Magnetic resonance guided laser induced thermal therapy for cerebellar metastases

Treating recurrent posterior fossa metastases after prior radiation therapy and surgical resection remains challenging. Magnetic resonance guided laser induced thermal therapy (MR-LITT) is a promising treatment for recurrent lesions, but data regarding safety, efficacy, and post-ablational volume change in the posterior fossa is lacking.

All patients with recurrent posterior fossa metastatic lesions treated with LITT by the senior neurosurgeon in the Department of Neurological Surgery, University of Miami Miller School of Medicine, Florida, USA, were included in the study. Pre- and postoperative follow-up MRIs were used to measure lesional and perilesional edema volume. These measurements were compared to calculate percent ablation volume. All patients' clinical examinations were followed closely.

Four patients with recurrent cerebellar metastases were treated with LITT. Average percent of lesion ablated was 97.1% (Range 88.2-100%). Average preoperative lesion volume was 3.3 cm3 (range 1.1 cm3 to 7.2 cm3), and average final postoperative volume was 3.8 cm3 (range 0.5 cm3 to 7.6 cm3). Lesion volume increased to maximum volume on postoperative day 1, with average 486.9% increase. Extrapolated average time until the lesion decreased to a volume smaller than that of the initial size was 294.5 days. There was a trend toward a decrease in average edema volume from preoperative MRI of 17.8 cm3 to final postoperative follow-up MRI of 3.4 cm3 (p=0.0952). No postoperative hydrocephalus or complications occurred.

This pilot study shows that LITT appears to be a safe and promising treatment for recurrent posterior fossa metastatic lesions up to 7.2 cm3. Further randomized controlled studies are warranted to further characterize the long-term efficacy of this therapy. ¹⁾