The Role of Imaging for Gastrointestinal Bleeding: Consensus Recommendations From the American College of Gastroenterology and Society of Abdominal Radiology.

Gastrointestinal (GI) bleeding is the most common GI diagnosis leading to hospitalization within the United States. Prompt diagnosis and treatment of GI bleeding is critical to improving patient outcomes and reducing high healthcare utilization and costs. Radiologic techniques including computed tomography angiography, catheter angiography, computed tomography enterography, magnetic resonance enterography, nuclear medicine red blood cell scan, and technetium-99m pertechnetate scintigraphy (Meckel scan) are frequently used to evaluate patients with GI bleeding and are complementary to GI endoscopy. However, multiple management guidelines exist which differ in the recommended utilization of these radiologic examinations. This variability can lead to confusion as to how these tests should be used in the evaluation of GI bleeding. In this document, a panel of experts from the American College of Gastroenterology and Society of Abdominal Radiology provide a review of the radiologic examinations used to evaluate for GI bleeding including nomenclature, technique, performance, advantages, and limitations. A comparison of advantages and limitations relative to endoscopic examinations is also included. Finally, consensus statements and recommendations on technical parameters and utilization of radiologic techniques for GI bleeding are provided.

The Role of Imaging for GI Bleeding: ACG and SAR Consensus Recommendations.

Gastrointestinal (GI) bleeding is the most common GI diagnosis leading to hospitalization within the United States. Prompt diagnosis and treatment of GI bleeding is critical to improving patient outcomes and reducing high health care utilization and costs. Radiologic techniques including CT angiography, catheter angiography, CT enterography, MR enterography, nuclear medicine red blood cell scan, and technetium-99m pertechnetate scintigraphy (Meckel scan) are frequently used to evaluate patients with GI bleeding and are complementary to GI endoscopy. However, multiple management guidelines exist, which differ in the recommended utilization of these radiologic examinations. This variability can lead to confusion as to how these tests should be used in the evaluation of GI bleeding. In this document, a panel of experts from the American College of Gastroenterology and Society of Abdominal Radiology provide a review of the radiologic examinations used to evaluate for GI bleeding including nomenclature, technique, performance, advantages, and limitations. A comparison of advantages and limitations relative to endoscopic examinations is also included. Finally, consensus statements and recommendations on technical parameters and utilization of radiologic techniques for GI bleeding are provided. © Radiological Society of North America and the American College of Gastroenterology, 2024. Supplemental material is available for this article. This article is being published concurrently in American Journal of Gastroenterology and Radiology. The articles are identical except for minor stylistic and spelling differences in keeping with each journal's style. Citations from either journal can be used when citing this article. See also the editorial by Lockhart in this issue.

The Early-Enhancing Hepatic Vein: Differentiating Focal Nodular Hyperplasia and Hepatic Adenoma With Pathologic Validation in MRI.

BACKGROUND: Focal nodular hyperplasia (FNH) and hepatic adenoma (HA) are two common benign liver lesions with different management options. In particular, resection is considered for large HA lesions to avoid possible bleeding complications or rarely malignant degeneration. PURPOSE: To determine whether early enhancement of a draining hepatic vein (EDHV) and absence of perilesional enhancement (PLE) on arterial phase MR images are useful for distinguishing FNH from HA. STUDY TYPE: Retrospective. POPULATION: A total of 34 patients: 16 with FNH and 18 with HA lesions. FIELD STRENGTH/SEQUENCE: A1.5 T, axial T1 fat-suppressed arterial postcontrast. ASSESMENT: Four abdominal radiologists blinded to pathologic diagnosis assessed for the presence or absence of EDHV in association with the lesion, definitively characterized by pathology. This was considered present if contrast could be identified in a hepatic vein contiguous with the lesion in question. Secondarily, PLE was evaluated. STATISTICAL TESTS: Fleiss's multirater kappa statistic, Chi-squared statistic, Phi-coefficient. Significance level P < 0.05. RESULTS: Considering all observations obtained from the four readers, an EDHV was identified with FNH 48.5% of the time. EDHV was seen with HA in 8.8% of cases. PLE was seen with significantly greater frequency in HA. The presence of an EDHV was associated with the absence of PLE. DATA CONCLUSION: In a lesion that may be either an FNH or HA, confident identification on arterial phase images of an EDHV should lead the reader to favor FNH, while the presence PLE should dissuade the reader from FNH. EVIDENCE LEVEL: 4. TECHNICAL EFFICACY: Stage 2.

