Faculty Bibliography

BACKGROUND:Pancreatic adenocarcinoma (PC) is a highly lethal malignancy with a survival rate of only 12%. Surveillance is recommended for high-risk individuals (HRIs), but it is not widely adopted. To address this unmet clinical need and drive early diagnosis research, we established the Pancreatic Cancer Early Detection (PRECEDE) Consortium. METHODS:PRECEDE is a multi-institutional international collaboration that has undertaken an observational prospective cohort study. Individuals (aged 18-90 years) are enrolled into 1 of 7 cohorts based on family history and pathogenic germline variant (PGV) status. From April 1, 2020, to November 21, 2022, a total of 3,402 participants were enrolled in 1 of 7 study cohorts, with 1,759 (51.7%) meeting criteria for the highest-risk cohort (Cohort 1). Cohort 1 HRIs underwent germline testing and pancreas imaging by MRI/MR-cholangiopancreatography or endoscopic ultrasound. RESULTS:A total of 1,400 participants in Cohort 1 (79.6%) had completed baseline imaging and were subclassified into 3 groups based on familial PC (FPC; n=670), a PGV and FPC (PGV+/FPC+; n=115), and a PGV with a pedigree that does not meet FPC criteria (PGV+/FPC-; n=615). One HRI was diagnosed with stage IIB PC on study entry, and 35.1% of HRIs harbored pancreatic cysts. Increasing age (odds ratio, 1.05; P<.001) and FPC group assignment (odds ratio, 1.57; P<.001; relative to PGV+/FPC-) were independent predictors of harboring a pancreatic cyst. CONCLUSIONS:PRECEDE provides infrastructure support to increase access to clinical surveillance for HRIs worldwide, while aiming to drive early PC detection advancements through longitudinal standardized clinical data, imaging, and biospecimen captures. Increased cyst prevalence in HRIs with FPC suggests that FPC may infer distinct biological processes. To enable the development of PC surveillance approaches better tailored to risk category, we recommend adoption of subclassification of HRIs into FPC, PGV+/FPC+, and PGV+/FPC- risk groups by surveillance protocols.

Respiratory motion-induced image blurring and artifacts can compromise image quality in dynamic contrast-enhanced MRI (DCE-MRI) of the liver. Despite remarkable advances in respiratory motion detection and compensation in past years, these techniques have not yet seen widespread clinical adoption. The accuracy of image-based motion detection can be especially compromised in the presence of contrast enhancement and/or in situations involving deep and/or irregular breathing patterns. This work proposes a framework that combines GRASP-Pro (Golden-angle RAdial Sparse Parallel MRI with imProved performance) MRI with a new radial sampling scheme called navi-stack-of-stars for free-breathing DCE-MRI of the liver without the need for explicit respiratory motion compensation. A prototype 3D golden-angle radial sequence with a navi-stack-of-stars sampling scheme that intermittently acquires a 2D navigator was implemented. Free-breathing DCE-MRI of the liver was conducted in 24 subjects at 3T including 17 volunteers and 7 patients. GRASP-Pro reconstruction was performed with a temporal resolution of 0.34"“0.45 s per volume, whereas standard GRASP reconstruction was performed with a temporal resolution of 15 s per volume. Motion compensation was not performed in all image reconstruction tasks. Liver images in different contrast phases from both GRASP and GRASP-Pro reconstructions were visually scored by two experienced abdominal radiologists for comparison. The nonparametric paired two-tailed Wilcoxon signed-rank test was used to compare image quality scores, and the Cohen's kappa coefficient was calculated to evaluate the inter-reader agreement. GRASP-Pro MRI with sub-second temporal resolution consistently received significantly higher image quality scores (P < 0.05) than standard GRASP MRI throughout all contrast enhancement phases and across all assessment categories. There was a substantial inter-reader agreement for all assessment categories (ranging from 0.67 to 0.89). The proposed technique using GRASP-Pro reconstruction with navi-stack-of-stars sampling holds great promise for free-breathing DCE-MRI of the liver without respiratory motion compensation.

INTRODUCTION/BACKGROUND:Prostate cancer diffusion weighted imaging (DWI) MRI is typically performed at high-field strength (3.0 T) in order to overcome low signal-to-noise ratio (SNR). In this study, we demonstrate the feasibility of prostate DWI at low field enabled by random matrix theory (RMT)-based denoising, relying on the MP-PCA algorithm applied during image reconstruction from multiple coils. METHODS:Twenty-one volunteers and 2 prostate cancer patients were imaged with a 6-channel pelvic surface array coil and an 18-channel spine array on a prototype 0.55 T system created by ramping down a commercial magnetic resonance imaging system (1.5 T MAGNETOM Aera Siemens Healthcare) with 45 mT/m gradients and 200 T/m/s slew rate. Diffusion-weighted imagings were acquired with 4 non-collinear directions, for which b = 50 s/mm2 was used with 8 averages and b = 1000 s/mm2 with 40 averages; 2 extra b = 50 s/mm2 were used as part of the dynamic field correction. Standard and RMT-based reconstructions were applied on DWI over different ranges of averages. Accuracy/precision was evaluated using the apparent diffusion coefficient (ADC), and image quality was evaluated over 5 separate reconstructions by 3 radiologists with a 5-point Likert scale. For the 2 patients, we compare image quality and lesion visibility of the RMT reconstruction versus the standard one on 0.55 T and on clinical 3.0 T. RESULTS:The RMT-based reconstruction in this study reduces the noise floor by a factor of 5.8, thereby alleviating the bias on prostate ADC. Moreover, the precision of the ADC in prostate tissue after RMT increases over a range of 30%-130%, with the increase in both signal-to-noise ratio and precision being more prominent for a low number of averages. Raters found that the images were consistently of moderate to good overall quality (3-4 on the Likert scale). Moreover, they determined that b = 1000 s/mm2 images from a 1:55-minute scan with the RMT-based reconstruction were on par with the corresponding images from a 14:20-minute scan with standard reconstruction. Prostate cancer was visible on ADC and calculated b = 1500 images even with the abbreviated 1:55 scan reconstructed with RMT. CONCLUSIONS:Prostate imaging using DWI is feasible at low field and can be performed more rapidly with noninferior image quality compared with standard reconstruction.

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.

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.

This manuscript is part of the ileal pouch symposium and will describe the water-soluble contrast enema, CT, and small bowel series. MRI and other imaging modalities are discussed elsewhere in the symposium. Water-soluble contrast enema and CT are excellent for the evaluation of the ileal pouch. Contrast enema and CT with anal contrast administration can allow for anastomotic integrity and pouch assessment. Pre-pouch ileum, extra-intestinal manifestations, and acute symptomatology are best assessed with CT. The contrast small bowel examination is of limited utility in pouch patients and should not be performed. Indications, imaging technique, and anatomic pouch assessment with water-soluble contrast enema, CT, and contrast small bowel examination will be reviewed here.

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.

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.

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.