THE UTILITY OF ADDING A LIQUID NUTRIENT MEAL TO AID INTERPRETATION OF SMALL BOWEL TRANSIT SCINTIGRAPHY

Abstract

Small bowel transit scintigraphy (SBTS) evaluates the accumulation of a radiolabeled meal in the terminal ileal reservoir (TIR) 6 hours after meal ingestion. The TIR may be difficult to determine as anatomic information is limited; for equivocal studies, the patient is asked to return the next day to help determine the TIR location by potential transit into the colon. The purpose of this study was to evaluate whether a liquid nutrient meal (LNM) at 6 hours can promote movement of the radiolabeled meal to aid in the interpretation of SBTS. Methods: This retrospective study reviewed 117 SBTS from 2/2017 to 9/2019. Patients were fed a standardized mixed radiolabeled solid- liquid meal for gastric emptying with SBTS according to SNMMI Practice Guidelines. Additional LNM was given at 6 hr, and post-LNM images were obtained at least 20 minutes after the LNM. Two board-certified nuclear medicine physicians independently evaluated all images at 6 hours as equivocal or diagnostic. Results: Of the 117 patients (71.8% female, median age 42.0) undergoing SBTS, 37 were equivocal cases at 6 hours pre-LNM (31.6%, 95% CI=23.3%-40.9%) compared to 12 equivocal cases post-LNM (10.3%, 95% CI=5.4%-17.2%). Of the equivocal cases, 25 (69.4%, 95% CI=51.9%-83.7%) had a definitive result after LNM administration while 11 (30.6%, 95% CI=16.4%-48.1%) remained equivocal, and 1 showed rapid transit. In patients with gastroparesis, only 13/23 (57%) responded to LMN, while 0/3 IBS patients responded. Conclusion: The number of equivocal SBTS cases decreased after administration of a LNM at 6 hours, converting to a definitive result. This suggests that with use of a LNM a majority of patients can complete SBTS in one day without the need for repeat imaging at 24 hours. Administering a LNM appears to be less effective for patients with gastric disorders. However, the clinical significance remains to be explored and it is unclear if these patients have both a gastric and small bowel disorder, hence reducing any motility-promoting effect of the LNM.