Estimation of myocardial blood flow and myocardial flow reserve by ^99mTc-sestamibi imaging: comparison with the results of [¹⁵O]H₂O PET

Abstract.

We developed a noninvasive method to quantitatively estimate the myocardial blood flow (MBF) index and flow reserve (MFR) using dynamic and static data obtained with technetium-99m sestamibi, and compared the results with MBF and MFR measured by oxygen-15-labeled water ([¹⁵O]H₂O) PET. Twenty patients with coronary artery disease (CAD) and nine normal subjects underwent both ^99mTc-sestamibi and PET studies within 2 weeks. From the anterior view, dynamic data were acquired for 2 min immediately after the injection of ^99mTc-sestamibi, and planar static images were also obtained after 5 min at rest and during ATP stress (0.16 mg kg^–1 min^–1 for 5 min) on another day. The area under the time-activity curve on the aortic arch (Aorta ACU), myocardial weight with the SPET image (M), and the myocardial count on the planar image for 1 min (C _m) were obtained. The MBF index (MBFI) was calculated as follows: MBFI=<I>C</I><SUB>m</SUB>/Aorta ACU×100/<I>M</I>. MFR was measured by dividing the MBFI at ATP stress by MBFI at rest. The MBFI measured by ^99mTc-sestamibi was significantly correlated with MBF obtained using [¹⁵O]H₂O PET (MBFI=13.174+11.732×MBF, r=0.821, P<0.001). Furthermore, MFR measured by ^99mTc-sestamibi was well correlated with that obtained using [¹⁵O]H₂O PET, with some underestimation (r=0.845, P<0.001). MFR using ^99mTc-sestamibi in patients with CAD was significantly lower than that in normal subjects (CAD: 1.484±0.256 vs normal: 2.127±0.308, P<0.001). These data suggest that the MBFI and MFR can be measured with ^99mTc-sestamibi. This may be useful for the quantitative assessment of CAD, especially in those patients with diffuse coronary disease.