Positron emission tomography and X-ray computed tomography: tools for mouse phenotyping?

Significant advances in imaging technology now permit non-invasive imaging of mice with high spatial resolution and high sensitivity to biochemical and molecular alterations. Two imaging technologies will be discussed. X-ray computed tomography uses transmission of X-rays through a mouse to create high-resolution anatomic images, which can be useful for detecting phenotypic-related alterations in morphology. Positron emission tomography utilizes trace amounts of radiopharmaceuticals to measure biologic function, for example glucose metabolism, receptor binding and gene expression. Screening of genetically engineered mice with positron emission tomography and a radiopharmaceutical that correlates with glucose metabolism has demonstrated sensitivity to phenotypic changes. Ultimately, the merger of these two complementary imaging modalities, providing spatially registered images of anatomy and function, may provide a powerful tool for whole-body phenotypic analysis, although a number of challenges must be addressed to realize a high-throughput imaging tool for these applications.