Faculty Bibliography

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.

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.

Ileal pouch anal anastomosis (IPAA) is gold standard surgical procedure for treatment of ulcerative colitis and majority of patients with familial adenomatous polyposis. This procedure allows preservation of fecal continence and gastrointestinal continuity. However, it is associated with a wide variety of complications, which often have nonspecific and overlapping clinical presentations, making imaging an important part of work up for pouch dysfunction. The purpose of this article is to propose structured reporting templates for Magnetic Resonance Imaging (MRI) and Water Soluble Contrast Enema (WSCE) in IPAA patients based on our referral pouch center's experience. Included will be a review of salient surgical technique, pouch anatomy and imaging protocols, with an emphasis on systematic search pattern for evaluation of ileal pouch complications using proposed structured reporting MRI and WSCE templates.

Vulvar cancer is an uncommon gynecologic tumor and one of several human papillomavirus-associated malignancies. Squamous cell carcinoma is the most prevalent histologic subtype of vulvar cancer, accounting for the majority of cases. Imaging plays an important role in managing vulvar cancer. At initial diagnosis, imaging is useful to assess the size and extent of primary tumor and to evaluate the status of inguinofemoral lymph nodes. If recurrent disease is suspected, imaging is essential to demonstrate local extent of tumor and to identify lymph node and distant metastases. In this publication, we summarize the recent literature and describe the panel's recommendations about the appropriate use of imaging for various phases of patient management including initial staging, surveillance, and restaging of vulvar cancer. 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.

There have been many publications detailing imaging features of malignant transformation of intraductal papillary mucinous neoplasms (IPMN), management and recommendations for imaging follow-up of diagnosed or presumed IPMN. However, there is no consensus on several practical aspects of imaging IPMN that could serve as a clinical guide for radiologists and enable future data mining for research. These aspects include how to measure IPMN, define reporting terminology, standardize reporting and unify guidelines for surveillance. The Society of Abdominal Radiology (SAR) created multiple Disease-Focused Panels (DFP) comprised multidisciplinary panel members who focus on a particular disease, with the goal to develop ways for radiologists to improve patient care, education, and research. DFP members met to identify the current controversies and limitations of imaging pancreatic IPMN. This paper aims to provide a practical review of the key imaging characteristics of IPMN for trainees and practicing radiologists, to guide uniformity of performance and interpretation of surveillance imaging studies, and to improve communication with clinicians by providing a lexicon and reporting template based on the experience of the SAR-DFP panel members.

ABSTRACT/UNASSIGNED:Magnetic resonance imaging (MRI) has emerged as the imaging method of choice for evaluation of perianal fistulizing disease. As treatment of Crohn disease and associated perianal fistulas has evolved to include a combination of systemic treatments and surgical interventions, perianal MRI provides critical information to guide treatment selection and timing. Radiologists need to be familiar with the normal regional anatomy to accurately describe perianal fistulas and any associated complications which can then be used to classify fistulas based on several available classification systems. Following treatment, MRI can provide information that suggests treatment success or failure. We propose a perianal fistula reporting template that includes the necessary information to convey fistula complexity, guide treatment, and evaluate treatment response. This review article will also discuss the postoperative appearance of many treatments currently used for management of perianal fistulizing disease and some associated complications.