THE VEX-TEST FOR MYOCARDIAL SCINTIGRAPHY WITH TL-201 AND SESTAMIBI - EFFECT ON ABDOMINAL BACKGROUND ACTIVITY

High abdominal background activity of Tc-99m-sestamibi may interfere w ith the diagnosis in studies in which a coronary vasodilator is used; supplemental dynamic exercise might reduce this problem. Methods: Clin ical and angiographic determinants of subdiaphragmatic-to-myocardial a ctivity ratios were measured on immediate poststress left anterior obl ique images and on corresponding tomographic studies 1 hr after inject ion in 600 sestamibi studies. Similar measurements were made in 550 hi storic controls with planar Tl-201 imaging. Patients performed symptom -limited ergometry when there were no limiting factors, dipyridamole-h andgrip in which ergometry was not possible and VEX (vasodilator follo wed by symptom-limited ergometry) in which exercise capacity was reduc ed. Results: Abdominal activity was higher with sestamibi than with Tl -201, in women versus men, and with dipyridamole-based tests compared to exercise alone. Compared to the dipyridamole-handgrip, 3 min of erg ometry as part of VEX decreased abdominal background (p less than or e qual to 0.02) by 18% on immediate Tl-201 images, by 13% on immediate s estamibi images and by 12% on 1-hr delayed sestamibi tomoacquisitions. Conclusion: Poststress abdominal background activity is influenced by similar factors with both agents. Supplemental exercise following dip yridamole reduces potentially interfering abdominal activity but perha ps not as efficiently with sestamibi as with Tl-201.