Mapping of temperature elevation using focused ultrasound phased arrays

Temperature monitoring is most important during the application of thermal treatment, such as in the case of Focused Ultrasound Surgery (FUS). Currently, Magnetic Resonance Imaging (MRI) is the predominant method for temperature mapping of FUS. However, its high cost, low temporal resolution and limited availability and applicability often result in its restricted use. In this paper, a new device for temperature mapping is introduced that only uses focused ultrasound to both apply and monitor the treatment temporally and spatially. By utilizing the principle of the recently introduced Ultrasound-Stimulated Acoustic Emission (USAE) as well as the phased array capability of steering the beam, the temperature distribution at various instants during the application of the treatment could be assessed. The target used here was a silicone gel with tissue-mimicking properties. The temperature spot could be detected during the application of the treatment and the temperature elevation could be both mapped spatially and monitored temporally. In conclusion, an all ultrasound-based system could serve as a more applicable alternative to MR techniques for thermal therapy monitoring. Our plan is to use the same array for the therapy sonication and monitoring of the treatment in the focal zone. This could provide a potential for realizing the ultimate clinical goal: an economic, fully integrated closed loop feedback system for therapy control.