Dual-Energy CT Evaluation of Gastrointestinal Bleeding.

Gastrointestinal (GI) bleeding is a potentially life-threatening condition accounting for more than 300 000 annual hospitalizations. Multidetector abdominopelvic CT angiography is commonly used in the evaluation of patients with GI bleeding. Given that many patients with severe overt GI bleeding are unlikely to tolerate bowel preparation, and inpatient colonoscopy is frequently limited by suboptimal preparation obscuring mucosal visibility, CT angiography is recommended as a first-line diagnostic test in patients with severe hematochezia to localize a source of bleeding. Assessment of these patients with conventional single-energy CT systems typically requires the performance of a noncontrast series followed by imaging during multiple postcontrast phases. Dual-energy CT (DECT) offers several potential advantages for performing these examinations. DECT may eliminate the need for a noncontrast acquisition by allowing the creation of virtual noncontrast (VNC) images from contrast-enhanced data, affording significant radiation dose reduction while maintaining diagnostic accuracy. VNC images can help radiologists to differentiate active bleeding, hyperattenuating enteric contents, hematomas, and enhancing masses. Additional postprocessing techniques such as low-kiloelectron voltage virtual monoenergetic images, iodine maps, and iodine overlay images can increase the conspicuity of contrast material extravasation and improve the visibility of subtle causes of GI bleeding, thereby increasing diagnostic confidence and assisting with problem solving. GI bleeding can also be diagnosed with routine single-phase DECT scans by constructing VNC images and iodine maps. Radiologists should also be aware of the potential pitfalls and limitations of DECT. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Liver Fibrosis, Fat, and Iron Evaluation with MRI and Fibrosis and Fat Evaluation with US: A Practical Guide for Radiologists.

Quantitative imaging biomarkers of liver disease measured by using MRI and US are emerging as important clinical tools in the management of patients with chronic liver disease (CLD). Because of their high accuracy and noninvasive nature, in many cases, these techniques have replaced liver biopsy for the diagnosis, quantitative staging, and treatment monitoring of patients with CLD. The most commonly evaluated imaging biomarkers are surrogates for liver fibrosis, fat, and iron. MR elastography is now routinely performed to evaluate for liver fibrosis and typically combined with MRI-based liver fat and iron quantification to exclude or grade hepatic steatosis and iron overload, respectively. US elastography is also widely performed to evaluate for liver fibrosis and has the advantage of lower equipment cost and greater availability compared with those of MRI. Emerging US fat quantification methods can be performed along with US elastography. The author group, consisting of members of the Society of Abdominal Radiology (SAR) Liver Fibrosis Disease-Focused Panel (DFP), the SAR Hepatic Iron Overload DFP, and the European Society of Radiology, review the basics of liver fibrosis, fat, and iron quantification with MRI and liver fibrosis and fat quantification with US. The authors cover technical requirements, typical case display, quality control and proper measurement technique and case interpretation guidelines, pitfalls, and confounding factors. The authors aim to provide a practical guide for radiologists interpreting these examinations. © RSNA, 2023 See the invited commentary by Ronot in this issue. Quiz questions for this article are available in the supplemental material.

Ultrasound-Based Machine Learning Approach for Detection of Nonalcoholic Fatty Liver Disease.

