PURPOSE: To evaluate the feasibility of a technique of MR-guided stereotactic 
radio frequency ablation, which was developed as a minimally invasive treatment 
for brain tumors, and to determine MR characteristics and sequential evolution 
of radio frequency lesions created to ablate brain tumors.
METHODS: Fourteen lesions in 12 patients with primary and metastatic brain 
tumors were treated with this technique and followed for up to 10 months. The 
stereotactic coordinates of the tumor and the angle of the radio frequency probe 
were calculated on MR imaging. The radio frequency lesion was generated in the 
awake patient by increasing the temperature to 80 degrees C within the tumor for 
1 minute. This was repeated until the entire tumor volume was destroyed. MR 
imaging was performed before, during, and immediately after the radio frequency 
procedure, and sequential MR was obtained during clinical follow-up.
RESULTS: MR imaging clearly showed well-defined radio frequency lesions and 
provided feedback for treatment planning. The radio frequency lesion boundary 
was well identified as a dark signal rim on T2-weighted images and showed ring 
enhancement on contrast-enhanced T1-weighted images. The sequential MR imaging 
showed the radio frequency lesions decreased in volume in all cases, suggesting 
focal control.
CONCLUSION: Stereotactic MR-guided radio frequency brain tumor ablation is a 
feasible and promising technique that can be an attractive brain tumor treatment 
alternative. MR provided not only accurate tumor location but also visualization 
of feedback of thermal tissue changes that reflected therapeutic effect.