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.

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.

The role of saline flush injection rate in displacement of CT-injectable peripherally inserted central catheter tip during power injection of contrast material.

OBJECTIVE: The purpose of this article is to determine the rate and the cause of displacement of CT power-injectable peripherally inserted central catheters (CT-PICCs) during contrast material and saline flush injection and to modify CT-scanning protocols to decrease the frequency of displacement. MATERIALS AND METHODS: In the laboratory setting, in vitro modeling of CTPICC displacement during power injection was examined while varying the initial rate of injection of the saline flush. In the clinical setting, the CT images of all patients at a large academic hospital for one calendar year who underwent power injection of CT contrast media were reviewed for CT-PICC displacement. A retrospective comparison of the rate of displacement during the 8 months before implementing a protocol with a lower initial rate of saline flush and the rate of displacement for the 4 months after the protocol change was performed. RESULTS: Laboratory modeling showed dramatic movement of the CT-PICC at higher rates of saline flush. This movement was attributed to differences in viscosity between contrast media and saline. The clinical arm of the study found that 8.2% of the 243 examinations performed before implementing the new protocol resulted in displacement, in comparison with 2.2% of the 138 examinations performed afterward. This difference was considered statistically significant (p = 0.023). CONCLUSION: Initiation of saline flush at high injection rates correlates with a higher rate of CT-PICC displacement. The use of a slower initial rate of saline flush injection significantly reduces the rate of displacement.

Anomalies, anatomic variants, and sources of diagnostic pitfalls in pancreatic imaging.

In this review, a brief discussion of the important events of pancreatic embryology is followed by presentation of congenital anomalies and normal variants. For each variant, the appearance at different radiologic modalities including computed tomography, magnetic resonance (MR) imaging, endoscopic retrograde cholangiopancreatography, MR cholangiopancreatography, and fluoroscopy will be demonstrated.

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.

A comprehensive approach to CT radiation dose reduction: one institution's experience.

OBJECTIVE: The purpose of this article is to review the process of creating and implementing a comprehensive plan to reduce diagnostic radiation exposure at our institution. CONCLUSION: This process, which was initiated by forming a radiation dose reduction committee, addressed several different issues to improve patient safety. These include avoidance of unnecessary CT examinations, adjusting individual scanning parameters, revising protocols, use of shielding and dose monitoring, and implementing computer-based dose modulation software as well as educating referring physicians and radiologic technologists.

Detection and Intervention of Clinically Masquerading Inferior Mesenteric Artery AVMs.

We demonstrate a rare case of inferior mesenteric artery arteriovenous malformations leading to ischemic colitis in a 76-year-old female. Our patient presented with three months of nausea, vomiting, and diarrhea. Colonoscopy displayed diffuse mucosal vascular congestion while CTA and MRA displayed AVMs in the region of the IMA; however, cohesive clinical agreement on AVM from multiple specialties was difficult given its rare occurrence and nonspecific clinical, histopathologic, and directly visualized findings. The three noted dominant AVMs were eventually selected with coil and liquid embolization with successful cessation of symptoms and no major complications. Our discussion focuses on intervention and stressing the importance of radiologic findings, as IMA AVMs, rarely present as ischemic colitis and therefore can clinically masquerade as other etiologies.

Cholecystohepatic Duct: A Biliary Duct Variant Resulting in Postcholecystectomy Bile Leak-Case Report and Review of Normal and Common Variant Biliary Anatomy.

Although relatively infrequent, bile duct leaks are among the primary complications of hepatobiliary surgery and cholecystectomy given the large number of these operations performed annually around the world. Variant biliary anatomy increases the risk of surgical complications, especially if unrecognized on preoperative imaging or intraoperatively. Presented here is a case of a patient with an unrecognized cholecystohepatic duct at the time of surgery leading to bile leak after cholecystectomy. Numerous factors made for a technically difficult surgery with obscuration of the true anatomy, ultimately resulting in transection of the cholecystohepatic duct. Understanding normal and variant biliary anatomy will help prevent avoidable complications of hepatobiliary surgery.

