Performance of O-RADS MRI Score in Differentiating Benign From Malignant Ovarian Teratomas: MR Feature Analysis for Differentiating O-RADS 4 From O-RADS 2.

OBJECTIVE: The aim of the study is to evaluate the performance of the ovarian-adnexal reporting and data system magnetic resonance imaging (O-RADS MRI) score and perform individual MRI feature analysis for differentiating between benign and malignant ovarian teratomas. METHODS: In this institutional review board-approved retrospective study, consecutive patients with a pathology-proven fat-containing ovarian mass imaged with contrast-enhanced MRI (1.5T or 3T) from 2013 to 2022 were included. Two blinded radiologists independently evaluated masses per the O-RADS MRI lexicon, including having a "characteristic" or "large" Rokitansky nodule (RN). Additional features analyzed included the following: nodule size/percentage volume relative to total teratoma volume, presence of bulk/intravoxel fat in the nodule, diffusion restriction in the nodule, angular interface, nodule extension through the teratoma border, presence/type of nodule enhancement pattern (solid versus peripheral), and evidence for metastatic disease. An overall O-RADS MRI score was assigned. Patient and lesion features associated with malignancy were evaluated and used to create a malignant teratoma score. χ2, Fisher's exact tests, receiver operating characteristic curve, and κ analysis was performed. RESULTS: One hundred thirty-seven women (median age 34, range 9-84 years) with 123 benign and 14 malignant lesions were included. Mean teratoma size was 7.3 cm (malignant: 14.4 cm, benign: 6.5 cm). 18/123 (14.6%) of benign teratomas were assigned an O-RADS 4 based on the presence of a "large" (11/18) or "noncharacteristic" (12/18) RN. 12/14 malignant nodules occupied >25% of the total teratoma volume (P = 0.09). Features associated with malignancy included the following: age <18 years, an enhancing noncharacteristic RN, teratoma size >12 cm, irregular cystic border, and extralesional extension; these were incorporated into a malignant teratoma score, with a score of 2 or more associated with area under the curve of 0.991 for reviewer 1 and 0.993 for reviewer 2. Peripheral enhancement in a RN was never seen with malignancy (64/123 benign, 0/14 malignant) and would have appropriated downgraded 9/18 overcalled O-RADS 4 benign teratomas. CONCLUSIONS: O-RADS MRI overcalled 15% (18/123) benign teratomas as O-RADS 4 but correctly captured all malignant teratomas. We propose defining a "characteristic" RN as an intravoxel or bulk fat-containing nodule. Observation of a peripheral rim of enhancement in a noncharacteristic RN allowed more accurate prediction of benignity and should be added to the MRI lexicon for improved O-RADS performance.

ACR Appropriateness Criteria® Pretreatment Evaluation and Follow-Up of Invasive Cancer of the Cervix: 2023 Update.

Cervical cancer is a common gynecological malignancy worldwide. Cervical cancer is staged based on the International Federation of Gynecology and Obstetrics (FIGO) classification system, which was revised in 2018 to incorporate radiologic and pathologic data. Imaging plays an important role in pretreatment assessment including initial staging and treatment response assessment of cervical cancer. Accurate determination of tumor size, local extension, and nodal and distant metastases is important for treatment selection and for prognostication. Although local recurrence can be diagnosed by physical examination, imaging plays a critical role in detection and follow-up of local and distant recurrence and subsequent treatment selection. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Utility of ADC Values for Differentiating Uterine Sarcomas From Leiomyomas: Systematic Review and Meta-Analysis.

