Comparison of Functional MR Imaging Guidance to Electrical Cortical Mapping for Targeting Selective Motor Cortex Areas in Neuropathic Pain: A Study Based on Intraoperative Stereotactic Navigation
Benoit Pirottea,
Carine Neugroschlb,
Thierry Metensb,
David Wiklera,
Vincent Denolinb,
Philippe Voordeckera,
Alfred Joffroya,
Nicolas Massagera,
Jacques Brotchia,
Marc Leviviera and
Danielle Baleriauxb
a Department of Neurosurgery, Erasme Hospital, University of Brussels, Brussels, Belgium
b Department of Neuroradiology, Erasme Hospital, University of Brussels, Brussels, Belgium
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FIG 1. A, Virtual 3D reconstruction (cortex surfacing method) of the right hemisphere in the navigation workstation showing the integration of data from iCM and fMRI in the case of patient 8. The iCM-defined central sulcus (yellow line), the iCM-defined sensorimotor target of the hand (red diabolo), and the fMRI-activated area after motor tasks of the hand (at initial analysis threshold, green area; at more restrictive values, white cross), the fMRI-activated area after motor of the tongue (at initial analysis threshold, orange area; at more restrictive values, yellow area) projected in the portion of the precentral gyrus anatomically devoted to the face (pink area). The iCM-defined motor target of the hand (red cross) corresponds spatially with the fMRI precentral activation (green area).
B, Virtual 3D reconstruction (cortex surfacing method) of the right hemisphere in the navigation workstation showing the integration of data from iCM and fMRI in the case of patient 21. The iCM-defined central sulcus (green line), the iCM-defined sensorimotor target of the hand (red diabolo), the fMRI-activated area after motor tasks of the hand (at initial analysis threshold, violet area; at more restrictive values, white cross), and the fMRI-activated area after motor of the foot (at initial analysis threshold, azure area; at more restrictive values, white cross) projected in the portion of the parasagittal precentral convexity. The iCM-defined motor target of the hand (red cross) corresponds spatially with the fMRI precentral activation (violet area). The significant postcentral activations obtained after sensory activation paradigms of the hand (orange area) and foot (blue area) enable validation of the precentral motor activations of the same segments.
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FIG 2. Axial functional MR imaging sequences showing the bilateral precentral cortical activation after motor tasks of the left hand in patients 14 (A) and 20 (B), amputated from the right upper limb (blue cross, enabling correlation between both images on B). This activation is obtained for analysis threshold corresponding to P values much greater than .0001. Minor differences are observed in surface and distribution of the activation between both sides.
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FIG 3. Correlation, in the navigation system, between the iCM-defined targets (center of a 1-cm area between 2 poles of the grid but represented by a red cross) and the contours of the fMRI-defined activation areas (green and pink surfaces for hand and face, respectively, including focus of highest significance [centroid of the blob, black cross] designated as "fMRI target") at the initial (or more restrictive) analysis threshold corresponding to P < .001 (or P < .0001). These pictures and the surface of cortical activation are only illustrative and do not represent actual data.
A, When targets are unambiguous (focal/reproducible/significant/with no artifact), we estimate that they correspond spatially only if the contours of the fMRI-activated area include the target of highest iCM wave.
B, When repeated iCM recordings provide ambiguous (diffused, not reproducible, altered by artifacts) results (red pointed square crosses), we designate as the iCM target the one defined by the recording presenting the highest amplitude (red cross). If this target is projected within the contours of the fMRI-activated area, we estimate that targets from both techniques corresponded spatially. When no iCM target is available, no comparison is possible.
C, When spatial concordance between both targets was obtained with lower thresholds than that corresponding to P < .001 (ie, when P < .01), we estimate that the concordance is not significant.
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