Monitoring of high-intensity focused ultrasound-induced temperature changes in vitro using an interleaved spiral acquisition

An interleaved, spoiled gradient-echo spiral acquisition technique was impl emented to monitor high-intensity focused ultrasound heating of porcine kid ney ex vivo by measuring temperature induced phase shifts in the detected M R signal. Echo time, flip angle, repetition time, number of interleaves, an d readout time were varied to observes effects on temperature sensitivity a nd phase-difference noise. The temperature response of the interleaved spir al acquisition was found to be comparable to a spoiled fast gradient-echo s equence of comparable in-plane spatial resolution. However, when imaging wi th an optimal echo time, spiral acquisition offers dramatically increased t emporal resolution for comparable spatial resolution. Magn Reson Med 43:909 -912, 2000. (C) 2000 Wiley-Liss, Inc.