CT with and without contrast, an MRI with and without contrast may aid in characterization of renal masses and perinephric fluid collections. Although the risk of nephrotoxicity following gadolinium chelate contrast administration remains controversial [39], there is increased risk for NSF in this patient population that often has compromised renal function [34,40]. Fortunately, nonenhanced MRI pulse sequences may provide useful information in patients that have contrast contraindications and serve as an alternative to CT. Unfortunately, MRA suffers from a few pitfalls that may lead to a false diagnosis of stenosis or an overestimation of a stenosis. These include artifacts caused by metallic surgical clips near the transplant artery that result in signal loss near the artery, giving the false impression of stenosis. Venous contamination due to inaccurate timing of the arterial bolus is another artifact that can affect the accuracy of diagnosis. Careful evaluation of the source images and multiplanar reformats will help solve these problems [45]. In addition to depicting areas of stenosis in the main renal artery, MRA is able to depict areas of infarction within the kidney, which are seen as areas of heterogeneous T1 and T2 signal intensity and as focal areas of nonenhancement on the postcontrast images.


Renal Transplant Dysfunction

Renal Transplant Dysfunction. Using 3D gadolinium-enhanced MRA for the detection of transplant RAS, Ismaeel et al [46] showed a sensitivity of 93.7%, a specificity of 80%, and an accuracy of 88.5%. In addition, outer cortical necrosis, cortical necrosis with large patches, diffuse cortical necrosis, and both cortical and medullary necrosis were visualized [47]. The loss of corticomedullary differentiation has been described in post-transplant patients with cyclosporine toxicity, rejection, and ATN [12,48,49]. Noncontrast MRA (NC-MRA) with steady-state free precession imaging can help avoid contrast utilization and avoid the risk of NSF [50]. Several studies have evaluated the value of NC-MRA in the evaluation of native RAS [51-57]. In these studies, NC-MRA of renal arteries demonstrated a sensitivity of 78% to 100%, a specificity of 82% to 99%, and an NPV of 95% to 100% in the detection of significant arterial stenosis (>50%). The PPV (57% to 92%) was lower than other parameters. The high NPV suggests that NC-MRA can be used as a screening tool for detecting RAS. When positive, other imaging modalities can be utilized for confirmation and to better assess the degree of stenosis [51]. Although technically more challenging and requiring a longer examination time, 2 small studies suggested that NC-MRA was capable of detecting transplant RAS with a similar accuracy to gadolinium-enhanced MRA [50,58]. Radiography Intravenous Urography and Pyelography Radiography intravenous urography and pyelography are no longer used for evaluation of the renal transplant. Nuclear Medicine Radionuclide tests are valuable in renal transplantation since they provide a noninvasive means to evaluate transplant function qualitatively and also screen for surgical complications. Only scintigraphic studies are able to separate function of the graft from residual function of the native kidneys or any remaining prior failed graft [3]. Renal scintigraphy assesses the 3 sequential phases of renal function.


Renal Transplant Dysfunction

Renal Transplant Dysfunction. For the first minute following tracer injection, rapid dynamic imaging evaluates perfusion. The nephrons extract the tracer from the blood and excrete it by glomerular filtration and/or tubular secretion in the second phase. In the third phase, the tracer drainage allows assessment of urinary flow [67]. Although the use of radionuclide renal imaging during the early post-transplantation period has decreased, there are still centers that routinely perform them prior to patient discharge from the hospital to serve as a baseline study for future comparison. An advantage of renography is that it provides functional information, whereas blood creatinine levels lag behind function and radiographic studies are primarily anatomic. Because of this, it can be helpful in evaluating the return of function after ATN or rejection. Yazici et al [68] found scintigraphy performed within 2 days of transplantation was superior to RI in predicting long-term graft function. Heaf et al [69] found that a renogram performed 1 to 2 days after transplantation could predict primary graft nonfunction, prolonged time to graft function, low hospital discharge chromium EDTA clearance, and low 1- and 5-year graft survival, whereas a renogram performed at discharge could predict late (>6 months) graft loss. Although sensitive in the detection of graft dysfunction, scintigraphic parameters do not yield sufficient diagnostic power for a specific diagnosis. Like RI, renogram changes do not contribute to the differential diagnosis between acute rejection, ATN, and cyclosporine toxicity [69,70]. RAS appears similar to the scintigraphic findings seen with rejection. Angiotensin-converting enzyme inhibitor renography can aid in the diagnosis if baseline studies are available for comparison. In obstruction, scintigraphy can be used in conjunction with furosemide, as it is in native kidneys. Urinary leaks can be identified by the presence of radioactivity in an abnormal location.


