Comparison of the diagnostic performances of CT attenuation corrected and non-attenuation corrected SPECT myocardial perfusion scintigraphy in coronary artery disease.

Introduction and objectives: Tissue attenuation reduces the specificity of the myocardial perfusion imaging single photon emission tomography (SPECT), which leads reduced diagnostic accuracy. The aim of this study is to compare performances of non-attenuation corrected (NAC), computed tomography based-attenuation corrected (AC) and prone images for qualitative and semi-quantitative analysis of myocardial perfusion SPECT in diagnosis of coronary artery disease (CAD).

Materials and methods: Eightysix patients in whom NAC, AC and prone images were obtained with SPECT at Selcuk University Faculty of Medicine, and whose coronary angiography/CT coronary angiography was completed within 3 months, were retrospectively studied. Myocardial perfusion scintigraphy was performed using SPECT/CT dual-headed gamma camera. Images were evaluated qualitatively and semi-quantitatively using 20-segment model. Analyzes of global myocardium and LAD, RCA, Cx vascular areas as regional analysis were performed. In qualitative evaluation, if SPECT study was abnormal, relevant coronary artery area was recorded. Quantitative Perfusion SPECT (QPS) program was used in semi-quantitative analysis; SSS ≥ 4 was accepted for presence of CAD in per-patient analysis. In regional analysis SSS ≥ 2 was taken into account. Coronary angiography/CT coronary angiography was used as gold standard. Threshold value was determined as ≥50% and above luminal diameter narrowing. While AC and NAC methods were compared for per-patient analysis and each vascular area; 3 imaging methods including prone acqusition, were compared for the RCA area. Diagnostic performances of the methods were evaluated by comparing the areas under the curve with ROC analysis.

Results: In visual evaluation, sensitivity of AC was significantly lower than NAC in analyzes of per-patient, RCA and Cx areas (global 76.92% vs 86.15%, RCA 60.87% vs 82.61%, Cx 58.97% vs 69.23%, respectively; p < 0.05). Sensitivity of prone imaging was significantly higher than AC in analysis of the RCA area (76.09% vs 60.87%, respectively; p < 0.05) Specificity values ​​were higher in analyzes of global, RCA and Cx areas in AC than in NAC method; this difference was significant in RCA and Cx areas (RCA 70% vs 42.50%, Cx 85.11% vs 70.21%, respectively; p < 0.05). In semi-quantitative evaluation, AC and NAC had similar sensitivity and specificity in global and regional analyzes; in RCA area, no significant difference was detected between the 3 methods. In ROC analysis, no significant difference was detected between methods in per-patient and regional analyzes both in visual and semi-quantitative evaluation.

Conclusions: CT-based attenuation correction increases specificity, but reduces sensitivity in the diagnosis of CAD in regional areas of RCA and Cx. Prone imaging remains important in evaluation of RCA area.