Sincalide-Stimulated Cholescintigraphy: A Retrospective Study and Proposal of a Modified Workflow

Current guidelines for sincalide-stimulated cholescintigraphy (SSC) call for a 60-minute sincalide infusion, and a gallbladder ejection fraction (GBEF) ≥38% is considered normal. In this retrospective study, we hypothesize that most patients reach a normal GBEF by 30 minutes.

Eligible patients had undergone a 60-minute SSC from January to December 2019. The clinical SSC data were previously processed on a Xeleris workstation (GE Healthcare). In subjects with GBEF ≥38% based on standard SSC, the GBEF at 20 minutes and 30 minutes were retrospectively calculated using manual pixel height measurements. Receiving operating characteristic was analyzed to determine the best GBEF cutoff at 30 minutes.

Of 302 subjects, mean age of 46 ± 17 years, 33 (10.9%) showed an abnormal GBEF <38% suggestive of functional gallbladder disorder. In the remaining 269 patients (89.1%) with a normal GBEF, 60.6% and 86.6% reached a normal GBEF at 20 minutes and 30 minutes, respectively. Moreover, a GBEF threshold >29.1% at 30 minutes was associated with a negative predictive value of 99.6%, indicating that a 60-minute SSC was not necessary. The GBEF values were not associated with sex, age, patient symptoms, or type of referral. Manually calculated GBEFs on the time-activity curve showed excellent correlation with the primary values. We propose a modified workflow that splits the 60-minute SSC into two 30-minute image sets to allow for a screening GBEF at 30 minutes. If GBEF is >29.1% at 30 minutes, the second image set may be stopped, and the examination is complete.

The majority of patients (77.2%) undergoing the standard 60-minute SSC reach a normal GBEF already by 30 minutes. The proposed workflow shortens the SCC procedure by 30 minutes, while maintaining high diagnostic accuracy and contributing to improved procedure efficiency and reduced patient discomfort as well as symptoms.