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MRI plays an important role in the evaluation of kidney allografts for vascular complications as well as parenchymal insults. Transplant renal artery stenosis, the most common vascular complication of kidney transplant, can be evaluated by MRA using gadolinium and nongadolinium contrast agents as well as by unenhanced MRA techniques. Parenchymal injury occurs through a variety of pathways, including graft rejection, acute tubular injury, BK polyomavirus infection, drug-induced interstitial nephritis, and pyelonephritis. Investigational MRI techniques have sought to differentiate among these causes of dysfunction as well as to assess the degree of interstitial fibrosis or tubular atrophy (IFTA)-the common end pathway for all of these processes-which is currently evaluated by invasively obtained core biopsies. Some of these MRI sequences have shown promise in not only assessing the cause of parenchymal injury but also assessing IFTA noninvasively. This review describes current clinically used MRI techniques and previews promising investigational MRI techniques for assessing complications of kidney grafts.

ObjectivesWhat sonographic variables are most predictive for acute cholecystitis? What variables differentiate acute and chronic cholecystitis?MethodsThe surgical pathology database was reviewed to identify adult patients who underwent cholecystectomy for cholecystitis and had a preceding ultrasound of the right upper quadrant within 7 days. A total of 236 patients were included in the study. A comprehensive imaging review was performed to assess for gallstones, gallbladder wall thickening, gallbladder distension, pericholecystic fluid, gallstone mobility, the sonographic Murphy's sign, mural hyperemia, and the common hepatic artery peak systolic velocity.ResultsOf 236 patients with a cholecystectomy, 119 had acute cholecystitis and 117 had chronic cholecystitis on surgical pathology. Statistical models were created for prediction. The simple model consists of three sonographic variables and has a sensitivity of 60% and specificity of 83% in predicting acute versus chronic cholecystitis. The most predictive variables for acute cholecystitis were elevated common hepatic artery peak systolic velocity, gallbladder distension, and gallbladder mural abnormalities. If a patient had all three of these findings on their preoperative ultrasound, the patient had a 96% chance of having acute cholecystitis. Two of these variables gave a 73-93% chance of having acute cholecystitis. One of the three variables gave a 40-76% chance of having acute cholecystitis. If the patient had 0 of 3 of the predictor variables, there was a 29% chance of having acute cholecystitis.ConclusionsGallbladder distension, gallbladder mural abnormalities, and elevated common hepatic artery peak systolic velocity are the most important sonographic variables in predicting acute versus chronic cholecystitis.

PURPOSE: To determine institutional practice requirements for personal protective equipment (PPE) in cross-sectional interventional radiology (CSIR) procedures among a variety of radiology practices in the USA and Canada. METHODS: Members of the Society of Abdominal Radiology (SAR) CSIR Emerging Technology Commission (ETC) were sent an eight-question survey about what PPE they were required to use during common CSIR procedures: paracentesis, thoracentesis, thyroid fine needle aspiration (FNA), superficial lymph node biopsy, deep lymph node biopsy, solid organ biopsy, and ablation. Types of PPE evaluated were sterile gloves, surgical masks, gowns, surgical hats, eye shields, foot covers, and scrubs. RESULTS: 26/38 surveys were completed by respondents at 20/22 (91%) institutions. The most common PPE was sterile gloves, required by 20/20 (100%) institutions for every procedure. The second most common PPE was masks, required by 14/20 (70%) institutions for superficial and deep procedures and 12/12 (100%) institutions for ablation. Scrubs, sterile gowns, eye shields, and surgical hats were required at nearly all institutions for ablation, whereas approximately half of institutions required their use for deep lymph node and solid organ biopsy. Compared with other types of PPE, required mask and eye shield use showed the greatest increase during the SARS-CoV-2 pandemic. CONCLUSION: PPE use during common cross-sectional procedures is widely variable. Given the environmental and financial impact and lack of consensus practice, further studies examining the appropriate level of PPE are needed.

