Multivariate Study Design Using Short- and Long-lived Radioisotopes, In Vivo Positron Emission Tomography (PET/CT) and Planar Scintigraphy, and Ex Vivo Autoradiography to Assess Biodistribution and Pharmacokinetics of Bone-Targeting Test Material in a Canine Surgical Model

Next to blood transfusions, bone is the most commonly implanted material in the human body, with an estimated 600,000 grafts performed annually. New methods for replacing bone or stimulating bone formation in disease settings, such as arthritis and acute injury, can be challenging to evaluate in traditional preclinical models. Image-guided techniques are playing an increasingly important role in evaluating the biodistribution and pharmacokinetics of drugs or drug delivery systems in this context. In combination with anatomical imaging modalities such as magnetic resonance imaging (MRI) and X-ray computed tomography (CT), molecular imaging modalities such as positron emission tomography (PET), single-photon emission computed tomography (SPECT) and planar scintigraphy allow for quantitation of radioisotopes to target and off-target tissues. Here we applied these techniques to evaluate the distribution and pharmacokinetics of a compound, dual-radiolabeled with 124I and 125I, in a canine pancarpal arthrodesis model.