Background: Uterine sarcomas are rare; however, they display imaging features that overlap those of leiomyomas. The potential for undetected uterine sarcomas is clinically relevant because minimally invasive treatment of leiomyomas may lead to cancer dissemination. ADC values have shown potential for differentiating benign and malignant uterine masses. Objective: The purpose of this study was to perform a systematic review of the diagnostic performance of ADC values in differentiating uterine sarcomas from leiomyomas. Evidence acquisition: We searched three electronic databases (MEDLINE, EMBASE, and Cochrane databases) for studies distinguishing uterine sarcomas from leiomyomas using MRI, including ADC, with pathologic tissue confirmation or imaging follow-up as the reference standard. Data extraction and QUADAS-2 quality assessment were performed. Sensitivity and specificity were pooled using hierarchic models, including bivariate and hierarchic summary ROC models. Metaregression was used to assess the impact of various factors on heterogeneity. Evidence synthesis: Twenty-one studies met study inclusion criteria. Pooled sensitivity and specificity were 89% (95% CI, 82-94%) and 86% (95% CI, 78-92%), respectively. Area under the summary ROC curve was 94% (95% CI, 92-96%). Context of ADC interpretation (i.e., standalone vs part of multiparametric MRI [mpMRI]) was the only factor found to account significantly for heterogeneity (p = .01). Higher specificity (95% [95% CI, 92-99%] vs 82% [95% CI, 75-89%]) and similar sensitivity (94% [95% CI, 89-99%] vs 88% [95% CI, 82-93%]) were observed when ADC was evaluated among mpMRI features as compared with standalone ADC assessment. ADC cutoff values ranged (0.87-1.29 × 10-3 mm2/s) but were not associated with statistically different performance (p = .37). Pooled mean ADC values in sarcomas and leiomyomas were 0.904 × 10-3 mm2/s and 1.287 × 10-3 mm2/s, respectively. Conclusion: As part of mpMRI evaluation of uterine masses, mass ADC value less than 0.904 × 10-3 mm2/s may be a useful test-positive threshold for uterine sarcoma, consistent with a prior expert consensus statement. Institutional protocols may influence locally selected ADC values. Clinical Impact: Using ADC as part of mpMRI assessment improves detection of uterine sarcoma, which could influence candidate selection for minimally invasive treatments.

Imaging of Antepartum and Postpartum Hemorrhage.

Severe obstetric hemorrhage is a leading cause of maternal mortality and morbidity worldwide. Major hemorrhage in the antepartum period presents potential risks for both the mother and the fetus. Similarly, postpartum hemorrhage (PPH) accounts for up to a quarter of maternal deaths worldwide. Potential causes of severe antepartum hemorrhage that radiologists should be familiar with include placental abruption, placenta previa, placenta accreta spectrum disorders, and vasa previa. Common causes of PPH that the authors discuss include uterine atony, puerperal genital hematomas, uterine rupture and dehiscence, retained products of conception, and vascular anomalies. Bleeding complications unique to or most frequently encountered after cesarean delivery are also enumerated, including entities such as bladder flap hematomas, rectus sheath and subfascial hemorrhage, and infectious complications of endometritis and uterine dehiscence. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material. See the invited commentary by Javitt and Madrazo in this issue.

O-RADS MRI risk stratification system: pearls and pitfalls.

In 2021, the American College of Radiology (ACR) Ovarian-Adnexal Reporting and Data System (O-RADS) MRI Committee developed a risk stratification system and lexicon for assessing adnexal lesions using MRI. Like the BI-RADS classification, O-RADS MRI provides a standardized language for communication between radiologists and clinicians. It is essential for radiologists to be familiar with the O-RADS algorithmic approach to avoid misclassifications. Training, like that offered by International Ovarian Tumor Analysis (IOTA), is essential to ensure accurate and consistent application of the O-RADS MRI system. Tools such as the O-RADS MRI calculator aim to ensure an algorithmic approach. This review highlights the key teaching points, pearls, and pitfalls when using the O-RADS MRI risk stratification system.Critical relevance statement This article highlights the pearls and pitfalls of using the O-RADS MRI scoring system in clinical practice.Key points• Solid tissue is described as displaying post- contrast enhancement.• Endosalpingeal folds, fimbriated end of the tube, smooth wall, or septa are not solid tissue.• Low-risk TIC has no shoulder or plateau. An intermediate-risk TIC has a shoulder and plateau, though the shoulder is less steep compared to outer myometrium.

Current Concepts in the Imaging of Uterine Sarcomas.

Uterine sarcomas are a group of rare uterine tumors comprised of multiple subtypes with different histologic characteristics, prognoses, and imaging appearances. Identification of uterine sarcomas and their differentiation from benign uterine disease on imaging is of critical importance for treatment planning to guide appropriate management and optimize patient outcomes. Herein, we review the spectrum of uterine sarcomas with a focus on the classification of primary sarcoma subtypes and presenting the typical MR imaging appearances.

Accuracy of Ultrasound Imaging for Etiology of New-Onset Painless Jaundice.