Renal Transplant Dysfunction

Renal Transplant Dysfunction. In some centers and especially in Europe, renal clearances are performed serially to evaluate renal function. These are performed less frequently in the United States. Numerous quantitative indexes are used to evaluate transplants. Although no single parameter has achieved acceptance, it appears that they may be useful. Tc-99m diethylenetriamine pentaacetic acid (DTPA) or Tc-99m mercaptoacetyltriglycine (MAG3) can be used to follow the transplant. Because of its higher extraction fraction and better image quality, MAG3 is preferred at most transplant centers. DTPA, which is not excreted, is limited in the evaluation for obstruction, only demonstrating early impact on glomerular filtration. In a limited number of studies, MAG3 has not been proven superior to DTPA [67]. Angiography RAS is reported to occur in 1% to 23% of patients following transplantation and accounts for 1% to 5% of renal transplant hypertension [26,71,72]. Percutaneous therapeutic angioplasty (PTA) and stenting (PTAS) is the treatment of choice for RAS, with a success rate of 65% to 100% [73-84]. The complication rate from PTA and PTAS of 0% to 10% is low compared to surgery, which has a graft loss rate of 15% and mortality rate of 5%. Renal Transplant Dysfunction However, in 1 long-term study over a 24-year period, Peregrin et al [80] found a higher complication rate of 25.5% (usually without clinical sequelae). The majority of these complications were related to arterial access. In a study of 44 patients by Ghazanfar et al [76], the technical success rate of PTA was 100% and the 5-year graft survival rate was 86%. The restenosis rate after PTA has been reported to be between 10% and 56% [85]. Pappas et al [79] found a technical success rate of 100% with no acute complications, amelioration of arterial hypertension, and improvement of graft function within 7 postoperative days following PTAS.


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis .  Introduction/Background Urinary tract stones are thought to result from either excessive excretion or precipitation of salts in the urine or a relative lack of inhibiting substances. Men are more commonly affected than women, and the incidence increases with age until 60 years of age. For example, it is estimated that 19% of men and 9% of women will be diagnosed with a kidney stone by 70 years of age [1]. Stones also tend to be recurrent with recurrence rates shown to be higher in those with 2 or more previous stone episodes [2]. Special Imaging Considerations 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. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for the evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. In an effort to minimize patient radiation dose, low-dose CT examinations can replace traditional noncontrast CT examinations and are often performed using a combination of lowering milliampere-seconds, kilovoltage peak, and


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . 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 Acute Onset Flank Pain-Suspicion of Stone Disease scan range. Dual-energy CT allows for the characterization of stone composition (ie, uric acid, cystine, and calcium) and the generation of virtual unenhanced images simulating noncontrast CT images [6-8]. MR urography (MRU) is also tailored to improve visualization of the urinary system. Unenhanced MRU relies upon the intrinsic high signal intensity from urine on heavily T2-weighted imaging for the evaluation of the urinary tract. IV contrast is administered to provide additional information regarding obstruction, urothelial thickening, focal lesions, and stones. Contrast-enhanced T1-weighted series should include corticomedullary, nephrographic, and excretory phases. 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 MRI 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. The addition of digital tomosynthesis (DT) to standard digital radiography allows for additional radiographic projections at multiple angles, thus removing overlying structures and providing depth information about stones compared with 2-D radiographs.


