Invited. 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‐frequency 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 therapy with a temporal resolution of 20 seconds. Irradiation was discontinued as soon as the 60 to 65°C isotherm reached the margin of the tumor. A contrast‐enhanced MRI study performed immediately after therapy showed a good correlation of the size of an enhancing rim around the lesion with the 60 to 65°C isotherm. The preliminary results of our study indicate that MRI guidance of LITT may be improved by temperature quantification based on the proton‐resonance‐frequency method.

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