Study of laser ablation in the in vivo rabbit brain with MR thermometry

Abstract

Purpose To investigate the peak temperature and thermal dose (T₄₃) as tissue damage indicators for thermal therapy. Materials and Methods The proton resonant frequency (PRF) shift thermal coefficient was calibrated on six in vivo rabbit brains during interstitial laser ablation. The peak temperature and T₄₃ were correlated with the lesion boundary observed on T2-weighted spin-echo (SE) MRI at 4 hours post-heating in seven thermal lesions using direct MR measurement and analysis based on a binary discriminate model. Results The peak temperature and T₄₃ were 48.3 ± 1.7°C and 191 ± 219 minutes, respectively, from the direct MR measurement. The values derived by the binary discriminate analysis were 47.8 ± 2.2°C and 28 ± 41 minutes, respectively. Conclusion Our results suggest that tissue damage in rabbit brain 4 hours after thermal ablation can be predicted reliably from a threshold temperature of approximately 48°C. J. Magn. Reson. Imaging 2002;16:147–152.