Cholangiocarcinoma (CCA) is a heterogenous group of malignancies originating in the biliary tree, and associated with poor prognosis. Until recently, treatment options have been limited to surgical resection, liver-directed therapies, and chemotherapy. Identification of actionable genomic alterations with biomarker testing has revolutionized the treatment paradigm for these patients. However, several challenges exist to the seamless adoption of precision medicine in patients with CCA, relating to a lack of awareness of the importance of biomarker testing, hurdles in tissue acquisition, and ineffective collaboration among the multidisciplinary team (MDT). To identify gaps in standard practices and define best practices, multidisciplinary hepatobiliary teams from the University of California (UC) Davis and UC Irvine were convened; discussions of the meeting, including optimal approaches to tissue acquisition for diagnosis and biomarker testing, communication among academic and community healthcare teams, and physician education regarding biomarker testing, are summarized in this review.

ObjectivesThe 9th International Forum for Liver Magnetic Resonance Imaging (MRI) was held in Singapore in September 2019, bringing together radiologists and allied specialists to discuss the latest developments in and formulate consensus statements for liver MRI, including the applications of gadoxetic acid-enhanced imaging.MethodsAs at previous Liver Forums, the meeting was held over 2 days. Presentations by the faculty on days 1 and 2 and breakout group discussions on day 1 were followed by delegate voting on consensus statements presented on day 2. Presentations and discussions centered on two main meeting themes relating to the use of gadoxetic acid-enhanced MRI in primary liver cancer and metastatic liver disease.Results and conclusionsGadoxetic acid-enhanced MRI offers the ability to monitor response to systemic therapy and to assist in pre-surgical/pre-interventional planning in liver metastases. In hepatocellular carcinoma, gadoxetic acid-enhanced MRI provides precise staging information for accurate treatment decision-making and follow-up post therapy. Gadoxetic acid-enhanced MRI also has potential, currently investigational, indications for the functional assessment of the liver and the biliary system. Additional voting sessions at the Liver Forum debated the role of multidisciplinary care in the management of patients with liver disease, evidence to support the use of abbreviated imaging protocols, and the importance of standardizing nomenclature in international guidelines in order to increase the sharing of scientific data and improve the communication between centers.Key points• Gadoxetic acid-enhanced MRI is the preferred imaging method for pre-surgical or pre-interventional planning for liver metastases after systemic therapy. • Gadoxetic acid-enhanced MRI provides accurate staging of HCC before and after treatment with locoregional/biologic therapies. • Abbreviated protocols for gadoxetic acid-enhanced MRI offer potential time and cost savings, but more evidence is necessary. The use of gadoxetic acid-enhanced MRI for the assessment of liver and biliary function is under active investigation.

ObjectiveThe aim of the study was to determine the prevalence of clinically important masses among incidental hyperenhancing liver observations on portal venous phase computed tomography (CT) in patients without known malignancy or liver disease.MethodsRetrospective search of portal venous phase CTs was performed to identify hyperenhancing liver observations in patients without cancer or liver disease. Observations were assigned a morphology of homogeneous, hemangioma, or heterogeneous. The reference standard was pathology (n = 2), liver protocol CT/magnetic resonance imaging (n = 40), follow-up portal venous phase CT for 2 years or more (n = 81), or clinical follow-up for 5 years or more (n = 107).ResultsThere were no clinically important masses among 83 observations with homogeneous morphology or 110 with hemangioma morphology. There were 2 clinically important masses (1 hepatocellular carcinoma and 1 hepatic adenoma) among 37 (5.4%) heterogeneous morphology observations.ConclusionsIncidental hyperenhancing liver observations on portal venous phase CT with homogeneous or typical hemangioma morphology in patients without known cancer or liver disease are highly likely benign.

