Fast metabolic response to drug intervention through analysis on a miniaturized, highly integrated molecular imaging system.

UNLABELLED: We report on a radiopharmaceutical imaging platform designed to capture the kinetics of cellular responses to drugs. METHODS: A portable in vitro molecular imaging system comprising a microchip and a ß-particle imaging camera permitted routine cell-based radioassays of small numbers of either suspended or adherent cells. We investigated the kinetics of responses of model lymphoma and glioblastoma cancer cell lines to (18)F-FDG uptake after drug exposure. Those responses were correlated with kinetic changes in the cell cycle or with changes in receptor tyrosine kinase signaling. RESULTS: The platform enabled direct radioassays of multiple cell types and yielded results comparable to those from conventional approaches; however, the platform used smaller sample sizes, permitted a higher level of quantitation, and did not require cell lysis. CONCLUSION: The kinetic analysis enabled by the platform provided a rapid (≈ 1 h) drug screening assay.

Attenuation correction for small animal PET tomographs.

Attenuation correction is one of the important corrections required for quantitative positron emission tomography (PET). This work will compare the quantitative accuracy of attenuation correction using a simple global scale factor with traditional transmission-based methods acquired either with a small animal PET or a small animal x-ray computed tomography (CT) scanner. Two phantoms (one mouse-sized and one rat-sized) and two animal subjects (one mouse and one rat) were scanned in CTI Concorde Microsystem's microPET Focus for emission and transmission data and in ImTek's MicroCAT II for transmission data. PET emission image values were calibrated against a scintillation well counter. Results indicate that the scale factor method of attenuation correction places the average measured activity concentration about the expected value, without correcting for the cupping artefact from attenuation. Noise analysis in the phantom studies with the PET-based method shows that noise in the transmission data increases the noise in the corrected emission data. The CT-based method was accurate and delivered low-noise images suitable for both PET data correction and PET tracer localization.