PURPOSE: Ultrasound (US) is considered a first-line study for painless jaundice. However, in our hospital system, patients with new-onset painless jaundice often have a contrast-enhanced computed tomography (CECT) or magnetic resonance cholangiopancreatography (MRCP) regardless of the sonographic findings. Thus, we investigated the accuracy of US for detection of biliary dilatation in patients with new-onset painless jaundice. METHODS: Our electronic medical record was searched from January 1, 2012, to January 1, 2020, for adult patients with new-onset painless jaundice. Presenting complaint/setting, laboratory values, imaging studies/findings, and final diagnoses were recorded. Patients with pain or known liver disease were excluded. A gastrointestinal physician reviewed the laboratory values/chart to classify the type of suspected obstruction. Two radiologists blindly re-reviewed the US scans, and κ between the radiologists was calculated. Fisher exact test and the 2-sample t test were used for statistical analysis. RESULTS: Three hundred sixty patients presented with jaundice (>3 mg/dL), of whom 68 met the inclusion criteria (no pain and no known liver disease). Laboratory values had an overall accuracy of 54%, but were accurate in 87.5% and 85% for obstructing stones/pancreaticobiliary cancer. Ultrasound demonstrated overall accuracy of 78%, but only 69% for pancreaticobiliary cancer and 12.5% for common bile duct stone. Seventy-five percent of the patients underwent follow-up CECT or MRCP regardless of presenting setting. In the emergency department or inpatient setting, 92% of the patients underwent CECT or MRCP regardless of US, and 81% had follow-up CECT or MRCP within 24 hours. CONCLUSION: A US-first strategy in the setting of new-onset painless jaundice is accurate only 78% of the time. In practice, US was almost never a stand-alone imaging examination in patients presenting to the emergency department or inpatient setting with new-onset painless jaundice, no matter the suspected diagnosis based on clinical and laboratory grounds or on the US findings themselves. However, for milder elevations of unconjugated bilirubin (suspicious for Gilbert disease) in the outpatient setting, a US demonstrating lack of biliary dilatation was often a definitive study for exclusion of pathology.

How We Got Here: The Legacy of Anti-Black Discrimination in Radiology.

Current disparities in the access to diagnostic imaging for Black patients and the underrepresentation of Black physicians in radiology, relative to their representation in the general U.S. population, reflect contemporary consequences of historical anti-Black discrimination. These disparities have existed within the field of radiology and professional medical organizations since their inception. Explicit and implicit racism against Black patients and physicians was institutional policy in the early 20th century when radiology was being developed as a clinical medical field. Early radiology organizations also embraced this structural discrimination, creating strong barriers to professional Black radiologist involvement. Nevertheless, there were numerous pioneering Black radiologists who advanced scholarship, patient care, and diversity within medicine and radiology during the early 20th century. This work remains important in the present day, as race-based health care disparities persist and continue to decrease the quality of radiology-delivered patient care. There are also structural barriers within radiology affecting workforce diversity that negatively impact marginalized groups. Multiple opportunities exist today for antiracism work to improve quality of care and to apply standards of social justice and health equity to the field of radiology. An initial step is to expand education on the disparities in access to imaging and health care among Black patients. Institutional interventions include implementing community-based outreach and applying antibias methodology in artificial intelligence algorithms, while systemic interventions include identifying national race-based quality measures and ensuring imaging guidelines properly address the unique cancer risks in the Black patient population. These approaches reflect some of the strategies that may mutually serve to address health care disparities in radiology. © RSNA, 2023 See the invited commentary by Scott in this issue. Quiz questions for this article are available in the supplemental material.

Ovarian-Adnexal Reporting and Data Systems MR Imaging: Nuts and Bolts.

MR imaging plays a key role in the characterization of adnexal lesions of indeterminate malignant potential found at ultrasound. Recently, the Ovarian-Adnexal Reporting and Data Systems (O-RADS) MRI lexicon and scoring system was developed to aid in standardization of reporting and interpretation of adnexal lesions, allowing for risk stratification based on MR imaging findings. This in turn can help improve communication between radiologists and referring providers, and potentially aid the selection of optimal treatment options. This article provides a detailed review of the lexicon and the scoring rubric of the O-RADS MRI risk stratification system.

MRI Evaluation of Uterine Masses for Risk of Leiomyosarcoma: A Consensus Statement.

