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).