Prostate Cancer: MR Imaging and Thermometry during Microwave Thermal Ablation-Initial Experience

Abstract

Percutaneous interstitial microwave thermoablation of locally recurrent prostate carcinoma was continually guided with magnetic resonance (MR) imaging. Phase images and data were obtained with a rapid gradient-echo technique and were used to derive tissue temperature change on the basis of proton-resonance shift. Thermally devitalized regions correlated well with the phase image findings. MR imaging-derived temperatures were linearly related to the fluoroptic tissue temperatures. MR imaging can be used to guide thermoablation.

MR‐guided microwave thermocoagulation therapy of liver tumors: Initial clinical experiences using a 0.5 T open MR system

“…The difference in the frequencies between the two systems is larger than a previous report with a 1.5 T MR system and microwave coagulator at 915 MHz (14). In our preparative study on a 2.0 T MR system, no electromagnetic noise was observed from our microwave coagulator (10).…”

“…In Europe and America, a microwave coagulator at 915 MHz has been developed and the feasibility of microwave ablation under MR environment has been reported (12,13). Recently, MR temperature monitoring during microwave ablation of prostate cancer was reported using a conventional 1.5 T MR system (14). In that study, ultrasonography was used for image guidance in the insertion of the microwave electrode.…”

Thermal Therapy, Part IV: Electromagnetic and Thermal Dosimetry

“…255 Efforts to establish noninvasive thermometry techniques with thermal therapy have been made in recent years. 182,256 However, there are two issues that must be solved in order to implement noninvasive thermometry effi ciently. First, the EM compatibility problem of interference between thermometry devices such as the MR tomograph and the thermal therapy applicator must be solved.…”

Evaluation of MR thermometry with proton resonance frequency method at 7T

“…For example, Botnar et al used the PRF technique to acquire and generate temperature maps after radio frequency (RF) ablation with an open 0.5T MRI system under ex vivo and in vivo conditions (16), and Kuroda et al developed a self-reference thermometry technique using complex field estimation and optimized the technique for 0.5T (17). The developments and applications of temperature mapping have been mostly done at 1.5T and 3T (15,(18)(19)(20). Typically, when using low field clinical scanners, the PRF shifts associated with the local tissue temperature changes are very small, and therefore, the sensitivity to temperature change (or temperature-tonoise ratio, TNR) generated by the phase shifts is low.…”