Imaging of the Inferior Mesenteric Vasculature.

The inferior mesenteric artery (IMA) and inferior mesenteric vein (IMV) supply and drain blood from the distal colon and rectum, respectively. Routinely imaged at cross-sectional imaging of the abdomen and pelvis, these vessels play a vital role in gastrointestinal tract health but may be neglected due to their diminutive caliber relative to other mesenteric vessels and potential lack of inclusion in routine search patterns. The authors describe and illustrate normal and abnormal appearances of the IMA and IMV and findings that are diagnostic of primary vascular abnormalities or can offer diagnostic clues. After the embryologic features, normal anatomy, and anatomic variants of the IMA and IMV are reviewed, various manifestations of IMA and IMV abnormalities, such as aneurysm and pseudoaneurysm, stenosis, occlusion, dissection, hemorrhage, arteriovenous malformations and fistulas, tumoral invasion, vasculitis, and perivascular lymphatic dilatation, are explored with use of case examples. The role of the IMA and IMV as collateral vasculature, including the clinical scenarios of superior mesenteric arterial occlusion, aortic endoleak, and portosystemic venous shunt, are discussed. Finally, diagnostic clues that the inferior mesenteric vessels and adjacent soft tissues can provide, including mesenteric venous gas, compression or displacement from bowel volvulus or internal hernias, lymphadenopathy, and venous flow artifacts, are highlighted. The authors provide a comprehensive reference for radiologists who evaluate the IMA and IMV on cross-sectional images and shine a spotlight on these neglected but important vessels. ©RSNA, 2024 Supplemental material is available for this article.

Simulated learning environment for diagnosis of appendicitis and other causes of abdominal pain in pregnant patients using MRI.

OBJECTIVES: Acute appendicitis is a common surgical condition which is usually diagnosed on CT in adult patients, though MRI is frequently used as a first-line diagnostic test in pregnant patients due to its lack of ionizing radiation and superior ability to visualize the appendix compared to ultrasound. Interpretation of abdominal MRI exams in pregnant patients with suspected appendicitis is an important skill in clinical practice, but one that is difficult to become proficient at due to its relative infrequence, even in a high-volume practice. METHODS: We created a simulation-based platform built on an online radiology viewing platform (Pacsbin) for training residents and abdominal imaging fellows to interpret pregnant appendicitis MRI exams, which we made publicly available for use by trainees at any institution (forms.office.com/r/FYyq06rw0v). This platform was used to train our 2024-2025 abdominal imaging fellows (N=8), and we collected pre- and post-intervention survey data which included level of confidence (Likert scale,1-5) in approaching these studies. RESULTS: We discuss and illustrate the content of our case set, including various teaching points we emphasize throughout the exercise. Among our eight body imaging fellows, the level of confidence in approaching pregnant appendicitis MRI studies after the intervention increased from 2.4 ± 0.7 (range 1-3) to 3.6 ± 0.5 (range 3-4; p = 0.01). CONCLUSION: Simulation-based training sets such as this have the potential to supplement traditional approaches in radiology education across a broad range of radiology subspecialities and imaging modalities.

Abdominal CT findings characteristic of Castleman disease: multi-centre review of 76 adult cases with abdominopelvic nodal involvement.

OBJECTIVE: Characterize the CT findings of abdominopelvic Castleman disease, including a new observation involving the perinodal fat. METHODS: Multi-centre search at 5 institutions yielded 76 adults (mean age, 42.1 ± 14.3 years; 38 women/38 men) meeting inclusion criteria of histopathologically proven Castleman disease with nodal involvement at abdominopelvic CT. Retrospective review of the dominant nodal mass was assessed for size, attenuation, and presence of calcification, and for prominence and soft-tissue infiltration of the perinodal fat. Hypervascular nodal enhancement was based on both subjective and objective comparison with aortic blood pool attenuation. RESULTS: Abdominal involvement was unicentric in 48.7% (37/76) and multicentric in 51.3% (39/76), including 31 cases with extra-abdominal involvement. Histopathologic subtypes included hyaline vascular variant (HVV), plasma cell variant (PCV), mixed HVV/PCV, and HHV-8 variant in 39, 25, 3 and 9 cases, respectively. The dominant nodal mass measured 4.4 ± 1.9 cm and 3.2 ± 1.7 cm in mean long- and short-axis, respectively, and appeared hypervascular in 58.6% (41/70 with IV contrast). Internal calcification was seen in 22.4% (17/76). Infiltration of the perinodal fat, with or without hypertrophy, was present in 56.6% (43/76), more frequent with hypervascular vs non-hypervascular nodal masses (80.5% vs 20.7%; P < .001). Among HVV cases, 76.9% were unicentric, 71.1% appeared hypervascular, and 69.2% demonstrated perinodal fat infiltration. CONCLUSION: Hypervascular nodal masses demonstrating prominence and infiltration of perinodal fat at CT can suggest the specific diagnosis of Castleman disease, especially the HVV. ADVANCES IN KNOWLEDGE: Abdominopelvic nodal masses that demonstrate hypervascular enhancement and prominent infiltration of the perinodal fat at CT can suggest the diagnosis of Castleman disease, but nonetheless requires tissue sampling.