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . Compared with noncontrast CT, DT has demonstrated similar intrarenal stone detection rates with respect to stone counts and stone area [9]. In another study, for intrarenal stones, radiography covering the kidneys, ureters, and bladder (KUB) with DT was significantly more accurate than KUB alone (81% versus 48%), with no difference seen between KUB with DT and CT (81% versus 81%). However, in an ex vivo study, accuracy for ureteral stones was lower, with an identification rate of only 24% with KUB and DT, although it was significantly higher than that with KUB alone (13%) [10]. It should be noted that at the time of writing, DT is not available/widely used at many institutions. Lastly, for the purposes of this document, ultrasound (US) examinations for urolithiasis are assumed to include both grayscale and targeted use of color Doppler images for nonvascular assessment, the latter allowing for the assessment of twinkling artifact, appearing as an intense multicolored signal deep to a stone [11]. CT Abdomen and Pelvis Without and With IV Contrast In the genitourinary system, CT abdomen and pelvis without and with IV contrast is commonly performed to evaluate for the presence of enhancement within a renal lesion such as a cyst or mass. There is no relevant literature documenting the additional benefit of nonexcretory phase postcontrast CT in addition to noncontrast CT in the evaluation of urolithiasis. Stone location and size can be accurately depicted at noncontrast CT and have also been associated with spontaneous stone passage rates, with more proximal as well as larger stones having a higher need for intervention [3]. Furthermore, larger stone size and higher density measured at CT have also been shown to be predictors of the need for invasive management [20]. CT allows for accurate assessment of stone size, which is important in planning urologic management.


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . CT techniques shown to improve accuracy of stone measurements include use of coronal reformations, viewing on bone window, and use of magnified views [21-23]. Lastly, noncontrast CT has also shown utility in aiding in diagnosis of flank pain other than urolithiasis [24]. CTU Without and With IV Contrast CTU involves the addition of a delayed, excretory phase images that opacifies the upper and lower urinary tracts and allows for more complete evaluation of these structures relative to nonurogram CT techniques. With urinary tract opacification, CTU confirms the ureteral location of a calculus, distinguishing from stone mimics such as an adjacent phlebolith. CTU can better confirm the degree of obstruction caused by a ureteral stone and potentially also aid in diagnosing a radiolucent stone, albeit a rare entity. However, there is no relevant literature documenting a difference in accuracy of additional excretory phase postcontrast imaging relative to noncontrast CT alone in the evaluation of urolithiasis. MRI Abdomen and Pelvis Without and With IV Contrast MRI abdomen and pelvis without and with IV contrast is defined as any MRI 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. There is limited literature on the use of MRI abdomen and pelvis without and with IV contrast in the evaluation of the patient with suspected urolithiasis; however, in one study, T2- weighted imaging has been shown to improve sensitivity of detection of perirenal fluid in the setting of acute calculus ureteric obstruction compared with fat stranding on unenhanced CT (77% versus 45%, respectively) [25]. In another study, also in the setting of acute ureteric obstruction, both excretory urography and T2-weighted MRI showed obstruction in a high percentage of cases [26].


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . There is no relevant literature documenting the additional benefit of MRI abdomen and pelvis with IV contrast in the nonexcretory phase in a patient with acute flank pain and suspicion of stone disease. MRI Abdomen and Pelvis Without IV Contrast MRI abdomen and pelvis without IV contrast is defined as any MRI protocol not specifically tailored for evaluation of the upper and lower urinary tracts, which includes precontrast imaging but does not include heavily T2-weighted images of the urinary tract. There is limited literature on the use of MRI abdomen and pelvis without and with IV Acute Onset Flank Pain-Suspicion of Stone Disease contrast in the evaluation of the patient with suspected urolithiasis; however, in one study, T2-weighted imaging has been shown to improve sensitivity of detection of perirenal fluid in the setting of acute calculus ureteric obstruction compared with fat stranding on unenhanced CT (77% versus 45%, respectively) [25]. In another study, also in the setting of acute ureteric obstruction, both excretory urography and T2-weighted MRI showed obstruction in a high percentage of cases [26]. MRU Without and With IV Contrast MRU is an alternative means of obtaining cross-sectional, excretory phase images without the use of iodinated contrast. Limited studies are available detailing the utility of contrast-enhanced MRU in the detection of urolithiasis. In a study published in 2001, the use of gadolinium-enhanced 3-D fast low-angle shot MRU was shown to provide higher sensitivity in detection of stones compared with noncontrast MR technique (heavily T2-weighted; combined thin-slice half-Fourier acquisition single-shot turbo spin-echo and thick-slab single-shot turbo spin-echo; 96%- 100% versus 54%-58%, respectively) [27].


