Minimizing liver, bowel, and gastric activity in myocardial perfusion SPECT.

UNLABELLED: When using 99mTc-tetrofosmin for myocardial perfusion SPECT, increased liver, intestinal, or gastric activity may create a major problem in the visual and quantitative interpretation Of the inferoposteroseptal walls, particularly at rest. The aim of this study was to determine what measures were required to minimize this extracardial activity. METHODS: Ninety-seven patients had a SPECT scan at rest without attenuation correction. They were divided into 3 groups. Preparation consisted of no action taken (group 1), 150 mL whole milk 10 min after administration of tetrofosmin (group 2), or 450 mL water 10 min before acquisition (group 3). A further 55 patients had a SPECT scan at rest with attenuation correction. They were also divided into 3 groups, and preparation consisted of 150 mL whole milk 10 min after administration of tetrofosmin (group 4), 450 mL water 10 min before acquisition (group 5), or both whole milk and water (group 6). The presence of activity in liver, bowel, and stomach was determined visually on reconstructed images. Activity was defined as interfering when it might result in either an underestimation or an overestimation of the uptake in the myocardial wall. RESULTS: Interfering activity was seen in 83% of the patients in group 1, in 74% in group 2, in 33% in group 3, in 61% in group 4, in 67% in group 5, and in 20% of group 6. CONCLUSION: The interpretation of inferoposteroseptal wall activity on myocardial rest SPECT images is facilitated by having the patient drink both whole milk and water at specified times before data acquisition.