Volumetric computed tomography measurements as predictors for outcomes in a cohort of Fournier's gangrene patients.

PURPOSE: This study evaluates the prognostic value of CT findings, including volumetric measurements, in predicting outcomes for patients with Fournier gangrene (FG), focusing on mortality, ICU admission, hospital stay length, and healthcare costs. METHODS: A retrospective study was conducted on 38 FG patients who underwent CT scans before surgical debridement. We analyzed demographic data, CT volumetric measurements, and clinical outcomes using logistic and linear regression models. RESULTS: No single CT measurement significantly predicted mortality or ICU admission. The best model for mortality prediction included age, air volume, NSTI score, and male sex, with an AUC of 0.911. Intubation likelihood was modeled with an AUC of 0.913 using age, NSTI score, and visceral to subcutaneous fat ratio. The ICU admission model achieved an AUC of 0.677. Hospital stay was predicted by air volume (ß = 0.0002656, p = 0.0505) with an adjusted R-squared of 0.1287. Air volume significantly predicted hospital costs (ß = 2.859, p = 0.00558), resulting in an adjusted R-squared of 0.2165. CONCLUSION: Volumetric CT findings provide valuable prognostic insights for FG patients, suggesting a basis for informed clinical decisions and resource allocation. Further validation in larger, multi-center studies is recommended to develop robust predictive models for FG outcomes.

Bowel Emergencies in Patients With Cancer.

Cancer is the second most common cause of death worldwide. Bowel emergencies in patients with cancer are becoming increasingly more prevalent due to advances in cancer therapy and longer overall patient survival. When these patients present acutely, they are often frail and may have pre-existing co-morbidities. This article discusses the imaging features of bowel emergencies commonly encountered in oncological patients in clinical practice. These include chemotherapy related colitis, neutropenia enterocolitis and typhlitis, toxic megacolon, bowel perforation, malignant bowel obstruction and gastrointestinal haemorrhage. The radiologist plays a key role in identifying these oncological emergencies and guiding further management.

Pearls and Pitfalls of Imaging Small Bowel Obstruction.

Small bowel obstruction (SBO) is a common condition encountered by radiologists in the evaluation of patients with abdominal pain, and is an important diagnosis to be comfortable with given substantial associated morbidity and mortality. In this review, we summarize an imaging approach to evaluating patients with suspected SBO, discuss the role of certain imaging modalities such as radiography and small bowel follow through, CT, and MRI, as well as review some common and also less common causes of SBO such as internal hernia. We will also discuss tailoring the imaging approach to address specific clinical questions and special patient populations such as imaging the pregnant patient with suspected SBO, and the inflammatory bowel disease patient.

Female-specific pancreatic cancer survival from CT imaging of visceral fat implicates glutathione metabolism in solid tumors.

RATIONALE AND OBJECTIVES: To identify if body composition, assessed with preoperative CT-based visceral fat ratio quantification as well as tumor metabolic gene expression, predicts sex-dependent overall survival (OS) in patients with pancreatic ductal adenocarcinoma (PDAC). MATERIALS AND METHODS: This was a retrospective analysis of preoperative CT in 98 male and 107 female patients with PDAC. Relative visceral fat (rVFA; visceral fat normalized to total fat) was measured automatically using software and corrected manually. Median and optimized rVFA thresholds were determined according to published methods. Kaplan Meier and log-rank tests were used to estimate OS. Multivariate models were developed to identify interactions between sex, rVFA, and OS. Unsupervised gene expression analysis of PDAC tumors from The Cancer Genome Atlas (TCGA) was performed to identify metabolic pathways with similar survival patterns to rVFA. RESULTS: Optimized preoperative rVFA threshold of 38.9% predicted significantly different OS in females with a median OS of 15 months (above threshold) vs 24 months (below threshold; p = 0.004). No significant threshold was identified in males. This female-specific significance was independent of age, stage, and presence of chronic pancreatitis (p = 0.02). Tumor gene expression analysis identified female-specific stratification from a five-gene signature of glutathione S-transferases. This was observed for PDAC as well as clear cell renal carcinoma and glioblastoma. CONCLUSION: CT-based assessments of visceral fat can predict pancreatic cancer OS in females. Glutathione S-transferase expression in tumors predicts female-specific OS in a similar fashion.

