Gamut of Extratesticular Scrotal Masses: Anatomic Approach to Sonographic Differential Diagnosis.

The commonly taught tenet that intratesticular lesions are always malignant and extratesticular scrotal lesions are always benign is a simplistic statement that erroneously minimizes the significance of extratesticular scrotal masses and their diagnosis. Yet, disease in the extratesticular space is commonly encountered by clinicians and radiologists and is often a source of uncertainty in diagnosis and management. Given the embryologically rooted complex anatomy of this region, a wide range of pathologic conditions is possible. Radiologists may not be familiar with some of these conditions; further, many of these lesions can have a specific sonographic appearance, allowing accurate diagnosis that can minimize surgical intervention. Lastly, malignancies can occur in the extratesticular space-although this is less common than in the testicles-and proper recognition of findings that warrant additional imaging or surgery is critical in optimizing outcomes. The authors present a compartmental anatomic framework for differential diagnosis of extratesticular scrotal masses and provide a comprehensive illustrative display of many of the pathologic conditions that can be encountered to familiarize radiologists with the sonographic appearances of these lesions. They also review management of these lesions and scenarios where US may not be definitive in diagnosis and selective use of scrotal MRI can be helpful. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Assessing the accuracy of multiparametric MRI to predict clinically significant prostate cancer in biopsy naïve men across racial/ethnic groups.

INTRODUCTION: The Prostate Imaging Reporting and Data System (PIRADS) has shown promise in improving the detection of Gleason grade group (GG) 2-5 prostate cancer (PCa) and reducing the detection of indolent GG1 PCa. However, data on the performance of PIRADS in Black and Hispanic men is sparse. We evaluated the accuracy of PIRADS scores in detecting GG2-5 PCa in White, Black, and Hispanic men. METHODS: We performed a multicenter retrospective review of biopsy-naïve Black (n = 108), White (n = 108), and Hispanic (n = 64) men who underwent prostate biopsy (PB) following multiparametric MRI. Sensitivity and specificity of PIRADS for GG2-5 PCa were calculated. Race-stratified binary logistic regression models for GG2-5 PCa using standard clinical variables and PIRADS were used to calculate area under the receiver operating characteristics curves (AUC). RESULTS: Rates of GG2-5 PCa were statistically similar between Blacks, Whites, and Hispanics (52.8% vs 42.6% vs 37.5% respectively, p = 0.12). Sensitivity was lower in Hispanic men compared to White men (87.5% vs 97.8% respectively, p = 0.01). Specificity was similar in Black versus White men (21.6% vs 27.4%, p = 0.32) and White versus Hispanic men (27.4% vs 17.5%, p = 0.14). The AUCs of the PIRADS added to standard clinical data (age, PSA and suspicious prostate exam) were similar when comparing Black versus White men (0.75 vs 0.73, p = 0.79) and White versus Hispanic men (0.73 vs 0.59, p = 0.11). The AUCs for the Base model and PIRADS model alone were statistically similar when comparing Black versus White men and White versus Hispanic men. CONCLUSIONS: The accuracy of the PIRADS and clinical data for detecting GG2-5 PCa seems statistically similar across race. However, there is concern that PIRADS 2.0 has lower sensitivity in Hispanic men compared to White men. Prospective validation studies are needed.

Performance of prostate health index and PSA density in a diverse biopsy-naïve cohort with mpMRI for detecting significant prostate cancer.