OBJECTIVES: Current diagnosis of nonalcoholic fatty liver disease (NAFLD) relies on biopsy or MR-based fat quantification. This prospective study explored the use of ultrasound with artificial intelligence for the detection of NAFLD. METHODS: One hundred and twenty subjects with clinical suspicion of NAFLD and 10 healthy volunteers consented to participate in this institutional review board-approved study. Subjects were categorized as NAFLD and non-NAFLD according to MR proton density fat fraction (PDFF) findings. Ultrasound images from 10 different locations in the right and left hepatic lobes were collected following a standard protocol. MRI-based liver fat quantification was used as the reference standard with >6.4% indicative of NAFLD. A supervised machine learning model was developed for assessment of NAFLD. To validate model performance, a balanced testing dataset of 24 subjects was used. Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy with 95% confidence interval were calculated. RESULTS: A total of 1119 images from 106 participants was used for model development. The internal evaluation achieved an average precision of 0.941, recall of 88.2%, and precision of 89.0%. In the testing set AutoML achieved a sensitivity of 72.2% (63.1%-80.1%), specificity of 94.6% (88.7%-98.0%), positive predictive value (PPV) of 93.1% (86.0%-96.7%), negative predictive value of 77.3% (71.6%-82.1%), and accuracy of 83.4% (77.9%-88.0%). The average agreement for an individual subject was 92%. CONCLUSIONS: An ultrasound-based machine learning model for identification of NAFLD showed high specificity and PPV in this prospective trial. This approach may in the future be used as an inexpensive and noninvasive screening tool for identifying NAFLD in high-risk patients.

Beyond the Liver Function Tests: A Radiologist's Guide to the Liver Blood Tests.

Liver blood tests (often also known as liver chemistries, liver tests, or the common misnomer liver function tests) are routinely used in diagnosis and management of hepatobiliary disease. Abnormal liver blood test results are often the first indicator of hepatobiliary disease and a common indication for abdominal imaging with US, CT, or MRI. Most of the disease entities can be categorized into hepatocellular or cholestatic patterns, with characteristic traits on liver blood tests. Each pattern has a specific differential, which can help narrow the differential diagnosis when combined with the clinical history and imaging findings. This article reviews the major liver blood tests as well as a general approach to recognizing common patterns of hepatobiliary disease within these tests (hepatocellular, cholestatic, acute liver failure, isolated hyperbilirubinemia). Examples of hepatobiliary disease with hepatocellular or cholestatic patterns are presented with characteristic test abnormalities and imaging findings. The commonly encountered scenario of chronic hepatitis with possible fibrosis is also reviewed, with discussion of potential further imaging such as elastography. The role of liver blood tests and imaging in evaluating complications of hepatic transplant is also discussed. Overall, integrating liver blood test patterns with imaging findings can help the radiologist accurately diagnose hepatobiliary disease, especially in cases where imaging findings may not allow differentiation between different entities. ©RSNA, 2021.

Gastrointestinal Bleeding at CT Angiography and CT Enterography: Imaging Atlas and Glossary of Terms.

Gastrointestinal (GI) bleeding is a common potentially life-threatening medical condition frequently requiring multidisciplinary collaboration to reach the proper diagnosis and guide management. GI bleeding can be overt (eg, visible hemorrhage such as hematemesis, hematochezia, or melena) or occult (eg, positive fecal occult blood test or iron deficiency anemia). Upper GI bleeding, which originates proximal to the ligament of Treitz, is more common than lower GI bleeding, which arises distal to the ligament of Treitz. Small bowel bleeding accounts for 5-10% of GI bleeding cases commonly manifesting as obscure GI bleeding, where the source remains unknown after complete GI tract endoscopic and imaging evaluation. CT can aid in identifying the location and cause of bleeding and is an important complementary tool to endoscopy, nuclear medicine, and angiography in evaluating patients with GI bleeding. For radiologists, interpreting CT scans in patients with GI bleeding can be challenging owing to the large number of images and the diverse potential causes of bleeding. The purpose of this pictorial review by the Society of Abdominal Radiology GI Bleeding Disease-Focused Panel is to provide a practical resource for radiologists interpreting GI bleeding CT studies that reviews the proper GI bleeding terminology, the most common causes of GI bleeding, key patient history and risk factors, the optimal CT imaging technique, and guidelines for case interpretation and illustrates many common causes of GI bleeding. A CT reporting template is included to help generate radiology reports that can add value to patient care. An invited commentary by Al Hawary is available online. Online supplemental material is available for this article. ©RSNA, 2021.

