Laser interstitial thermal therapy systems (NeuroBlate, Visualase)

Laser interstitial thermal therapy became practical when MRI thermometry allowed the surgeon to see heat spreading in real time. Medtronic's Visualase, cleared in 2007 and acquired by Medtronic in 2014, uses a 980 nm diode laser in a saline-cooled catheter with software that estimates thermal damage from the MRI temperature maps and shuts the laser off when set limits at chosen points are reached. Monteris Medical's NeuroBlate, cleared in 2009, uses a 1064 nm laser with a gas-cooled probe available as a side-firing directional tip that can sculpt the ablation zone, driven by a robotic positioner from the MRI control room. Both are placed stereotactically through a small burr hole, with a frame, a skull-mounted bolt or a robot, and the patient usually goes home within a day or two. Neuro-oncology uses are recurrent glioblastoma, deep or eloquent-area gliomas, brain metastases that recur after radiosurgery, and radiation necrosis, where the LAANTERN registry has published outcomes; the same devices treat epilepsy foci. Interstitial laser fibres from the same vendors and from biolitec are also used percutaneously in liver, thyroid and prostate.

Against craniotomy, the approach is minimally invasive and reaches otherwise inoperable sites; against radiosurgery it works on lesions that have already been irradiated and provides tissue for diagnosis. The limits are lesion size (larger tumours need several trajectories or staged treatments), swelling and heat spread near vessels or the ventricles, the cost of MRI suite time, and the absence of a randomised comparison with resection or radiosurgery.