Meta-analysis of ¹²³I-MIBG cardiac scintigraphy for the diagnosis of Lewy body-related disorders

Patients with parkinsonism pose a diagnostic challenge. Parkinson's disease may be difficult to distinguish from multiple system atrophy and progressive supranuclear palsy, whereas Parkinson's disease and dementia with Lewy bodies can be difficult to distinguish from Alzheimer's disease and other dementias. A number of studies have found diminished cardiac ¹²³I-metaiodobenzylguanidine uptake in Lewy body-related conditions (Parkinson's disease and Lewy body dementia). In 2005, the Dementia With Lewy Bodies Consortium considered ¹²³I-metaiodobenzylguanidine cardiac scintigraphy a "supportive" diagnostic feature, based on limited evidence. We report a meta-analysis of the literature and an assessment of the utility of ¹²³I-metaiodobenzylguanidine for the diagnosis of dementia with Lewy bodies and Parkinson's disease. A search was conducted of articles published between 1950 and June 2010. Forty-six studies involving neuropsychiatric and movement disorders, comprising 2680 subjects, were included in the analysis. A mixed-effects regression model was used to analyze the delayed mean heart-to-mediastinum ratio of ¹²³I-metaiodobenzylguanidine uptake. ¹²³I-metaiodobenzylguanidine cardiac scintigraphy sensitively detected and specifically distinguished 2 diagnostic clusters: (1) Parkinson's disease, dementia with Lewy bodies, and rapid eye movement sleep behavior disorder; and (2) normal controls and patients with Alzheimer's disease, multiple system atrophy, progressive supranuclear palsy, vascular dementia, and frontotemporal dementia. The area under the receiver operating characteristic curve was 0.987 at a cluster discriminatory heart-to-mediastinum ratio threshold of 1.77. This threshold yielded 94% sensitivity and 91% specificity for the discrimination of these diagnostic clusters. ¹²³I-metaiodobenzylguanidine cardiac scintigraphy can accurately distinguish between 2 movement disorders, Parkinson's disease and multiple system atrophy, and between 2 common causes of dementia, Alzheimer's disease and dementia with Lewy bodies.