Laparoscopic myomectomy, a common gynecologic operation in premenopausal women, has become heavily regulated since 2014 following the dissemination of unsuspected uterine leiomyosarcoma (LMS) throughout the pelvis of a physician treated for symptomatic leiomyoma. Research since that time suggests a higher prevalence than previously suspected of uterine LMS in resected masses presumed to represent leiomyoma, as high as one in 770 women (0.13%). Though rare, the dissemination of an aggressive malignant neoplasm due to noncontained electromechanical morcellation in laparoscopic myomectomy is a devastating outcome. Gynecologic surgeons' desire for an evidence-based, noninvasive evaluation for LMS is driven by a clear need to avoid such harms while maintaining the availability of minimally invasive surgery for symptomatic leiomyoma. Laparoscopic gynecologists could rely upon the distinction of higher-risk uterine masses preoperatively to plan oncologic surgery (ie, potential hysterectomy) for patients with elevated risk for LMS and, conversely, to safely offer women with no or minimal indicators of elevated risk the fertility-preserving laparoscopic myomectomy. MRI evaluation for LMS may potentially serve this purpose in symptomatic women with leiomyomas. This evidence review and consensus statement defines imaging and disease-related terms to allow more uniform and reliable interpretation and identifies the highest priorities for future research on LMS evaluation.

Case series demonstrating in vivo MR safety of stainless steel (Chinese/Ring) IUDs.

Intrauterine devices (IUDs) are one of the most common forms of long-term contraception used by patients around the world. Many studies have been performed over the past few decades demonstrating the safety of many common hormonal and metallic intrauterine devices in Magnetic Resonance (MR) imaging; however, the stainless steel ring IUD (often termed the "Chinese" IUD) is still considered MR Unsafe. This device was used in the 1980s and 1990s in China, where as many as 60 million women in China were using an IUD by 1988, and approximately 90% of those were stainless steel ring IUDs. In a major metropolitan area hospital such as ours with a large immigrant population, we encounter females with this ring IUD several times a year. As this population ages, the need for medical care (and concomitantly, MR imaging) is projected to increase. The purpose of this case review is to examine the imaging and clinical course of patients with stainless-steel ring intrauterine devices who safely received 1.5T Brain MR scans at our institution for clinically necessary diagnostic imaging.

Peripheral vascular lesions in adults referred to MRI/MRA: Multivariable analysis of imaging features to help differentiate benign vascular anomalies from malignancies.

PURPOSE: Symptomatic peripheral vascular lesions in adults are often clinically diagnosed as benign vascular anomalies and may receive MRI/MRA for pre-treatment vascular mapping. Malignant neoplasms are difficult to distinguish from benign vascular anomalies on MRI/MRA. This study was performed to determine if there are imaging signs that can distinguish malignancies from benign vascular anomalies in adults imaged with MRI/MRA. MATERIALS AND METHODS: A radiology database was retrospectively searched for ISSVA classification terms in MRI/MRA reports from 1/1/2002-1/1/2019. Adult patients (n = 50, 52 corresponding lesions) with contrast-enhanced MRI/MRA, peripheral soft tissue based lesion (s), and available pathology or long-term (>1 year) imaging follow-up were included. MRI/MRA images were reviewed by 3 readers for the following lesional characteristics: morphology (marginal lobulation, internal septations, distinct soft tissue mass), peri-articular location, T2-weighted characteristics (hyperintensity, heterogeneity, perilesional edema, and adjacent triangular T2-peaks), bulk fat, hemorrhage, enhancement pattern (peripheral, diffuse, or absent), neovascularity, low-flow venous malformation type enhancement, arterial enhancement within 6 s, enhancement curve (progressive, plateau, or washout), measured size, and multifocality. The MRI/MRA features' associated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. To identify factors predictive of malignancy, a two-stage multivariable analysis was performed. RESULTS: 23% (12/52) of the lesions, corresponding to 22% (11/50) of the patients, were malignant neoplasms. No single imaging feature reliably predicted malignancy (PPV ≤ 60%). Absence of distinct soft tissue mass excluded malignancy (NPV 100%). Multivariate analysis derived a summary score based on the five strongest predictors of malignancy: adjacent T2 peaks, age ≥ 70 years, distinct soft tissue mass, lesion size ≥ 5 cm, and absence of septations. A score ≥ 3 resulted in sensitivity of 92% and specificity of 85%. CONCLUSION: Extremity MRI/MRA rarely differentiates malignant from benign soft-tissue vascular tumors in adults. However, MRI/MRA can suggest malignancy when patient age and multiple imaging features are considered. Periodic clinical follow-up after the planned endovascular or operative procedure should be performed to avoid missing a malignancy.

Multicenter Evaluation of Multiparametric MRI Clear Cell Likelihood Scores in Solid Indeterminate Small Renal Masses.