Small Bowel Crohn Disease at CT and MR Enterography: Imaging Atlas and Glossary of Terms.

Representatives from the Society of Abdominal Radiology Crohn's Disease-Focused Panel, the Society for Pediatric Radiology, the American Gastroenterological Association, and other international experts recently reported consensus recommendations for standardized nomenclature for the interpretation and reporting of CT enterography and MR enterography findings of small bowel Crohn disease. The consensus recommendations included CT enterography and MR enterography bowel wall findings that are associated with Crohn disease, findings that occur with penetrating Crohn disease, and changes that occur in the mesentery related to Crohn disease. Also included were recommended radiology report impression statements that summarize the findings of small bowel Crohn disease at CT enterography and MR enterography. This article, authored by the Society of Abdominal Radiology Crohn's Disease-Focused Panel, illustrates the imaging findings and recommended radiology report impression statements described in the consensus recommendations with examples of CT enterography and MR enterography images. Additional interpretation guidelines for reporting CT enterography and MR enterography examinations are also presented. The recommended standardized nomenclature can be used to generate radiology report dictations that will help guide medical and surgical management for patients with small bowel Crohn disease. Online supplemental material is available for this article. ©RSNA, 2020See discussion on this article by Heverhagen.

Liver MR Elastography Technique and Image Interpretation: Pearls and Pitfalls.

Liver MR elastography is an imaging technique used to measure liver stiffness in the evaluation for possible fibrosis or cirrhosis. Liver stiffness measurement (LSM) is useful for predicting the stage of liver fibrosis. However, obtaining and reporting accurate and reliable LSMs with MR elastography require an understanding of the three core components of liver MR elastography: optimization of imaging technique, prompt quality control of images, and proper interpretation and reporting of elastogram findings. When performing MR elastography, six important technical parameters that should be optimized are patient fasting before the examination, proper passive driver placement, proper MR elastography section positioning over the largest area of the liver, use of MR elastography-related sequences at end expiration, choosing the best timing of the MR elastography sequence, and optimization of several essential pulse sequence parameters. As soon as the MR elastography examination is performed, the elastograms should be reviewed to ensure that they are of diagnostic quality so that corrective steps can be taken, if needed, and MR elastography can be repeated before the diagnostic portion of the examination concludes. Finally, the interpreting radiologist needs to understand and be able to perform the proper technique for LSMs, including determining which areas of the liver to include or avoid in the measurements; knowing which conditions, other than fibrosis or cirrhosis, can increase liver stiffness; and understanding how to report elastography results. This article reviews the proper technique for performing liver MR elastography and subsequent quality control assessment, as well as the principles for interpreting and reporting studies. This review may be helpful for implementing and operating a clinical liver MR elastography service.Online supplemental material is available for this article.©RSNA, 2019.

Contributions of Magnetic Resonance Imaging to Gastroenterological Practice: MRIs for GIs.

MRI has transformed from the theoretical, investigative realm to mainstream clinical medicine over the past four decades and has become a core component of the diagnostic toolbox in the practice of gastroenterology (GI). Its success is attributable to exquisite contrast and the ability to isolate specific proton species through the use of different pulse sequences (i.e., T1-weighted, T2-weighted, diffusion-weighted) and exploiting extracellular and hepatobiliary contrast agents. Consequently, MRI has gained preeminence in various GI clinical applications: liver and pancreatic lesion evaluation and detection, liver transplantation evaluation, pancreatitis evaluation, Crohn's disease evaluation (using MR enterography) rectal cancer staging and perianal fistula evaluation. MR elastography, in concert with technical innovations allowing for fat and iron quantification, provides a noninvasive approach, or "MRI virtual liver biopsy" for diagnosis and management of chronic liver diseases. In the future, the arrival of ultra-high-field MR systems (7 T) and the ability to perform magnetic resonance spectroscopy in the abdomen promise even greater diagnostic insight into chronic liver disease.

