Quantitative in vivo micro-computed tomography for monitoring disease activity and treatment response in a collagen-induced arthritis mouse model.

A painful, chronic condition, Rheumatoid Arthritis, is marked by bone erosion and soft tissue swelling at the joint. As treatments are investigated in pre-clinical models, characterizing disease progression is integral to assessing treatment efficacy. Here, in vivo and ex vivo micro-computed tomography (µCT) are used in parallel with traditional caliper score measurement to quantify physiological changes in the tarsal region in a murine, collagen-induced arthritis model. In vivo imaging methods, which are validated here through comparison to ex vivo and caliper methods, afford longitudinal analysis of both bone and soft tissue through a single image acquisition. This method removes the subjectivity of swelling quantification which is inherently associated with traditional caliper measurements. Histopathology offers an additional assessment of bone erosion and inflammation by providing a microscopic characterization of disease activity. In comparison to untreated animals, daily prednisolone (glucocorticoid) treatment is shown to restore bone volume, as reflected through in vivo and ex vivo µCT images, as well as histopathology. Prednisolone-associated reduction in inflammation is shown through in vivo µCT soft tissue volume measurements, paw caliper measurements, and histopathology. The findings reported here provide a comprehensive validation of in vivo µCT with a sensitivity that enables characterization of pre-clinical disease assessment in response to treatment in a murine, collagen-induced arthritis model.