[99mTc]Tc-TRODAT-1 scan diagnostic accuracy for differentiation of dementia of Lewy body from Alzheimer's disease

Introduction: Dopamine transporter (DAT) receptors are reduced in the striatum in dementia of Lewy body (DLB) but normal in Alzheimer's disease (AD). We assessed the diagnostic accuracy of TRODAT-1 imaging to differentiate patients with DLB from AD. Methods: Patients with DLB or AD underwent SPECT TRODAT imaging by [99mTc]Tc-TRODAT-1. Visual interpretation and quantification analyses were done. The activity of the right and left caudate nucleus (CN), putamen (P), striatum (S) as a whole, background (BG), and occipital area (OC) were calculated in addition to the ratio of right and left CN/OC, P/OC, and S/BG. Absolute right and left value difference of the striatum ( increment S), putamen ( increment P), and caudate ( increment CN) to OC or BG were also calculated. The diagnostic accuracy of the visual and quantitative method were compared between patients with AD and LBD. The area under the ROC curve (AUC) was analyzed. Results: Twenty-five patients (15 DLB and 10 AD) were included. Scans were visually interpreted as DLB, AD, and non-diagnostic in 11, 13, and one patients, respectively. Sensitivity, specificity, and accuracy of the scan were 57.1% (28.9-82.3), 70% (34.8-93.3), and 62.5% (40.6-81.2), respectively. CN/OC, P/OC, and S/BG in the left, right, and bilaterally were statistically same between two groups. The AUC of increment CN/OC was 70.7%. The optimal cut-off value for increment CN/BG to diagnose DLB was 6.6% with a sensitivity, specificity, and accuracy, of 86.7%, 50%, and 72.0%, respectively. Conclusion: The [99mTc]Tc-TRODAT-1 imaging has limited diagnostic accuracy for discrimination of DLB and AD patients.