Noninvasive temperature monitoring using ultrasound tissue characterization method

Microwave thermotherapy (MT) is an oncological treatment. At present the invasive thermometer probes are clinically used for temperature measuring during an MT. Any invasive handling of tumors is of high-risk. A new method of noninvasive monitoring of temperature distribution in tissue has been developed. An MT treatment of the experimentally induced pedicle-tumors of the rat was prepared. It consists of an intelligent regulation loop controlling a high frequency (HF) generator according to the maximal measured temperature in the tissue and a special HF MT applicator. The loop is also equipped with an invasive thermometer (4 invasive probes). During the MT treatment the series of ultrasound B-mode images were obtained. The texture parameters were evaluated from the obtained ultrasound images. These parameters were correlated with the invasively measured temperature during the MT session. For 60 rat samples a strong correlation between the mean gray level in the ROIs in the ultrasound pictures and the invasively measured temperature in the range 37-44 degC (98.6-111.2 F) was found. The correlation coefficient of the mean gray level and the invasively measured temperature is 0.96plusmn0.05. A system for representation of changes of spatial temperature distribution of the whole tumor during MT will be presented