HELSINKI, Finland – June 15, 2012 -- Neurosurgeons at the Charité University Hospital, Berlin, Germany have established a novel approach for fiber tracking based on cortical mapping data from Navigated Brain Stimulation (NBS). Using the NBS System to accurately map the patient´s primary motor cortex and a new algorithm for determination of an individualized fractional anisotropy value, they were able to reliably and objectively perform fiber tracking. The article authored by Frey et al. is titled "A new approach for corticospinal tract reconstruction based on navigated transcranial stimulation and standardized fractional anisotropy values".
It is well understood that the reliability of fiber tracking is dependent on the correct selection of seeding points. Conventionally, the seeding points have been selected based on solely on the knowledge and skill of the examiner. However, it is increasingly understood that anatomical landmarks are difficult to identify in patients with brain tumors, and landmarks visible on MRI may even be misleading. Cortical mapping with the NBS System provides objective seed point definition, which, when combined with individual fractional anisotropy threshold value setting, enables a novel approach to fiber tracking.
By comparing the new technique to the conventional method, the clinical value of the new technique was also demonstrated in this study. A blinded comparison showed that the new technique using the NBS System led to a change or modification in the surgical strategy more than twice as often as when using the conventional method.
In their conclusion, the clinicians state that using the NBS System, a navigated TMS device, with an individualized fractional anisotropy algorithm "represents an objective visualization method based on functional data and provides a valuable instrument for preoperative planning and intraoperative orientation and monitoring".
Frey D, Strack V, Wiener E, Jussen D, Vajkoczy P, Picht T.
A new approach for corticospinal tract reconstruction based on navigated transcranial stimulation and standardized fractional anisotropy values.
Neuroimage. 2012 May 29. [Epub ahead of print]