XXXX -124 as a label for pharmacological PET imaging.

@entity1 @entity1496 @entity5377 @entity5434 @entity35
With the growing number of biotechnology products and drug delivery systems entering preclinical and clinical studies, pharmacological imaging studies with PET play an increasingly significant role. Such studies often require investigation of slow and complex pharmacokinetics (PK). This suggests labeling of the drug candidate with radionuclides that have long physical half-lives. Among the currently available PET positron emitters,        I has the longest physical half-life (4.2 days). This, combined with the well-investigated behavior of @entity1496 in vivo, makes        I very attractive for pharmacological studies. However, the high energy of the positrons emitted by        I and the presence of single photons in the        I emission can potentially introduce limitations in the quantitative analysis of the images. The objective of this research was to determine whether the use of        I as a PET label provides data quality suitable for PK studies. The study was carried out using MicroPET P4 scanner ( @entity5377 ). Spatial resolution, count-rate performance, sensitivity and scatter fraction were measured using a line source and a cylindrical phantom. Model animal studies in @entity35 and @entity5434 were carried out using @entity1 recombinant proteins. The proteins were labeled with        I, up to 185 MBq/mg. The transaxial and axial spatial resolutions in the center of the camera were satisfactory and higher for OSEM3D/MAP than FORE-2DFBP (FWHM 2.52 vs 3.31 mm, and 3.10 vs 3.69 mm). Linearity of the true coincidence count-rate was observed up to 44 MBq. Animal studies demonstrated excellent delineation and resolution of even very small organs. At optimal doses, 2-10 MBq per animal for rodents and 4-10 MBq per kg of body weight for larger animals, the quality of numerical data was appropriate for PK analysis in all experimental timeframes from minutes (dynamic studies) to 10 days. Overall, the data suggest that        I is an excellent label for quantitative pharmacological PET imaging studies.