Objective: To compare Prostate Health Index (PHI) and prostate-specific antigen (PSA) density as secondary tests after multiparametric magnetic resonance imaging (mpMRI) in improving the detection accuracy of Gleason grade group (GG) 2-5 prostate cancer (PCa) and in decreasing unnecessary biopsies in a multiethnic biopsy-naïve population. Methods: From February 2017 to February 2020, we recruited consecutive biopsy-naïve men in participating urology clinics for elevated PSA levels. They all had a PHI score, mpMRI, and prostate biopsy. Experienced genitourinary radiologists read all mpMRI studies based on PIRADS version 2.0. Logistic regression models were used to generate receiver operating characteristic curves. Models were tested for effect modification between Race (Black vs White) and both PHI and PSA density, and Race and PIRADS to determine if race impacted their prediction accuracy. Sensitivity, specificity, and predictive values of PHI and PSA density thresholds were calculated by PIRADS scores. The primary outcome was GG2-5 PCa, that is, Gleason score ≥3 + 4. Results: The study included 143 men, of which 65 (45.5%) were self-reported Black. Median age was 62.0 years and 55 men (38.4%) had GG2-5 PCa. Overall, 18.1% had PIRADS 1-2, 32.9% had PIRADS 3, and 49.0% had PIRADS 4-5. For the binary logistic regressions, the interactions between PIRADS and Race (P = .08), Log (PHI) and Race (P = .17), and Log (PSA density) and Race (P = .42) were not statistically significant. Within PIRADS 3 lesions, a PHI ≥49 prevented unnecessary biopsies in 55% of men and missed no GG2-5 PCa, yielding a negative predictive value of 100%. There was no reliable PHI or PSA density threshold to avoid PCa biopsies in PIRADS 1-2 or 4-5. Conclusions: PHI and PSA density can be used after mpMRI to improve the detection of GG2-5 PCa in a biopsy-naïve cohort. PHI may be superior to PSA density in PIRADS 3 lesions by avoiding 55% of unnecessary biopsies. Using both PHI and PSA density in series may further increase specificity and lead to fewer unnecessary biopsies, but further larger studies are warranted to determine the optimal threshold of each biomarker.

Variability of the Positive Predictive Value of PI-RADS for Prostate MRI across 26 Centers: Experience of the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel.

Background Prostate MRI is used widely in clinical care for guiding tissue sampling, active surveillance, and staging. The Prostate Imaging Reporting and Data System (PI-RADS) helps provide a standardized probabilistic approach for identifying clinically significant prostate cancer. Despite widespread use, the variability in performance of prostate MRI across practices remains unknown. Purpose To estimate the positive predictive value (PPV) of PI-RADS for the detection of high-grade prostate cancer across imaging centers. Materials and Methods This retrospective cross-sectional study was compliant with the HIPAA. Twenty-six centers with members in the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel submitted data from men with suspected or biopsy-proven untreated prostate cancer. MRI scans were obtained between January 2015 and April 2018. This was followed with targeted biopsy. Only men with at least one MRI lesion assigned a PI-RADS score of 2-5 were included. Outcome was prostate cancer with Gleason score (GS) greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2). A mixed-model logistic regression with institution and individuals as random effects was used to estimate overall PPVs. The variability of observed PPV of PI-RADS across imaging centers was described by using the median and interquartile range. Results The authors evaluated 3449 men (mean age, 65 years ± 8 [standard deviation]) with 5082 lesions. Biopsy results showed 1698 cancers with GS greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2) in 2082 men. Across all centers, the estimated PPV was 35% (95% confidence interval [CI]: 27%, 43%) for a PI-RADS score greater than or equal to 3 and 49% (95% CI: 40%, 58%) for a PI-RADS score greater than or equal to 4. The interquartile ranges of PPV at these same PI-RADS score thresholds were 27%-44% and 27%-48%, respectively. Conclusion The positive predictive value of the Prostate Imaging and Reporting Data System was low and varied widely across centers. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Milot in this issue.

MR imaging findings of the prostate gland following prostate artery embolization: results from a prospective phase 2 study.

PURPOSE: To assess changes in imaging and volume characteristics of the prostate gland by magnetic resonance (MR) following prostatic artery embolization (PAE) for benign prostate hyperplasia. METHODS: With IRB approval, we analyzed prospectively acquired MR data of PAE patients at baseline and 6-month following treatment from 2015 to 2017. We reviewed prostate MRs looking for sequelae of embolization [changes in signal intensity and/or enhancement, infection/inflammation, infarction, edema, and change in intravesical prostatic protrusion (IPP)]. We calculated the total volume (TV) and central gland volumes (CGV) using DynaCAD® and measured change in volumes. Analyses were performed using SPSS with p < 0.05 considered significant. RESULTS: Forty-three patients (n = 43) met our inclusion criteria. 93% (30/43) and 100% (43/43) showed a decrease in TV and CGV at 6-months respectively. At baseline, median TV was 86 cc (range 29.4-232) and median CGV was 54.4 cc (range 12.9-165.5). Median decrease in TV was 18.2% (CI 13.3-27.2) (p = 0.0001) and median decrease in CGV was 26.7% (CI 20.4-35.9) (p = 0.0001). Thirty-seven percent (16/43) of patients had IPP at baseline; 100% showed a decrease in size of median lobe at follow-up. At 6-month follow-up, 33% (14/43) showed imaging features of infarction, 79% (34/43) had decrease in T2-signal intensity, and 51% (22/43) showed a decrease in enhancement. None had edema, peri-prostatic fat changes or infection/inflammation. CONCLUSION: PAE causes a statistically significant reduction in the TV and CGV. There is also a reduction of the degree of IPP. Non-specific findings of infarction, decrease in T2-signal, and enhancement were also seen.

