The volume effect of the stomach on intestinal activity on same-day exercise--rest Tc-99m tetrofosmin myocardial...

The aim of this study was to investigate quantitatively the volume effect of the stomach on the prevention of intestinal artifacts in the rest phase on same-day exercise--rest Tc-99m tetrofosmin myocardial perfusion scintigraphy.

The study was performed in 81 consecutive patients (43 men, 38 women; mean age, 57 +/- 9 years) who were referred for routine Tc-99m tetrofosmin exercise--rest SPECT myocardial perfusion imaging with normal scintigrams or completely normal inferior wall perfusion on visual assessment of SPECT images. Group A (control group, n = 41) and group B (n = 40) were given 200 ml milk to enhance the hepatobiliary clearance of tetrofosmin 30 minutes before the exercise SPECT acquisition study and just after the injection for the rest SPECT acquisition study. For the rest SPECT acquisition study, patients in group B were given, in addition to milk, a standard solid and fluid meal to enhance the volume of the stomach after the injection of Tc-99m tetrofosmin. In all patients, both exercise and rest SPECT acquisitions were started 45 minutes after the injection of Tc-99m tetrofosmin. Myocardial and abdominal activity were assessed on three separate views in the rest phase of the study, and the mean myocardium-to-abdomen count ratios were calculated. In addition, the presence of interfering intestinal activity was assessed visually on SPECT images. Infracardiac activity was described as absent when it was equal to lung background.

The myocardial-to-abdominal ratios were 1.38 +/- 0.05 and 1.95 +/- 0.04 in groups A and B, respectively (P < 0.0001). Interfering intestinal activity with varying degrees of intensity was seen in 20 patients in group A (49%) and in 5 patients in group B (13%; P < 0.001).

These results suggest that filling of the stomach with some fluid and solid food before rest acquisition on the same-day stress--rest protocol, because of its volume effect, may provide a high target-to-nontarget ratio for myocardial imaging and thus may reduce the frequency of intestinal artifacts.