Transplantation for type 1 diabetes: radiologist's primer on islet, pancreas and pancreas-kidney transplantation imaging.

Whole-organ pancreas, pancreatic-kidney and islet transplantation are surgical therapeutic options for the treatment of type 1 diabetes. They can enable effective glycemic control, improve quality of life and delay/reduce the secondary complications of type 1 diabetes mellitus. Radiologists are integral members of the multidisciplinary transplantation team involved in these procedures, with multimodality imaging serving as the mainstay for early recognition and management of transplant related complications. This review highlights the transplantation procedures available for patients with type 1 Diabetes Mellitus with a focus on the imaging appearance of transplantation-related complications.

Transurethral Vapor Ablation in Patients with Intermediate-Risk Localized Prostate Cancer.

Purpose: We report results of a prospective, multicenter single-arm study of transurethral vapor ablation (TUVA) of prostate tissue in patients with unilateral, intermediate-risk, localized prostate cancer (PCa). Materials and Methods: Men ≥45 years of age with biopsy-confirmed unilateral Gleason grade group 2 (GGG2) adenocarcinoma of the prostate, prostate volume of 20-80 cc, and prostate-specific antigen (PSA) ≤15 ng/mL were enrolled. Cystoscopy and transrectal ultrasound (TRUS) guidance were used to deliver ∼103°C water vapor to prostate zones for unilateral hemigland ablation, including destruction of cancers detected by multiparametric MRI (mpMRI) and confirmed by biopsy. The primary outcomes were device-related serious adverse events (SAEs). At 7 days and 6 months postprocedure, the ablation extent was assessed by mpMRI; MRI/TRUS fusion biopsies were completed at 6 months. Quality of life (QOL) was assessed with validated questionnaires. Results: All subjects underwent a single hemigland TUVA procedure. No SAEs occurred. Grade 2 procedure-related AEs included transient urinary retention (n = 4) and erectile (n = 1) or ejaculatory dysfunction (n = 1). At 7 days, mpMRI revealed complete ablation of 14/17 (82%) visible lesions. At 6 months, biopsies showed no Gleason pattern ≥4 or ≥GGG2 cancer on the treated side of prostates in 13/15 (87%) subjects. Ten of 15 (67%) subjects were biopsy negative. Of the 5 biopsy-negative subjects, 2 had one core each of 3 + 4 disease and 3 had one core each of 3 + 3 disease with ≤5% involvement. Median prostate volume was reduced by 40.7% and PSA by 58%. Extensive QOL assessments showed, on average, no appreciable negative effects of treatment. Conclusions: Initial evidence suggests that TUVA is safe in men with intermediate-risk PCa. Preliminary results demonstrate the absence of ≥GGG2 disease on the treated side in 87% of men and a favorable QOL profile.

Design and Rationale for the Use of Magnetic Resonance Imaging Biomarkers to Predict Diabetes After Acute Pancreatitis in the Diabetes RElated to Acute Pancreatitis and Its Mechanisms Study: From the Type 1 Diabetes in Acute Pancreatitis Consortium.

ABSTRACT: This core component of the Diabetes RElated to Acute pancreatitis and its Mechanisms (DREAM) study will examine the hypothesis that advanced magnetic resonance imaging (MRI) techniques can reflect underlying pathophysiologic changes and provide imaging biomarkers that predict diabetes mellitus (DM) after acute pancreatitis (AP). A subset of participants in the DREAM study will enroll and undergo serial MRI examinations using a specific research protocol. The aim of the study is to differentiate at-risk individuals from those who remain euglycemic by identifying parenchymal features after AP. Performing longitudinal MRI will enable us to observe and understand the natural history of post-AP DM. We will compare MRI parameters obtained by interrogating tissue properties in euglycemic, prediabetic, and incident diabetes subjects and correlate them with metabolic, genetic, and immunological phenotypes. Differentiating imaging parameters will be combined to develop a quantitative composite risk score. This composite risk score will potentially have the ability to monitor the risk of DM in clinical practice or trials. We will use artificial intelligence, specifically deep learning, algorithms to optimize the predictive ability of MRI. In addition to the research MRI, the DREAM study will also correlate clinical computed tomography and MRI scans with DM development.

Diagnosing Prostate Cancer: The Role of Intravesical Prostatic Gland Protrusion on Accuracy of Prostate Biopsies.