Contrast-Enhanced Ultrasound for Image-Guided Procedures.

Contrast-enhanced ultrasound (CEUS) uses intravenously injected gas microbubbles as a pure blood pool contrast agent to demonstrate blood flow and tissue perfusion at a much higher sensitivity than color Doppler and power Doppler ultrasound. CEUS has gained traction in abdominal diagnostic imaging for improved lesion detection and characterization and a complementary problem-solving tool to CT and MRI. In addition to its diagnostic applications, CEUS has also proven useful for pre-procedure planning, procedure guidance, and post-procedure evaluation. This review provides a practical overview and guides to the application of CEUS in percutaneous, ultrasound-guided, needle-driven procedures, focusing on 2 common procedures, which illustrate the many benefits of CEUS- core needle biopsy (CNB) and percutaneous hepatic lesion ablation.

ACR Appropriateness Criteria® Left Lower Quadrant Pain: 2023 Update.

The differential diagnosis for left lower quadrant pain is wide and conditions range from the benign and self-limited to life-threatening surgical emergencies. Along with patient history, physical examination, and laboratory tests, imaging is often critical to limit the differential diagnosis and identify life-threatening abnormalities. This document will discuss the guidelines for the appropriate use of imaging in the initial workup for patients who present with left lower quadrant pain, patients with suspected diverticulitis, and patients with suspected complications from diverticulitis. 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 process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Low grade endometrial stromal sarcoma in pregnancy: A case in support of safe abortion access.

Background: Endometrial stromal sarcoma (ESS) is extremely rare in pregnancy. It shares clinical and imaging features with more common pregnancy findings such as leiomyoma and molar gestations, which makes diagnosis challenging. Case: A 36-year-old patient presented at 8 weeks and 1 day gestation for vaginal bleeding. An intrauterine pregnancy with an appropriately sized embryo with heart motion and a 9.5 cm complex uterine mass was found on ultrasound. MRI showed an 11.4 cm cystic mass with nodular septations causing mass effect on the endometrial cavity. After extensive counseling, the patient underwent a gravid abdominal hysterectomy and bilateral salpingectomy. Final pathology showed low grade ESS. Conclusion: This case highlights the importance of evaluating suspicious uterine masses in pregnancy and the necessity for safe abortion access.

Preoperative computed tomography in Fournier's gangrene does not delay time to surgery.

PURPOSE: Fournier's gangrene (FG), a rapidly progressive necrotizing soft tissue infection of the external genitalia and perineum, necessitates urgent surgical debridement. The time to surgery effect of preoperative computed tomography (CT) in managing this condition is yet to be fully explored. The purpose of this study was to assess whether obtaining a preoperative CT in patients with FG impacts the time to surgical intervention. METHODS: This was a single-center retrospective study of patients who underwent CT prior to surgical debridement of FG during a 9-year period vs patients who did not undergo CT. In 76 patients (male = 39, mean age = 51.8), 38 patients with FG received a preoperative CT, and 38 patients with FG did not receive CT prior to surgical debridement. Time to operating room and outcome metrics were compared between CT and non-CT groups. RESULTS: The time from hospital presentation to surgical intervention was not significantly different between patients who underwent CT and those who did not (6.65 ± 3.71 vs 5.73 ± 4.33 h, p = 0.37). There were also no significant differences in cost ($130,000 ± $102,000 vs $142,000 ± $152,000, p = 0.37), mortality (8 vs 7, p = 1), duration of hospital stay (15.5 ± 15 vs 15.7 ± 11.6 days, p = 0.95), average intensive care unit stay (5.82 ± 5.38 days vs 6.97 ± 8.58 days, p = 0.48), and APACHE score (12 ± 4.65 vs 13.9 ± 5.6, p =0.12). CONCLUSION: Obtaining a preoperative CT did not delay surgical intervention in patients with FG.

Analysis of Superficial Subcutaneous Fat Camper's and Scarpa's Fascia in a United States Cohort.

