CT on-line monitoring of HIFU therapy

It was the aim of this study to evaluate the feasibility of a clinical CT scanner for temperature mapping in high intensity focused ultrasound tumor therapy. The authors used a 1.2 MHz ultrasound transducer for HIFU on fresh pig muscle. Image acquisition was performed with a clinical CT Scanner before, during and after HIFU. They were able to determine the spatial and temporal temperature development during HIFU application as hypodense zones in the performed images. Thermal necroses were shown as hyperdense areas in the CT images. Moreover, the authors were able to detect bubble formation due to vaporization during US application. Calibration showed a CT thermosensitivity of -0.43 HU//spl deg/C in pig muscle tissue.