心臓サルコイドーシスにおける123I-MIBGシンチグラムの臨床的有用性

Clinical Usefulness of 123I-MIBG Myocardial Spect in Patients with Cardiac Sarcoidosis

　¹²³I-metaiodobenzylguanidine（MIBG）シンチグラムの，心臓サルコイドーシスの診断における有用性を検討する目的で，サルコイドーシス45例に，²⁰¹Tl-Cl（T1）とMIBGのdualSPECTを施行し，視覚的判定に加えてBull’s eye法より算出した異常スコア［severityscore（S．S．）とextent score（E．S．）］での定量評価を行った．結果は，心臓超音波検査異常8％，心電図異常22％，Tlシンチ異常40％，MIBGシンチ異常64％とMIBGシンチ異常が最も高率であった．心電図異常10例は全例にMIBG異常を認めたが，Tl異常は7例であった．心電図正常群35例と心電図異常群10例間では，Tl異常スコア，MIBG異常スコアともに後者が有意に高値であった．心電図正常35例中，Tl,MIBG両核種ともに異常を呈した症例は11例（A群），MIBGのみ異常を呈した症例は8例（B群），両核種とも正常であったのは16例（C群）であった．MIBG S．S．は，A群（11.3±7.8），B群（5.3±3.1），C群（2.6±3.2）と，A群はB群（p＜0.05），C群（p＜0.01）のMIBGS．S．より有意に高かった．かつA群のMIBG S．S．はTl S．S．（5.5±2.8）に比し有意に高値（p＜0.05）であった．以上より，MIBGはTlよりも鋭敏に心病変を検出しうると考えられ，心臓サルコイドーシスの早期診断に有用と思われた．また，心電図が正常でもMIBG異常が認められれば強く心病変を疑い，繰り返しホルター心電図を施行し重症不整脈の早期検出に心掛けるべきと考えた．

Although cardiac sarcoidosis is the main cause of death among patients with sarcoidosis in Japan. it has been extremely difficult to diagnose it without postmor-tem pathological examination. This study was under-taken to assess whether ¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy, which has been developed for evaluating the function of the myocardial sympathetic nerve in various cardiac disease, 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, TI and MIBG extent score (E. S.) and severity score (S. S.) were culculated 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 Holler 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 septa] wall. At the inferior wall, abnormal-ities 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 Ti 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 (p＜0.05, and 0.01) 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 (p＜0.05) than TI S. S. (5.5±2.8). In a case of normal ECG with abnormal MIBG images, we seriously suspect cardiac involvements and recommend repeated IIolter ECG tests as necesary in order to detect critical arrythmia. MIBG scintigraphy appeared to be a sensitive and useful method for the early detection of cardiac sarcoidosis.