How to perform and interpret cine MR enterography.

Magnetic resonance (MR) enterography has become a fundamental tool for small bowel evaluation. Multiphasic cine imaging is a useful component of MR enterography evaluation because it provides functional information about bowel motility. Cine MR enterography can be used to evaluate for strictures and adhesions. Bowel motility evaluation has been shown to increase pathologic lesion detection in Crohn's disease and has been incorporated into disease activity scoring systems. Currently, cine MR enterography remains underutilized. The purpose of this article is to outline how to perform and interpret cine MR enterography. The authors describe how to perform a multiphasic balanced steady state free precession sequence using different MR systems and give practical advice on how to display and interpret the cine sequence. Sample cases illustrate how the cine sequence complements standard MR enterography evaluation with T2 -weighted, contrast-enhanced T1 -weighted, and diffusion-weighted imaging.

MR enterography in Crohn's disease: current consensus on optimal imaging technique and future advances from the SAR Crohn's disease-focused panel.

MR enterography is a powerful tool for the non-invasive evaluation of patients with Crohn's disease (CD) without ionizing radiation. The following paper describes the current consensus on optimal imaging technique, interpretation, and future advances from the Society of Abdominal Radiology CD-focused panel.

Identifying decreased peristalsis of abnormal small bowel segments in Crohn's disease using cine MR enterography: the frozen bowel sign.

PURPOSE: The purpose of this study was to evaluate whether affected bowel in Crohn's disease patients can be identified by observing decreased peristalsis (frozen bowel sign) using cine balanced steady-state free precession (cine BSSFP) images. MATERIALS AND METHODS: 5 radiologists independently reviewed cine BSSFP sequences from randomized MR Enterography (MRE) exams for 30 normal and 30 Crohn's disease patients, graded overall small bowel peristalsis from slowest to fastest, and graded peristalsis for the most abnormal small bowel segment. Sensitivity and specificity of the frozen bowel sign for diagnosing Crohn's disease were calculated. T tests of the peristalsis difference between abnormal segments and overall small bowel were conducted. RESULTS: For 5 readers, the sensitivity and specificity of cine BSSFP of the frozen bowel sign for diagnosing Crohn's disease ranged from 70% to 100% and 87% to 100%, respectively. There were significant differences in peristalsis between abnormal small bowel segments and the overall small bowel for Crohn's patients, but not in the overall small bowel between normal-MRE patients and Crohn's disease patients. CONCLUSION: Abnormal Crohn's small bowel segments have significantly decreased peristalsis compared to normal small bowel, which can be identified using cine BSSFP sequences as the frozen bowel sign.

Erratum to: Identifying decreased peristalsis of abnormal small bowel segments in Crohn's disease using cine MR enterography: the frozen bowel sign.

PURPOSE: The purpose of this study was to evaluate whether affected bowel in Crohn's disease patients can be identified by observing decreased peristalsis (frozen bowel sign) using cine balanced steady-state free precession (cine BSSFP) images. MATERIALS AND METHODS: 5 radiologists independently reviewed cine BSSFP sequences from randomized MR Enterography (MRE) exams for 30 normal and 30 Crohn's disease patients, graded overall small bowel peristalsis from slowest to fastest, and graded peristalsis for the most abnormal small bowel segment. Sensitivity and specificity of the frozen bowel sign for diagnosing Crohn's disease were calculated. T tests of the peristalsis difference between abnormal segments and overall small bowel were conducted. RESULTS: For 5 readers, the sensitivity and specificity of cine BSSFP of the frozen bowel sign for diagnosing Crohn's disease ranged from 70% to 100% and 87% to 100%, respectively. There were significant differences in peristalsis between abnormal small bowel segments and the overall small bowel for Crohn's patients, but not in the overall small bowel between normal-MRE patients and Crohn's disease patients. CONCLUSION: Abnormal Crohn's small bowel segments have significantly decreased peristalsis compared to normal small bowel, which can be identified using cine BSSFP sequences as the frozen bowel sign.