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . Owing to its superior detection of fluid with T2-weighted sequences, MRU has been shown to be more sensitive than noncontrast CT in the detection of secondary signs of obstruction in the presence of urolithiasis such as hydronephrosis and perinephric fluid [28]. MRU Without IV Contrast MRU can also evaluate the urinary system without the use of IV contrast. In an early study performed in patients with acutely obstructed kidneys, noncontrast MRU was found to be 100% sensitive for diagnosing obstruction with perirenal fluid seen in 87% of cases, with the site of the obstruction seen in 80% of these obstructed kidneys. In an early study, when referenced to IVU, corresponding filling defects at MRU were seen in 12 of 18 patients with ureteric obstruction caused by a stone ranging from 4 to 20 mm in size [26]. In a more recent study performed at 3T, in patients presenting with renal colic, noncontrast MRU only detected stones in 50% of patients compared with 91% with noncontrast CT. However, the combination of stone or perinephric fluid and ureteral dilation gave MRU a sensitivity of 84%, specificity of 100%, and accuracy of 86% for stone detection when compared with CT [28]. Radiography Intravenous Urography IV urography (IVU) was once considered the reference standard for the diagnosis of urolithiasis. With the administration of contrast, IVU provides additional information beyond radiography including structural and functional information about kidneys, ureters, and urinary bladder, including the site and degree of obstruction from urolithiasis. A study comparing IVU with noncontrast CT demonstrated a sensitivity and specificity of IVU to be 75% and 92%, respectively, compared with 85% and 98%, respectively, at noncontrast CT [31]. Another study demonstrated significantly greater performance of noncontrast CT over IVU with sensitivities and specificities of 96% and 100%, respectively, for CT versus 87% and 94%, respectively, for IVU [32].


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . US Color Doppler Kidneys and Bladder Retroperitoneal There is no evidence to support the use of dedicated US color Doppler in the evaluation of patients with acute onset flank pain and suspicion for urolithiasis and with no history of stone disease. This procedure is intended for evaluation of vasculature. US Kidneys and Bladder Retroperitoneal Using grayscale techniques, US demonstrates variable performance in the detection of renal calculi depending on the clinical scenario and associated complications. Compared with noncontrast CT, initial studies evaluating grayscale US demonstrated an overall sensitivity of 24% to 57% for stone detection with decreased sensitivity for smaller stones [33,34]. Detection of ureteral calculi is also reduced compared with CT, demonstrating sensitivity up to 61% with a specificity of 100%, although sensitivity is improved if there are associated signs of obstruction US has been found to be up to 100% sensitive and 90% specific for the diagnosis of ureteral obstruction (hydronephrosis, ureterectasis, and perinephric fluid) in patients presenting with acute flank pain [37]. However, within the first 2 hours of presentation, these findings are less sensitive because secondary signs of obstruction may not have had time to develop [38]. Furthermore, although hydronephrosis on US does not accurately predict the presence or absence of a ureteral stone on computerized tomography in up to 25% of patients [39], it has been shown that in an US-first approach, the lack of hydronephrosis on US makes the presence of a larger ureteral stone (>5 mm) less likely [40]. The addition of color Doppler and assessment of twinkling artifact has been shown to provide higher sensitivity, particularly for small renal stones, with described sensitivity reported as high as 99% for stones <5 mm in patients with lumbar pain or history of renal stones [11].


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . However, twinkling artifact is prone to false-positives, with a false- positive rate reported up to 60% [41]. Also, the performance of color Doppler is influenced by stone site and diameter [42]. It should be noted that the targeted use of Doppler for nonvascular assessment does not constitute a full Doppler examination. US can also be combined with radiography to improve stone detection and has been pursued as an alternative to CT, particularly for the detection of clinically significant stones. In a prospective study of 66 patients, the combination of US and radiography demonstrated a sensitivity of 79% (versus 93% for noncontrast CT) for detecting stones. However, in this series, all missed cases had spontaneous stone passage, in which case noncontrast CT may not have added useful information [37]. In a more recent study, the combination of US and radiography yielded a sensitivity of 90% and specificity of 68%, with decreased detection rates for stones <5 mm [30]. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature documenting the additional benefit of repeat noncontrast CT followed by CT abdomen and pelvis with IV contrast in a patient with known current stone disease, diagnosed on recent imaging with recurrent symptoms of stone disease. CT Abdomen and Pelvis Without IV Contrast The patient with known current stone disease, diagnosed on recent imaging, with recurrent symptoms of stone disease is more likely to have urolithiasis as the etiology of flank pain than other etiologies. As such, it is important to assess if symptoms are related to interval stone migration or passage as opposed to complications of urolithiasis such as infection, perinephric abscess, urinoma, etc. Similar to Variant 1, noncontrast CT is currently considered the reference standard for the evaluation of urolithiasis, with a reported sensitivity as high as 97% [15,16].