Background Solid small renal masses (SRMs) (≤4 cm) represent benign and malignant tumors. Among SRMs, clear cell renal cell carcinoma (ccRCC) is frequently aggressive. When compared with invasive percutaneous biopsies, the objective of the proposed clear cell likelihood score (ccLS) is to classify ccRCC noninvasively by using multiparametric MRI, but it lacks external validation. Purpose To evaluate the performance of and interobserver agreement for ccLS to diagnose ccRCC among solid SRMs. Materials and Methods This retrospective multicenter cross-sectional study included patients with consecutive solid (≥25% approximate volume enhancement) SRMs undergoing multiparametric MRI between December 2012 and December 2019 at five academic medical centers with histologic confirmation of diagnosis. Masses with macroscopic fat were excluded. After a 1.5-hour training session, two abdominal radiologists per center independently rendered a ccLS for 50 masses. The diagnostic performance for ccRCC was calculated using random-effects logistic regression modeling. The distribution of ccRCC by ccLS was tabulated. Interobserver agreement for ccLS was evaluated with the Fleiss κ statistic. Results A total of 241 patients (mean age, 60 years ± 13 [SD]; 174 men) with 250 solid SRMs were evaluated. The mean size was 25 mm ± 8 (range, 10-39 mm). Of the 250 SRMs, 119 (48%) were ccRCC. The sensitivity, specificity, and positive predictive value for the diagnosis of ccRCC when ccLS was 4 or higher were 75% (95% CI: 68, 81), 78% (72, 84), and 76% (69, 81), respectively. The negative predictive value of a ccLS of 2 or lower was 88% (95% CI: 81, 93). The percentages of ccRCC according to the ccLS were 6% (range, 0%-18%), 38% (range, 0%-100%), 32% (range, 60%-83%), 72% (range, 40%-88%), and 81% (range, 73%-100%) for ccLSs of 1-5, respectively. The mean interobserver agreement was moderate (κ = 0.58; 95% CI: 0.42, 0.75). Conclusion The clear cell likelihood score applied to multiparametric MRI had moderate interobserver agreement and differentiated clear cell renal cell carcinoma from other solid renal masses, with a negative predictive value of 88%. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Mileto and Potretzke in this issue.

ACR Appropriateness Criteria® Staging and Follow-up of Primary Vaginal Cancer.

Primary vaginal cancer is rare, comprising 1% to 2% of gynecologic malignancies and 20% of all malignancies involving the vagina. More frequently, the vagina is involved secondarily by direct invasion from malignancies originating in adjacent organs or by metastases from other pelvic or extrapelvic primary malignancies. Data on the use of imaging in vaginal cancer are sparse. Insights are derived from the study of imaging in cervical cancer and have reasonable generalizability to vaginal cancer due to similar tumor biology. Given the trend toward definitive chemoradiation for both cancers in all but early stage lesions, principles of postchemoradiation tumor response evaluation are largely analogous. Accordingly, many of the recommendations outlined here are informed by principles translated from the literature on cervical cancer. For pretreatment assessment of local tumor burden and in the case of recurrent vaginal cancer, MRI is the preferred imaging modality. PET/CT has demonstrated utility for the detection of nodal metastatic and unexpected distant metastatic disease. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Feasibility of Abdominal Magnetic Resonance Imaging in Patients With Residual Concentrated Enteric Contrast After Fluoroscopic Abdominal Examination.

OBJECTIVE: This study aimed to evaluate the image quality, image artifacts, radiologist confidence, and ability to provide definitive diagnosis for all patients with magnetic resonance imaging (MRI) performed after an abdominal fluoroscopic examination and to determine the utility of MRI in this setting. METHODS: Thirty-one MRI examinations performed a median of 2 days after fluoroscopic bowel evaluation (barium, n = 13; iodine, n = 18), 20 within 3 days of MRI, were retrospectively reviewed. The image quality, artifact emanating from bowel, inhomogeneity artifact, radiologist confidence, ability to render a definitive diagnosis, and identification of emergent or important findings for all MRI examinations were assessed. These same features were evaluated on 5 computed tomographies performed after fluoroscopy (before the MRI) in the same cohort. RESULTS: All 31 MRI examinations performed after fluoroscopic studies with concentrated barium or iodine solutions were diagnostic for answering the clinical question according to radiologist and report review, regardless of magnet strength and type of fluoroscopic contrast ingested. Magnetic resonance imaging after fluoroscopy had excellent overall image quality (mean score, 4.74/5), minimal to no artifact emanating from bowel (mean, 4.63/5), minimal inhomogeneity artifact (mean, 4.38/5), and excellent diagnostic confidence (mean, 4.98/5). No additional imaging was necessary for diagnosis after MRI. Computed tomography after fluoroscopy had lower overall image quality, more image artifacts, and lower diagnostic confidence (P < 0.05). CONCLUSIONS: Magnetic resonance imaging is a useful tool for evaluating patients with retained concentrated enteric contrast from recent fluoroscopic examinations. In the absence of contraindication, MRI should be considered in the evaluation of urgent clinical problems in patients who recently underwent a fluoroscopic bowel evaluation.