Society of abdominal radiology gastrointestinal bleeding disease-focused panel consensus recommendations for CTA technical parameters in the evaluation of acute overt gastrointestinal bleeding.

PURPOSE: To formulate consensus recommendations for CT angiography technical parameters used to evaluate overt gastrointestinal (GI) bleeding. METHODS: An electronic questionnaire consisting of 17 questions was sent to a panel of 16 radiologists with expertise on the imaging of GI bleeding from the Society of Abdominal Radiology GI Bleeding disease-focused panel to obtain consensus agreement on issues related to CTA technical parameters for imaging overt GI bleeding. A multi-round Delphi method of voting was performed to obtain consensus which was defined as ≥ 80% agreement. RESULTS: Consensus agreement was reached in 15/17 (89%) of the questions including the technique for the administration of IV contrast, the number of phases, scan timing, and image reconstruction. CONCLUSIONS: A panel of experts on the imaging of GI bleeding from the Society of Abdominal Radiology was able to reach consensus on the majority of technical parameters used for CTA of overt GI bleeding. These recommendations should improve the quality of patient care by adopting these minimal technical requirements for optimal exam performance and lead to less variation in the performance of these exams which will facilitate collecting and comparing published data from different centers. These recommendations will need revisions as additional scientific data become available.

Intravascular Large B-Cell Lymphoma Presenting with Diffuse Gallbladder Wall Thickening: A Case Report and Literature Review.

Intravascular large B-cell lymphoma is a rare subtype of extranodal diffuse B-cell lymphoma characterized by proliferation of neoplastic cells within the lumen of small and medium sized vessels. Clinical and imaging findings are nebulous as the intravascular subtype of lymphoma can involve a multitude of organs. Involvement of the gallbladder is extremely uncommon, and imaging findings can be easily confused for more prevalent pathologies. We report a case of intravascular large B-cell lymphoma in an 83-year-old male and review clinical presentation and imaging findings on CT, ultrasound, hepatobiliary iminodiacetic acid (HIDA) scan, and MRI. It is important for the radiologist to know about this disease as the imaging findings are atypical of other types of lymphoma, and this may lead to a delay in diagnosis and treatment.

Getting the GIST: a pictorial review of the various patterns of presentation of gastrointestinal stromal tumors on imaging.

Gastrointestinal stromal tumors (GISTs), the most common mesenchymal tumors of the gastrointestinal tract, are a relatively recently described entity. Most exhibit a mutated tyrosine kinase receptor gene and in some capacity are treated by tyrosine kinase inhibitors. GISTs can occur across the age spectrum but are more common in patients older than 40 years. They exhibit a wide range of clinical presentations and imaging characteristics. All patterns of enhancement on contrast enhanced computed tomography (CECT) can be seen with GISTs, including hypoenhancing, isoenhancing, and hyperenhancing tumors. They can be large or small, endoluminal or exophytic. Clinical presentations include asymptomatic patients, nonspecific symptoms, obstruction, and bleeding. Bleeding can take the form of slow, intraluminal GI bleeding or massive intraperitoneal bleeding secondary to rupture and can be seen regardless of the enhancement pattern. Some can cavitate, ulcerate, rupture or cause fistulae. The radiologist's knowledge of the variety of combinations of presentations can narrow the differential diagnosis and ultimately lead to faster diagnosis and treatment.

Multidetector CT enterography of focal small bowel lesions: a radiological-pathological correlation.

