In vivo MRI thermometry using a phase-sensitive sequence: Preliminary experience during MRI-guided laser-induced interstitial thermotherapy of brain tumors

The purpose of this study was the application of the proton-resonance-frequ ency method to monitor laser-induced interstitial thermotherapy (LITT) in a patient with an astrocytoma WHO II, A phase-sensitive two-dimensional (2D) fast low-angle shot (FLASH) sequence was used to determine the temperature -related phase shifts during LITT. Temperature maps were displayed during t herapy with a temporal resolution of 20 seconds. Irradiation was discontinu ed as soon as the 60 to 65 degrees C isotherm reached the margin of the tum or. A contrast-enhanced MRI study performed immediately after therapy showe d a good correlation of the size of an enhancing rim around the lesion with the 60 to 65 degrees C isotherm. The preliminary results of our study indi cate that MRI guidance of LITT may be improved by temperature quantificatio n based on the proton-resonance-frequency method.