Nexstim webinar discussed benefits of NBS mapping in planning for radiosurgical treatment

HELSINKI, Finland – June 26, 2013 -- Participants in the June 18th webinar heard presentations by Dr. Kufeld from the Charité CyberKnife Center at the Charité - Universitätsmedizin Berlin, Germany and from Assistant Professor Conti from the Department of Neurosurgery in University of Messina, Italy.

The neurosurgeons shared their experiences of using the NBS System for presurgical mapping of the motor cortex and speech-relevant eloquent cortex to help in optimizing dose delivery in radiosurgery. NBS data has also been used for seeding fiber tracking by DTI - and this data has also been used in radiosurgery planning.

From their experiences at the Charité CyberKnife Center, Dr. Kufeld told that NBS results influenced radiosurgery planning in approximately half of their patient cases and the NBS data was considered a useful tool for risk estimation also in the remaining cases. In a series of 10 patients followed up by questionnaire, 1 patient benefitted from a dose reduction of 10% (which they considered significant) and 2 patients benefitted from a dose reduction of 5%. In a further 2 patients isodose optimization was achieved with the addition of NBS data. It was found that NBS data was easy to integrate into planning systems. Easily integrating the results of fiber tracking results requires development, however. The fact that the NBS data was already available when patients were referred to the CyberKnife Center from neurosurgery at the Charité eases the adoption of routine use of NBS in radiosurgical planning.

The webinar sparked a lively discussion on the issue of radiation effects. Patients are surviving treatment for longer periods of time now than earlier, making radiation necrosis an important issue to address. In particular, patients treated for AVMs are typically relatively young and need to live with the radiation side-effects of treatment much longer than, for example, late-stage brain cancer patients. Since there is little evidence of a safe upper limit on radiation dose, the dose should be minimized whenever possible. Ultimately what is needed is a balance between local control and radiation effects.

The clinicians concluded that NBS data can be easily integrated into radiosurgery planning systems and that NBS mapping can be easily made part of the clinical routine. Quantifying the benefit of NBS mapping to patient outcomes warrants further research.