Whole-body skeletal imaging in mice utilizing microPET: optimization of reproducibility and applications in animal models of bone disease

Abstract

The aims were to optimize reproducibility and establish [(18)F]fluoride ion bone scanning in mice, using a dedicated small animal positron emission tomography (PET) scanner (microPET) and to correlate functional findings with anatomical imaging using computed tomography (microCAT). Optimal tracer uptake time for [(18)F]fluoride ion was determined by performing dynamic microPET scans. Quantitative reproducibility was measured using region of interest (ROI)-based counts normalized to (a) the injected dose, (b) integral of the heart time-activity curve, or (c) ROI over the whole skeleton. Bone lesions were repetitively imaged. Functional images were correlated with X-ray and microCAT. The plateau of [(18)F]fluoride uptake occurs 60 min after injection. The highest reproducibility was achieved by normalizing to an ROI over the whole skeleton, with a mean percent coefficient of variation [(SD/mean) x 100] of <15%-20%. Benign and malignant bone lesions were successfully repetitively imaged. Preliminary correlation of microPET with microCAT demonstrated the high sensitivity of microPET and the ability of microCAT to detect small osteolytic lesions. Whole-body [(18)F]fluoride ion bone imaging using microPET is reproducible and can be used to serially monitor normal and pathological changes to the mouse skeleton. Morphological imaging with microCAT is useful to display correlative changes in anatomy. Detailed in vivo studies of the murine skeleton in various small animal models of bone diseases should now be possible.