Creating a Sustainable Foundation for Interventional Radiology Services and Training in Sub-Saharan Africa: Five-Year Update on the Road2IR Initiative.

PURPOSE: To evaluate the growth and quality of an IR training model designed for resource-constrained settings and implemented in Tanzania, as well as its overall potential to increase access to minimally invasive procedures across the region. MATERIALS AND METHODS: IR training in Tanzania began in 10/2018 through monthly deployment of visiting teaching teams for hands-on training combined with in-person and remote lectures. A competency-based two-year Master of Science (MSc) in IR curriculum was inaugurated at the nation's main teaching hospital in 10/2019, graduating its first two classes in 2021 and 2022. Procedural data, demographics, and clinical outcomes were collected and analyzed throughout the duration of this program. RESULTS: From 10/2018 to 7/2022, 1,595 procedures were performed in Tanzania: 1,236 non-vascular and 359 vascular, all with local fellows as primary operators. 97.2% were technically successful, 95.2% were without complication, and 28.9% were performed independently by Tanzanian fellows and faculty with no difference in complication and technical success rates (p=0.63 and 0.90, respectively), irrespective of procedural class. Ten IR physicians graduated from this program during the study period, followed by another three per year going forward. Partner training programs in Uganda and Rwanda mirroring this model commenced in 2023 and 2024, respectively. CONCLUSION: The reported training model offers a practical and effective solution to meet many of the challenges associated with the lack of access to IR in sub-Saharan Africa.

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.

Percutaneous CT-Guided Cryoablation for Locally Recurrent Prostate Cancer: Technical Feasibility, Safety, and Effectiveness.

PURPOSE: To assess the feasibility and safety of using computed tomography (CT) guidance for ablation of prostate cancer in the salvage setting. MATERIALS AND METHODS: This institutional review board-approved retrospective study of consecutive patients who presented with prostate cancer recurrence and underwent percutaneous CT-guided cryoablation was conducted between July 2020 and September 2022. A total of 18 patients met the inclusion criteria, and a total of 19 procedures were performed. Demographic details; preablation and postablation urinary, rectal, and erectile function assessment; procedure details; and preoperative and postoperative imaging findings and prostate-specific antigen (PSA) values were recorded. RESULTS: The mean treated tumor size was 15.7 mm ± 6.2. Technical success was achieved in 18 of the 19 procedures (94.7%), with 1 procedure aborted due to inability to obtain a safe plane. The mean follow-up time was 10.0 months (range, 2.3-26.7 months) at the time of manuscript preparation. The mean PSA before ablation was 8.1 ng/mL ± 9.3, and postablation PSA nadir was 2.6 ng/mL ± 4.0 (P = .002). Of the 18 patients who had postoperative imaging, 16 (88.9%) had a complete response (ie, no evidence of residual disease), and 2 (11.1%) patients had residual disease. Overall, 16 (88.9%) of the 18 treated patients demonstrated a PSA and/or imaging response to ablation. Mild adverse events occurred in 4 (22%) of the 18 cases. CONCLUSIONS: CT-guided cryoablation appears to be a technically feasible, safe option for treating locally recurrent prostate cancer.

Image-Guided Prostate Cryoablation: State-of-the-Art.

Image-guided focal therapy has increased in popularity as a treatment option for patients with primary and locally recurrent prostate cancer. This review will cover the basic indications, evaluation, treatment algorithm, and follow-up for patients undergoing image-guided ablation of the prostate. Additionally, this paper will serve as an overview of some technical approaches to cases so that physicians can familiarize themselves with working in this space. While the focus of this paper is prostate cryoablation, readers will obtain a basic literature overview of some of the additional available image-guided treatment modalities for focal prostate therapy.

Assessment of Required Patient Travel to Receive Interventional Radiology Services in the Resource-Limited Setting of Tanzania.

This study aimed to evaluate the geographic patient profile of a country's first interventional radiology (IR) service in sub-Saharan Africa. From October 2018 to August 2022, travel time (1,339 patients) and home region (1,184 patients) were recorded from 1,434 patients who underwent IR procedures at Tanzania's largest referral center. Distances traveled by road were calculated from the administrative capital of each region using a web mapping platform (google.com/maps). The effect of various factors on distance and time traveled were assessed. Patients from all 31 regions in Tanzania underwent IR procedures. The mean and maximum calculated distance traveled by patients were 241.6 km and 1,387 km, respectively (Sk2 = 1.66); 25.0% of patients traveled for over 6 hours for their procedure. Patients traveled furthest for genitourinary procedures (mean = 293.4 km) and least for angioplasty and stent placement (mean = 123.9 km) (P < .001). To increase population access and reduce travel times, geographic data should be used to decentralize services.