Lesions Without Borders: Scrotal Lesions That Involve Both the Intratesticular and Extratesticular Regions.

OBJECTIVE: Differentiation of scrotal lesions is often dictated by whether they are intraor extratesticular. However, these regions are not entirely isolated, and disease processes can span both spaces. We review a variety of lesions that can involve both regions, describe the relevant anatomy, and illustrate their imaging appearances. CONCLUSION: Identification of involvement of both intra- and extratesticular regions by a single process can narrow the differential considerations and help arrive at the correct diagnosis.

Differentiation of Solid Renal Tumors with Multiparametric MR Imaging.

Characterization of renal tumors is critical to determine the best therapeutic approach and improve overall patient survival. Because of increased use of high-resolution cross-sectional imaging in clinical practice, renal masses are being discovered with increased frequency. As a result, accurate imaging characterization of these lesions is more important than ever. However, because of the wide array of imaging features encountered as well as overlapping characteristics, identifying reliable imaging criteria for differentiating malignant from benign renal masses remains a challenge. Multiparametric magnetic resonance (MR) imaging based on various anatomic and functional parameters has an important role and adds diagnostic value in detection and characterization of renal masses. MR imaging may allow distinction of benign solid renal masses from several renal cell carcinoma (RCC) subtypes, potentially suggest the histologic grade of a neoplasm, and play an important role in ensuring appropriate patient management to avoid unnecessary surgery or other interventions. It is also a useful noninvasive imaging tool for patients who undergo active surveillance of renal masses and for follow-up after treatment of a renal mass. The purpose of this article is to review the characteristic MR imaging features of RCC and common benign renal masses and propose a diagnostic imaging approach to evaluation of solid renal masses using multiparametric MR imaging. ©RSNA, 2017.

Radiology Education of Physician Extenders: What Role Should Radiologists Play?

As physician extenders (PEs) enter the medical community in large numbers, they have an increasing impact on imaging utilization and imaging-based procedures. Physician assistants (PAs) and nurse practitioners (NPs) have an advanced level of education and some practice autonomously. However, PA and NP programs are not required to provide any basic radiology education. For PEs who did receive basic radiology education during their graduate program, the curriculum is nonstandard and there is a wide variation. PEs working in primary care and nonradiology specialties place imaging orders, review report findings, and answer patient questions. Other PEs working within radiology practices operate as liaisons with patients in diagnostic radiology or perform an increasing number of interventional procedures. Basic radiology education in formal PE certificate programs as well as on-the-job education about radiology may benefit patients, radiologists, and the health-care system. What role, if any, should the radiologist assume for educating PE students and practicing PAs and NPs? This review analyzes the benefits and drawbacks of radiologists educating PEs.

Dramatic increase in the utilization of multiparametric magnetic resonance imaging for detection and management of prostate cancer.

PURPOSE: Multiparametric MRI (mpMRI) of the prostate is an evolving technology that provides functional information of the prostate that helps distinguish benign from malignant lesions. We hypothesized that mpMRI is rapidly adopted in the US to fill the unmet need for a non-invasive, accurate screening tool. The aim of this study is to assess the increasing utilization of mpMRI for the diagnosis and management of prostate cancer. METHODS: We conducted a retrospective review of an institutional clinical data repository of four million patients. Clinical information from all men undergoing mpMRI from October 2013 to December 2015 was collected in a prospectively designed database. Individual chart reviews were performed for each patient. RESULTS: 1521 mpMRI of the prostate were performed with an increase in the use of 486% over 26 months. The most common indication for mpMRI was abnormal screening (64%) and 47% of these men went on to prostate biopsy, either by cognitive mapping (65%) or MRI-US fusion targeting (35%). 261 men elected to defer prostate needle biopsy after informative decision-making with their urologist. 12.7% of mpMRI were performed for active surveillance, 7.5% for clinical staging, and 3.2% by radiation oncologists planning radiotherapy. 7% of mpMRI were performed to evaluate the pelvis for biochemical recurrence, a third of which identified a region of suspicion for targeted. CONCLUSION: Prostate mpMRI is increasingly performed for both the diagnosis and management of prostate cancer. As clinical utilization increases along with the diffusion of technology and radiologic expertise, MpMRI has the potential to influence clinical decision-making and fulfill the need for a non-invasive, accurate tool for the diagnosis and management of prostate cancer.

