gms | German Medical Science

56. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e. V. (DGNC)
3èmes journées françaises de Neurochirurgie (SFNC)

Deutsche Gesellschaft für Neurochirurgie e. V.
Société Française de Neurochirurgie

07. bis 11.05.2005, Strasbourg

Implementation of "FLAIR-Navigation" for guidance in diagnostic and resective surgery of small epileptogenic lesions

Die Implementierung der "FLAIR-Navigation" in die invasive Diagnostik und Resektion von kleinen epileptogenen Läsionen

Meeting Abstract

  • corresponding author M. Mahvash - Department of Neurosurgery, University of Bonn
  • R. König - Department of Radiology, University of Bonn
  • H. Urbach - Department of Radiology, University of Bonn
  • J. von Oertzen - Department of Epileptology, University of Bonn
  • B. Meyer - Department of Neurosurgery, University of Bonn
  • C. Schaller - Department of Neurosurgery, University of Bonn

Deutsche Gesellschaft für Neurochirurgie. Société Française de Neurochirurgie. 56. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), 3èmes journées françaises de Neurochirurgie (SFNC). Strasbourg, 07.-11.05.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc11.05.-12.02

The electronic version of this article is the complete one and can be found online at:

Published: May 4, 2005

© 2005 Mahvash et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.




For technical reasons T2-weighted and fluid-attenuated inversion recovery (FLAIR) MRI sequences do not allow morphological orientation with high anatomical resolution, whereas they may show small epileptogenic lesions which are not visible on T1-weighted MRI. Considering the peculiarities of diagnostic and resective epilepsy surgery the present study focused on the co-registration of various MR-sequences for guided epilepsy surgery.


Fifty patients (24m, 26f) from 2-74 (mean: 32) years, in whom epileptogenic lesions were not readily identifiable on 3D T1-weighted MRI underwent additional 2D T2-weighted and FLAIR sequences prior to diagnostic and/or resective epilepsy surgery. FLAIR- and/or T2-weighted images were co-registered to the T1-weighted data set and displayed on the navigation station on site for guided invasive diagnostics and for resection according to an individualised resection plan. Postoperative MRI was performed routinely for assessment of resection extent.


All n=50 patients underwent lesionectomy plus perilesional resection. N=14 patients underwent image guided placement of subdural electrodes centred over the visualised, but frequently invisible (n=42) lesion on brain surface. Co-registered T1- and FLAIR-/T2-images allowed for image guided intraoperative identification of all n=50 lesions which were seen as hyperintensities exclusively (n=36) or mainly (n=14) on the FLAIR sequences. The sizes of the epileptogenic lesions ranged between four to 70 mm (mean: 20,2 mm) measured on maximal diameter. Control MRI revealed that complete resection was performed as planned prior to the operation in n=49 patients and incomplete resection in one patient. Preliminary seizure outcome with a mean follow-up of 14 months (range 7-24 months) was assigned according to the Engel classification: class I: 78%, class II: 12% , class III: 4%, class: IV 6%.


Image guidance on the basis of image fusion/co-registration of T1- and FLAIR-/T2-images improves the intraoperative identification of otherwise poorly visible small epileptogenic lesions on standard MRI-sequences. Recall of this information during surgery from the navigation system's screen assists in achieving the goal of precise electrode placement, or complete resection of the lesion as well as of the perilesional epileptogenic tissue and improves the surgeon's intraoperative orientation.