Insights into bone metabolism of avian embryos in ovo via 3D and 4D 18F-fluoride positron emission tomography.

PURPOSE: The chick embryo is a well-known economical in vivo model system and is widely applied in preclinical research, e.g., bone development studies. It is therefore surprising that no studies concerning the application of (18)F-fluoride microPET to bone metabolism have been reported so far. This may be due to motion artifacts or the lack of convenient tracer injection sites. METHODS: We resolved the above problems using a combination of sample preparation, anesthesia, microPET imaging, and computational processing, and describe a convenient way of visualizing three- and four- dimensional features of bone metabolism in living chick embryos. RESULTS: The application of (18)F-fluoride microPET facilitates repeat measurements, highly reproducible and motion-artifact-free skeletal imaging, and provides quantitative measurements of in ovo metabolic activities in the bones of developing chick. During microPET measurement, radio tracer was injected intravascularly using a custom-made catheter system, allowing us to additionally investigate early time points in tracer kinetics and uptake. CONCLUSIONS: Our results show that bone metabolism in living chick embryos can be reproducibly studied and quantified in ovo, even for multiple tracer injections over a longer time period. The use of dynamic (18)F-fluoride microPET imaging made it possible to visualize and analyze even small bone structures with excellent quality. Moreover, as our data are comparable to data from corresponding rodent experiments, the use of embryonated chicken eggs is a convenient and economical alternative to other animal models.

Implementation of 89Zr production and in vivo imaging of B-cells in mice with 89Zr-labeled anti-B-cell antibodies by small animal PET/CT.

We examined the production, separation, and characterization of (89)Zr, including supplementation of a commercial Cyclone(®) 18/9 with a self-made Solid Target System (STS). Obtained [(89)Zr]Zr-oxalate was used for the labeling of anti-B cell antibodies with desferrioxamine-p-SCN as a bifunctional chelator. (89)Zr-labeled antibodies were injected in DBA/1 mice to examine usability for detection of B cells in vivo. PET measurements showed binding of (89)Zr-labeled anti-B cell antibodies in tissues with high frequencies of B cells, i.e. in spleen and lymph nodes.

Motion-artifact-free in vivo imaging utilizing narcotized avian embryos in ovo.

PURPOSE: The chick embryo in ovo is a well-accessible and economical in vivo model, but its use in molecular imaging has been limited because of motion artifacts on resulting images. The purpose of this study was to develop a method using narcotics to inhibit motility and to perform motion-artifact-free imaging of living chick embryos in ovo. PROCEDURES: Chick embryos in ovo were narcotized using three different narcotics: isoflurane, 2,2,2-tribromoethanol, and urethane/α-chloralose. Narcotized embryos were imaged using micro-computed tomography (microCT) at days 10-18 of incubation, and the resulting images were analyzed for reduction of motion artifacts. RESULTS: All three anesthetics could be used for anesthetizing living chick embryos in ovo thus allowing the acquisition of motion-artifact-free images. CONCLUSIONS: Our experiments revealed that isoflurane is the best-suited narcotic for single and repeated applications to image living chick embryos in ovo.