PET Imaging Analysis of Vitamin B Kinetics with [C]Thiamine and its Derivative [C]Thiamine Tetrahydrofurfuryl Disulfide in Rats.

Purpose: Thiamine is an essential component of glucose metabolism and energy production. The disulfide derivative, thiamine tetrahydrofurfuryl disulfide (TTFD), is better absorbed than readily-available water-soluble thiamine salts because it does not require the rate-limiting transport system required for thiamine absorption. However, the detailed pharmacokinetics of thiamine and TTFD under normal and pathological conditions have not yet been clarified. C-11-labeled thiamine and TTFD were recently synthesized by our group. In this study, to clarify the differences in pharmacokinetics and metabolism of these probes, a quantitative PET imaging study and radiometabolite analysis of C-11-labeled thiamine and TTFD were performed in the rat heart.

Procedures: Positron emission tomography (PET) imaging with [C]thiamine and [C]TTFD was performed in normal rats to determine the pharmacokinetics of these probes, and the radiometabolites of both probes from the blood and heart tissue were analyzed by thin-layer chromatography.

Results: Accumulation of [C]TTFD was significantly higher than that of [C]thiamine in the rat heart. Moreover, as a result of the radiometabolite analysis of heart tissue at 15 min after the injection of [C]TTFD, thiamine pyrophosphate, which serves as a cofactor for the enzymes involved in glucose metabolism, was found as the major radiometabolite and at a significantly higher level than in the [C]thiamine-injected group.

Conclusions: PET imaging techniques for visualizing the kinetics and metabolism of thiamine using [C]thiamine and [C]TTFD were developed in this study. Consequently, noninvasive PET imaging for the pathophysiology of thiamine-related cardiac function may provide novel information about heart failure and related disorders.