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . The key consideration in repeat studies of patients with urolithiasis is by optimizing dose in each study and reducing the overall number of imaging studies to the lowest number possible. CTU Without and With IV Contrast With urinary tract opacification, CTU confirms the ureteral location of a calculus, distinguishing from stone mimics such as an adjacent phlebolith or vascular calcification. CTU can better confirm the degree of obstruction caused by a ureteral stone and potentially also aid in diagnosing a radiolucent stone that may not be visualized with Acute Onset Flank Pain-Suspicion of Stone Disease noncontrast CT. However, there is no relevant literature documenting the benefit of additional CTU in a patient with known current stone disease, diagnosed on recent imaging with recurrent symptoms of stone disease. MRI Abdomen and Pelvis Without and With IV Contrast There is no relevant literature documenting the additional benefit of MRI without and with IV contrast in a patient with known current stone disease, diagnosed on recent imaging with recurrent symptoms of stone disease. MRI Abdomen and Pelvis Without IV Contrast There is no relevant literature documenting the additional benefit of MRI without IV contrast in a patient with known current stone disease, diagnosed on recent imaging with recurrent symptoms of stone disease. MRU Without and With IV Contrast There is no relevant literature documenting the additional benefit of MRU without and with IV contrast in a patient with known current stone disease, diagnosed on recent imaging with recurrent symptoms of stone disease. However, MRU has been shown in the setting of initial stone detection to be more sensitive than noncontrast CT in the detection of secondary signs of obstruction in the presence of urolithiasis, although this has not been specifically assessed in this clinical scenario [28].


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . MRU Without IV Contrast There is no relevant literature documenting the additional benefit of MRU without IV contrast in a patient with known current stone disease, diagnosed on recent imaging with recurrent symptoms of stone disease. Radiography Abdomen and Pelvis If a stone was initially radiopaque on initial KUB and/or CT, a follow-up KUB could indicate whether a stone has migrated/changed in position. However, there is no relevant literature documenting the benefit of KUB in a patient with known current stone disease, diagnosed on recent imaging with recurrent symptoms of stone disease. Radiography Intravenous Urography With urinary tract opacification, IVU may confirm the ureteral location of a calculus, distinguishing from stone mimics such as an adjacent phlebolith or vascular calcification. However, there is no relevant literature specifically assessing its use/benefit in this clinical scenario. US Color Doppler Kidneys and Bladder Retroperitoneal There is no evidence to support the use of dedicated US color Doppler in the evaluation of patients with known current stone disease, diagnosed on recent imaging with recurrent symptoms of stone disease. This procedure is intended for evaluation of vasculature. US Kidneys and Bladder Retroperitoneal Using grayscale techniques, US demonstrates variable performance in the detection of renal calculi depending on the clinical scenario but is used to assess for associated complications such as hydronephrosis. In one study, using US to guide clinical decision-making for patients with known residual calculi is limited by low sensitivity and the inability to size the stone accurately, which can lead to inappropriate counseling for patients [36]. Variant 3: Pregnant patient. Acute onset flank pain. Suspicion of stone disease. Initial or follow-up imaging. Stones can be a source of abdominal pain in pregnant patients.


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . Urolithiasis can also be associated with hydronephrosis if there is a component of obstruction; however, the differential diagnosis of hydronephrosis in the pregnant patient is confounded by ph ysiologic hy dronephrosis o f pregnancy, which is thought to be caused by compression of the ureters between the gravid uterus and the linea terminalis [46]. Physiologic hydronephrosis of pregnancy occurs in >80% of pregnant patients, more commonly occurs on the right than the left, and is generally seen beginning in the second trimester [46]. CT Abdomen and Pelvis With IV Contrast There is no relevant literature documenting the additional benefit of CT abdomen and pelvis with IV contrast, relative to noncontrast CT, in the pregnant patient for the evaluation of stones. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature documenting the additional benefit of CT abdomen and pelvis without and with IV contrast, relative to noncontrast CT alone, in the pregnant patient for the evaluation of stones. Acute Onset Flank Pain-Suspicion of Stone Disease CT Abdomen and Pelvis Without IV Contrast CT abdomen and pelvis without IV contrast has been shown to be a sensitive and specific test for diagnosing stones in pregnant patients [47]. The key consideration in CT studies for pregnant patients with suspected urolithiasis is mitigating effects of radiation dose by optimizing dose in each study and reducing the overall number of imaging studies to the lowest number possible. CTU Without and With IV Contrast There is no relevant literature documenting the additional benefit of CTU without and with IV contrast, relative to noncontrast CT alone, in the pregnant patient for the evaluation of stones.


