Usefulness of rapid low-dose/high-dose 1-day 99mTc-sestamibi ECG-gated myocardial perfusion single-photon emission computed tomography

Background The clinical usefulness of a rapid rest low-close/stress high-dose (dose ratio=1:5) Tc-99(m)-sestamibimyocardial perfusion single-photon emission computed tomography (SPECT) protocol for the detection of coronary artery disease was evaluated. Methods and Results In 89 patients, rest images were obtained immediately after the injection of Tc-99m-sestamibi (256.1 +/- 28.4 MBq) followed by drinking water (400ml). Exercise or vasodilator stress test was performed immediately after the completion of rest imaging with the injection of Tc-99m-sestamibi (1312.3 +/- 167.6 MBq). Prior to the post-stress imaging, patients were asked again to drink water (400 ml) in order to eliminate subdiaphragmatic tracer activity. The myocardial count ratio (stress/rest) of Tc-99m-sestamibi was calculated. Image quality was scored using a 4-point scale system (4=excellent, 3=good, 2=poor, 1=unacceptable). Coronary angiography was performed in 56 patients within I month of the SPECT scan. All patients successfully performed the protocol and total examination time was 108 +/- 7 min. The myocardial count ratio of Tc-99m-sestamibi was always greater than 6. The image quality was satisfactory both at rest (3.4 +/- 0.9) and after stress (3.9 +/- 0.2). The sensitivity and specificity to detect coronary artery stenosis > 50% was 84% and 97%, respectively. Conclusions This rapid one-day Tc-99m-sestamibi protocol provides adequate image quality and diagnostic accuracy for detecting coronary artery disease.