Together, the Camper's and Scarpa's fasciae form the superficial fat layer of the abdominal wall. Though they have clinical and surgical relevance, little is known about their role in body composition across diverse patient populations. This study aimed to determine the relationship between patient characteristics, including sex and body mass index, and the distribution of Camper's and Scarpa's fascial layers in the abdominal wall. A total of 458 patients' abdominal CT examinations were segmented via CoreSlicer 1.0 to determine the surface area of each patient's Camper's, Scarpa's, and visceral fascia layers. The reproducibility of segmentation was corroborated by an inter-rater analysis of segmented data for 20 randomly chosen patients divided between three study investigators. Pearson correlation and Student's t-test analyses were performed to characterize the relationship between fascia distribution and demographic factors. The ratios of Camper's fascia, both as a proportion of superficial fat (r = -0.44 and p < 0.0001) and as a proportion of total body fat (r = -0.34 and p < 0.0001), showed statistically significant negative correlations with BMI. In contrast, the ratios of Scarpa's fascia, both as a proportion of superficial fat (r = 0.44 and p < 0.0001) and as a proportion of total body fat (r = 0.41 and p < 0.0001), exhibited statistically significant positive correlations with BMI. Between sexes, the females had a higher ratio of Scarpa's facia to total body fat compared to the males (36.9% vs. 31% and p < 0.0001). The ICC values for the visceral fat, Scarpa fascia, and Camper fascia were 0.995, 0.991, and 0.995, respectively, which were all within the 'almost perfect' range (ICC = 0.81-1.00). These findings contribute novel insights by revealing that as BMI increases the proportion of Camper's fascia decreases, while the ratio of Scarpa's fascia increases. Such insights expand the scope of body composition studies, which typically focus solely on superficial and visceral fat ratios.

Subcutaneous and visceral fat are associated with worse outcomes in gunshot injuries but not stab injuries to the torso.

Purpose: The effect of obesity in penetrating trauma outcomes is poorly understood. The purpose of this study was to determine if there is a protective effect of subcutaneous or visceral fat from stab and gunshot wounds. Methods: 443 patients admitted after penetrating traumatic injury of the torso were retrospectively identified from our institution's trauma registry. CT scans performed at presentation were used to determine cross-sectional area of visceral and subcutaneous fat at the level of the umbilicus via manual segmentation. Obesity-associated parameters including body mass index, visceral and subcutaneous fat were compared with injury severity score, length of hospital/intesive care unit (ICU) stay, and number of operating room (OR) visits. Parameters were compared between patients who sustained stab wounds versus gunshot injuries. Results: Comparing all patients with gunshot injuries with those with stab injuries, gunshots resulted in increased hospital and ICU length of stay, and injury severity score (ISS). For patients with gunshot wounds, all obesity-related parameters correlated with increased length of stay and total ICU stay; subcutaneous fat and visceral fat were correlated with increased OR visits, but there was no significant correlation between obesity-related parameters and ISS. In contrast, with stab wounds there were no statistically significant associations between obesity parameters and any of the outcome measures. Conclusion: For penetrating trauma in the torso, obesity is correlated with worse outcomes with gunshot injuries but not in stab injuries. Level of evidence: Level III, prognostic and epidemiological.

RadioGraphics Update: New Follow-up and Management Recommendations for Polypoid Lesions of the Gallbladder.

Editor's Note.-RadioGraphics Update articles supplement or update information found in full-length articles previously published in RadioGraphics. These updates, written by at least one author of the previous article, provide a brief synopsis that emphasizes important new informaion such as technological advances, revised imaging protocols, new clinical guidelines involving imaging, or updated classification schemes.

Urinary Bladder Masses, Rare Subtypes, and Masslike Lesions: Radiologic-Pathologic Correlation.

Urinary bladder masses are commonly encountered in clinical practice, with 95% arising from the epithelial layer and rarer tumors arising from the lamina propria, muscularis propria, serosa, and adventitia. The extent of neoplastic invasion into these bladder layers is assessed with multimodality imaging, and the MRI-based Vesical Imaging Reporting and Data System is increasingly used to aid tumor staging. Given the multiple layers and cell lineages, a diverse array of pathologic entities can arise from the urinary bladder, and distinguishing among benign, malignant, and nonneoplastic entities is not reliably feasible in most cases. Pathologic assessment remains the standard of care for classification of bladder masses. Although urothelial carcinoma accounts for most urinary bladder malignancies in the United States, several histopathologic entities exist, including squamous cell carcinoma, adenocarcinoma, melanoma, and neuroendocrine tumors. Furthermore, there are variant histopathologic subtypes of urothelial carcinoma (eg, the plasmacytoid variant), which are often aggressive. Atypical benign bladder masses are diverse and can have inflammatory or iatrogenic causes and mimic malignancy. © RSNA, 2022 Online supplemental material is available for this article.