Faculty Bibliography

PURPOSE/OBJECTIVE:Given that ileal pouch-anal anastomosis (IPAA) surgery is a technically challenging and high-morbidity procedure, there are numerous pertinent imaging findings that need to be clearly and efficiently communicated to the IBD surgeons for essential patient management and surgical planning. Structured reporting has been increasingly used over the past decade throughout various radiology subspecialties to improve reporting clarity and completeness. We compare structured versus non-structured reporting of pelvic MRI for ileal pouch to evaluate for clarity and effectiveness. METHODS:164 consecutive pelvic MRI's for ileal pouch evaluation, excluding subsequent exams for the same patient, acquired between 1/1/2019 and 7/31/2021 at one institution were included, before and after implementation (11/15/2020) of a structured reporting template, which was created with institutional IBD surgeons. Reports were assessed for the presence of 18 key features required for complete ileal pouch assessment: anastomosis (IPAA, tip of J, pouch body), cuff (length, cuffitis), pouch body (size, pouchitis, stricture), pouch inlet/pre-pouch ileum (stricture, inflammation, sharp angulation), pouch outlet (stricture), peripouch mesentery (position, mesentery twist), pelvic abscess, peri-anal fistula, pelvic lymph nodes, and skeletal abnormalities. Subgroup analysis was performed based on reader experience and divided into three categories: experienced (n = 2), other intra-institutional (n = 20), or affiliate site (n = 6). RESULTS:57 (35%) structured and 107 (65%) non-structured pelvic MRI reports were reviewed. Structured reports contained 16.6 [SD:4.0] key features whereas non-structured reports contained 6.3 [SD:2.5] key features (p < .001). The largest improvement following template implementation was for reporting sharp angulation of the pouch inlet (91.2% vs. 0.9%, p < .001), tip of J suture line and pouch body anastomosis (both improved to 91.2% from 3.7%). Structured versus non-structured reports contained mean 17.7 versus 9.1 key features for experienced readers, 17.0 versus 5.9 for other intra-institutional readers, and 8.7 versus 5.3 for affiliate site readers. CONCLUSION/CONCLUSIONS:Structured reporting of pelvic MRI guides a systematic search pattern and comprehensive evaluation of ileal pouches, and therefore facilitates surgical planning and clinical management. This standardized reporting template can serve as baseline at other institutions for adaptation based on specific radiology and surgery preferences, fostering a collaborative environment between radiology and surgery, and ultimately improving patient care.

Ileal pouch surgery is the surgical gold standard treatment for patients with ulcerative colitis (UC) and familial adenomatous polyposis (FAP). However, ileal pouch surgery is a technically challenging procedure and is associated with high morbidity. Clinical presentations of pouch complications are often nonspecific but imaging can identify many of these complications and is essential in clinical management. This paper will focus on magnetic resonance imaging (MRI) of the ileal pouch, including recommended MRI protocol and approach to imaging interpretation with an emphasis on those ileal pouch complications particularly well evaluated with MRI.

IMPORTANCE:Intravenous (IV) contrast medium is sometimes withheld due to risk of complication or lack of availability in patients undergoing computed tomography (CT) for abdominal pain. The risk from withholding contrast medium is understudied. OBJECTIVE:To determine the diagnostic accuracy of unenhanced abdominopelvic CT using contemporaneous contrast-enhanced CT as the reference standard in emergency department (ED) patients with acute abdominal pain. DESIGN, SETTING, AND PARTICIPANTS:This was an institutional review board-approved, multicenter retrospective diagnostic accuracy study of 201 consecutive adult ED patients who underwent dual-energy contrast-enhanced CT for the evaluation of acute abdominal pain from April 1, 2017, through April 22, 2017. Three blinded radiologists interpreted these scans to establish the reference standard by majority rule. IV and oral contrast media were then digitally subtracted using dual-energy techniques. Six different blinded radiologists from 3 institutions (3 specialist faculty and 3 residents) interpreted the resulting unenhanced CT examinations. Participants included a consecutive sample of ED patients with abdominal pain who underwent dual-energy CT. EXPOSURE:Contrast-enhanced and virtual unenhanced CT derived from dual-energy CT. MAIN OUTCOME:Diagnostic accuracy of unenhanced CT for primary (ie, principal cause[s] of pain) and actionable secondary (ie, incidental findings requiring management) diagnoses. The Gwet interrater agreement coefficient was calculated. RESULTS:There were 201 included patients (female, 108; male, 93) with a mean age of 50.1 (SD, 20.9) years and mean BMI of 25.5 (SD, 5.4). Overall accuracy of unenhanced CT was 70% (faculty, 68% to 74%; residents, 69% to 70%). Faculty had higher accuracy than residents for primary diagnoses (82% vs 76%; adjusted odds ratio [OR], 1.83; 95% CI, 1.26-2.67; P = .002) but lower accuracy for actionable secondary diagnoses (87% vs 90%; OR, 0.57; 95% CI, 0.35-0.93; P < .001). This was because faculty made fewer false-negative primary diagnoses (38% vs 62%; OR, 0.23; 95% CI, 0.13-0.41; P < .001) but more false-positive actionable secondary diagnoses (63% vs 37%; OR, 2.11, 95% CI, 1.26-3.54; P = .01). False-negative (19%) and false-positive (14%) results were common. Interrater agreement for overall accuracy was moderate (Gwet agreement coefficient, 0.58). CONCLUSION:Unenhanced CT was approximately 30% less accurate than contrast-enhanced CT for evaluating abdominal pain in the ED. This should be balanced with the risk of administering contrast material to patients with risk factors for kidney injury or hypersensitivity reaction.

