Gated SPECT provides ejection fractions comparable to various modalities, however in patients with a smaller body surface area (BSA) this relationship is less consistent.
Retrospective analysis of myocardial perfusion images (MPI) was performed on 88 patients, each with Tc-99m sestamibi SPECT post-stress quantification software (Cedars Sinai). All underwent cardiac catheterization within a 30-day period with no major clinical events in the interim. Ventriculography was measured via planimetry averaging two consecutive beats. Nine patients were excluded from the study due to ventricular arrhythmias. The main indication for initial MPI was chest pain(63%), the majority of patients underwent exercise treadmill testing (60%) with the remaining undergoing vasodilator testing.
88 patients were divided in four groups based on sex and BSA. Forty-eight (55%) patients were male: 19 with a BSA<2.0 and 29 with a BSA>2.0. Forty (45%) patients were female: 25 with a BSA<1.8 and 15 with a BSA>1.8. For all patients in the study, comparison of SPECT and angiography revealed a high degree of correlation (correlation coefficient = 0.73 and p<0.005). The two groups with larger BSA had a much higher correlation coefficient:0.86 compared to the lower BSA groups with a correlation coefficient:0.44.
This study demonstrates a high degree of correlation between results of SPECT analysis and those obtained by angiography in the group as a whole. However, gated SPECT does not consistently correlate to angiography when studying patients with smaller body surface areas.
Although gated SPECT is an accepted modality in assessing ejection fraction, one needs to be aware of the disparities that exist in smaller patients. Table 1.
SPECT and Angiographic CorrelationGroupSexBSANSPECT EF Mean(SD)ANGIO EF Mean(SD)Correlation CoefficientP Value1F<1.82562(±10)62(±6)0.36<0.0052F≥1.81560(±8)61(±8)0.77<0.0053M<2.01950(±9)54(±11)0.57<0.0054M≥2.02952(±12)54(±12)0.87=0.001Total8856(±11)58(±10)0.73<0.005
M.G. Reinig, None.