Dual-modality imaging in an in vivo preclinical model of OA. Sagittal (a, b) and coronal (c, d) plane images of the rat knee obtained from co-registered high-field MRI (a, c) and micro-CT (b, d). The MRI volume was resampled to isotropic voxel dimensions prior to co-registration, which allowed the delineation of bone and non-bone components in the meniscus (MN) and the accurate depiction of tendon (PT, patellar tendon), ligament (ACL, anterior cruciate ligament), and cartilage (horizontal arrowheads). ROI, region of interest, identifies approximate location where volumetric bone mineral density was calculated above the SBC. micro-CT, micro computed tomography; MRI, magnetic resonance imaging; OA, osteoarthritis.