Abstract No. 682 Workup of GI bleeds: nuclear medicine vs. CT angiography

Abstract

With an aging population acute gastrointestinal bleeding (GIB) requiring hospitalization and treatment continues to rise with an incidence of approximately 36/100,0001. The diagnostic imaging gold standard has historically been radionuclide labeled red blood cell scintigraphy (RBC scan) that has been able to detect bleeding rates as low as 0.1 ml/min2. However, RBC scans have several shortcomings such as preparation and scan time, technologist and equipment availability, and the requirement for relative hemodynamic stability for an extended time period. Additionally, RBC scans cannot identify other mimickers of GIB or provide anatomic detail. Given these limitations, our institution has begun employing triple phase CT angiography (CTA) as the initial, preferred diagnostic test for GIB, thought to have a minimum detectable bleeding rate of 0.35 ml/min3. Our institutional CTA GIB protocol requires no special patient preparation. Scanning is performed through the abdomen and pelvis starting with a non-contrast phase, followed by an arterial phase and finally a five-minute delay scan. As many of these GIB patients are critically ill and trend towards being hemodynamically unstable, the increased availability offered by CT scan is paramount for rapid treatment stratification. Since January 2017, over an 8-month time period, our institution performed a total of 31 RBC scans and 42 CTA GIB scans. The mean turnaround time from test initiation to release of a completed report was 208 minutes for RBC scans and 48 minutes for CTA GIB scans. RBC scans resulted in 38.7% (12/31) positive cases with six going onto catheter directed angiography. Conversely, 23.8% (10/42) of CTA GIB scans were positive and five proceeded to the interventional suite. RBC scans have been part of the diagnostic armamentarium since the 1970s and will continue to have a role in GIB management. However, given the tenuous clinical status of these patients, the speed, accuracy, and ubiquity of CTA will continue to grow. RBC scans and CTA GIB had the same rate (50%) of patients going onto mesenteric angiography. However, our results show that CTA’s reduced turnaround time to definitive therapy greatly impr