Abstract
1701
Objectives: Several studies have demonstrated the diminished myocardial sympathetic function in Parkinson's disease (PD) and multiple system atrophy (MSA). We aimed to use multiple-phase (15min, 4h, 24h) 131I-MIBG myocardial scintigraphy to evaluate the change of cardiac sympathetic function in PD, MSA and essential tremor (ET) patients and meanwhile assess the effects of this method for differentiating PD from the other two diseases in Chinese population.
Methods: We retrospectively investigated data of 64 patients (24 PD, 16 MSA, 10 ET patients and 14 healthy controls (HC)) who underwent 131I- MIBG cardiac scintigraphy. Following thyroid gland blocking with compound iodine oral solution, subjects received an intravenous injection of 111 MBq of 131I- MIBG. Anterior planar images of the chest were obtained after 15 min (early image), 4 h (delayed image) and 24h using a triple-headed gamma camera (Precedence 6 SPECT, PHILIPS, Netherland). The photopeak of 131I was centered at 364 keV with a 20% energy window and a static image was obtained in 128 × 128 image matrix with 500K radioactive counts at least. 131I-MIBG myocardial uptake was simultaneously visually evaluated and quantified by an average count ratio of heart/mediastinum(H/M), which was calculated in the early, delayed and 24h phases, respectively. All statistical analyses were performed using the SPSS software for Windows (version, 20.0). One-way analysis of covariance (ANOVA) followed by least significant difference (LSD) test were used to compare the averages and variances among the four groups. The cutoff H/M ratio in all phases for differentiating PD from the other two disease (MSA and ET) was determined from a Receiver Operating Characteristic (ROC) curve. Sensitivity (Se), specificity (Sp) and accuracy were calculated. P-values less than 0.05 were considered significant.
Results: 1) By visual evaluation, 91.7% (22/24)of PD patients and 37.5% (6/16)of MSA patients had significantly decreased or no 131I-MIBG myocardial uptake in all phases.2) The H/M ratios in the HC group generally increased at first, reaching the peak in the delayed phase, and decreased in the 24h phase.There were no significant differences in MIBG accumulation level and variation trend between the ET and HC group (all P > 0.05).Compared with the HC group, the H/M ratios of PD and MSA patients with decreased or no MIBG uptake in visual evaluation were significantly lower in all phases (all P < 0.05), and presented a sustained declining trend with the imaging time prolonged.The H/M ratios of the rest MSA patients had basically the same MIBG variation trend as the HC group, but is lower than the HC group in early (P = 0.00) and delayed (P = 0.00) phases than the HC group. 3) 131I-MIBG scintigraphy helped to distinguish PD from the other two diseases with 0.83 area under the ROC curve in early phases (P =0.00) ,0.86 in delayed phases (P =0.00) and 0.86 in 24h phases (P =0.00). The cutoff H/M value to differentiate PD from the other two was 1.81 in the early-phase imaging (sensitivity 75%, specificity 84.6% and accuracy 80.4%), 2.09 in the delayed-phase imaging (sensitivity 91.7%, specificity 73.1% and accuracy 82 %), 1.3 in the 24h phase imaging (sensitivity 75%, specificity 92.6% and accuracy 84%), respectively.
Conclusions: PD and MSA patients have myocardial sympathetic dysfunction, and the function keeps normal in ET patients. 131I-MIBG myocardial scintigraphy can be an effective diagnostic tool in differentiating PD from MSA and ET.
Comparison of H/M ratios among PD, MSA, ET, and HC groups
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