PURPOSE: We evaluated the association between intravesical prostate protrusion (IPP) and the detection rate of clinically significant prostate cancer (csPCa) on magnetic resonance imaging (MRI)-transrectal ultrasound (TRUS) fusion targeted biopsy (TB). MATERIALS AND METHODS: A total of 538 consecutive men who underwent MRI-TRUS fusion TB and concomitant systematic biopsy were evaluated. IPP on MRI was independently measured by 4 blinded reviewers. The primary outcome was per-lesion detection of csPCa on TB. We assessed the association between IPP and csPCa detection on TB, controlling for age, prostate specific antigen, Prostate Imaging Reporting and Data System® (PI-RADS®) score, prostate volume, targeted cores sampled and previous biopsy experience. RESULTS: A total of 847 PI-RADS 3 or greater lesions were targeted across 570 biopsies. Intra- and interrater reliability for measuring IPP was strong. A total of 81 (14.2%), 127 (22.3%), 237 (41.6%) and 125 (21.9%) men had 0, small, medium and large IPP, respectively. A total of 230, 392 and 196 lesions were PI-RADS 3, 4 and 5, respectively. Of the lesions 198 (34.7%) had csPCa on TB. The overall relationship between IPP size and csPCa found on TB was not significant; however, large IPP is associated with a significantly lower rate of csPCa detection than 0 IPP (p=0.007). Every mm increase in IPP is associated with a 5.6% decrease in the odds of csPCa detection on TB (p=0.004) and a 66.5% decrease in odds of detection in large IPP compared to 0 IPP (p=0.003). CONCLUSIONS: As the size of the IPP and volume increase, there is a decrease in the detection rate of csPCa on MRI-guided TB. These findings may be driven by poor MRI-TRUS co-registration and prostate asymmetry.

AUR-RRA Review: Logistics of Academic-Industry Partnerships in Artificial Intelligence.

The Radiology Research Alliance (RRA) of the Association of University Radiologists (AUR) convenes Task Forces to address current topics in radiology. In this article, the AUR-RRA Task Force on Academic-Industry Partnerships for Artificial Intelligence, considered issues of importance to academic radiology departments contemplating industry partnerships in artificial intelligence (AI) development, testing and evaluation. Our goal was to create a framework encompassing the domains of clinical, technical, regulatory, legal and financial considerations that impact the arrangement and success of such partnerships.

Training Convolutional Networks for Prostate Segmentation With Limited Data.

Multi-zonal segmentation is a critical component of computer-aided diagnostic systems for detecting and staging prostate cancer. Previously, convolutional neural networks such as the U-Net have been used to produce fully automatic multi-zonal prostate segmentation on magnetic resonance images (MRIs) with performance comparable to human experts, but these often require large amounts of manually segmented training data to produce acceptable results. For institutions that have limited amounts of labeled MRI exams, it is not clear how much data is needed to train a segmentation model, and which training strategy should be used to maximize the value of the available data. This work compares how the strategies of transfer learning and aggregated training using publicly available external data can improve segmentation performance on internal, site-specific prostate MR images, and evaluates how the performance varies with the amount of internal data used for training. Cross training experiments were performed to show that differences between internal and external data were impactful. Using a standard U-Net architecture, optimizations were performed to select between 2D and 3D variants, and to determine the depth of fine-tuning required for optimal transfer learning. With the optimized architecture, the performance of transfer learning and aggregated training were compared for a range of 5-40 internal datasets. The results show that both strategies consistently improve performance and produced segmentation results that are comparable to that of human experts with approximately 20 site-specific MRI datasets. These findings can help guide the development of site-specific prostate segmentation models for both clinical and research applications.

Impact of 18-French Rectal Tube Placement on Image Quality of Multiparametric Prostate MRI.

This study compared prostate multiparametric MRI (mpMRI) performed using an 18-French rectal tube in place throughout the examination after initial placement by a technologist (n = 97) with mpMRI performed without rectal tube placement (n = 99). Acquisition parameters were otherwise identical. Two radiologists scored subjective image quality and measured rectal diameter. For both readers, rectal tube placement was associated (p < .001) with improved ADC map quality, decreased DWI distortion, decreased rectal gas, and decreased rectal diameter. Findings support routine rectal tube placement for prostate mpMRI.

Atypical Hepatic Steatosis Patterns on MRI After Total Pancreatectomy With Islet Autotransplant.

