Laser-induced thermal lesions in the human brain: Short-and long-term appearance on MRI

Purpose: The purpose of our study was to investigate with MRI the development of thermal lesions in the human brain up to almost 4 years after laser-induced interstitial thermotherapy (LITT). Method: Eighteen patients with brain tumors who underwent LITT entered the study. Results: In all patients the acute lesion comprised five concentric zones that showed reverse signal intensities on T1- versus T2-weighted images. Lesion development over time was uniform in 89% of the lesions. In twocases variations were observed. Conclusion: The results of our MR follow-up studies showed that post-LITT, laser-induced lesions will shrink exponentially after an initial expansion without any pseudocystic effects.