Quantification of Microvasculature after Osteogenic Mechanical Loading using Magnetic Resonance Imaging

Introduction: Bone is typically highly vascularized. Inadequate blood supply has been associated with decreased bone formation and bone mass, and severe vascular dysfunction may result in osteonecrosis. In addition, bone vascularity has been implicated as a crucial factor during both skeletal development and repair. Fatigue loading of bone can produce a stress fracture and stimulate new bone formation. Sufficient vascularity is likely crucial for this process because large increases in vascularity have been observed at the site of new woven bone formation. In previous work, we have used ex vivo vascular perfusion to quantify blood vessels in the region adjacent to bone formation. However, in vivo methods are needed for examining the time course of the vascular response to mechanical loading. Here, we developed a magnetic resonance imaging (MRI) method to quantify the vasculature near the site of bone formation after damaging osteogenic mechanical loading in a small animal (rat) model.