OBJECTIVE. The purpose of this retrospective study was to investigate the prevalence and patterns of hepatic steatosis after total pancreatectomy with islet autotransplant (TPIAT) and to determine if the unique patterns of steatosis seen in this study correlated with islet graft function. MATERIALS AND METHODS. Fifty-two subjects who had undergone MRI after TPIAT were reviewed for the presence of hepatic steatosis. Patterns of steatosis were categorized into three groups: normal (no steatosis), homogeneous, and atypical. Demographics and outcomes were compared between the groups. Islet graft function 1 year after surgery was classified as full graft function, partial graft function, and graft failure. Statistical analysis was performed using ANOVA, Kruskal-Wallis, and Fisher exact tests. RESULTS. Sixty-three percent of patients had steatosis present on MRI after TPIAT (33 subjects of 52 total), and 48% (25/52) exhibited an atypical pattern. Twenty-four percent of the 37 patients who had MRI examinations before TPIAT showed steatosis preoperatively, yet none of these showed an atypical steatosis pattern. Islet graft function was not statistically different between the groups. The only statistically significant variable difference between the groups was body mass index (p = .02). CONCLUSION. Steatosis is a common finding after TPIAT, and atypical steatosis patterns frequently develop after the procedure, implying that the procedure itself is the causal factor. There was no correlation between islet graft function and the presence or pattern of steatosis. An atypical pattern of hepatic steatosis can therefore be considered an incidental finding after TPIAT and does not require additional workup or treatment.

A Fatal Case of Diffuse Alveolar Hemorrhage in the Setting of Systemic Lupus Erythematosus: A Case Report and Review of Noninfectious Causes of Acute Pulmonary Hemorrhage in Adults.

Systemic lupus erythematosus (SLE) is an autoimmune connective tissue disease, characterized by autoantibody production and immune complex formation, that has the potential to affect virtually any organ. Pleuropulmonary involvement occurs in 50-70% and commonly manifests as pleuritis and pleural effusion. Diffuse alveolar hemorrhage (DAH) is a rare manifestation of SLE. Most cases of DAH occur in young adults with an underlying autoimmune disease such as systemic vasculitis or Goodpasture syndrome. SLE is typically lower on the list of initial differential diagnoses of DAH due to its rarity compared to other etiologies. We present a case of a patient with dyspnea on exertion, dry coughs, lower extremity edema, and intermittent periorbital edema who ultimately succumbed to respiratory failure secondary to DAH in the setting of SLE. The diagnosis of SLE was suspected clinically and confirmed at autopsy due to her rapid clinical deterioration. DAH requires prompt intervention, and management is guided by the underlying disease process. SLE is a potentially treatable disease; therefore, timely diagnosis is important in order to exclude other noninfectious causes of DAH (reviewed in this report) and to initiate appropriate therapy.

Surgical microwave ablation for multifocal non-resectable liver metastases: a single institution experience treating five or more liver lesions.

BACKGROUND: Thermal ablation is an effective treatment for patients with metastatic colon and rectal cancer and allows surgeons to offer curative intent therapy to patients who are otherwise not candidates for resection. We aimed to report outcomes of a single institution experience using microwave ablation (MWA) with or without resection to treat five or more liver metastases. METHODS: In this retrospective cohort study, the University of Minnesota Division of Surgical Oncology liver surgery database was queried to identify all patients who underwent thermal ablation of five or more colorectal liver metastases (CRLM) between 2012-2018. We reviewed patient, disease, and tumor characteristics and measured local, intrahepatic, and extrahepatic recurrence (EHR) rates. We also calculated median overall survival (OS) and disease-free survival (DFS). RESULTS: Ten patients identified had five or more (range, 5-18) tumors ablated with or without combined liver and bowel resection. Median age was 50, and most patients were male (70%) and Caucasian (90%). Four patients received ablation alone (5-12 lesions), while six had combined resection and ablation (5-18 lesions). Ablation was performed laparoscopically in six patients, and four had ablations without resection. All patients received pre- and post-operative chemotherapy. A median of 7 tumors were ablated per patient. Median follow-up was 2.3 years. Among 75 tumors ablated, ablation site recurrence (ASR) (within 1 cm of ablation site) was seen in three with a per-lesion recurrence rate of 4%. Intrahepatic recurrence (IHR) occurred in 6 (60%) patients and EHR in 1 (10%). Five patients underwent retreatment of IHR during follow-up. Median OS was 3 years and DFS was 7.1 months. At the time of last follow up, 6 patients were disease-free. CONCLUSIONS: Thermal ablation can provide acceptable DFS and OS, even with high volume metastatic colorectal cancers. Future efforts should be focused on defining selection criteria for those most likely to benefit from this aggressive approach.

Surgical microwave ablation of otherwise non-resectable colorectal cancer liver metastases: Expanding opportunities for long term survival.

