Fig. 4

MRgFUS treatment planning. MRgFUS treatment of tibial osteoid osteoma, showing the InSightec ExAblate user interface. Subtracted phase images (top panel) are used to calculate temperature, with temperatures reaching 65 °C at the target (bottom right panel). A magnified EPI magnitude image (bottom left panel) shows the targeting. The position of the single focus (green plus sign) is adjusted such that the beam path (blue hourglass) intersects the bone (green line), creating a sonication spot (green circle). Thermal dose (green) is present at the bone surface. Note that the focal zone has been placed deep to the bone cortex in order to heat a larger bone surface area, and the beam has been oriented to avoid the neurovascular bundle