Focal small bowel lesions present a diagnostic challenge for both the radiologist and gastroenterologist. Both the detection and characterization of small bowel masses have greatly improved with the advent of multidetector CT enterography (MD-CTE). As such, MD-CTE is increasingly utilized in the workup of occult gastrointestinal bleeding. In this article, we review the spectrum of focal small bowel masses with pathologic correlation. Adenocarcinoma, the most common primary small bowel malignancy, presents as a focal irregular mass occasionally with circumferential extension leading to obstruction. Small bowel carcinoid tumors most commonly arise in the ileum and are characterized by avid enhancement and marked desmoplastic response of metastatic lesions. Aneurysmal dilatation of small bowel is pathognomonic for lymphoma and secondary findings of lymphadenopathy and splenomegaly should be sought. Benign small bowel masses such as leiomyoma and adenoma may be responsible for occult gastrointestinal bleeding. However, primary vascular lesions of the small bowel remain the most common cause for occult small bowel gastrointestinal bleeding. The arterial phase of contrast obtained with CTE aids in recognition of the vascular nature of these lesions. Systemic conditions such as Peutz-Jeghers syndrome and Crohn's disease may be suggested by the presence of multiple small bowel lesions. Lastly, potential pitfalls such as ingested material should be considered when faced with focal small bowel masses.

Transnasal endoscopic resection of juvenile nasopharyngeal angiofibroma without preoperative embolization.

Juvenile nasopharyngeal angiofibroma (JNA) is a benign, highly vascular, and locally invasive tumor. Because the location of these tumors makes conventional surgery difficult, interest in endoscopic resection is increasing, particularly for the treatment of lesions that do not extend laterally into the infratemporal fossa. We report the results of our series of 23 patients with JNA (stage IIB or lower) who underwent transnasal endoscopic resection under hypotensive general anesthesia without preoperative embolization of the tumor All tumors were successfully excised. The amount of intraoperative blood loss was acceptable. We observed only 1 recurrence, which was diagnosed 19 months postoperatively in a patient with a stage IIB primary tumor. We observed only 3 complications during follow-up-all synechia. We conclude that endoscopic resection of JNAs is safe and effective. The low incidence of recurrence and complications in this series indicates that preoperative embolization may not be necessary for lesions that have not undergone extensive spread; instead, intraoperative bleeding can be adequately controlled with good hypotensive general anesthesia.

MRI for appendicitis in pregnancy: is seeing believing? clinical outcomes in cases of appendix nonvisualization.

PURPOSE: The primary objective of this study was to determine the clinical outcomes in cases of appendix nonvisualization with MRI in pregnant patients with suspected appendicitis and the implications of appendix nonvisualization for excluding appendicitis. METHODS: Fifty-eight pregnant patients with suspected appendicitis evaluated with MRI at three centers from a single institution were retrospectively reviewed by three radiologists with varying levels of abdominal imaging experience. All scans were performed on a 1.5-Tesla Siemens unit. Cases were evaluated for diagnostic quality, visualization of the appendix, presence of appendicitis, and alternate diagnoses. Clinical outcomes were gathered from the electronic medical record. RESULTS: Of the 58 patients who underwent MRI for suspected appendicitis, 50 cases were considered adequate diagnostic quality by all three radiologists. The rate of appendix visualization among the three radiologists ranged from 60 to 76% (p = 0.44). The appendix was nonvisualized by at least one of the three radiologists in 25 cases (50%). Of these, none had a final diagnosis of appendicitis including one patient who underwent appendectomy. MRI suggested an alternate diagnosis in 6 (24%) patients with appendix nonvisualization. For the three reviewers, the agreement level on whether or not the appendix was visualized on the MRI had a Light's kappa value of 0.526, indicating a "moderate" level of agreement (p value < 0.01). CONCLUSION: Despite only moderate level of interobserver agreement for appendix visualization, appendix nonvisualization on MRI in pregnant patients with suspected appendicitis confers a significant reduction in the risk of appendicitis compared to all comers as long as the study is adequate diagnostic quality and there are no secondary signs of appendicitis present.

Hepatobiliary Iminodiacetic Acid Scanning Detects High-Grade Biliary Obstruction Secondary to IgG4-Related Sclerosing Cholangitis.

