Purpose: The aim of this study was to evaluate the diagnostic potential of cardiac (123)I-labelled metaiodobenzylguanidine ((123)I-MIBG) scintigraphy in idiopathic Parkinson's disease (PD). The diagnosis was confirmed by positron emission tomography (PET) imaging with (11)C-labelled 2beta-carbomethoxy-3beta-(4-fluorophenyl)-tropane ((11)C-CFT) and (11)C-raclopride (together designated as dopamine PET).
Methods: Cardiac (123)I-MIBG scintigraphy and dopamine PET were performed for 39 parkinsonian patients. To estimate the cardiac (123)I-MIBG uptake, heart to mediastinum (H/M) ratios in early and delayed images were calculated. On the basis of established clinical criteria and our dopamine PET findings, 24 patients were classified into the PD group and 15 into the non-PD (NPD) group.
Results: Both early and delayed images showed that the H/M ratios were significantly lower in the PD group than in the NPD group. When the optimal cut-off levels of the H/M ratio were set at 1.95 and 1.60 in the early and delayed images, respectively, by receiver-operating characteristic analysis, the sensitivity of cardiac (123)I-MIBG scintigraphy for the diagnosis of PD was 79.2 and 70.8% and the specificity was 93.3 and 93.3% in the early and delayed images, respectively. In the Hoehn and Yahr 1 and 2 PD patients, the sensitivity decreased by 69.2 and 53.8% in the early and delayed images, respectively.
Conclusion: In early PD cases, cardiac (123)I-MIBG scintigraphy is of limited value in the diagnosis, because of its relatively lower sensitivity. However, because of its high specificity for the overall cases, cardiac (123)I-MIBG scintigraphy may assist in the diagnosis of PD in a complementary role with the dopaminergic neuroimaging.