Tc-99m-sestamibi whole-body distribution after stress testing with arbutamine and dipyrimadole: a comparison with resting condition

Aim: Arbutamine is a new catecholamine that has been developed as a pharmacologic stress agent for the diagnosis of coronary artery disease. Optionally, it can be used in myocardial scintigraphy. The pharmacologic effect compared to dipyridamole was assessed looking at the whole body distribution of Tc-99m-Sestamibi. Methods: 9 Patients were investigated after injection of Tc-99m-Sestamibi during rest, after infusion of arbutamine, and after vasodilatation with dipyridamole. Results: Infusion of arbutamine results in a measurable diminished radiotracer deposition in the lower limb as compared to dipyridamole. The amount of myocardial activity of Tc-99m-sestamibi, however, is also reduced as shown by the percentage of myocardial activity compared to the whole body distribution (2.5%±0.4% for arbutamine vs. 2.8%±0.5% for dipyridamole). In addition, the heart/lung ratio is lower after application of arbutamine (2.1%±0.5% vs. 2.4%±0.4). Conclusion: After infusion of arbutamine the percentage of myocardial activity as well as the contrast of the myocardium to the surrounding lungs is decreased as compared to dipyridamole. Further studies should reveal whether this difference is relevant in diagnosing coronary artery disease. (orig.)