Visualization of the Gastric Mechanical Systole Using a New Scintigraphic Technique

Abstract

Using the standard radionuclide gastric emptying test combined with a new data acquisition and processing method, we have been able to visualize the contractions of the stomach and to generate the gastric mechanical systole. After ingestion of a radiolabeled test meal, list mode images of the stomach were acquired at different time intervals for 2 hr and processed to generate distal stomach time-activity curves. A curve-peak finding algorithm was applied to each time-activity curve to indicate the start of every gastric cycle. List mode images were re-framed in 20 images per cycle and 20 pseudo-gated images consisting of the sum of the same numbered frame interval in every cycle were generated for each dynamic acquisition set. Fourier analysis of the time-activity curve in each gastric pixel location of the 20 pseudo-gated images allowed for the generation of phase images of the stomach in a color scale. The closed-loop cinematic display of the phase images during a gastric cycle enables one to visualize the progression of the gastric contraction wave, that is, the gastric mechanical systole. Correlations between the antral time-activity curve cycles and gastric contractions were established in five dogs using simultaneous isotopic and serosal electrogastrographic recordings. The patterns of phase distribution and sequential phase changes of the food in the stomach that we have observed noninvasively indicate that the proximal stomach does not undergo phasic contractions, while in the distal stomach contractions originate in mid-corpus and propagate aborrally to the pylorus. The scintigraphic test can be used to noninvasively visualize gastric contractions and to delineate the spatial progression of the gastric electromechanical wave of contraction.