Diagnostic performance of myocardial perfusion single-photon emission computed tomography with attenuation correction

Abstract

A b s t r a c tBackground: Myocardial perfusion single-photon emission computed tomography (SPECT) is one of the basic tools used for the purpose of diagnosis of coronary artery disease (CAD), prognosis of its unfavourable consequences, and evaluation of therapy effectiveness. However, its efficacy is compromised by a relatively low specificity of detection of perfusion defects, which is attributed to attenuation of gamma rays inside the patient's body, causing artefacts erroneously taken for perfusion defects. It is expected that attenuation correction (AC) could eliminate such artefacts. Aim:To evaluate whether visual, semi-quantitative analysis of attenuation-corrected myocardial perfusion imaging provides an advantage over a non-corrected study. Methods:A retrospective study applying AC was performed in 107 patients who had coronary angiography within three months. Patients underwent a stress/rest Tc-99m methoxyisobutylisonitrile (MIBI, POLATOM) double day SPECT/CT myocardial perfusion imaging. Images were analysed by two experienced nuclear medicine specialists (a consensus) applying a visual semiquantitative method. Coronary angiography findings were used as a reference for the analysis of diagnostic performance of myocardial perfusion study protocols.Results: AC increased the specificity of detection of CAD in the whole group of patients from 63% to 86% (p = 0.0005), with a slight reduction in sensitivity (from 83% to 79%). The improved specificity was also noted in subgroups of male and female patients. Accuracy in the whole group of patients increased from 71% to 83% (p = 0.01). AC improved the specificity and accuracy of the method in the detection of perfusion defects in the right coronary artery (RCA) area from 73% to 88% (p = 0.005) and from 74% to 83% (p = 0.04), respectively, and the accuracy of the method in the left anterior descending (LAD) artery area from 79% to 87% (p = 0.043). It also reduced the number of ambiguous results of the study.Conclusions: AC improved the diagnostic performance of myocardial perfusion study in the detection of CAD and identification of critically stenosed LAD and RCA vessels, with enhanced comfort of study interpretation.

Clinical Utility of CT-based Attenuation-correction in Myocardial Perfusion SPECT Imaging

“…As the current study demonstrated, the vascular area that most benefited from attenuation correction was RCA. Similar to the literature, attenuation correction yielded a decrease in the sensitivity in the whole group, while the specificity increased in the whole group and male subgroup ( 6 ).…”

“…There are also papers that have reported that attenuation correction increases the capacitance of the detection of LAD disease ( 26 ). In contrast to Wolak et al ( 27 ), AC imaging has also been reported to be useful in female patients ( 6 ). Additionally, some publications have argued that apical defects observed in AC images may be secondary to true apical thinning ( 28 ).…”

“…However, as AC imaging provides high left ventricular count homogeneity, attenuation correction is thought to facilitate the separation of patients with positive and negative data according to coronary angiography. In a study conducted by Płachcińska et al ( 6 ), specificity and accuracy in CAD detection increased statistically through AC imaging, and the increase in specificity was also observed in the male and female subgroups. According to Huang et al ( 24 ), CT-AC reduced the defect size in the inferior wall in both male and female groups; however, AC imaging was found to be more beneficial in male than in female subgroups as diaphragmatic attenuation artifact in the inferior wall was seen more frequently in men than in women.…”

“…Many methods such as electrocardiogram (ECG) gated imaging, prone imaging, and transmission mapping with external radioactive sources have been developed to overcome attenuation artifacts ( 4 , 5 ). Attenuation artifacts are partially eliminated by ECG-gated single-photon emission computed tomography (SPECT) imaging, which is frequently used in clinical practice to assess regional myocardial contractility ( 6 ). However, in inhomogeneous attenuation regions, such as thorax, attenuation maps obtained by transmission imaging are thought to be more effective than ECG-gated SPECT in attenuation correction ( 7 ).…”