MR bone imaging

Background/introduction Bone is highly relevant to focused ultrasound therapy, both as a potential treatment target and because it interferes with treatment of other organs such as the brain. It is challenging to image cortical bone using MRI, however, due to low water density and fast signal decay in bony tissues. Ultrashort echo time (UTE) imaging is a specialized MR technique that allows the weak, short-lived signal from cortical bone to be imaged despite these limitations. Potential applications of UTE bone imaging in MR-guided focused ultrasound include direct MR thermometry of bone heating, which is not possible using standard proton resonance shift (PRFS) techniques, and in situ skull imaging during brain treatment procedures, which could replace the separate CT scan currently required for transcranial focused ultrasound.