Uterine artery embolization in Tanzania: a procedure with major public health implications.

BACKGROUND: The burden of uterine fibroids is substantial in sub-Saharan Africa (SSA), with up to 80% of black women harboring them in their lifetime. While uterine artery embolization (UAE) has emerged as an effective alternative to surgery to manage this condition, the procedure is not available to the vast majority of women living in SSA due to limited access to interventional radiology (IR) in the region. One of the few countries in SSA now offering UAE in a public hospital setting is Tanzania. This study aims to assess the safety and effectiveness of UAE in this new environment. METHODS: From June 2019 to July 2022, a single-center, retrospective cohort study was conducted at Tanzania's first IR service on all patients who underwent UAE for the management of symptomatic fibroids or adenomyosis. Patients were selected for the procedure based on symptom severity, imaging findings, and medical management failure. Procedural technical success and adverse events were recorded for all UAEs. Self-reported symptom severity and volumetric response on imaging were compared between baseline and six-months post-procedure using paired sample t-tests. RESULTS: During the study period, 92.1% (n = 35/38) of patients underwent UAE for the management of symptomatic fibroids and 7.9% (n = 3/38) for adenomyosis. All (n = 38/38) were considered technically successful and one minor adverse event occurred (2.7%). Self-reported symptom-severity scores at six-months post-procedure decreased in all categories: abnormal uterine bleeding from 8.8 to 3.1 (-5.7), pain from 6.7 to 3.2 (-3.5), and bulk symptoms from 2.8 to 1 (-1.8) (p < 0.01). 100% of patients reported satisfaction with outcomes. Among the nine patients with follow-up imaging, there was a mean volumetric decrease of 35.5% (p = 0.109). CONCLUSIONS: UAE for fibroids and adenomyosis can be performed with high technical success and low complication rates in a low-resource setting like Tanzania, resulting in significant symptom relief for patients. Building capacity for UAE has major public health implications not only for fibroids and adenomyosis, but can help address the region's leading cause of maternal mortality, postpartum hemorrhage.

Comparative Analysis of Percutaneous Drainage versus Operative Drainage of Intra-Abdominal Abscesses in a Resource-Limited Setting: The Tanzanian Experience.

Background: Intra-abdominal abscesses (IAAs) are a major cause of morbidity and mortality worldwide. While image-guided percutaneous abscess drainage (PAD) has become the standard of care in many countries, over half of the global population does not have access to interventional radiology (IR) and are left with surgery as the only option for source control. Objective: The purpose of this study is to evaluate the development, implementation, and role of a PAD service in a resource-limited setting. Method: A retrospective cohort study was performed on all patients who underwent percutaneous or surgical abscess drainage (SAD) of IAAs at Tanzania's national referral hospital from 10/2018 to 4/2021. Patients were identified through a match case search of institutional records and inclusion was confirmed through manual chart review. Demographics, patient presentation, procedural data, and clinical outcomes were recorded in a password-encrypted database and compared between groups. Findings: Sixty-three patients underwent abscess drainage: 32 percutaneously and 31 surgically. In the PAD group, there was a 100% technical success rate and a 0% complication rate. In the SAD group, there was a 64.5% technical success rate and ten deaths within 30 days (32.3%), and one additional complication requiring major therapy (3.2%) (p < 0.001). Conclusion: Results from this study demonstrate that PAD can be performed with high technical success and without complication by trained IR physicians in Tanzania. The development of a successful PAD program exemplifies the drastic need to support the growth of IR services in this setting.

Interventional Approach to Portal Vein Thrombosis and Liver Transplantation: State of the Art.

Porto-mesenteric vein thrombosis (PVT) is a well-recognized but uncommon disease entity in patients with and without cirrhosis. Given the complexity of these patients, there are many differing treatment algorithms depending on the individual circumstances of a given patient. The focus of this review is primarily patients with cirrhosis, with an emphasis on liver transplantation considerations. The presence of cirrhosis substantially affects work-up, prognosis, and management of these patients and will substantially affect the patient treatment and have additional implications for prognosis and long-term outcomes. Here, we review the incidence of portal vein thrombosis in known cirrhotic patients, medical and interventional treatment options that are currently used, and, in particular, how to approach cirrhotic patients with PVT who are awaiting liver transplantation.