Diagnostic Value of Guided Biopsies: Fusion and Cognitive-registration Magnetic Resonance Imaging Versus Conventional Ultrasound Biopsy of the Prostate.

OBJECTIVE: To better assess the increased utilization of multiparametric magnetic resonance imaging (mpMRI) and fusion biopsy of the prostate, we compared prostate cancer detection rates among (a) men undergoing MR-ultrasound (US) fusion biopsy, (b) mpMRI cognitive-registration biopsy, and (c) conventional transrectal US-guided biopsy for the detection of prostate cancer. MATERIALS AND METHODS: We present a retrospective review of consecutive patients undergoing mpMRI of the prostate with subsequent prostate biopsy from October 2013 to September 2015. Lesions concerning for prostate cancer visualized on mpMRI were targeted with cognitive-registration or MR-US fusion biopsies. A cohort of men undergoing conventional prostate biopsy was utilized for comparison. Rates of cancer detection were compared among the 3 cohorts. RESULTS: A total of 231 patients underwent mpMRI-targeted biopsy (81 fusion, 150 cognitive). There was no difference in prostate specific antigen, mpMRI-defined Prostate Imaging Reporting and Data System score or number of lesions, or history of prostate cancer among the cohorts. The overall detection rate of cancer was significantly higher in the fusion cohort (48.1%) compared with both the cognitive (34.6% P = .04) and conventional (32.0%, P = .03) cohorts. Cancer detection rates were comparable in the MRI-cognitive and transrectal prostate US biopsy groups (34.6% vs 32%). MR fusion detected significantly more Gleason ≥7 cancer (61.5 vs 37.5%, P = .04) and significantly less Gleason 6 cancer (38.5 vs 62.5%, P = .04) compared with conventional biopsy. CONCLUSION: Targeted biopsy of the prostate using MR-US fusion increased the cancer detection rate compared with both cognitive registration and conventional biopsy and was associated with detection of higher-grade cancer compared with conventional biopsy.

Update on the Diagnosis and Management of Renal Angiomyolipoma.

PURPOSE: Advances in minimally invasive therapies and novel targeted chemotherapeutics have provided a breadth of options for the management of renal masses. Management of renal angiomyolipoma has not been reviewed in a comprehensive fashion in more than a decade. We provide an updated review of the current diagnosis and management strategies for renal angiomyolipoma. MATERIALS AND METHODS: We conducted a PubMed(®) search of all available literature for renal or kidney angiomyolipoma. Further sources were identified in the reference lists of identified articles. We specifically reviewed case series of partial nephrectomy, selective arterial embolization and ablative therapies as well as trials of mTOR inhibitors for angiomyolipoma from 1999 to 2014. RESULTS: Renal angiomyolipoma is an uncommon benign renal tumor. Although associated with tuberous sclerosis complex, these tumors occur sporadically. Risk of life threatening hemorrhage is the main clinical concern. Due to the fat content, angiomyolipomas are generally readily identifiable on computerized tomography and magnetic resonance imaging. However, fat poor angiomyolipoma can present a diagnostic challenge. Novel research suggests that various strategies using magnetic resonance imaging, including chemical shift magnetic resonance imaging, have the potential to differentiate fat poor angiomyolipoma from renal cell carcinoma. Active surveillance is the accepted management for small asymptomatic masses. Generally, symptomatic masses and masses greater than 4 cm should be treated. However, other relative indications may apply. Options for treatment have traditionally included radical and partial nephrectomy, selective arterial embolization and ablative therapies, including cryoablation and radio frequency ablation, all of which we review and update. We also review recent advances in the medical treatment of patients with tuberous sclerosis complex associated angiomyolipomas with mTOR inhibitors. Specifically trials of everolimus for patients with tuberous sclerosis complex suggest that this agent may be safe and effective in treating angiomyolipoma tumor burden. A schema for the suggested management of renal angiomyolipoma is provided. CONCLUSIONS: Appropriately selected cases of renal angiomyolipoma can be managed by active surveillance. For those patients requiring treatment nephron sparing approaches, including partial nephrectomy and selective arterial embolization, are preferred options. For those with tuberous sclerosis complex mTOR inhibitors may represent a viable approach to control tumor burden while conserving renal parenchyma.

