Preclinical time of flight imaging

Medicilon is a Preclinical Research Outsourcing (CRO) company. With our more than 10 years experience on preclinical research services, we dedicated to provide our clients with customized preclinical services program in drug metabolism, pharmacokinetics, efficacy studies, and toxicology. We provide our clients a high-quality data and rapid turnaround time to support their drug development, preclinical studies and clinical research and to help them to select the most valuable drug candidates into clinical trials stage. Our preclinical research services consist in three major parts: pharmacokinetics, disease transplantation models and drug safety evaluation. Our services cover all of the aspects including design, in vivo studies, sample analysis, professional data analysis, IACUC review, and the preparation of application materials.

Website:www.medicilon.com Email:marketing@medicilon.com.cn

Time of flight PET imaging is similar, but makes use of the finite time difference between the substantially coincident gamma ray detection events to localize the positron-electron annihilation event along the line-of-response. A gamma ray travels at the speed of light (c), i.e. about 3 centimeters every 100 picoseconds. The spatial localization (Δx) is given by Δx˜c·Δt/2, so for a radiation detector having, as a typical example, a temporal resolution of about 600 picoseconds it follows that the time-of-flight localization provides a spatial resolution along the line-of-response of about 9 centimeters. In practice, this localization may be represented, for example, by a Gaussian distribution having a FWHM of about 9 centimeters. Spatial localization on the order of Δx=9 centimeters is advantageous for imaging a typical human subject having a size substantially larger than this spatial localization.

On the other hand, a mouse, rat, guinea pig, or other small animal of the type typically used in preclinical research is of a size smaller than or comparable with the spatial localization Δx provided by time-of-flight information. Accordingly, time-of-flight localization does not provide additional useful information as to the location of the positron-electron annihilation event within the animal. This recognition, coupled with the substantial additional expense of including high-speed radiation detectors and high-speed and high-capacity time-of-flight localization processing, has heretofore motivated against including time-of-flight capability in preclinical PET scanners.

Moreover, existing preclinical studies have typically used preclinical PET imaging to assess large-scale anatomical features of tumors or other large-scale growths resulting from cancer or other pathologies under study. For example, a study may quantify the effect of a therapy by the reduction in average tumor size (if any) in a statistically significant number of test animals. Such assessments are readily performed using PET imaging since the tumors of interest are substantially larger than the spatial resolution of a typical PET scanner. If the therapy successfully reduces the tumor size below the resolution of the conventional preclinical PET scanner, it is generally assumed that the therapy is indeed effective. This approach is convenient and provides readily comprehended metrics such as tumor size. However, the measured large-scale anatomical features may, or may not, be probative of outcome determinating aspects of the cancer such as the extent of metastasis, that is, the extent to which cancerous tissue has spread away from the primary tumor. It is known that most cancer patients succumb to the effects of metastatic cancer.