Sequential imaging analysis using MIBG scintigraphy revealed progressive degeneration of cardiac sympathetic nerve in Parkinson’s disease

BACKGROUND: Metaiodobenzylguanidine (MIBG) cardiac scintigraphy was used to differentiate Parkinson's disease (PD) with Lewy body pathology from other degenerative parkinsonisms. MIBG cardiac scintigraphy demonstrates the extent of degeneration of myocardial post-ganglionic sympathetic nerves in patients with PD. Because of its specificity for Lewy body (LB) pathology, MIBG scan might also be useful biomarker for the neurodegeneration attributed to PD. To estimate the utility of the imaging technique as a biomarker, we conducted sequential imaging analysis and power analysis. METHODS: Sixty-three patients who met the UK PD Society Brain Bank criteria were enrolled in this study. (123) I-MIBG myocardial scintigraphy was performed on all subjects, and the heart to mediastinum (H/M) ratio was calculated. A second imaging session was carried out after a mean interval of 268 days. RESULTS: Sequential imaging revealed a 2.9% decline of the H/M ratio from the baseline to the follow-up image, which reached statistical significance, but the power analysis showed that a relatively large number of patients would be required to demonstrate the neuroprotective effects of any therapy. CONCLUSIONS: Sequential imaging using (123) I-MIBG myocardial scintigraphy revealed progressive degeneration of the cardiac sympathetic nerve in 63 patients with PD. Although careful elimination of other disease conditions that damage the cardiac sympathetic nerve system is necessary, (123) I-MIBG myocardial scintigraphy may be a useful addition to clinical trials that intend to prove neuroprotection among patients with PD.