In this report, we present a case of high-grade biliary obstruction discovered on hepatobiliary scintigraphy secondary to IgG4-related sclerosing cholangitis with concomitant autoimmune pancreatitis, a recently described entity that is gaining recognition in the radiology literature. To our knowledge, the scintigraphic findings have yet to be described in the literature. We present the hepatobiliary scintigraphic findings and their correlation to findings on endoscopic retrograde cholangiopancreatography, CT, and MR cholangiopancreatography, with posttreatment follow-up imaging. IgG4-related sclerosing cholangitis is a rare yet important diagnostic consideration when high-grade obstruction is seen on hepatobiliary iminodiacetic acid scanning. We discuss the differential diagnosis of high-grade biliary obstruction seen on hepatobiliary iminodiacetic acid scanning.

Etiology, Diagnosis, and Management of Bilomas: A Current Update.

A biloma is a well-demarcated collection of bile outside the biliary tree. Traumatic and iatrogenic injuries, most commonly secondary to cholecystectomy, are the usual causes. Although bilomas are relatively uncommon, this pathologic entity may lead to significant morbidity and mortality if not promptly diagnosed and properly managed. As clinical signs and symptoms of bilomas are often nonspecific and laboratory values may be unremarkable, imaging modalities including ultrasound, computed tomography, magnetic resonance imaging, and hepatobiliary cholescintigraphy play a crucial role in the diagnosis of this condition. It is paramount that interventional radiologists not only be well versed in the management of bilomas but also be knowledgeable in the diagnosis as well as key imaging findings that dictate the interventional management. The purpose of this article is to review the etiology, pathophysiology, and clinical presentation of bilomas to primarily focus on the relevant multimodal imaging findings and the minimally invasive management options.

Hybrid repair of a ruptured right-sided aortic arch with an aberrant left subclavian artery arising from a diverticulum of Kommerell: a case report.

Right-sided aortic arch with an aberrant left subclavian artery is a rare aortic arch anomaly. Although usually asymptomatic, aneurysm formation, dissection, and rupture can occur due to the aberrant vasculature and can be life-threatening. Hybrid, endovascular techniques have been implemented in instances of elective repair of aneurysmal diverticula of Kommerell in similar anatomical settings, but little has been written regarding urgent cases of rupture. We report a case of ruptured right-sided aortic arch with an aberrant left subclavian artery arising from a diverticulum of Kommerell successfully treated with hybrid aortic debranching and thoracic endovascular aortic stenting.

Shielding artificially increases the attenuation of water: study of CT gradient attenuation induced by shielding (CT GAINS).

RATIONALE AND OBJECTIVES: Quantitatively analyze the computed tomography (CT) attenuation effects caused by bismuth shields, which are used to reduce superficial organ dose. MATERIALS AND METHODS: The solid water uniformity section of the American College of Radiology CT phantom was scanned with a modified chest CT protocol. Scans were performed with a bismuth breast shield in multiple configurations, emphasizing three clinically relevant orientations. Attenuation effects were measured as changes in mean Hounsfield unit (HU) values of equal midsagittal regions of interest (ROI). Multiple statistical techniques were used in regression analysis. RESULTS: Bismuth shielding resulted in significant positive shifts of the expected Hounsfield unit values. The mean nonshielded CT attenuation was -0.16 ± 0.75 HU. Based on the clinically relevant ROI distance from the shield (~3-16 cm), the shielded values ranged from 43.8-4 HU, 45.8-10.1 HU, and 50.6-4.5 HU for shields 1, 2, and 3, respectively. All shield configurations displayed a statistically significant shift (P < .0001) at all distance ranges. The best fitting regression model was a quadratic function of distance versus logarithmic function of HU. A prediction table of the approximate shift in water HU values as a function of ROI distance from the shield was generated per shield type from their respective close-fitting regressions. CONCLUSIONS: The data support the claim that bismuth shields increase the attenuation of water, which can cause inaccurate characterization of simple fluid, giving the appearance of complex fluid or even solid density. However, there is potential for anticipation of the attenuation effects to validate continued use of these shields for dose reduction.