Pancreatic cystic lesions are frequently identified on cross-sectional imaging. As many of these are presumed branch-duct intraductal papillary mucinous neoplasms, these lesions generate much anxiety for the patients and clinicians, often necessitating long-term follow-up imaging and even unnecessary surgical resections. However, the incidence of pancreatic cancer is overall low for patients with incidental pancreatic cystic lesions. Radiomics and deep learning are advanced tools of imaging analysis that have attracted much attention in addressing this unmet need, however, current publications on this topic show limited success and large-scale research is needed.

The detection of incidental pancreatic cystic lesions has increased over time. It is crucial to separate benign from potentially malignant or malignant lesions to guide management and reduce morbidity and mortality. The key imaging features used to fully characterize cystic lesions are optimally assessed by contrast-enhanced magnetic resonance imaging/magnetic resonance cholangiopancreatography, with pancreas protocol computed tomography offering a complementary role. While some imaging features have high specificity for a particular diagnosis, overlapping imaging features between diagnoses may require further investigation with follow-up diagnostic imaging or tissue sampling.

This work aimed to develop a modified stack-of-stars golden-angle radial sampling scheme with variable-density acceleration along the slice (kz) dimension (referred to as VD-stack-of-stars) and to test this new sampling trajectory with multi-coil compressed sensing reconstruction for rapid motion-robust 3D liver MRI. VD-stack-of-stars sampling implements additional variable-density undersampling along the kz dimension, so that slice resolution (or volumetric coverage) can be increased without prolonging scan time. The new sampling trajectory (with increased slice resolution) was compared with standard stack-of-stars sampling with fully sampled kz (with standard slice resolution) in both non-contrast-enhanced free-breathing liver MRI and dynamic contrast-enhanced MRI (DCE-MRI) of the liver in volunteers. For both sampling trajectories, respiratory motion was extracted from the acquired radial data, and images were reconstructed using motion-compensated (respiratory-resolved or respiratory-weighted) dynamic radial compressed sensing reconstruction techniques. Qualitative image quality assessment (visual assessment by experienced radiologists) and quantitative analysis (as a metric of image sharpness) were performed to compare images acquired using the new and standard stack-of-stars sampling trajectories. Compared to standard stack-of-stars sampling, both non-contrast-enhanced and DCE liver MR images acquired with VD-stack-of-stars sampling presented improved overall image quality, sharper liver edges and increased hepatic vessel clarity in all image planes. The results have suggested that the proposed VD-stack-of-stars sampling scheme can achieve improved performance (increased slice resolution or volumetric coverage with better image quality) over standard stack-of-stars sampling in free-breathing DCE-MRI without increasing scan time. The reformatted coronal and sagittal images with better slice resolution may provide added clinical value.

PURPOSE/OBJECTIVE:The aim of this study was to evaluate the diagnostic performance of preoperative cross-sectional imaging findings using the SAR-AGA definitions in Crohn's disease (CD) patients who underwent ileocolic resection (ICR) with and without surgically complex ileocolic CD (CIC-CD). METHODS:69 CD patients [38 men; mean (± SD) age: 40.6 (16.2) years] who underwent ICR were retrospectively classified by surgical complexity by a colorectal surgeon using operative findings. CIC-CD was defined as ileal CD, not confined to the distal ileum. Two radiologists retrospectively evaluated the preoperative imaging for the presence and type of penetrating disease, stricture, or probable stricture using the SAR-AGA consensus definitions. The diagnostic performance of preoperative imaging findings was compared for patients with and without CIC-CD. Estimated blood loss (EBL), operative time (OT), conversion to open surgery, diversion, and length of hospital stay (LOS) were compared. RESULTS:60.9% had CIC-CD and 79.7% underwent primary ICR. Penetrating disease was more common in patients with than without CIC-CD (76.2% vs. 40.7%, p = 0.0048) and similar among primary versus redo ICR (p = 0.12). Patients with CIC-CD had more complex fistulas (59.5% vs. 11.1%; p < 0.0001) and fewer simple fistulas (2.4% vs. 18.5%; p = 0.03) than those without. Mesenteric findings (abscess, inflammatory mass) were more frequent in patients with (35.7%) than without (0%) (p = 0.0002) CIC-CD. Stricture and probable stricture were similar (p = 0.59). CIC-CD patients had greater EBL (178 cc vs. 57 cc, p = 0.006), conversion rates (30% vs. 0%, p = 0.0026), and diversion (80% vs. 52%, p = 0.04). CONCLUSION/CONCLUSIONS:Complex fistula, mesenteric abscess, or inflammatory mass defined by the SAR-AGA guidelines suggests CIC-CD. ICR for CIC-CD had greater EBL, conversion to open surgery, and diversion.

