Regional gastric emptying scintigraphy reveals a spectrum of normal through delayed fundal emptying in patients with moderate gastroparesis

1209 Objectives: Gastric emptying scintigraphy (GES) is used to quantify overall gastric emptying in patients with dyspeptic symptoms including nausea, vomiting, post-prandial fullness, and early satiety. The contribution of regional abnormalities to disorders of gastric motility is not routinely assessed by scintigraphy. We analyzed fundal and whole-stomach gastric emptying in patients with moderately-delayed gastric emptying on standard GES. A cohort of patients with normal gastric emptying on standard GES was used to define normal fundal and whole-stomach emptying values which were then used to analyze the gastroparesis (GP) group. Defining subgroups of patients with GP may be instrumental in tailoring therapies to fit specific mechanisms of dysfunction. Methods: IRB approval was obtained. By review of nuclear medicine reports, we retrospectively identified a convenience sample of 40 patients who underwent standard GES which demonstrated moderately-delayed gastric emptying (gastric retention of 15-35% at 4-hrs). 25 patients were selected with normal emptying at GES by SNMMI guidelines. Using a commercial software package, a ‘fundal’ ROI was assigned by visually bifurcating the stomach in equal portions. Clearance from the fundal and entire ROIs was modeled by fitting an exponential curve to the geometric mean of decay- and background-corrected counts (Excel, version 2011, Microsoft Corporation) and deriving fundal and entire stomach clearance T½s. Normal values for fundal and whole-stomach emptying were developed based on measurement of the normal cohort and applied to the GP cohort. Results: Normal half-times of emptying (hours) were 0.81 ± 0.36 for whole stomach and 0.64 ± 0.35 for the fundus. In the GP group, the average whole-stomach (2.67 ± 0.83) and fundal (1.61 ± 0.88) half-times (hours) were significantly greater (Table) (p<<0.001). Based on an upper value of 1.53 hour for whole stomach and 1.34 hour for fundus, 1 (2.5%) of the 40 GP patients demonstrated normal whole stomach emptying rates while fully 17 (42%) of patients with GP had normal T½ fundal emptying. Discussions/Conclusions: There is regional information inherent in GES beyond a unidimensional value of total gastric emptying which we have exploited in our analysis of fundal vs. whole-gastric emptying. This can be used to develop an improved understanding of the underlying pathophysiology of gastric dysfunction. Over 40% of GP patients demonstrated normal fundal emptying in spite of abnormally-delayed whole-stomach emptying, suggesting a pyloric rather than generalized motility disorder. Our findings strengthen the relevance of regional motility measurements with implications for choosing optimal therapy in differing subsets of patients and demonstrates the role that scintigraphy can play in defining patient groups.