RT Journal Article SR Electronic T1 Characterization of Uptake of the New PET Imaging Compound 18F-Fluorobenzyl Triphenyl Phosphonium in Dog Myocardium JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1359 OP 1366 VO 47 IS 8 A1 Igal Madar A1 Hayden T. Ravert A1 Yong Du A1 John Hilton A1 Lana Volokh A1 Robert F. Dannals A1 James J. Frost A1 Joshua M. Hare YR 2006 UL http://jnm.snmjournals.org/content/47/8/1359.abstract AB 18F-Labeled p-fluorobenzyl triphenyl phosphonium cation (18F-FBnTP) is a member of a new class of positron-emitting lipophilic cations that may act as myocardial perfusion PET tracers. Here, we characterize the 18F-FBnTP uptake and retention kinetics, in vitro and in vivo, as well as the myocardial and whole-body biodistribution in healthy dogs, using PET. Methods: Time-dependent accumulation and retention of 18F-FBnTP in myocytes in vitro was studied. Seven anesthetized, mongrel dogs underwent dynamic PET scans of the heart after intravenous administration of 126−240 MBq 18F-FBnTP. In 4 of the 7 dogs, at the completion of a 60-min dynamic scan, whole-body scans (4 bed positions, 5-min emission and 3-min transmission per bed) were acquired. Arterial blood samples were collected at 0, 5, 10, 20, 30, and 60 min after administration, plasma activity was counted, and high-performance liquid chromatographic analyses for metabolites were performed. The extent of defluorination was assessed by measuring 18F-FBnTP bone uptake in mice, compared with 18F-fluoride. Results: The metabolite fraction comprised <5% of total activity in blood at 5 min and gradually increased to 25% at 30 min after injection. In vivo, 18F-FBnTP myocardial concentration reached a plateau level within a few minutes, which was retained throughout the scanning time. In contrast, activity in the blood pool and lungs cleared rapidly (half-life = 19.5 ± 4.4 and 30.7 ± 11.6 s, respectively). Liver uptake did not exceed the activity measured in the myocardium. At 60 min, the uptake ratios of left ventricular wall to blood, lung, and liver (mean of 7 dogs) were 16.6, 12.2, and 1.2, respectively. Summation of activity from 5 to 15 min and from 30 to 60 min after injection produced high-quality cardiac images of similar contrast. Circumferential sampling and a polar plot revealed a uniform distribution, near unitary value, throughout the entire myocardium. The mean coefficient of variance, on 30- to 60-min images along the septum-to-anterior wall and the apex-to-base axes was 7.58% ± 1.04% and 6.11% ± 0.89% (mean ± SD; n = 7), respectively, and on 5- to 15-min images was 7.25% ± 1.43% and 6.12% ± 1.88%, respectively. 18F-FBnTP whole-body distribution was highly organ specific with the kidney cortex being the major target organ, followed by the heart and the liver. Conclusion: 18F-FBnTP is a promising new radionuclide for cardiac imaging using PET with rapid kinetics, uniform myocardial distribution, and favorable organ biodistribution.