Clinical usefulness of 123I-MIBG myocardial spect in patients with cardiac sarcoidosis

This study was undertaken to assess whether 123I-MIBG scintigraphy is useful to detect cardiac involvements of sarcoidosis. In 45 patients with sarcoidosis, dual SPECT with 123I-MIBG and 201Tl-Cl(Tl) were performed, and the findings were compared with electrocardiogram (ECG), 24 hour Holter ECG and ultrasound echocardiography. In order to evaluate cardiac involvements, Tl and MIBG extent score (E.S.) and severity score (S.S.) were calculated by a Bull's eye map in addition to visual evaluation. Abnormal findings were recognized in 8.9% of all subjects in echocardiography, in 22.2% of those in ECG and Holter ECG, in 40% of those in Tl scintigraphy, and in 64.4% of those in MIBG scintigraphy. All of the Tl and MIBG abnormalities were detected in left ventricles, especially at the basal septal wall. At the inferior wall, abnormalities were observed more frequently by MIBG than by Tl. Tl E.S., Tl S.S. and MIBG E.S. were significantly higher in 10 patients with abnormal ECG findings than in 35 patients with normal ECG findings. Also, all of 10 patients with abnormal ECG findings had abnormal MIBG image, but 3 of them showed normal Tl images. 11 of 35 patients with normal ECG findings showed abnormal Tl and MIBG images (group A), 8 of 35 patients showed normal Tl images and abnormal MIBG images (group B), and 16 of 35 patients showed normal Tl and MIBG images (group C). MIBG S.S. of group A (11.3±7.8) was significantly higher than that of group B (5.3±3.1) or group C (2.6±3.2). Furthermore, in group A, MIBG S.S. was significantly higher than Tl S.S. (5.5±2.8). In a case of normal ECG with abnormal MIBG images, we seriously suspect cardiac involvements and recommend repeated Holter ECG tests as necessary in order to detect critical arrythmia. MIBG scintigraphy appeared to be a sensitive and useful method for the early detection of cardiac sarcoidosis. (J.P.N.)