PURPOSE/OBJECTIVE:To retrospectively evaluate which key imaging features described by SAR-AGA on outpatient surveillance MRE correlate with progression to surgery in adults with CD. METHODS:52 CD patients imaged with outpatient MRE from 10/2015 to 12/2016 and with available clinical information were included. Two abdominal radiologists reviewed the MRE for the presence of active inflammation, intramural edema, restricted diffusion, stricture, probable stricture, ulceration, sacculation, simple fistula, complex fistula, sinus tract, inflammatory mass, abscess, perienteric inflammation, engorged vasa recta, fibrofatty proliferation, and perianal disease. Bowel wall thickness, length of bowel involvement, and degree of upstream dilation in strictures were quantified. Subsequent bowel resection, prior bowel surgery, and available laboratory values were recorded. The association between progression to surgery and imaging features was evaluated using a logistic regression model adjusting for demographics, prior bowel surgery, medication usage, and body mass index. RESULTS:19.2% (10/52) of patients progressed to surgery. Restricted diffusion, greater degree of upstream dilation from stricture, complex fistula, perienteric inflammation, and fibrofatty proliferation were significantly more common in patients progressing to surgery (all p < 0.05). κ for these significant findings ranged 0.568-0.885. Patients progressing to surgery had longer length bowel involvement (p = 0.03). Platelet count, ESR, and fecal calprotectin were significantly higher, and serum albumin was significantly lower in patients progressing to surgery. Prior bowel surgery, sex, age, and all other parameters were similar. CONCLUSION/CONCLUSIONS:Radiologists should carefully describe bowel dilation upstream from strictures, penetrating and perienteric findings on outpatient MRE in CD patients, as these findings may herald progression to surgery.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies, with a dismal survival rate. Screening the general population for early detection of PDAC is not recommended, but because early detection improves survival, high-risk individuals, defined as those meeting criteria based on a family history of PDAC and/or the presence of known pathogenic germline variant genes with PDAC risk, are recommended to undergo screening with MRI and/or endoscopic ultrasound at regular intervals. The Pancreatic Cancer Early Detection (PRECEDE) Consortium was formed in 2018 and is composed of gastroenterologists, geneticists, pancreatic surgeons, radiologists, statisticians, and researchers from 40 sites in North America, Europe, and Asia. The overarching goal of the PRECEDE Consortium is to facilitate earlier diagnosis of PDAC for high-risk individuals to increase survival of the disease. A standardized MRI protocol and reporting template are needed to enhance the quality of screening examinations, improve consistency of clinical management, and facilitate multiinstitutional research. We present a consensus statement to standardize MRI screening and reporting for individuals with elevated risk of pancreatic cancer.

PURPOSE:To develop a protocol for abdominal imaging on a prototype 0.55 T scanner and to benchmark the image quality against conventional 1.5 T exam. METHODS:In this prospective IRB-approved HIPAA-compliant study, 10 healthy volunteers were recruited and imaged. A commercial MRI system was modified to operate at 0.55 T (LF) with two different gradient performance levels. Each subject underwent non-contrast abdominal examinations on the 0.55 T scanner utilizing higher gradients (LF-High), lower adjusted gradients (LF-Adjusted), and a conventional 1.5 T scanner. The following pulse sequences were optimized: fat-saturated T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and Dixon T1-weighted imaging (T1WI). Three readers independently evaluated image quality in a blinded fashion on a 5-point Likert scale, with a score of 1 being non-diagnostic and 5 being excellent. An exact paired sample Wilcoxon signed-rank test was used to compare the image quality. RESULTS:Diagnostic image quality (overall image quality score ≥ 3) was achieved at LF in all subjects for T2WI, DWI, and T1WI with no more than one unit lower score than 1.5 T. The mean difference in overall image quality score was not significantly different between LF-High and LF-Adjusted for T2WI (95% CI - 0.44 to 0.44; p = 0.98), DWI (95% CI - 0.43 to 0.36; p = 0.92), and for T1 in- and out-of-phase imaging (95%C I - 0.36 to 0.27; p = 0.91) or T1 fat-sat (water only) images (95% CI - 0.24 to 0.18; p = 1.0). CONCLUSION:Diagnostic abdominal MRI can be performed on a prototype 0.55 T scanner, either with conventional or with reduced gradient performance, within an acquisition time of 10 min or less.