A Novel Technique to Measure the Intensity of Abnormality on GI Bleeding Scans: Development, Initial Implementation, and Correlation With Conventional Angiography.

PURPOSE: Develop a technique to quantify intensity of lower gastrointestinal bleeding (LGIB) on Tc-labeled red blood cell (RBC) scintigraphy, correlate with angiography, and determine the tool's predictive value.

MATERIALS AND METHODS: An IRB-approved, single institution database query of GI bleeding scans performed between January 2013 and December 2015. Reports from all studies and imaging from all positive studies were reviewed. A technique was developed for scan analysis, allowing for calculation of percent increase of activity in the region of interest (ROI, area of bleeding) and ROI in the aorta and liver (controls). Database query determined which patients underwent angiography, and which had positive angiograms. Median ROI percent increase in patients with positive scintigraphy and positive angiography was compared to those with positive scintigraphy and negative angiography.

RESULTS: Of 194 bleeding scans performed during the study period, 71 were positive for active LGIB, 37 had angiography, and 9 had active contrast extravasation. The new tool was used to analyze the 37 cases with positive nuclear scans sent for angiography. Median percent increase in ROI activity was 50% in those with positive scan and positive angiogram and 26.8% in those with positive scan but negative angiogram. Using ROI percent change quartiles, we observed a statistically significant association between percent increase in ROI activity from baseline and the probability of having a positive angiogram (Cochran-Armitage trend test, P = 0.01), such that there are no positive angiogram cases when ROI change was <20% and a majority of the positive angiogram cases (67%) in the highest quartile.

CONCLUSIONS: Utilization of processing protocol to determine percent increase in activity from baseline within ROI of active LGIB on scintigraphy has predictive value in determining which patients will not benefit from conventional angiography.