Optimal Pre-procedural Imaging in Acute Lower Gastrointestinal Bleeding: Computed Tomographic Angiography vs. Nuclear Medicine Bleeding Scan

Purpose Retrospective analysis was performed to assess the diagnostic utility of computed tomographic angiography (CTA) in active lower gastrointestinal bleeding (LGIB) as compared with nuclear medicine bleeding scan (NMBS) to determine the optimal diagnostic imaging modality prior to visceral arteriography (VA).

Materials and Methods From January 2013 through February 2016, 56 patients underwent a total of 64 VA at our institution. Results of CTA and NMBS immediately preceding VA and time interval from the completion of the diagnostic imaging study to the initiation of VA were analyzed. CTA and VA were considered positive if active contrast extravasation or pseudoaneurysm was identified in the gastrointestinal tract distal to the ligament of Treitz. NMBS was considered positive if increased radiotracer pooling was localized in the gastrointestinal tract distal to the ligament of Treitz.

Results Twenty-eight NMBS and 30 CTAs were performed prior to VA. Twenty-seven (96%) out of 28 NMBS were positive. Of the 27 positive NMBS, 4 (15%) patients had a subsequent positive VA. Twenty-eight (93%) out of 30 CTAs were positive. Of the 28 positive CTA, 15 (54%) had a subsequent positive VA. Mean and median times between positive diagnostic study and VA are as follows: NMBS mean 517.59 minutes, median 318 minutes, and CTA mean 188.18 minutes and median 136 minutes with a p-value <0.0006.

Conclusion CTA is a better predictor of subsequent VA findings in evaluation of LGIB as compared with nuclear scintigraphy. Preferable technical and logistical aspects of CTA lead to reduction in time from positive CTA to potentially therapeutic VA.

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