Comparative study of201Tl-scintigraphic image and myocardial pathologic findings in patients with dilated cardiomyopathy

The objective of the present study was to characterize the production of²⁰¹Tl myocardial perfusion defects, the relation between the²⁰¹Tl multiple small defects and the myocardial damage indicated by myocardial fibrosis shown histopathologically in patients with dilated cardiomyopathy (DCM). Rest²⁰¹Tl scintigraphy was performed in thirty-seven patients with myocardial tissue fibrosis by endomyocardial biopsy, and without stenosis of the coronary artery.²⁰¹Tl myocardial SPECT images were visually classified into 4 grades according to the severity of inhomogeneous perfusion defects (IPD), 0: none, 1: slight, 2: moderate, 3: severe.²⁰¹Tl uptake, defect regions (DR), and coefficient of variation % (CV%) were also quantified by Bull’s eye quantification in nineteen patients. During cardiac catheterization, three biopsy specimens were obtained from the lateral wall to the apical region of the left ventricle and the amount of fibrosis was assessed by means of light microscopic morphometry. The myocardial fibrosis was also classified into 4 grades by a pointcounting method. Autopsy study was also assessed in six patients.²⁰¹Tl perfusion defects were observed in 35 (94.6%) patients, of whom 29 (78.4%) showed inhomogeneous perfusion defects. Twenty-four (64.9%) showed Stage 0 and 1²⁰¹Tl findings, and 21 (62.2%) had myocardial fibrosis in stage 1. Clinically, the correlation between the grades of the IPD, %²⁰¹Tl uptake, DR and CV% of myocardial uptake, which were calculated semiquantitatively by Bull’s eye image, and the histological grades of fibrosis were also good (IPD vs. fibrosis: r = 0.7014; %²⁰¹Tl uptake vs. fibrosis: r = ?0.6542; DR vs. fibrosis: r = 0.7027; CV% vs. fibrosis: r = 0.6985). The²⁰¹Tl SPECT findings were in close agreement with the severity of myocardial fibrosis confirmed by autopsy, but the grading of the IPD was not related to the ejection fraction or left ventricular diameter. It showed a higher rate of inhomogeneous²⁰¹Tl myocardial perfusion defects (78.4%) in patients with DCM. This result may contribute to the clinical evaluation of DCM or differentiation from other diseases. Furthermore, the grading of²⁰¹Tl inhomogeneous perfusion defects related to the myocardial fibrosis of left ventricular myocardium may contribute to speculation of the myocardial degenerative stage in clinical settings.