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Updated: Apr 16, 2026

High-Resolution Cardiac Positron Emission Tomography/Computed Tomography for Small Animals
Published on: December 16, 2022
Development of radioiodinated lipophilic cationic compounds for myocardial imaging
Toshihiro Sakai1, Yuriko Saito1, Misato Takashima1
1Department of Molecular Imaging, Medical Photonics Research Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka 431-3192, Japan.
Introduction:
Tc-99m compounds are mainly used in myocardial blood flow studies. These compounds, however, are produced by a generator and alternate single photon emission computed tomography (SPECT) radiopharmaceuticals are therefore required to avoid the risks posed by generator failure. Three radiolabeled compounds, including [(125)I]p-iodobenzyl triphenylphosphonium ([(125)I]ITPP), [(125)I]p-Iodobenzyl dipropylphenylphosphonium ([(125)I]IDPP) and [(125)I]p-iodobenzyl methyldiphenylphosphonium ([(125)I]IMPP), have been synthesized in the current study. All three of these compounds contain a lipophilic cation, which enhances their cell permeability properties and allows them to accumulate in the myocardium as SPECT probes.
Methods:
4-(2-Tributylstannyl) benzyl alcohol was mixed with [(125)I]NaI in the presence of aqueous hydrogen peroxide and hydrochloric acid to allow for the synthesis of 4-[(125)I]iodobenzyl alcohol. Bromination of the alcohol under standard conditions gave 4-[(125)I]iodo benzyl bromide, which was treated with triphenylphosphine, dipropylphenylphosphine or methyldiphenylphosphine to give [(125)I]ITPP, [(125)I]IDPP and [(125)I]IMPP, respectively. These compounds were evaluated in biodistribution and SPECT studies in normal ddY mice.
Results:
All three of the radiolabeled compounds were synthesized in approximately 60% yield with radiochemical purities greater than 99%. The specific activity of each compound was 74 GBq/μmol. The results of the biodistribution and SPECT studies showed that all compounds accumulated preferentially in the heart in vivo, especially [(125)I]IDPP.
Conclusion:
[(123)I] IDPP could be used in clinical practice as a novel myocardial imaging agent.
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