Assessing the Optimal Time Point for the Measurement of Extrastriatal Serotonin Transporter Binding with ^sup 123^I-FP-CIT SPECT in Healthy, Male Subjects

• Published in: The Journal of nuclear medicine (1978) Vol. 53; no. 7; p. 1087
• Main Authors: Koopman, Karin E, la Fleur, Susanne E, Fliers, Eric, Serlie, Mireille J, Booij, Jan
• Format: Journal Article
• Language: English
• Published: New York Society of Nuclear Medicine 01.07.2012
• Subjects: Brain; Dementia; Parkinson's disease; Proteins; Ratios; Serotonin; Statistical analysis
• ISSN: 0161-5505; 1535-5667

123I-N-v-fluoropropyl-2b-carboxymethoxy-3b-(4-iodophenyl) nortropane (123I-FP-CIT) is commonly used to assess the dopamine transporter in the striatum. However, recent studies suggest that this tracer may be used also to assess binding to monoamine transporters in the midbrain or diencephalon, which may reflect predominantly serotonin transporter (SERT) binding. However, it is still unclear at what time point after injection SPECT should be performed for optimal assessment of SERT with123I-FP-CIT. Therefore, we examined the time course of extrastriatal 123I-FP-CIT binding. Methods: Nineteen healthy, male subjects were included, and SPECT images were acquired up to 3 h after 123I-FP-CIT injection. Region-of-interest analysis was performed, and specific-to-nonspecific binding ratios were calculated. Results: Specific-to-nonspecific 123I-FP-CIT binding ratios in the midbrain and diencephalon were significantly higher 2 h after injection than 1 h after injection and remained stable between 2 and 3 h after injection. Conclusion: The optimal time frame for assessing 123I-FP-CIT binding to extrastriatal SERT is between 2 and 3 h after injection of the tracer. [PUBLICATION ABSTRACT]