Evaluation of an Artificial Intelligence Chatbot for Delivery of IR Patient Education Material: A Comparison with Societal Website Content.

PURPOSE: To assess the accuracy, completeness, and readability of patient educational material produced by a machine learning model and compare the output to that provided by a societal website. MATERIALS AND METHODS: Content from the Society of Interventional Radiology Patient Center website was retrieved, categorized, and organized into discrete questions. These questions were entered into the ChatGPT platform, and the output was analyzed for word and sentence counts, readability using multiple validated scales, factual correctness, and suitability for patient education using the Patient Education Materials Assessment Tool for Printable Materials (PEMAT-P) instrument. RESULTS: A total of 21,154 words were analyzed, including 7,917 words from the website and 13,377 words representing the total output of the ChatGPT platform across 22 text passages. Compared to the societal website, output from the ChatGPT platform was longer and more difficult to read on 4 of 5 readability scales. The ChatGPT output was incorrect for 12 (11.5%) of 104 questions. When reviewed using the PEMAT-P tool, the ChatGPT content scored lower than the website material. Content from both the website and ChatGPT were significantly above the recommended fifth or sixth grade level for patient education, with a mean Flesch-Kincaid grade level of 11.1 (±1.3) for the website and 11.9 (±1.6) for the ChatGPT content. CONCLUSIONS: The ChatGPT platform may produce incomplete or inaccurate patient educational content, and providers should be familiar with the limitations of the system in its current form. Opportunities may exist to fine-tune existing large language models, which could be optimized for the delivery of patient educational content.

Transjugular Intrahepatic Portosystemic Shunt and Thrombectomy (TIPS-Thrombectomy) for Symptomatic Acute Noncirrhotic Portal Vein Thrombosis.

PURPOSE: To report the safety and effectiveness of transjugular intrahepatic portosystemic shunt and mechanical thrombectomy (TIPS-thrombectomy) for symptomatic acute noncirrhotic portal vein thrombosis (NC-PVT). MATERIALS AND METHODS: Patients with acute NC-PVT who underwent TIPS-thrombectomy between 2014 and 2021 at a single academic medical center were retrospectively reviewed. Thirty-two patients were included (men, 56%; median age, 51 years [range, 39-62 years]). The causes for PVT included idiopathic (n = 12), prothrombotic disorders (n = 11), postsurgical sequelae (n = 6), pancreatitis (n = 2), and Budd-Chiari syndrome (n = 1). The indications for TIPS-thrombectomy included refractory abdominal pain (n = 14), intestinal venous ischemia (n = 9), ascites (n = 4), high-risk varices (n = 3), and variceal bleeding (n = 2). Variables studied included patient, disease, and procedure characteristics. Patients were monitored over the course of 1-year follow-up. RESULTS: Successful recanalization of occluded portal venous vessels occurred in all 32 patients (100%). Compared with pretreatment patency, recanalization with TIPS-thrombectomy resulted in an increase in patent veins (main portal vein [28% vs 97%, P < .001], superior mesenteric vein [13% vs 94%, P < .001], and splenic vein [66% vs 91%, P < .001]). Three procedure-related adverse events occurred (Society of Interventional Radiology grade 2 moderate). Hepatic encephalopathy developed in 1 (3%) of 32 patients after TIPS placement. At 1-year follow-up, return of symptoms occurred in 3 (9%) of 32 patients: (a) ascites (n = 1), (b) variceal bleeding (n = 1), and (c) intestinal venous ischemia (n = 1). The intention-to-treat 1-year portal vein and TIPS primary and secondary patency rates were 78% (25/32) and 100% (32/32), respectively. Seven patients required additional procedures, and the 1-year mortality rate was 3% (1/32). CONCLUSIONS: TIPS-thrombectomy is a safe and effective method for treating patients with symptomatic acute NC-PVT.

Technical Feasibility of Suction Thrombectomy Using a Large-Bore Aspiration System in the Portomesenteric Venous System.

