Myocardial Single-Photon-Emission Computed Tomography (SPECT)
Thallium-201 rest/adenosine stress technetium-99m-methoxyisobutylisonitrile-gated SPECT was performed preoperatively. The reconstructed images were analyzed using an automatic quantifying software package (AutoQUANT, Philips Medical Systems, Milpitas, CA) after overall image quality was assessed by 2 experts. A 20-segment model was adopted for regional analysis. Resting and stress segmental myocardial perfusion was quantified by measuring radioactivity and expressed as the percentage of the maximal radioactivity uptake. The reversibility score, defined as a measure of rest minus stress perfusion values, was used as an indicator of the reversibility of perfusion impairment. Of the 4 RCA territory segments, 2 segments (segment numbers 6 and 12) were subtended to the posterior descending coronary artery (PDA) territory and were analyzed to elucidate the mechanism of SV reopening grafted to the PDA (Figure 2).