[123I-MIBG myocardial scintigraphy in diabetic patients: association with autonomic neuropathy]

123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy was performed in 20 diabetic patients (NIDDM) and 8 control subjects to investigate the association between clinical autonomic nerve dysfunction and myocardial accumulation of MIBG. We used coefficient variance of R-R interval (CVR-R) as a index of the autonomic neuropathy and categorized diabetes into two groups (CVR-R > or = 2.0: non-autonomic neuropathy. CVR-R < 2.0: autonomic neuropathy). In planar imaging studies, heart to mediastinum MIBG uptake ratio (H/M) was calculated on both early and delayed images. The washout ratio of 123I-MIBG in the heart (%WR) was also obtained using myocardial tracer activity on the both images. Mean value of these indices in diabetic group did not reveal any significant difference with the value in the control group. On the SPECT images, low uptake was observed in the posterior-inferior wall with normal uptake of 201Tl in diabetic patients with non-autonomic neuropathy. These areas extended in patients with autonomic neuropathy. The mean value of count ratio of posterior-interior to anterior wall (posterior-inferior/anterior ratio: PI/A) in the diabetic autonomic neuropathy group was significantly higher than in the control group on the both early and delayed images. And the mean value of regional %WR in the posterior-inferior wall calculated by the both MIBG SPECT images was significantly higher in the non-autonomic neuropathy group than in the control group. In the diabetic patients, retention mechanism of 123I-MIBG was considered to be involved at an early stage without autonomic nerve dysfunction clinically. As autonomic neuropathy progressed severely, uptake mechanism was also supposed to be involved. Therefore, 123I-MIBG myocardial scintigraphy was useful for early detection of cardiac sympathetic nervous dysfunction in diabetic patients.