131I-MIBG myocardial scintigraphy for differentiation of Parkinson's disease from multiple system atrophy or essential tremor in Chinese population.

ABSTRACT

OBJECTIVE: Clinical distinction of Parkinson's disease (PD) from multiple system atrophy (MSA) or essential tremor (ET) is sometimes difficult. The purpose of this study was to assess changes in cardiac sympathetic nerve function in PD, MSA, and ET by 131I-MIBG myocardial scintigraphy METHODS: Patients with PD (25), MSA (18), or ET (11) and 10 healthy controls (HC) were enrolled. 131I-MIBG myocardial scintigraphy was performed for each subject, and heart/mediastinum (H/M) ratios were calculated at two sample times (15min and 4h after the injection of 131I-MIBG), representing the 131I-MIBG myocardial uptake ratios. The washout ratio (WOR) of MIBG which indicates the activity tone of the presynaptic sympathetic nerves was calculated for each subject. RESULTS: The H/M ratios at the two sample times (15min and 4h) were 1.65±0.36 and 1.50±0.43 in the PD group, 1.97±0.36 and 2.08±0.57 in the MSA group, 2.34±0.34 and 2.46±0.51 in the ET group, and 2.41±0.26 and 2.66±0.47 in the HC group. The H/M ratios at the two sample times were lower in the PD group than in the MSA, ET, or HC groups, with statistical significance (all P<0.05). The H/M ratios at the two sample times were significantly lower in the MSA group than in the HC group (all P<0.05). There was no significant difference in H/M ratios at either sample time between the ET and HC group (all P>0.05). The washout ratios (WORs) of MIBG were significantly increased in PD group compared with those in MSA, ET and HC groups. In subgroup analysis, The H/M ratios at the two sample times were decreased in early PD group compared with those in early MSA and early ET groups, with statistical significance (all P<0.05). CONCLUSIONS: Cardiac sympathetic dysfunction can occur in both PD and MSA patients, especially in PD patients, whereas it remains normal in ET patients. 131I-MIBG myocardial scintigraphy can help distinguish patients with PD from those with MSA or ET with good sensitivity and specificity.