BACKGROUND: Colorectal liver metastases (CRLM) are the most common extra-lymphatic metastases in colorectal cancers, however, only 15-20% of these patients are candidates for resection. We reviewed our institutional experience with 135 surgical ablations for unresectable CRLM. METHODS: Retrospective review of surgically ablated CRLM from 2009 to 2018. Patient-specific variables were obtained from the medical record. Kaplan-Meier modeling was performed for survival analyses. RESULTS: We ablated 135 CRLM in 36 patients over 40 procedures. Median age was 52 years and 58% of patients were male. All patients received systemic chemotherapy. The ablation procedure was completed laparoscopically in 68% of procedures. Median number of ablated lesions per patient was 2 (range 1-15). Median maximum diameter of ablated lesions was 1.9 cm (range 0.5-12.2). Median follow up of the study was 28 months. In this time, median disease-free survival was not reached. Of the 135 lesions ablated, the per-lesion recurrence rate was 6/135 (4.4%). Median overall survival was 81 months. CONCLUSIONS: Surgical ablation of CRLM can provide excellent local control and long-term survival outcomes in patients who may otherwise not be candidates for other liver-directed therapies.

Prostatic peripheral zone thickness: what is normal on magnetic resonance imaging?

PURPOSE: To report the precision of a technique of measuring the PZ thickness on T2-weighted MRI and report normal parameters in patients with normal-sized prostates. We also wanted to establish the mean and second standard deviations (2SD) above and below the mean as criteria for abnormally narrow or expanded PZ thickness. METHODS: Of the initial 1566 consecutive cohort referred for evaluation for carcinoma based on elevated PSA (prostate specific antibody) or DRE (digital rectal examination), 132 separate subjects with normal-sized prostates were selected for this study. Mean age was 58.2 years (15-82). Median serum PSA was 6.2 ng/mL (range 0.3-145). Most were asymptomatic for lower urinary tract symptoms (LUTS). Inclusion criteria in this study required technically adequate T2-weighted MRI and total prostatic volume (TPV) ≤ 25 cc. Exclusion criteria included post-prostatic surgical and radiation patients, patients having had medical management or minimally invasive therapy for BPH, those being treated for prostatitis. Patients with suspected tumor expanding or obscuring measurement boundaries were also not considered. Transition zone (TZ) and peripheral zone (PZ) volumes were determined using the prolate ellipsoid model. Posterolateral measurement of the PZ was obtained at the axial level of maximal transverse diameter of the prostate on a line drawn from the outer boundary of the TZ to the inner boundary of the external prostatic capsule (EPC). The data were normally distributed. Therefore, it was analyzed using the 2-sided student t-test and Pearson product correlation statistic. RESULTS: Mean pooled (composite) measurement for the posterolateral PZ (PLPZ) was 10 mm (CI 9.5-10.5 mm) with SD of 2.87 mm. Means were statistically the same for the 2 observers (p = 0.75). Pearson correlation between the two observers was 0.63. CONCLUSIONS: In a prostate ≤ 25 cc volume , the posterolateral PZ should be no thicker than 15.8 mm and averages 10.0 mm when measured in the maximal axial plane on MRI. These norms were independent of age or use of endorectal coil. The technique measurement demonstrated clinically useful precision.

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.

Minimally invasive microwave ablation provides excellent long-term outcomes for otherwise inaccessible hepatocellular cancer.

BACKGROUND AND OBJECTIVES: Thermal ablation can be used as a bridge to transplant or with curative intent for hepatocellular carcinoma (HCC). We report our experience with laparoscopic ablation of HCC in patients deemed inaccessible by the percutaneous approach. METHODS: We performed a retrospective review of surgical ablations from 2009 to 2017. Patient demographics, disease and treatment characteristics, and outcomes were abstracted from the medical record. Kaplan-Meier modeling was performed for survival and recurrence. RESULTS: Thirty-three patients were included with a median age of 62 (interquartile range [IQR], 57-67). Most patients were male (76%) and Caucasian (70%). Ninety-seven percent had underlying cirrhosis. Median model for end stage liver disease-sodium was 9.5 (IQR, 8-12). The median maximal diameter of ablated lesions was 2.6 cm (IQR, 1.8-3.0). Thirty-nine lesions were ablated; 97% were completed laparoscopically. The median maximal diameter of the ablation zone was 4.8 cm (IQR, 3.8-5.7) with a median difference of ablation zone to the tumor of 2.0 cm (IQR, 1.5-2.75). Twelve patients received additional treatment. Median disease-free survival was 66.7 months and median follow-up 42.9 months. Disease recurrence occurred in 13 patients (39%)-systemic recurrence in 6%, intrahepatic recurrence in 27% and local recurrence in 6%. CONCLUSION: Laparoscopic thermal ablation of HCC is safe and provides good oncologic outcomes for otherwise inaccessible tumors.

