Comparison of left ventricular ejection fraction calculated using attenuation-corrected and non-attenuation corrected images in gated cardiac spect imaging

Abstract

Background: Gated single photon emission computed tomography (SPECT) imaging allows ventricular function measurements to be obtained simultaneously with the perfusion images. Ordinarily, non-attenuation corrected images are reviewed to assess myocardial perfusion and function. Attenuation correction using simultaneous transmission and emission data acquisition method has been used to better assess the perfusion images. This may alter the configuration of the left ventricular cavity and affect the calculation of left ventricular ejection fraction (LVEF). The objective of this study was to evaluate the effect of attenuation correction on the assessment of left ventricular function. Methods: Gated cardiac SPECT studies of 32 patients with single vessel coronary artery disease were reviewed. All the studies were acquired using the Hawkeye V3 system (GE Medical Systems, Milwaukee, WI). Emission images were acquired after the intravenous injection of 1.48 GBq (40 mCi) of Tc-99m Sestamibi at peak exercise or pharmacological stress. Transmission data in the form of cross-sectional patient attenuation images were acquired using high-resolution, 3-D X-ray imaging system. Only the stress images were assessed and processed to calculate the LVEF using attenuation corrected and non-attenuation corrected images. LVEF was calculated using the QGS software by the standard volume based method based on the edge detection technique. Results: There is a good correlation between the LVEF calculated using attenuation corrected and non-attenuation corrected images (regression line: y = 0.9886x - 0.2229, coefficient of linearity: 0.97) for a wide range of ejection fractions (range: 15% - 70%). A paired student's t-test revealed that there is no statistically significant difference between the 2 groups (p > 0.05). Conclusion: Our results indicate that there is no significant difference between the LVEF calculated using the attenuation corrected and non-attenuation corrected images and attenuation corrected images can be used to assess left ventricular function.