HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Pinborg, L. H. Articles by Knudsen, G. M. Search for Related Content PubMed PubMed Citation Articles by Pinborg, L. H. Articles by Knudsen, G. M.

Quantification of ¹²³I-PE2I Binding to Dopamine Transporter with SPECT After Bolus and Bolus/Infusion

¹ Neurobiology Research Unit, University Hospital Rigshospitalet, Copenhagen, Denmark
² Department of Anesthesia, University Hospital Rigshospitalet, Copenhagen, Denmark

The aim of the present study was to describe a method combining easy implementation in a clinical setting with accuracy and precision in quantification of ¹²³I-labeled N-(3-iodoprop-(2E)-enyl)-2ß-carboxymethoxy-3ß-(4'-methylphenyl)nortropane (PE2I) binding to brain dopamine transporter. Methods: Five healthy subjects (mean age, 50 y; range, 40–68 y) were studied twice. In the first experiment, dynamic SPECT data and arterial plasma input curves obtained after ¹²³I-PE2I bolus injection were assessed using Logan, kinetic, transient equilibrium, and peak equilibrium analyses. Accurate and precise determination of BP₁ (binding potential times the free fraction in the metabolite-corrected plasma compartment) and BP₂ (binding potential times the free fraction in the intracerebral nonspecifically bound compartment) was achieved using Logan analysis and kinetic analysis, with a total study time of 90 min. In the second experiment, ¹²³I-PE2I was administrated as a combined bolus and constant infusion. The bolus was equivalent to 2.7 h of constant infusion. Results: The bolus-to-infusion ratio of 2.7 h was based on the average terminal clearance rate from plasma in the bolus experiments. Steady state was attained in brain and plasma within 2 h, and time-activity curves remained constant for another 2 h. Even when an average bolus-to-infusion ratio was used, the striatal BP₁ and BP₂ values calculated with kinetic analysis (BP₁ = 21.1 ± 1.1; BP₂ = 4.1 ± 0.4) did not significantly differ from those calculated with bolus/infusion analysis (BP₁ = 21.0 ± 1.2; BP₂ = 4.3 ± 0.3). Computer simulations confirmed that a 2-fold difference in terminal clearance rate from plasma translates into only a 10% difference in BP₁ and BP₂ calculated from 120 to 180 min after tracer administration. Conclusion: The bolus/infusion approach allows accurate and precise quantification of ¹²³I-PE2I binding to dopamine transporter and is easily implemented in a clinical setting.

Key Words: ¹²³I-PE2I • dopamine transporter • SPECT • kinetic analysis • Logan analysis • bolus/infusion analysis