Quantitative reference value of dopamine transporter single-photon emission computed tomography in healthy Japanese older adults

Abstract

Background: N-ω-fluoropropyl-2b-carbomethoxy-3b-(4-123I-iodophenyl) nortropane (123I-FP-CIT) single-photon emission computed tomography is an effective diagnostic tool for parkinsonism. However, a lack of quantitative reference values of the specific binding ratio of normal Japanese controls is a crucial limitation when we apply this procedure for evaluating Japanese parkinsonian patients. Aim: In the present study, we aimed to obtain a control database of specific binding ratio in healthy, Japanese older adults. Methods: We studied 123I-FP-CIT single-photon emission computed tomography in 20 healthy Japanese older adults, and obtained the specific binding ratio with and without attenuation correction. Results: Clinically and practically relevant data were obtained from 19 participants (10 women, 9 men, age 68.7 ± 8.8 years). The mean specific binding ratio with attenuation correction ± standard deviation was 6.84 ± 1.01, being significantly higher than that of the preceding study of Caucasians by Tossici-Bolt et al. The mean specific binding ratio without attenuation correction was 5.31 ± 1.04. These were not different between the sexes. The specific binding ratio decreased age-dependently in the specific binding ratio both with and without attenuation correction. The mean decreasing rate of specific binding ratio with AC was approximately 0.7 per decade. Most of the striatal asymmetry index of specific binding ratio with AC was lower than 8.4%. Conclusion: We presented the quantitative reference values of Japanese healthy older adults feasible for diagnostic and research use for Japanese parkinsonian patients.