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . MRI Abdomen and Pelvis Without IV Contrast There is no relevant literature documenting the additional benefit of MRI without IV contrast without dedicated urographic imaging, relative to noncontrast MRU, in the pregnant patient for the evaluation of stones; however, it can be helpful in follow-up imaging for stones and/or hydronephrosis, particularly if US is limited. MRI Abdomen and Pelvis Without and With IV Contrast There is no relevant literature documenting the additional benefit of MRI without and with IV contrast, relative to noncontrast MRU, in the pregnant patient for the evaluation of stones. MRU Without and With IV Contrast There is no relevant literature documenting the additional benefit of MRU without and with IV contrast, relative to noncontrast MRU, in the pregnant patient for the evaluation of stones. MRU Without IV Contrast With a goal of avoiding irradiation of the fetus, MRU has also been advocated for the detection of ureteral calculi at some centers [48] as well as hydronephrosis or other cause of renal obstruction. However, in a study by Shokeir et al [49] in nonpregnant patients, the site of stone impaction was identified by noncontrast CT in 146 of 146 renal units (100% sensitivity) and by MRU in only 101 of 146 renal units (69% sensitivity). A survey of academic medical centers found that radiologists are more likely to image for suspected renal calculus with CT than with MR in the second (35% versus 20%) and third (48% versus 18%) trimesters [50]. Radiography Abdomen and Pelvis There is no relevant literature documenting the benefit of KUB in the pregnant patient for the evaluation of stones. Radiography Intravenous Urography Limited IVU (example: scout radiograph, film at 30 seconds and film at 20 minutes) has also been used to diagnose ureteral obstruction in pregnant patients [51].


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . US Color Doppler Kidneys and Bladder Retroperitoneal There is no evidence to support the use of dedicated US color Doppler in the evaluation of pregnant patients with suspicion of stone disease. This procedure is intended for evaluation of vasculature. US Kidneys and Bladder Retroperitoneal US is frequently used as a screening examination, because US is a sensitive and specific test for diagnosing hydronephrosis and does not expose the patient or fetus to ionizing radiation [52-54]. Variant 4: Acute onset flank pain. Suspicion of stone disease. CT without contrast is inconclusive for the presence of stones. Next imaging study. In clinical practice, a no ncontract CT may b e inconclusive for stones when it is unclear whether an identified calcification is located within the ureter or an adjacent structure. Common mimics of ureteral stones in clude phleboliths or arterial calcifications. This uncertainty can be exacerbated in thin patients with a lack of sufficient fat planes separating the ureters from adjacent structures. Acute Onset Flank Pain-Suspicion of Stone Disease enhanced CT does also allow for the evaluation of other etiologies of flank pain [43]. In studies evaluating the use of CT abdomen and pelvis with IV contrast following a noncontrast CT, contrast-enhanced CT provided additional information or revealed a new diagnosis in 5% to 18% of cases, while ultimately changing clinical management in only 2% to 3% of cases [44,45]. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature documenting the additional benefit of repeat noncontrast CT followed by CT abdomen and pelvis with IV contrast after an inconclusive CT without IV contrast in the evaluation of stones. CT Abdomen and Pelvis Without IV Contrast There is no relevant literature documenting the additional benefit of repeat noncontrast CT after an inconclusive CT without IV contrast in the evaluation of stones.


Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . CTU Without and With IV Contrast With urinary tract opacification, CTU confirms the ureteral location of a calculus, distinguishing from stone mimics such as an adjacent phlebolith or vascular calcification. CTU can better confirm the degree of obstruction caused by a ureteral stone and potentially also aid in diagnosing a radiolucent stone that may not be visualized with noncontrast CT and can also detect urothelial masses on the excretory phase. However, there is no relevant literature documenting the additional benefit of additional CTU after an inconclusive CT without IV contrast in the evaluation of stones. MRI Abdomen and Pelvis Without and With IV Contrast There is no relevant literature documenting the additional benefit of MRI without and with IV contrast after an inconclusive CT without IV contrast in the evaluation of stones. MRI Abdomen and Pelvis Without IV Contrast There is no relevant literature documenting the additional benefit of MRI without IV contrast after an inconclusive CT without IV contrast in the evaluation of stones. MRU Without and With IV Contrast There is no relevant literature documenting the additional benefit of MRU without and with IV contrast after an inconclusive CT without IV contrast in the evaluation of stones. However, MRU has been shown in the setting of initial stone detection to be more sensitive than noncontrast CT in the detection of secondary signs of obstruction in the presence of urolithiasis, although this has not been specifically assessed in this clinical scenario [28]. MRU Without IV Contrast There is no relevant literature documenting the additional benefit of MRU without IV contrast after an inconclusive CT without IV contrast in the evaluation of stones. Radiography Abdomen and Pelvis There is no relevant literature documenting the additional benefit of KUB after an inconclusive CT without IV contrast in the evaluation of stones.


Suspected Lower Extremity Deep Vein Thrombosis.  It is clinically important to determine the location and extent of DVT [3,6]. DVT that is limited to the infrapopliteal calf veins (ie, below-the-knee or distal DVT) often resolves spontaneously and is rarely associated with pulmonary embolism or other adverse outcomes [3,7,8]. Above-the-knee or proximal DVT, on the other hand, is strongly associated with an increased risk for pulmonary embolism. The treatment of choice for DVT is anticoagulation to reduce the risk of DVT extension, recurrent DVT, pulmonary embolism, and post-thrombotic syndrome. It is generally accepted that the benefits of anticoagulation therapy in patients with proximal DVT outweigh its risks [3,6]. Because below-the-knee DVT rarely results in pulmonary embolism, the role of anticoagulation therapy in patients with distal DVT remains controversial [3,6,9]. However, because one-sixth of patients with distal DVT experience extension of thrombus proximally above the knee, serial imaging to exclude proximal DVT extension is recommended at 1 week if anticoagulation therapy is not initiated at presentation [3,6]. This issue is complicated by the variability in evaluation for below-the-knee DVT as part of a routine examination. Classically, a patient with symptomatic lower extremity DVT presents with either local pain or tenderness or with edema and swelling of the lower extremity. However, approximately one-third of patients with DVT do not have any symptoms [10]. Often, symptoms are not apparent until there is involvement above the knee [3]. The clinical diagnosis of DVT using clinical risk-stratification scores (eg, Wells score) alone has, therefore, been less than ideal [10]. Wells et al [11,12] suggested using a clinical DVT-prediction score (aka, Wells score) in combination with a blood evaluation for plasma D-dimer, a degradation product of cross-linked fibrin that is elevated during thromboembolic events.


Suspected Lower Extremity Deep Vein Thrombosis. DVT is unlikely if the clinical prediction score is low and the D-dimer levels are normal [3,6,10-12]. However, the highly variable nature of DVT presentation, numerous potential pathologic mimics for DVT, and variations in D-dimer assay performances in certain populations limit the reliability of diagnosis solely on the clinical DVT prediction score and D-dimer testing. DVT screening of select high-risk patients in intensive care units because of prolonged immobility has also shown benefit [13,14]. Lower extremity ultrasound (US) has also been included in an algorithm for the workup of patients who have a fever of unknown origin after more common causes have been excluded [15,16]. Imaging is frequently required to definitively exclude DVT and properly document the extent of venous thrombosis, which is critical for proper therapeutic management of DVT. Moreover, the clinical-prediction score 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 Lower Extremity DVT and D-dimer level are often unreliable for diagnosing recurrent DVT and are not useful for diagnosing alternative conditions, such as an intact or ruptured Baker cyst, cellulitis, lymphedema, chronic venous disease, and various musculoskeletal disorders that can clinically mimic DVT. Discussion of Procedures by Variant Variant 1: Suspected lower extremity deep vein thrombosis. Initial imaging. Catheter Venography Pelvis and Lower Extremity Contrast catheter venography is the historic and de facto gold standard for diagnosing DVT [3,6,10,11].