Abstract
Rationale: Dynamic antral contraction scintigraphy (DACS) has been used to evaluate for gastric dysmotility by measuring antral frequency and ejection fraction (EF). Fourier phase image analysis has the potential to assess gastric antral contractions for dyssynchrony as has been used for analyzing nuclear cardiology ventriculography(MUGA studies) for cardiac dyssynchrony. The aims of this study were to determine: 1) If Fourier phase analysis helps to characterize antral motility physiology; 2) If Fourier phase analysis correlates with conventional gastric emptying (GE); and 3) Which DACS parameters may aid in diagnosing gastric dysmotility, particularly delayed GE. Methods: DACS and GE studies of normal volunteers(n = 22) were compared to patients (n = 99) with symptoms of gastroparesis. New DACS Fourier phase analysis software was developed. Results: GE was delayed(n = 53) and normal(n = 46) in patients. There was a linear correlation of %Total of Proximal(P) and Distal(D) in-phase antral pixels @30 min(r = 0.37, P = 0.0001) and 60 min (r = 0.26, P = 0.007) with GE T1/2. In normals, the mean ratio P/D in-phase antral pixels increased from 1.67(30 min) to 2.65(120 min)(P = 0.035) and EF from 23%(30 min) to 32%(120 min)(P = 0.022). Multivariable regressions of %Total PD in-phase antral pixels (30 min) and EF(60 min) were best predictors of abnormal GE(adjusted odds ratio(95% CI):3.30(1.21, 9.00);2.97(1.08, 8.21)) respectively. Conclusion: This study used Fourier phase analysis to analyze DACS in normal subjects and patients with symptoms of gastroparesis. In addition to establishing normal values, new physiologic information on antral motility was obtained. In normal subjects, there is an increasing ratio of Proximal/Distal in-phase antral pixels and antral EF over time following meal ingestion. The % Total Proximal and Distal in-phase antral pixels at both 30 and 60 minutes had good correlation with T1/2 GE values. For symptomatic patients, the % Total Proximal and Distal in-phase antral pixels at 30 min and the EF at 60 min post meal ingestion correlated with delayed conventional GE. Thus, Fourier phase analysis of DACS appears to have potential to further aid in diagnosing gastric dysmotility in GE scintigraphy studies.
