Diagnostic accuracy of cadmium-zinc-telluridebased myocardial perfusion SPECT: Impact of attenuation correction using a co-registered external computed tomography

Introduction Computed tomography (CT)-based attenuation correction (AC) improves the accuracy of standard myocardial perfusion SPECT. Most dedicated cadmium-zinc-telluride (CZT) SPECT cameras are not equipped with an integrated CT component.We aimed to determine the impact of AC on diagnostic performance of CZT SPECT using co-registration with an external low-dose CT. Methods Sixty patients underwent CZT SPECT (GE Discovery 530c) with 99mTc-sestamibi at rest and following regadenoson stress. Using commercial software, SPECT images were co-registered with a low-dose CT acquired on a separate system (GE Discovery 670NMCT). Attenuation corrected and non-corrected (NC) images were reconstructed using an iterative algorithm. Accuracy was measured in 44 patients who had undergone invasive angiography within 6 months. Normalcy was compared in the remaining 16 patients who had a low pre-test likelihood (,5%) of coronary artery disease (CAD). Results Summed stress and rest scores were significantly lower in AC images (9+8 vs. 13+9 and 6+7 vs. 10+9, P 0.01), while summed difference score did not differ. According to angiography, 38 patients had significant CAD in 71 vascular territories. Attenuation correction improved accuracy globally (P 0.03) and in RCA territory (P 0.008). Specificity improved both globally (100 vs. 40%, P , 0.05) and in each individual territory (LAD: 63 vs. 36%, LCX: 70 vs. 33%, RCA: 81 vs. 19%, P , 0.01). Normalcy was 100% for AC and 62.5% for NC images (P , 0.05). Conclusion Attenuation correction with a co-registered external CT is feasible using CZT cameras and improves diagnostic accuracy mostly by improving specificity over uncorrected images.