Measurement of Prostate Volume with MRI (A Guide for the Perplexed): Biproximate Method with Analysis of Precision and Accuracy.

To review the anatomic basis of prostate boundary selection on T2-weighted magnetic resonance imaging (MRI). To introduce an alternative 3D ellipsoid measuring technique that maximizes precision, report the intra- and inter-observer reliability, and to advocate it's use for research involving multiple observers. We demonstrate prostate boundary anatomy using gross pathology and MRI examples. This provides background for selecting key boundary marks when measuring prostate volume. An alternative ellipsoid volume method is then proposed using these boundaries in an attempt to improve inter-observer precision. An IRB approved retrospective study of 140 patients with elevated serum prostate specific antigen levels and/or abnormal digital rectal examinations was done with T2-weighted MRI applying a new (Biproximate) technique. Measurements were made by 2 examiners, correlated with each other for inter-observer precision and correlated with an expert observer for accuracy. Correlation statistics, linear regression analysis, and tests of means were applied using p ≤ 0.05 as the threshold for significance. Inter-observer correlation (precision) was 0.95 between observers. Correlation between these observers and the expert (accuracy) was 0.94 and 0.97 respectively. Intra-observer correlation for the expert was 0.98. Means for inter-rater reliability and accuracy were all the same (p = 0.001). We conclude that using more precise reproducible landmarks with biproximate technique, precision and accuracy of total prostate volume is found to be demonstrated.

Spectrum of Early Postoperative Multidetector Computed Tomography Findings Following Cytoreductive Surgery With Hyperthermic Intraperitoneal Chemotherapy.

OBJECTIVE: To review and describe imaging findings on multidetector computed tomography in the early postoperative period after cytoreductive surgery with concomitant hyperthermic intraperitoneal chemotherapy (CRS + HIPEC). METHODS: This was a retrospective review of consecutive patients undergoing early (≤60 days) postoperative abdominopelvic multidetector computed tomography scans after CRS + HIPEC from 2014 to 2018 at a single institution. Two radiologists separately assessed bowel wall thickening, bowel wall enhancement, bowel dilation, ascites, and pleural effusion(s) and identified any other significant finding(s). RESULTS: Thirty-two patients met the inclusion criteria. The majority of patients demonstrated bowel wall thickening (53%; n = 17) and ascites (72%; n = 23), whereas postoperative ileus (35%; n = 10), pleural effusion(s) (24%; n = 7), and bowel wall hyperenhancement (6%; n = 1) were less common. Significant findings included anastomotic leak/perforation (13%; n = 4), fistula (13%; n = 4), abscess (13%; n = 4), and bladder leak (6%; n = 2). CONCLUSIONS: Multidetector computed tomography is an excellent imaging modality to identify common postoperative findings as well as complications following CRS + HIPEC.

MRI in differentiating malignant versus benign portal vein thrombosis in patients with hepatocellular carcinoma: Value of post contrast imaging with subtraction.

PURPOSE: To evaluate MR imaging parameters including quantitative multiphasic post-contrast enhancement with subtraction and qualitative diffusion weighted imaging (DWI) in differentiating benign versus malignant portal venous thrombosis (PVT) in patients with hepatocellular carcinoma (HCC). METHOD: Radiology reports over a 6-year period ending February 2016 were searched for key words indicating presence of both HCC and PVT on abdominal MRI. 39 patients were identified with PVT characterized as benign or malignant based on pathologic data or serial imaging growth criteria. Image review was performed by two subspecialized radiologists blinded to the diagnosis and medical chart. Signal intensity for regions of interest were recorded within the portal vein thrombus as well as the portal vein on pre-contrast and dynamic post-contrast phases without and with subtraction. Qualitative parameters for DWI and presence of PV expansion were also evaluated. RESULTS: Percent enhancement generated high area under the curve (AUC) for both readers on all non-subtraction phases: arterial (0.95/0.98), portal venous (0.97/0.97) and delayed phase (0.96/0.99) and subtraction phases: arterial (0.91/0.96), portal venous (0.94/0.99) and delayed phases (0.96/0.97). Statistically significant differences were observed between benign and malignant PVT for both readers for PV expansion (p= <0.001/0.006). No qualitative DWI parameter reached statistical significance for both readers. CONCLUSIONS: Post-contrast and subtraction MRI can reliably distinguish malignant from benign PVT in patients with HCC using subtracted or non-subtracted images and at arterial, portal venous, or delayed phase timing.