PURPOSE: To assess technical feasibility and safety of portal vein thrombectomy with suction thrombectomy using a large-bore thrombectomy device for portomesenteric venous thrombosis (PMVT). MATERIALS AND METHODS: After receiving approval from institutional review board, patients undergoing PMVT treatment using a large-bore aspiration thrombectomy device (Inari FlowTriever or ClotTriever) between July 2019 and June 2021 were identified at 2 medical centers. Charts were reviewed for demographic information, imaging findings, and procedural details. PMVT was categorized using the Yerdel grading system. The thrombectomy procedure was performed via transjugular access through the existing or a new transjugular intrahepatic portosystemic shunt (TIPS) or transsplenic or transhepatic approach. Technical success was defined as successful clot reduction and restoration of portal venous flow at the conclusion of the procedure. Patient outcomes based on clinical presentation, adverse events, and thrombectomy-associated adverse events were recorded. RESULTS: Twenty patients, with a median age of 58 years (range, 23-72 years), underwent large-bore aspiration thrombectomy, which was technically successful in 19 of 20 (95%) patients. In 9 of 20 (45%) patients, 9 of 20 (45%) patients, and 2 of 20 (10%) patients, the 20-F, 16-F, and 24-F devices were used, respectively. Fourteen patients had a pre-existing TIPS, and 6 patients had a TIPS created. In 5 of 20 (25%) patients, overnight lysis was performed in conjunction with Inari thrombectomy. Thrombus resolution with restoration of flow was achieved in 19 of 20 (95%) cases. There were no thrombectomy-associated adverse events. The mean follow-up time was 70 days (±113) at which time primary patency of the portal venous system was present in 16 of 20 (80%) patients. CONCLUSIONS: Large-bore aspiration portal vein thrombectomy is feasible for PMVT.

Filter-Assisted Shunt Embolization of Large Portosystemic Shunts: Technical Feasibility, Safety, and Outcomes.

PURPOSE: To describe the feasibility and outcomes of filter-assisted shunt embolization in patients with acquired large portosystemic shunts. METHODS: Two-center HIPAA compliant retrospective study of all patients who underwent filter-assisted shunt embolization between 03/2015-03/2021. Initial clinical evaluation, including demographic information, shunt sizing, and procedural details, was reviewed. Technical success was defined as successful occlusion of the targeted shunt. RESULTS: Eight patients (55 ± 10 years/88% male) had a large acquired portosystemic shunt which was suitable for filter-assisted shunt embolization. Indications for the procedure: 3 = pre-transplantation optimization, 2 = overt hepatic encephalopathy (HE), 1 = post-transplant thrombosis, 1 = portal vein thrombosis and encephalopathy, 1 = encephalopathy and variceal bleeding. Portosystemic shunts occurred between splenic and renal veins, inferior mesenteric and gonadal veins, and coronary veins. Mean shunt diameter was 27 ± 5 mm. The technical success of the procedure was 8/8 (100%). In 7 patients, a transjugular intrahepatic portosystemic shunt (TIPS) was also placed at the time of the shunt embolization due to either pre-transplant indication or sluggish portal flow. There were no intraprocedural complications from filter placement. OUTCOMES: 3 = currently listed for transplant, 2 = resolution of HE, 1 = made CMO, 1 patient with patent post-transplant vasculature. 1 = died as a complication related to TIPS placement (SIR Class F Complication). CONCLUSION: Filter-assisted shunt embolization is a technically feasible and safe technique to reduce or embolize large portosystemic shunts.

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.

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.

Safety and Feasibility of Percutaneous Gastrostomy Placement in Patients on Antiplatelet Therapy.

Background: Guidelines recommend the discontinuation of clopidogrel prior to gastrostomy tube placement. The aim of this study was to examine the safety and feasibility of performing radiologically inserted gastrostomy (RIG) tube placement in patients taking clopidogrel and/or aspirin. Methods: We performed an institutional review board-approved retrospective analysis of the medical records for 237 consecutive patients following RIG tube placement secondary to dysphagia from August 2017 to January 2019. Antiplatelet medications and RIG type placement techniques (push vs pull) were compared with bleeding complications. Complications were categorized based on the Society of Interventional Radiology clinical practice guidelines. Of the 237 patients with RIG tubes placed, 77 patients were on antiplatelet therapy: 55 on single antiplatelet therapy and 22 on dual antiplatelet therapy. Of the 55 patients on single antiplatelet therapy, 26 were taking clopidogrel and 29 were taking aspirin. Results: A total of 9 bleeding complications were observed. The most common complication was minimal bleeding or hematoma around the incision site (n=7). No statistically significant increase was seen in bleeding rates when comparing patients on any antiplatelet therapy regimen vs none (P=0.15), single antiplatelet therapy vs none (P=0.13), clopidogrel vs none (P=0.71), or dual antiplatelet therapy vs none (P=0.61). No significant increase in the bleeding complication rate was noted when comparing the aspirin-only regimen vs clopidogrel alone (P=0.34). Conclusion: These findings suggest that the risk of bleeding complications is not increased in patients taking clopidogrel and/or aspirin prior to RIG tube placement.