Objective: Management of thyroid nodules with Bethesda Category III and IV cytology on fine needle aspiration (FNA) is challenging as they cannot be adequately classified as benign or malignant. Ultrasound (US) patterns have demonstrated utility in evaluating the risk of malignancy (ROM) of Bethesda Category III nodules. This study aims to evaluate the value of three well established US grading systems (ATA, Korean-TIRADS, and ACR-TIRADS) in determining ROM in Bethesda Category IV nodules. Methods: 92 patients with 92 surgically resected thyroid nodules who had Bethesda Category IV cytology on FNA were identified. Nodule images were retrospectively graded using the three systems in a blinded manner. Associations between US risk category and malignant pathology for each system were analyzed. Results: Of the 92 nodules, 56 (61%) were benign and 36 (39%) were malignant. 47% of ATA high risk nodules, 53% of K-TIRADS category 5 nodules, and 50% of ACR-TIRADS category 5 nodules were malignant. The ATA high-risk category had 25% sensitivity, 82% specificity, 47% PPV for malignancy. K-TIRADS category 5 had 25% sensitivity, 85% specificity, 53% PPV for malignancy. ACR-TIRADS category 5 had 25% sensitivity, 84% specificity, 50% PPV for malignancy. None of the three grading systems yielded statistically significant correlation between US risk category and the ROM (p =0.30, 0.72, 0.28). Conclusion: The ATA, Korean-TIRADS, and ACR-TIRADS classification systems are not helpful in stratifying ROM in patients with Bethesda Category IV nodules. Clinicians should be cautious of using ultrasound alone when deciding between therapeutic options for patients with Bethesda Category IV thyroid nodules.

BackgroundTo determine the relationship between adipose tissue and skeletal muscle measurements on computed tomography (CT) and overall survival and major postoperative complications in patients with soft-tissue sarcoma (STS).MethodsThe retrospective study included 137 STS patients (75 men, 62 women; mean age, 53 years, SD 17.7; mean BMI, 28.5, SD 6.6) who had abdominal CT exams. On a single CT image, at the L4 pedicle level, measurements of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and skeletal muscle area and attenuation were obtained using clinical PACS and specialized segmentation software. Clinical information was recorded, including STS characteristics (size, depth, grade, stage, and site), overall survival, and postoperative complications. The relationships between CT metrics and survival were analyzed using Cox proportional hazard models and those between CT metrics and postoperative complications using logistic regression models.ResultsThere were 33 deaths and 41 major postoperative complications. Measured on clinical PACS, the psoas area (P=0.003), psoas index (P=0.006), psoas attenuation (P=0.011), and total muscle attenuation (P=0.023) were associated with overall survival. Using specialized software, psoas attenuation was also associated with overall survival (P=0.018). Adipose tissue metrics were not associated with survival or postoperative complications.ConclusionsIn STS patients, CT-derived muscle size and attenuation are associated with overall survival. These prognostic biomarkers can be obtained using specialized segmentation software or routine clinical PACS.

Adrenal collision tumors are rare and produce unique diagnostic challenges for clinicians. We report the case of a 45-year-old woman with obesity and diabetes mellitus and an incidentally-discovered adrenal mass containing macroscopic fat, thought to be a myelolipoma. A functional workup confirmed adrenocorticotropic hormone- (ACTH-) independent Cushing's syndrome. The patient underwent a successful laparoscopic adrenalectomy with pathology showing an adrenal collision tumor consisting of an adrenocortical adenoma and a myelolipoma. Postoperatively, the clinical symptoms, body mass index, and hemoglobin A1C all improved. Clinicians should consider a functional workup in patients with radiographically diagnosed myelolipomas as some may prove to be hormonally active collision tumors.

ObjectiveThe aim of this study was to determine the prevalence and computed tomography (CT) features of malignancy in incidental focal fundal gallbladder wall thickening.MethodsPatients with incidental focal fundal gallbladder wall thickening on CT were included if they had an ultrasound or magnetic resonance imaging diagnostic of the etiology (n = 19), stability on CT for 1 year (n = 84), or pathological correlation (n = 13). Morphologies were classified as type 1 (nodular/pinched intramural low attenuation), type 2 (intramural low attenuation), type 3 (homogeneous enhancement), type 4 (nodular/pinched homogeneous enhancement), type 5 (intramural cystic spaces), or type 6 (hyperenhancing/heterogeneous enhancement).ResultsOne hundred sixteen patients had the following morphologies: type 1 (n = 57), type 2 (n = 10), type 3 (n = 6), type 4 (n = 19), type 5 (n = 14), and type 6 (n = 10). Four cases (3.4%; 95% confidence interval, 0.9%-8.6%) of malignancy were identified (type 6 in 3 and type 3 in 1).ConclusionsIncidental focal fundal gallbladder wall thickening is usually benign. Computed tomography features help distinguish benign from malignant etiologies.