ACR Appropriateness Criteria indeterminate renal mass.

Renal masses are increasingly detected in asymptomatic individuals as incidental findings. An indeterminate renal mass is one that cannot be diagnosed confidently as benign or malignant at the time it is discovered. CT, ultrasonography, and MRI of renal masses with fast-scan techniques and intravenous (IV) contrast are the mainstays of evaluation. Dual-energy CT, contrast-enhanced ultrasonography, PET/CT, and percutaneous biopsy are all technologies that are gaining traction in the characterization of the indeterminate renal mass. In cases in which IV contrast cannot be used, whether because of IV contrast allergy or renal insufficiency, renal mass classification with CT is markedly limited. In the absence of IV contrast, ultrasonography, MRI, and biopsy have some advantages. Owing to the low malignant and metastatic potential of small renal cell carcinomas (≤4 cm in diameter), active surveillance is additionally emerging as a diagnostic strategy for patients who have high surgical risk or limited life expectancy. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and application by the panel of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

CT and MR imaging for evaluation of cystic renal lesions and diseases.

Cystic renal lesions are commonly encountered in abdominal imaging. Although most cystic renal lesions are benign simple cysts, complex renal cysts, infectious cystic renal disease, and multifocal cystic renal disease are also common phenomena. The Bosniak classification system provides a useful means of categorizing cystic renal lesions but places less emphasis on their underlying pathophysiology. Cystic renal diseases can be categorized as focal, multifocal, or infectious lesions. Diseases that manifest with focal lesions, such as cystic renal cell carcinoma, mixed epithelial and stromal tumor, and cystic nephroma, are often difficult to differentiate but have differing implications for follow-up after resection. Multifocal cystic renal lesions can be categorized as acquired or heritable. Acquired entities, such as glomerulocystic kidney disease, lithium-induced nephrotoxicity, acquired cystic kidney disease, multicystic dysplastic kidney, and localized cystic renal disease, often have distinct imaging and clinical features that allow definitive diagnosis. Heritable diseases, such as autosomal dominant polycystic kidney disease, von Hippel-Lindau disease, and tuberous sclerosis, are usually easily identified and have various implications for patient management. Infectious diseases have varied imaging appearances, and the possibility of infection must not be overlooked when assessing a cystic renal lesion. A thorough understanding of the spectrum of cystic renal disease will allow the radiologist to make a more specific diagnosis and provide the clinician with optimal recommendations for further diagnostic testing and follow-up imaging.

ACR Appropriateness Criteria(®) on renal failure.

Imaging plays a role in the management of patients with acute kidney injury or chronic kidney disease. However, clinical circumstances strongly impact the appropriateness of imaging use. In patients with newly detected renal dysfunction, ultrasonography can assess for reversible causes, assess renal size and echogenicity, and thus, establish the chronicity of disease. Urinary obstruction can be detected, but imaging is most useful in high-risk groups or in patients in whom there is a strong clinical suspicion for obstruction. Computed tomography, computed tomography or magnetic resonance arteriography, and percutaneous ultrasound-guided renal biopsy are valuable in other clinical situations. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR appropriateness criteria post-treatment follow-up of renal cell carcinoma.

Although localized renal cell carcinoma can be effectively treated by surgery or ablative therapies, local or distant metastatic recurrence after treatment is not uncommon. Because recurrent disease can be effectively treated, patient surveillance after treatment of renal cell carcinoma is very important. Surveillance protocols are generally based on the primary tumor's size, stage, and nuclear grade at the time of resection, as well as patterns of tumor recurrence, including where and when metastases occur. Various imaging modalities may be used in the evaluation of these patients. Literature on the indications and usefulness of these radiologic studies is reviewed. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Asymmetric spermatic cord vessel enhancement on CT: a sign of epididymitis or testicular neoplasm.

