抄録
Backgrounds: Myocardial single-photon emission computerized tomography (SPECT) with the patient in the prone position has recently been applied to improve the percentage uptake (%uptake) in the inferior wall by reducing diaphragmatic attenuation. We hypothesized that the type of stress might cause a difference in the %uptake improvement in inferior regions in the prone position. The purpose of this study was to compare the %uptake improvement between exercise and pharmacological vasodilator stress in prone myocardial SPECT.
Methods: Following a SPECT study in the supine position, a second SPECT study was performed in the prone position. The cases of 41 patients were studied prospectively: 21 patients with pharmacological stress and 20 with exercise stress. A segmental %uptake based on the quantification of a polar map was used. Liver and heart average counts were measured with a supine planar image. The correlation between the liver-to-heart ratio and the %uptake increase in the inferior wall was then examined.
Results: Pharmacological stress showed a significantly higher average %uptake increase in the inferior wall compared to exercise stress (5.59±2.86% vs. 3.18±1.84%, p<0.05). The average liver-to-heart ratio was significantly higher in pharmacological than in exercise stress (1.04±0.40% vs. 0.72±0.22%, p<0.01). As the liver-to-heart ratio increased, the %uptake increase in the inferior wall increased (y=5.54x -0.51, r=0.74; p<0.05).
Conclusions: Pharmacological stress in the prone position showed greater increase in the %uptake in the inferior wall compared to the exercise-stress patients, mainly due to the higher liver uptake in the former group.
