Quantification of heterogeneity on 201Tl Gated SPECT: Evaluation of coronary artery disease

PURPOSE: The purpose of this study was to propose a new index that quantifies the heterogeneity of myocardial uptake on gated myocardial perfusion SPECT (GMPS) with Tl and investigate its utility in diagnosing multivessel coronary artery disease (CAD). METHODS: In 51 patients with CAD, adenosine-stress Tl GMPS and coronary angiography (CAG) were performed. On the basis of the American Heart Association's 17-segment model, segmental percentage uptake on stress, and redistribution images of GMPS were measured at end-systole and end-diastole. The coefficient of variance (CV) of 17 segmental percentage uptake for each patient was used as an estimate of the heterogeneity of myocardial uptake. According to the results of CAG, patients were divided into insignificant coronary artery stenosis (insignificant-CAD), single-vessel CAD, and multivessel CAD groups. The differences in CV among the 3 groups were analyzed by 1-way analysis of variance and Tukey-Kramer test. The diagnostic capability for multivessel CAD was analyzed using the receiver operating characteristics (ROC) curve analysis. RESULTS: Stress end-diastolic CV for patients with multivessel CAD [mean (SD), 18.1% (3.5%)] was significantly greater than that for single-vessel CAD [12.8% (2.9%), P < 0.0001] and insignificant-CAD [10.1% (0.9%), P < 0.0001]. Stress end-systolic CV for patients with multivessel CAD [23.4% (5.2%)] was significantly greater than that for insignificant-CAD [16.5% (4.1%), P = 0.002], whereas there was no difference between single-vessel [20.9% (6.1%)] and multivessel CAD. Using an optimal cutoff of stress end-diastolic CV diagnosed multivessel CAD with a sensitivity of 84%, a specificity of 92%, an accuracy of 88%, and an area under the curve of 0.89. CONCLUSIONS: The heterogeneity of myocardial percentage uptake on Tl GMPS was correlated with the severity of CAD. Stress end-diastolic CV value is a candidate index for differentiating patients with multivessel CAD from single-vessel CAD and insignificant-CAD.