PURPOSE: To determine whether asymmetric spermatic cord vessel enhancement (ASE) on contrast-enhanced computed tomography (CECT) indicates scrotal pathology. METHODS: Sixty-one male patients with scrotal symptoms who underwent both scrotal ultrasound (US) and CECT within 24 h were identified through a radiology information system. Twenty-eight emergency department patients who underwent CECT only for unrelated symptoms were included for comparison. Two blinded radiologists independently reviewed each CECT scan for qualitative ASE. These data were compared with US diagnoses, when present. A third blinded radiologist reviewed each CECT scan for quantitative ASE by measuring Hounsfield unit (HU) density ratios. McNemar, Kappa, Student's t test, and ANOVA were used for analysis. RESULTS: Eighty-nine total patients included 28 with CECT only and 61 with CECT and US, of which 41 had abnormal US: 15 acute epididymitis and/or orchitis, 7 testicular neoplasms, 11 varicoceles, and 8 with other pathologies. Twenty patients with normal US and 28 patients with CECT only served as control groups. Identification of ASE agreed with US diagnosis of epididymitis (and/or orchitis) or testicular neoplasm (reader 1: κ = 0.79, reader 2: κ = 0.75) with average 95.5% sensitivity and 88.8% specificity, and no significant difference between readers (p = 0.58). For epididymitis (and/or orchitis) or testicular neoplasm patients, the average ratio of spermatic cord HU density (ipsilateral:contralateral) was significantly different from other patients (4.01 vs. 1.26, p = 0.0025). CONCLUSION: ASE on CECT shows stronger correlation with epididymitis (and/or orchitis) and testicular neoplasm compared with other scrotal pathologies. If discovered on CECT, this should prompt further clinical and/or imaging workup.

ACR Appropriateness Criteria prostate cancer--pretreatment detection, staging, and surveillance.

Prostate cancer is the most common noncutaneous male malignancy in the United States. The use of serum prostate-specific antigen as a screening tool is complicated by a significant fraction of nonlethal cancers diagnosed by biopsy. Ultrasound is used predominately as a biopsy guidance tool. Combined rectal examination, prostate-specific antigen testing, and histology from ultrasound-guided biopsy provide risk stratification for locally advanced and metastatic disease. Imaging in low-risk patients is unlikely to guide management for patients electing up-front treatment. MRI, CT, and bone scans are appropriate in intermediate-risk to high-risk patients to better assess the extent of disease, guide therapy decisions, and predict outcomes. MRI (particularly with an endorectal coil and multiparametric functional imaging) provides the best imaging for cancer detection and staging. There may be a role for prostate MRI in the context of active surveillance for low-risk patients and in cancer detection for undiagnosed clinically suspected cancer after negative biopsy results. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

ACR Appropriateness Criteria® acute onset flank pain--suspicion of stone disease.

Low dose (<3 mSv) noncontrast CT (NCCT) is the imaging study of choice for accurate evaluation of patients with acute onset of flank pain and suspicion of stone disease (sensitivity 97%, specificity 95%). NCCT can reliably characterize the location and size of an offending ureteral calculus, identify complications, and diagnose alternative etiologies of abdominal pain such as appendicitis. By comparison, the sensitivity of radiographs (59%) and ultrasound (24-57%) for the detection of renal and ureteral calculi is relatively poor. Ultrasound can accurately diagnose pelvicaliectasis and ureterectasis, but it may take several hours for these findings to develop. In the pregnant patient, however, ultrasound is a first line test as it does not expose the fetus to ionizing radiation. MR is an accurate test for the diagnosis of pelvicaliectasis and ureterectasis, but is less sensitive than CT for the diagnosis of renal and ureteral calculi. For patients with known stone disease whose stones are visible on radiographs, radiographs are a good tool for post-treatment follow-up.The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every two years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Imaging features of common and uncommon bladder neoplasms.

In this article, the authors discuss imaging features of common and less-common epithelial and nonepithelial bladder neoplasms. Epithelial tumors include entities, such as urothelial cell carcinoma, squamous cell carcinoma, and adenocarcinoma, along with less-common entities, such as small cell and carcinoid tumors. Nonepithelial or mesenchymal tumors are also less commonly encountered and include benign entities, such as leiomyoma and neurofibroma, and malignant entities, including leiomyosarcoma and lymphoma. Their imaging features with an emphasis on computed tomography and magnetic resonance imaging are described.