Bosniak Classification of Cystic Renal Masses, Version 2019: A Pictorial Guide to Clinical Use.

Cystic renal masses are commonly encountered in clinical practice. In 2019, the Bosniak classification of cystic renal masses, originally developed for CT, underwent a major revision to incorporate MRI and is referred to as the Bosniak Classification, version 2019. The proposed changes attempt to (a) define renal masses (ie, cystic tumors with less than 25% enhancing tissue) to which the classification should be applied; (b) emphasize specificity for diagnosis of cystic renal cancers, thereby decreasing the number of benign and indolent cystic masses that are unnecessarily treated or imaged further; (c) improve interobserver agreement by defining imaging features, terms, and classes of cystic renal masses; (d) reduce variation in reported malignancy rates for each of the Bosniak classes; (e) incorporate MRI and to some extent US; and (f) be applicable to all cystic renal masses encountered in clinical practice, including those that had been considered indeterminate with the original classification. The authors instruct how, using CT, MRI, and to some extent US, the revised classification can be applied, with representative clinical examples and images. Practical tips, pitfalls to avoid, and decision tree rules are included to help radiologists and other physicians apply the Bosniak Classification, version 2019 and better manage cystic renal masses. An online resource and mobile application are also available for clinical assistance. An invited commentary by Siegel and Cohan is available online. ©RSNA, 2021.

Bosniak classification of cystic renal masses, version 2019: interpretation pitfalls and recommendations to avoid misclassification.

The purpose of this review is to describe the potential sources of variability or discrepancy in interpretation of cystic renal masses under the Bosniak v2019 classification system. Strategies to avoid these pitfalls and clinical examples of diagnostic approaches are also presented. Potential pitfalls in the application of Bosniak v2019 are divided into three categories: interpretative, technical, and mass related. An organized, comprehensive review of possible discrepancies in interpreting Bosniak v2019 cystic masses is presented with pictorial examples of difficult clinical cases and proposed solutions. The scheme provided can guide readers to consistent, precise application of the classification system. Radiologists should be aware of the possible sources of misinterpretation of cystic renal masses when applying Bosniak v2019. Knowing which features and types of cystic masses are prone to interpretive errors, in addition to the inherent trade-offs between the CT and MR techniques used to characterize them, can help radiologists avoid these pitfalls.

Changing National Medicare Utilization of Catheter, Computed Tomography, and Magnetic Resonance Extremity Angiography: A Specialty-focused 16-Year Analysis.

To assess changing utilization of extremity angiography from 2001 to 2016, focusing on modalities and provider specialties. Medicare PSPS Master Files from 2001-2016 and POSPUF from 2016 were used to determine overall and specialty utilization of diagnostic catheter angiography (DCA), CT angiography (CTA), and MR angiography (MRA). From 2001 to 2016, extremity angiography increased from 1107 to 1590 extremities imaged per 100,000 beneficiaries, with rapid expansion of CTA (22 in 2001 to 619 in 2009; plateau of 645 in 2016), but declines in DCA (1039 to 914) and MRA (45 to 30). Over time, extremity angiography shifted from 94% DCA, 4% MRA, and 2% CTA to 58% DCA, 41% CTA, and 2% MRA. For radiologists, extremity angiography increased slightly (741 to 767) with increases in CTA (20 to 595) and large decreases in DCA (681 to 145), with MRA remaining low (40 to 27). Extremity angiography increased for cardiologists (197 to 349) and vascular surgeons (87 to 351), both overwhelmingly performing DCA. Radiologists' share of all extremity angiography shifted from 67% to 48%, with interventionalists (47%), generalists (43%), and abdominal radiologists (7.4%) providing most radiologist services in 2016. Throughout, radiologists were the dominant providers of CTA (89% to 92%) and MRA (89% to 90%). Extremity angiography utilization in Medicare beneficiaries increased nearly 50% from 2001 to 2016, largely related to CTA performed by radiologists. Of radiologists, interventionalists and generalists together render most services. Cardiologists and surgeons assumed a large share of DCA previously performed by radiologists.