Relationship between thalliuraa-201 myocardial SPECT and findings of endomyocardial biopsy specimens in dilated cardiomyopathy

The purpose of this study was to clarify which myocardial histological find ings associated with dilated cardiomyopathy (DCM) are reflected in quantita tive Tl-201 myocardial SPECT. We obtained studied SPECT images from 21 pati ents with DCM 10 minutes and 2 hours after they received an injection of 11 1 MBq Tl-201 at rest. We calculated the percent coefficient of variation of myocardial Tl-201 counts [%CV(Tl)], the washout rate (WR), standard deviat ion of WR [SD(WR)], extent score (ES) and severity score (SS). We used imag e analysis to measure % fibrosis, % myocytes, the ratio of fibrous tissue t o myocyte tissue (F/My), myocyte size and standard deviation of myocyte siz e [SD(My)] in left ventricular endomyocardial biopsy specimens. The %CV(Tl) was correlated with % fibrosis and F/My. The ES and SS also correlated wit h F/My. The correlation between SD(WR) and SD(My) was significant. The pres ent findings suggest that %CV(Tl), ES and SS of rest Tl-201 SPECT reflect m yocardial fibrosis and that the standard deviation of washout reflects the distribution of myocyte size.