Comparison of Magnetic Resonance-Based Elastography and Ultrasound Shear Wave Elastography in Patients With Suspicion of Nonalcoholic Fatty Liver Disease.

ABSTRACT: This study investigated the correlation between magnetic resonance elastography (MRE) and shear wave ultrasound elastography (SWE) in patients with clinically diagnosed or suspected nonalcoholic fatty liver disease (NAFLD). Subjects with or at risk of NAFLD identified by magnetic resonance imaging (MRI) proton density fat fraction (PDFF) were prospectively enrolled. For each patient, 6 valid 2-dimensional SWE measurements were acquired using a Logiq E10 scanner (GE HealthCare, Waukesha, WI). A reliability criterion of an interquartile range to median ratio of ≤15% was used for SWE to indicate quality dataset. Magnetic resonance elastography, and MR-fat quantification data were collected the same day as part of the patient's clinical standard of care. Magnetic resonance imaging PDFF was used as a reference to quantify fat with >6.4% indicating NAFLD. Pearson correlation and t-test were performed for statistical analyses. A total of 140 patients were enrolled, 112 of which met SWE reliability measurement criteria. Magnetic resonance elastography and 2-dimensional SWE showed a positive correlation across all study subjects ( r = 0.27; P = 0.004). When patients were grouped according to steatosis and fibrosis state, a positive correlation was observed between MRE and SWE in patients with fibrosis ( r = 0.30; P = 0.03), without fibrosis ( r = 0.27; P = 0.03), and with NAFLD ( r = 0.28; P = 0.02). No elastography technique correlated with liver fat quantification ( P > 0.52). Magnetic resonance elastography was significantly different between patients with and without fibrosis ( P < 0.0001). However, this difference was not apparent with SWE ( P = 0.09). In patients with suspected or known NAFLD, MRE, and SWE demonstrated a positive correlation. In addition, these noninvasive imaging modalities may be useful adjunct techniques for monitoring NAFLD.

Role of MR imaging of uterine leiomyomas before and after embolization.

Leiomyoma, the most common uterine neoplasm, is composed of smooth muscle with varying amounts of fibrous connective tissue. Most leiomyomas are asymptomatic, but patients may present with abnormal uterine bleeding or bulk-related symptoms. Over the past decade, uterine fibroid embolization (UFE) has been an effective minimally invasive treatment for symptomatic patients. Magnetic resonance (MR) imaging is the most accurate imaging technique for detection and evaluation of leiomyomas and therefore has become the imaging modality of choice before and after UFE. As leiomyomas enlarge, they may outgrow their blood supply, resulting in various forms of degeneration that change their appearance. Leiomyomas are classified as submucosal, intramural, or subserosal. Submucosal and subserosal leiomyomas may be pedunculated, thus simulating other conditions. Understanding the MR imaging appearance of leiomyomas allows differentiation from other entities. The superior tissue contrast of MR imaging allows diagnosis of leiomyomas with a high level of confidence, ultimately leading to a decrease in the number of surgeries performed and thus reducing healthcare expenditures. MR imaging findings that influence the planning of UFE include the location, size, number, and vascular supply of leiomyomas. In addition, MR imaging can be used to assess the success of UFE and evaluate for potential complications.

Sarcopenia Is More Prevalent Among Inflammatory Bowel Disease Patients Undergoing Surgery and Predicts Progression to Surgery Among Medically Treated Patients.

