Heat diffusion constrained inversion of backscattered ultrasound data to image temperature rise during high intensity focused ultrasound therapy

Noninvasive ablative high intensity focused ultrasound (HIFU) therapy must be guided with precision, and monitored in real‐time. Magnetic resonance imaging (MRI) can provide both high resolution tissue‐specific images and temperature maps, but even the most recently developed MRI methods cannot do so in less than a few seconds. Ultrasonic imaging techniques using a sequence of rf frames to measure heating‐induced apparent strain have been developed to produce heating maps, but the approach is challenging due to lack of sensitivity and substantial variability in tissue properties. To improve estimates of temperature rise, constraints based on heat diffusion modeling are imposed, thus minimizing the effects of noise and nonmonotonicity of the speed of sound with respect to temperature throughout the therapeutic range. Furthermore, noninvasive protocols for measuring relevant HIFU field and tissue properties in the region of interest enable patient‐calibrated mapping of temperature rise during HIFU, at ultra...