[en] In 41 patients with sarcoidosis (diagnosed according to criteria recommended by the Committee on Diffuse Pulmonary Disease, Ministry of Health and Welfare, Japan 1988), thallium-201 (²⁰¹Tl) myocardial SPECT was performed to investigate: the ability of ²⁰¹Tl SPECT to detect cardiac involvement of sarcoidosis with images recorded at rest and 2 hours later, and the relationships between ²⁰¹Tl myocardial SPECT findings and the activity of sarcoidosis or endomyocardial biopsy findings. As to the abnormal findings in ²⁰¹Tl myocardial SPECT, a low density area was seen in 13 of 41 cases (31.7%) and non-uniform uptake was found in 17 cases (41.5%), the mean washout ratio (n=39) was 16.5±7.4%, which is significantly lower than that found in normal subjects, 23.9±7.5% (n=10). Of the 19 patients judged visually to be normal, 5 patients had a reduced mean washout ratio less than 12%. Thus, the incidence of abnormal findings including all types of abnormality in sarcoidosis was 63.4% (26/41 cases). As measured by the serum ACE (angiotensin converting enzyme) or lysozyme level, or the presence of more than 30% symphocyte fraction in BALF (broncho-alveolar lavage fluid), 20 (80%) of 25 cases with ²⁰¹Tl abnormality were judged to be active sarcoidosis, while only 6 (37.5%) of 16 cases with normal findings on ²⁰¹Tl SPECT were judged to be active. This suggest that there is a significant relationship between the presence or absence of an abnormal finding on ²⁰¹Tl myocardial SPECT and the activity of sarcoidosis. Among 13 patients examined by endomyocardial biopsy, 10 patients had abnormal findings on ²⁰¹Tl myocardial SPECT and 7 of these 10 patients had no histological evidence of cardiac sarcoidosis. In all of these 7 patients, however, sarcoidosis was judged to be active. This suggest that endomyocardial biopsy is of limited value in the diagnosis of cardiac sarcoidosis. (author)