Comparison of parameters of 123I-metaiodobenzylguanidine scintigraphy for differential diagnosis in patients with parkinsonism. Correlation with clinical features

The purpose of this study was to estimate the diagnostic accuracy of 123I-metaiodobenzylguanidine (MIBG) scintigraphy to diagnose Lewy body disease (LBD), including Parkinson's disease (PD) and dementia with Lewy bodies, and to clarify the relationship between MIBG parameters and the clinical findings. One hundred-and-forty-four patients with parkinsonism without diabetes mellitus or a history of cardiac disease were retrospectively selected in the study. Clinical diagnosis was confirmed by follow-up during more than 6 months by neurologists. All patients underwent MIBG imaging at 15 min (initial) and 4 h (delayed) after the tracer injection, and clinical features such as Hoehn and Yahr (H-Y) classification or symptoms specific to parkinsonism were also investigated. The heart to mediastinum ratio (H/M) and the washout ratio (WR) of MIBG were calculated, and correlation with the clinical features was analyzed. Ninety-seven and 47 patients were diagnosed as LBD and Parkinson's syndrome (PS), respectively. Initial and delayed H/M were significantly lower and WR was significantly higher in LBD than in PS (p<0.0001). The initial H/M was independently correlated with tremor (F value 10.45), hesitation (F=4.49), and hallucinations (F=5.09) (p<0.0001). The sensitivity and specificity for the diagnosis of LBD were 64.9 and 87.2% with initial H/M, 78.4 and 68.1% with delayed H/M, and 80.4 and 61.7% with WR, respectively. Using multivariate analysis, initial H/M (F=39.33) and tremor (F=10.46) were independently correlated to the diagnosis of LBD (r=0.562, p<0.0001) among the MIBG and various clinical parameters. The initial H/M was the most useful of the 3 different parameters of MIBG for the diagnosis of LBD, but had low sensitivity. WR and delayed H/M had no incremental value to initial H/M for the diagnosis of PD. Careful long-term follow-up is needed for patients with parkinsonism who are clinically diagnosed as LBD with normal initial H/M, or diagnosed as no LBD with low initial H/M. (author)