Differentiation of Parkinson's disease and multiple system atrophy by cardiac I-123 MIBG scintigraphy

1200 Objectives: In idiopathic Parkinson9s disease (PD) postganglionic involvement of the autonomic nervous system predominates, whereas in multiple system atrophy (MSA) preganglionic structures are mainly affected. Since cardiac I-123 metaiodobenzylguanidine (MIBG) scintigraphy can assess functional integrity of postganglionic sympathetic neurons, we evaluated its ability to differentiate PD and MSA. Methods: Cardiac MIBG scintigraphy was performed on 47 patients (26 PD and 21 MSA patients; 25 males, 62 ± 9 yr) and 8 normal controls (NCs; 3 males, 45 ± 9 yr). All patients were excluded for myocardial ischemia by Tl-201 SPECT. MSA patients were predominantly parkinsonism (MSA-p) and cerebellar subtypes (MSA-c) in 11 and 10 cases, respectively. Early (20 min) and delayed images (4 hr) were used to obtain heart/mediastinum count (H/M) ratios and washout rates (WRs). Results: The both early and delayed H/M ratios were significantly decreased in PD (early; 1.54 ± 0.23, delayed; 1.36 ± 0.24, respectively) as well as MSA (early; 1.80 ± 0.44, delayed; 1.88 ± 0.51, respectively) patients compared to NCs (early; 2.74 ± 0.97, delayed; 2.94 ± 1.20) (all P Conclusions: Cardiac MIBG scintigraphy was useful for differentiation of PD from MSA by delayed H/M ratio with WR.