Faculty Bibliography

OBJECTIVE:The purpose of this study was to determine the percentage of small (< 4 cm) Bosniak category 2F, 3, and 4 lesions that regress during active surveillance. MATERIALS AND METHODS/METHODS:In this retrospective study, a hospital database was searched from January 1, 2005, through September 9, 2017, for small (< 4 cm) Bosniak category 2F, 3, and 4 lesions studied with initial and follow-up unenhanced and contrast-enhanced CT or MRI. Prospective Bosniak categories were recorded. Two blinded radiologists retrospectively reassigned Bosniak categories to the initial and last follow-up studies. Interreader variability was analyzed. Rates of stability, regression, and progression were calculated and stratified by size. Logistic regression was used to assess the effects of lesion size, lesion growth, and duration of follow-up on the change in Bosniak categories. RESULTS:The search identified 123 patients (85 men, 38 women) with 138 renal lesions (according to the blinded readings, 83 Bosniak category 2F, 37 category 3, and 18 category 4) and followed for 1-12.3 years (median, 2.7 years). Fifty-one percent (70/138) of the lesions were smaller than 2 cm. Eighty-eight percent (73/83) of category 2F lesions were downgraded or remained stable. Forty-five percent (25/55) of category 3 or 4 lesions were downgraded to 2F or lower. Kappa values were 0.94 between the two readers and 0.72-0.76 between the readers and the prospective Bosniak categories. There was no association between initial size, change in size, or duration of follow-up and change in Bosniak category. CONCLUSION/CONCLUSIONS:Approximately one-half of small (< 4 cm) Bosniak category 3 and 4 cystic renal lesions were downgraded, and the majority (88%) of small Bosniak category 2F lesions regressed or remained stable during active surveillance. Therefore, small size should be a consideration for conservative management.

Purpose: To assess changing utilization in extremity angiography from 2001 to 2016, focusing on relative shifts between modalities and provider specialties. Materials: Medicare PSPS Master Files from 2001-2016 were used to determine national utilization of traditional invasive catheter angiography, CTA, and MRA, normalized to extremities imaged per 100,000 beneficiaries. Result(s): From 2001 to 2016, extremity angiography increased from 769 to 1,352 total extremities imaged per 100,000 beneficiaries, largely attributable to massive early growth in CTA (22 in 2001 to 614 in 2009; plateau of 645 in 2016), with small changes in catheter angiography (702 to 676) and MRA (45 to 30). Extremity angiography shifted from 91% catheter, 6% MRA, 3% CTA in 2001 to 50% catheter, 48% CTA, and 2% MRA in 2016. For radiologists, overall angiography increased (488 to 733) due to a large increase in CTA (20 to 595) despite a large decrease in catheter (428 to 122), while MRA remained low (40 to 27); extremity angiography by radiologists shifted from 88% catheter, 8% MRA, and 4% CTA in 2001 to 81% CTA, 15% catheter, and 4% MRA in 2016. For cardiologists, there were increases in angiography overall (155 to 240) and catheter (153 to 205), and to a lesser extent in CTA (1 to 33); extremity angiography by cardiologists shifted from 99% catheter, <1% CTA, <1% MRA in 2001 to 85% catheter, 14% CTA, <1% MRA in 2016. For surgeons, overall angiography increased from 65 to 261 and was 99% catheter in both 2001 and 2016. Radiologists' market share of extremity angiography varied from 63% (2001) to 54% (2016). Despite a marked decrease in radiologists' share for catheter (61% to 17%), radiologists were the dominant provider throughout for CTA (89% to 92%) and MRA (89% to 90%). Conclusion(s): Utilization of extremity angiography in Medicare beneficiaries nearly tripled from 2001 to 2016, almost entirely due to the advent of CTA by radiologists. Cardiologists and surgeons acquired the large volume of catheter angiography given up by radiologists. Further work is necessary to assess if the growth of CTA represents additive (i.e., expanded patient populations being evaluated) vs. duplicative (i.e., same patients undergoing both tests) imaging.

Hematuria evaluation remains a common problem, particularly in patients who smoke and are at risk for urothelial tumors. Lifetime surveillance of the urothelium is often required once urothelial cancer is diagnosed. Computed tomography urography (CTU) has exquisite sensitivity and specificity for identification of renal and urothelial lesions. The examination is well accepted by patients and physicians. Possible harms include radiation exposure and contrast-induced nephropathy. MR imaging is also an accurate test, but requires longer exam times, and may not demonstrate stones. We present the technical and interpretation skills required to use MR urography and CTU effectively.