Clinical and laboratory parameters in blunt pelvic trauma not associated with subsequent positive conventional angiography in patients with positive CTA.

PURPOSE: This study evaluates clinical and laboratory parameters, as well as extravasation and hematoma size on CTA as potential predictors of conventional angiogram (CA) results. METHODS: This is a retrospective study of 380 adult patients presenting with pelvic trauma over a 9-year period. Of these patients, 91 were found to have active arterial extravasation on initial CTA. Statistical analysis between the two groups +CA versus -CA was performed to determine whether clinical and laboratory parameters, as well as extravasation size and hematoma size could predict CA results. RESULTS: There were no significant differences in all clinical and laboratory data, including hemodynamic instability (defined as systolic blood pressure < 90 mmHg) on presentation (22.2% vs. 21.4%), except for Glasgow Coma Scale (p = 0.015) when comparing the two groups. Extravasation size and hematoma size as continuous or categorical variables were not predictive of subsequent positive CA. Secondary analysis demonstrated no association between select parameters (i.e., hematocrit, systolic blood pressure, and lactate) and subsequent positive CA while controlling for extravasation size or hematoma size. CONCLUSION: Clinical and laboratory parameters in blunt pelvic trauma with arterial hemorrhage were not significantly associated with subsequent conventional angiography results, once accounting for degree of hemorrhage. The area of the foci of active extravasation and hematoma size in the axial plane were not significantly associated with the need for embolization. We conclude from these findings that catheter angiography should be considered in patients with blunt pelvic trauma found to have active arterial extravasation, regardless of size of bleed or the patient's clinical or laboratory values.

A Comparative Study Between Septal Quilting Sutures Without Nasal Packing and Only Nasal Packing Post-septal Correction.

Septal correction is the commonest surgery by rhinologists worldwide. We aimed at studying the comfort level of the patient with standard postoperative nasal packing with Merocel and placing quilting sutures in septum leaving the nose unpacked in the postoperative period. We conducted the study in the tertiary care centre enrolling 82 patients in a quasi-randomised method of odd and even numbers placing them in the nasal packing group and the quilting group respectively. We used analogue scoring method for subjective assessment of comfort level in the postoperative period and the surgeon objectively assessed the patient on follow up. The results were tabulated and analysed. Postoperative pain, headache and sleep disturbance was significantly more in the nasal packing group. We found that the crusting is commonly seen in patients in the nasal packing group. Quilting the nasal septum and leaving the nasal cavity unpacked increases the comfort level of the patient in the postoperative period. The resultant pain, headache and sleep disturbance caused by nasal packing can be significantly avoided by using quilting the septum without nasal packing. We also observed that by avoiding nasal packing postoperatively, the patients were more comfortable and compliant with the treatment regimen and follow-up.

CTA measurements of acute lower gastrointestinal bleeding size predict subsequent positive catheter angiography.

PURPOSE: The purpose of this study was to determine whether the measured size of active gastrointestinal hemorrhage was useful in predicting subsequent positive findings at catheter angiography. MATERIALS AND METHODS: This was a single-institution retrospective study consisting of 32 patients with computed tomography angiography (CTA) positive for gastrointestinal bleeding who went on to receive catheter angiography. Each CTA was reviewed, with axial measurements of the anterior-posterior and transverse dimensions of the largest foci of hemorrhage recorded. Volumetric analysis was used to measure the volume of hemorrhage. These measurements were performed for both the arterial and portal venous phases. Additionally, the interval growth between the arterial and portal venous phase was also calculated. RESULTS: There was a statistically significant difference in the absolute size of the maximum transverse dimension on portal venous phase imaging (mean = 19.8 mm, p < 0.001), as well as an interval increase in transverse (mean = 8.5 mm, p < 0.001) and anteriorposterior (mean = 5.4 mm, p = 0.027) size between arterial and portal venous phases in patients with positive catheter angiography versus negative catheter angiography. There was a statistically significant difference in the volume of hemorrhage on arterial (mean = 1.72 cm3, p = 0.020) and portal venous phases (mean = 5.89 cm3, p = 0.016), as well as an interval change in the size of hemorrhage between the two phases (mean = 4.17 cm3, p = 0.020) in patients with positive catheter angiography versus patients in the negative catheter angiography group. CONCLUSIONS: The absolute axial size and volume of hemorrhage, as well as the interval change between the arterial and portal venous phases of CTA imaging is predictive of subsequent positive catheter angiography.