Accuracy of Cardiac Innervation Scintigraphy for Mild Cognitive Impairment With Lewy Bodies.

ObjectiveTo provide evidence that cardiac mIBG scintigraphy differentiates probable mild cognitive impairment with Lewy bodies (MCI-LB) from MCI due to Alzheimer's disease (MCI-AD) we scanned patients with MCI and obtained consensus clinical diagnoses of their MCI subtype. We also performed baseline FP-CIT scans to compare the accuracy of mIBG and FP-CIT.MethodsWe conducted a prospective cohort study into the accuracy of cardiac mIBG scintigraphy in the diagnosis of MCI-LB. Follow up clinical assessment was used to diagnose MCI-AD (no core features of MCI-LB and normal FP-CIT); probable MCI-LB (2 or more core features, or 1 core feature with abnormal FP-CIT) or possible MCI-LB (1 core feature or abnormal FP-CIT). For the comparison between mIBG and FP-CIT, only core clinical features were used for diagnosis.ResultsWe recruited 95 people with mild cognitive impairment. Cardiac mIBG was abnormal in 22/37 probable and 2/15 possible MCI-LB cases and normal in 38/43 MCI-AD. The sensitivity in probable MCI-LB was 59% (95% CI 42 to 75%), specificity 88% (75 to 96%) and accuracy 75% (64 to 84%). The positive likelihood ratio was 5.1 and negative likelihood ratio 0.46. With symptom-only diagnoses, the accuracies were 79% for mIBG (95% CI: 68 to 87%) and 76% for FP-CIT (95% CI: 65 to 85%).ConclusionsCardiac mIBG appears useful in early disease, with an abnormal scan highly suggestive of MCI-LB. Validation in a multicentre setting is justified.Classification of EvidenceThis study provides Class I evidence that cardiac mIBG distinguishes MCI-LB from MCI-AD.