BACKGROUND: Sarcopenia is common in inflammatory bowel disease (IBD); however, estimates of its prevalence and impact on clinical outcomes are variable. This study sought to compare the prevalence of sarcopenia in IBD patients starting new biologics vs patients undergoing IBD surgeries, and its association with common clinical predictors of nutritional status, adverse events, and clinical outcomes. METHODS: This was a multicenter retrospective cohort study of IBD patients who had a computed tomography (CT) scan within 6 months prior to new biologic initiation (medical cohort) or IBD surgery (surgery cohort). The lowest sex-specific quartile of the total psoas area index at the L3 level defined sarcopenia. Prevalence and predictors of sarcopenia, performance of common clinical nutritional markers, and association with adverse events and clinical outcomes at 1 year were determined. RESULTS: A total of 156 patients were included (48% medical cohort, 52% surgery cohort). Sarcopenia was more common in the surgery cohort (32% vs 16%; P < .02). In the medical cohort, sarcopenia predicted need for surgery at 1 year (odds ratio, 4.75; 95% confidence interval, 1.10-20.57; P = .04). Low albumin and body mass index (BMI) were associated with the presence of sarcopenia; however, 24% of sarcopenic patients had both normal BMI and albumin. CONCLUSIONS: Sarcopenia is more prevalent among IBD patients undergoing surgery and predicts the need for surgery in patients starting new biologic therapy. Low albumin and BMI were similar between cohorts, suggesting a unique role for sarcopenia as a relevant clinical marker of lean muscle mass depletion for surgically and medically treated IBD patients.

Sarcopenia is more common in inflammatory bowel disease surgery patients compared with medical patients, and predicts need for surgery in medical patients. Differences in skeletal muscle measurements compared with albumin and body mass index suggest that sarcopenia may be challenging to detect in routine clinical settings.

Magnetic resonance elastography of the liver: everything you need to know to get started.

Magnetic resonance elastography (MRE) of the liver has emerged as the non-invasive standard for the evaluation of liver fibrosis in chronic liver diseases (CLDs). The utility of MRE in the evaluation of different CLD in both adults and children has been demonstrated in several studies, and MRE has been recommended by several clinical societies. Consequently, the clinical indications for evaluation of CLD with MRE have increased, and MRE is currently used as an add-on test during routine liver MRI studies or as a standalone test. To meet the increasing clinical demand, MRE is being installed in many academic and private practice imaging centers. There is a need for a comprehensive practical guide to help these practices to deliver high-quality liver MRE studies as well as troubleshoot the common issues with MRE to ensure smooth running of the service. This comprehensive clinical practice review summarizes the indications and provides an overview on why to use MRE, technical requirements, system set-up, patient preparation, acquiring the data, and interpretation.

Management of gastrointestinal bleeding: Society of Abdominal Radiology (SAR) Institutional Survey.

Despite guidelines developed to standardize the diagnosis and management of gastrointestinal (GI) bleeding, significant variability remains in recommendations and practice. The purpose of this survey was to obtain information on practice patterns for the evaluation of overt lower GI bleeding (LGIB) and suspected small bowel bleeding. A 34-question electronic survey was sent to all Society of Abdominal Radiology (SAR) members. Responses were received from 52 unique institutions (40 from the United States). Only 26 (50%) utilize LGIB management guidelines. 32 (62%) use CT angiography (CTA) for initial evaluation in unstable patients. In stable patients with suspected LGIB, CTA is the preferred initial exam at 21 (40%) versus colonoscopy at 24 (46%) institutions. CTA use increases after hours for both unstable (n = 32 vs. 35, 62% vs. 67%) and stable patients (n = 21 vs. 27, 40% vs 52%). CTA is required before conventional angiography for stable (n = 36, 69%) and unstable (n = 15, 29%) patients. 38 (73%) institutions obtain two post-contrast phases for CTA. 49 (94%) institutions perform CT enterography (CTE) for occult small bowel bleeding with capsule endoscopy (n = 26, 50%) and CTE (n = 21, 40%) being the initial test performed. 35 (67%) institutions perform multiphase CTE for occult small bowel bleeding. In summary, stable and unstable patients with overt lower GI are frequently imaged with CTA, while CTE is frequently performed for suspected occult small bowel bleeding.