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.

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.

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.

Comparing the productivity of teaching and non-teaching workflow models in an academic abdominal imaging division.

PURPOSE: To evaluate the productivity difference between teaching and non-teaching workflow models in an abdominal imaging division in an academic radiology department. METHODS AND MATERIALS: RVU data were compiled for six faculty members from the abdominal imaging division over a six-month period. Modalities included ultrasound and CT of the abdomen and pelvis. The relative RVU productivity for faculty members by workflow was compared individually and the composite data for the workflow models were compared. The relative RVU productivity for each faculty member was compared individually and in aggregate to study the effect of the workflow models on RVUs using factorial ANOVA. Turnaround times (TAT) were compared for each attending under both models. TAT data were analyzed using paired t-tests with Bonferroni corrections for multiple comparisons. RESULTS: Daily RVU data from 387 instances were analyzed. Daily RVUs for faculty members ranged from 23.5 ± 2.3 (mean ± standard error) to 46.2 ± 2.4 with non-teaching and from 29.8 ± 2.2 to 54.4 ± 2.7 with teaching workflow, respectively. There was a significant main effect of the workflow model on RVU productivity (p < 0.05). A significant increase of 27.8% in RVUs was noted with teaching workflow (42.8 ± 0.9) relative to non-teaching workflow (33.5 ± 1.7; p < 0.05). Teaching workflow resulted in significantly higher view-final and complete-final TATs (593 ± 112 min, mean ± SE and 841 ± 96 min, mean ± SE, respectively) compared to the non-teaching workflow (385 ± 124 min). CONCLUSION: Teaching workflow improves abdominal imaging productivity with an increase in report turnaround times.

The pre-operative and post-operative imaging appearances of urethral strictures and surgical techniques.

Urethral strictures arise from a variety of etiologies, most commonly either iatrogenic or inflammatory in the anterior urethra and iatrogenic/surgical or traumatic etiologies in the posterior urethra. Diagnosis and treatment planning depend on urethrography, usually performed with a combination of retrograde urethrography (RUG) and voiding cystourethrography (VCUG) to evaluate the anterior and posterior urethra, respectively. While this is most commonly performed fluoroscopically, sonographic urethrography is an alternative, although at the expense of the posterior urethra, it is only visualized using a transrectal approach. In addition to understand urethral anatomy, familiarity with normal periurethral structures is necessary to avoid misdiagnosis, such as Cowper's ducts, the glands of Littré, and the prostatic and ejaculatory ducts. Surgical management depends on the stricture location, length, and number and options range from balloon dilatation to endoscopic urethrotomy to anastomotic and substitution urethrotomy. Postprocedural management includes urethrography to identify potential complications including urethral leak, graft failure, and stricture recurrence.

Biliary excretion of gadobenate dimeglumine causing degradation of magnetic resonance cholangiopancreatography (MRCP).

PURPOSE: To assess the effect of gadobenate dimeglumine on magnetic resonance cholangiopancreatography (MRCP) and determine an appropriate time frame for performing MRCP sequences. MATERIALS AND METHODS: 2D MRCP sequences obtained after intravenous administration of gadobenate dimeglumine or gadobutrol over 14 months were reviewed retrospectively in randomized order by five abdominal radiologists, using a 3-point scale to rate biliary and pancreatic duct clarity (1 = no-, 2 = limited-, 3 = good visualization). Intraclass correlation coefficients were computed and mean scores were compared for both agents. For gadobenate dimeglumine exams, time delays between arterial phase and MRCP acquisition times were analyzed concerning duct clarity. For gadobutrol, only exams with delays ≥ 15 min were included. RESULTS: 134 exams (107 gadobenate dimeglumine, 27 gadobutrol) were included. Moderate reliability for pancreatic duct visualization and excellent reliability for visualization of intrahepatic bile ducts and upper and lower extrahepatic bile ducts were noted. No difference in mean scores was noted for pancreatic duct visualization (p = 0.66). Bile duct segment scores were lower with gadobenate dimeglumine (mean: 2.1-2.6) compared with gadobutrol (mean: 2.8-2.9) (p ≤ 0.006). For gadobenate dimeglumine, visualization scores varied depending on the delay between the arterial phase and MRCP acquisition (p ≤ 0.047). Good visualization for all bile duct segments was noted with delays of 7.2-9.4 min (95% confidence interval; mean 8.3 min). CONCLUSION: Bile duct clarity degraded on MRCP images with an increasing delay following gadobenate dimeglumine injection. 2D MRCP, thus, should be performed within 7.2 min after obtaining the arterial phase sequence to ensure good visualization of the entire biliary system.