Reference Values for Dopamine Transporter Imaging With 99m Tc-TRODAT-1 in Healthy Subjects and Parkinson's Disease Patients.

Purpose: The aim of this study was to evaluate different quantitative indexes of striatum dopamine transporter density in healthy subjects and patients with PD.
Patients and Methods: Sixty-seven patients, 23 healthy (8 male; 59 ± 11 years old) and 44 age-matched patients (29 male; 59 ± 7 years old), with various degrees of severity of idiopathic PD (duration of symptoms, 10 ± 6 years; Hoehn and Yahr Scale, 2.16 ± 0.65; UPDRS-3, 29.74 ± 17.79). All patients performed 99m Tc-TRODAT-1 SPECT. Binding potential indexes (BPIs) of striatum and subregions, asymmetry index (AI), and putamen/caudate ratio (P/C) were calculated.
Results: Binding potential index was lower in the PD than in healthy subjects. A BPI cutoff for striatum and putamen ranging from 0.73 to 0.78 showed 95% to 100% sensitivity and 84% to 88% specificity. For the caudate nucleus, a BPI threshold of 0.8 to 0.88 revealed 100% sensitivity and 77% to 84% specificity. The BPI's respective areas under the curve ranged from 0.92 to 0.98. For AI and P/C, the area under the curve was less than 0.70. Binding potential index intraclass correlation coefficient was close to 1.0 in the intraobserver evaluation and 0.76 to 0.87 in the interobserver assessment. Intraclass correlation coefficient for AI and P/C was inferior to 0.75 in the intraobserver and interobserver evaluations.
Conclusions: Different semiquantitative indices differentiated PD and healthy subjects and may help the differential diagnosis of other entities involving the dopaminergic system. Asymmetry index and P/C performances were lower than BPI, including their intraobserver and interobserver reliability, and therefore should be used with caution.
Competing Interests: Conflicts of interest and sources of funding: All authors have no financial arrangement or affiliation with the industry. Two authors received MSc and PhD scholarships, A.C.T. (CAPES 2012/14152-4) and E.N.I. (FAPESP 2012/14152-4). The authors gratefully acknowledge financial support from the following: (a) grant/project #049/2013 (AUXPE No. 2880/2013, L.W.A.) from CAPES/NUFFIC, Brazil Netherlands International Cooperation; (b) grant# 2013/25.987-2 (L.W.A.), grant# 2015/50089-3 FAPESP SPRINT (L.W.A.), and grant# 2021/12671-3 from the State of São Paulo Research Foundation–FAPESP; and (c) grant/project #425775/2016-0 from the Brazilian National Council for Scientific and Technological Development, Ministry of Science and Technology. None of these funding agencies played a role in the design, data collection, management, analysis, interpretation of the data, and preparation, review, or approval of the manuscript. We confirm that we have read the journal’s position on issues involved in ethical publication and affirm that this report has the approval of our institutional ethics committee. The authors declare no conflicts of interest.
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