OBJECTIVE:The purpose of this study was to assess the use of apparent diffusion coefficient (ADC) during DWI for predicting complete pathologic response of rectal cancer after neoadjuvant therapy. MATERIALS AND METHODS/METHODS:A systematic review of available literature was conducted to retrieve studies focused on the identification of complete pathologic response of locally advanced rectal cancer after neoadjuvant chemoradiation, through the assessment of ADC evaluated before, after, or both before and after treatment, as well as in terms of the difference between pretreatment and posttreatment ADC. Pooled mean pretreatment ADC, posttreatment ADC, and Δ-ADC (calculated as posttreatment ADC minus pretreatment ADC divided by pretreatment ADC and multiplied by 100) in complete responders versus incomplete responders were calculated. For each parameter, we also pooled sensitivity and specificity and calculated the area under the summary ROC curve. RESULTS:/s, in complete and incomplete responders, respectively (p = 0.00001). The Δ-ADC percentages were also significantly higher in complete responders than in incomplete responders (59.7% vs 29.7%, respectively, p = 0.016). Pooled sensitivity, specificity, and AUC were 0.743, 0.755, and 0.841 for pretreatment ADC; 0.800, 0.737, and 0.782 for posttreatment ADC; and 0.832, 0.806, and 0.895 for Δ-ADC. CONCLUSION/CONCLUSIONS:Use of ADC during DWI is a promising technique for assessment of results of neoadjuvant treatment of rectal cancer.

Perforated duodenal ulcer following RYGB is an unusual clinical situation that may be a diagnostic challenge. Only 23 cases have previously been reported. We present five cases. The hallmark of visceral perforation, namely pneumoperitoneum, was not seen in three of the four cases that underwent cross sectional imaging. This is perhaps due to the altered anatomy of the RYGB that excludes air from the duodenum. Our cases had more free fluid than expected. The bariatric surgeon should not wait for free intraperitoneal air to suspect duodenal perforation after RYGB.

This article provides an updated review on the imaging evaluation of cystic renal masses with focus on the Bosniak classification system, discusses current imaging techniques for evaluating these lesions, reviews benign and malignant etiologies of cystic renal masses, describes pitfalls in the evaluation of these lesions, and discusses current and future directions in the management of cystic renal masses.

The ACR Incidental Findings Committee (IFC) presents recommendations for renal masses that are incidentally detected on CT. These recommendations represent an update from the renal component of the JACR 2010 white paper on managing incidental findings in the adrenal glands, kidneys, liver, and pancreas. The Renal Subcommittee, consisting of six abdominal radiologists and one urologist, developed this algorithm. The recommendations draw from published evidence and expert opinion and were finalized by informal iterative consensus. Each flowchart within the algorithm describes imaging features that identify when there is a need for additional imaging, surveillance, or referral for management. Our goal is to improve quality of care by providing guidance for managing incidentally detected renal masses.

Because liver fibrosis can be treated, it is important to diagnose liver fibrosis noninvasively and monitor response to treatment. Although ultrasound (grayscale and Doppler) can diagnose cirrhosis, it does so unreliably using morphologic and sonographic features and cannot diagnose the earlier, treatable stages of hepatic fibrosis. Transient elastography, ultrasound elastography with acoustic radiation force impulse, and MR elastography are modalities that can assess for hepatic fibrosis. Although all international organizations recommend ultrasound for screening for hepatocellular carcinoma, ultrasound is particularly limited for identifying hepatocellular carcinoma in patients with obesity, nonalcoholic fatty liver disease, and nodular cirrhotic livers. In these patient groups as well as patients who are on the liver transplant wait list, ultrasound is so limited that consideration can be made for screening for hepatocellular carcinoma with either MRI or multiphase CT. Additionally, patients who have been previously diagnosed with and treated for hepatocellular carcinoma require continued surveillance for recurrent hepatocellular carcinoma. 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.

Pancreatic adenocarcinoma is associated with poor overall prognosis. Complete surgical resection is the only possible option for cure. As such, increasingly complex surgical techniques including sophisticated vascular reconstruction are being used. Continued advances in surgical techniques, in conjunction with use of combination systemic therapies, and radiation therapy have been suggested to improve outcomes. A key aspect to surgical success is reporting of pivotal findings beyond absence of distant metastases, such as tumor size, location, and degree of tumor involvement of specific vessels associated with potential perineural tumor spread. Multiphase contrast-enhanced multidetector CT and MRI are the imaging modalities of choice for pretreatment staging and presurgical determination of resectability. Imaging modalities such as endoscopic ultrasound and fluorine-18-2-fluoro-2-deoxy-D-glucose imaging with PET/CT are indicated for specific scenarios such as biopsy guidance and confirmation of distant metastases, respectively. 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.