ObjectiveThe purpose of this study is to determine the correlation between malignancy risk of focal liver observations in patients at risk for hepatocellular carcinoma (HCC) implied by phrases used in nonstructured radiology reports with the risk inferred by hepatologists.Materials and methodsWe performed a retrospective review of nonstructured radiology reports issued before Liver Imaging and Reporting Data System (LI-RADS) adoption from four-phase liver CT examinations of patients at risk for HCC. The phrase used by the radiologist in the report impression to describe each focal liver observation was recorded. Five hepatologists independently inferred the LI-RADS category from each phrase. Two abdominal radiologists independently reviewed the images and, blinded to all other information, assigned a LI-RADS category to each observation. Discrepancies were resolved by consensus.ResultsOne hundred five observations in 77 patients were reported by 23 radiologists using 29 phrases. The most common phrase, "consistent with HCC" (n = 20), was applied to radiologist-assigned LR-3 (n = 1), LR-4 (n = 5), LR-5 (n = 11), and LR-5V (n = 3) observations. Eleven phrases were used more than once. Sixteen phrases were associated with LR-4 or higher observations; among these, hepatologists misinterpreted 37% of LR-4 or lower observations as definitely HCC and 46% of LR-5 and LR-5V observations as not definitely HCC. Overall, there was modest correlation (r = 0.69) between radiologist-assigned and hepatologist-inferred categories.ConclusionNonstandardized terminology results in inaccurate communication of HCC risk. Structured reporting systems such as LI-RADS may improve communication by conveying unambiguous estimates of malignancy risk.

ObjectiveThe purposes of this study were to correlate fetal z-axis location within the maternal abdomen on CT with gestational age and estimate fetal dose reduction of a study limited to the abdomen only, with its lower aspect at the top of the iliac crests, compared with full abdominopelvic CT in pregnant trauma patients.Materials and methodsWe performed a study of pregnant patients who underwent CT of the abdomen and pelvis for trauma at a single institution over a 10-year period. The inferior aspect of maternal liver, spleen, gallbladder, pancreas, adrenals, and kidneys was recorded as above or below the iliac crests. The distance from the iliac crest to the top of the fetus or gestational sac was determined. The CT images of the limited and full scanning studies were independently reviewed by two blinded radiologists to identify traumatic injuries. Fetal dose profiles, including both scatter and primary radiation, were computed analytically along the central axis of the patient to estimate fetal dose reduction. Linear regression analysis was performed between gestational age and distance of the fetus to the iliac crests.ResultsThirty-five patients were included (mean age, 26.2 years). Gestational age ranged from 5 to 38 weeks, with 5, 19, and 11 gestations in the first, second, and third trimesters, respectively. All solid organs were above the iliac crests in all patients. In three of six patients, traumatic findings in the pelvis would have been missed with the limited study. There was high correlation between gestational age and distance of the fetus to the iliac crests (R(2) = 0.84). The mean gestational age at which the top of the fetus was at the iliac crest was 17.3 weeks. Using the limited scanning study, fetuses at 5, 20, and 40 weeks of gestation would receive an estimated 4.3%, 26.2%, and 59.9% of the dose, respectively, compared with the dose for the full scanning study.ConclusionIn pregnant patients in our series with a history of trauma, CT of the abdomen only was an effective technique to reduce fetal radiation exposure compared with full abdomen and pelvis CT.

Rationale and objectivesThis work aimed to quantify the differences in signal-to-noise ratio (SNR) and vessel sharpness between steady-state and first-pass magnetic resonance angiography (MRA) with ferumoxytol in renal transplant recipients.Materials and methodsWe performed a retrospective study of adult patients who underwent steady-state and first-pass MRA with ferumoxytol to evaluate renal transplant vasculature. SNR was calculated in the external iliac artery, and vessel sharpness was calculated in the external iliac and renal transplant arteries for both acquisitions. Data were compared using Student's t test.ResultsFifteen patients were included (mean age 56.9 years, 10 males). The mean SNR of the external iliac artery was 42.2 (SD, 11.9) for the first-pass MRA and 41.8 (SD, 9.7) for the steady-state MRA (p = 0.92). The mean vessel sharpness was significantly higher for the steady-state MRA compared to first-pass MRA for both external iliac (1.24 vs. 0.80 mm(-1), p