Artikel
Test-retest reliability of primary motor cortex mapping: Neuronavigated transcranial magnetic brain stimulation (nTMS) versus functional MRI (fMRI)
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Veröffentlicht: | 4. Juni 2012 |
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Objective: Presurgical functional brain mapping is essential for optimized resection planning of eloquently located brain tumors. Functional magnetic resonance imaging (fMRI) has been the most established method for presurgical motor mapping but was shown to have a rather low test-retest reliability, especially for the face and the tongue area. Recently, neuronavigated Transcranial Magnetic Stimulation (nTMS) has attracted rising attention as an alternative motor mapping method applicable for clinical routine. Anyway, little was known about the reliability of nTMS. Thus, we compared the reliability of both motor mapping approaches in a preclinical trial.
Methods: We examined 10 healthy, right-handed subjects on three days (d0, d3–5, week 3–5) by nTMS (eXimia 3.2.2, 110% of resting motor threshold on dominant primary motor cortex, MEP recordings: abductor pollicis brevis muscle, plantaris muscle, perioral muscles, tongue) and fMRI (Siemens 3T Trio, motor paradigms: [1] bilateral thumb abduction, [2] unilateral toe flexion, [3] pursing lips, [4] tongue abduction). Euclidean distances (ED) between hotspots and centers of gravity (CoG) of the three mapping sessions were calculated. Spatial reliability was tested by intersession overlaps and voxel-wise interclass correlation (ICC).
Results: Overall, the mean ED of the hotspots was higher for nTMS (10.77 ± 1.88 mm) as compared to fMRI (6.2 ± 1.1 mm), whereas there was no difference in ED of the CoGs (mean 6.7 mm). Regarding the spatial reliability (i.e., overlap volumes and ICC), nTMS was superior for hand and foot mappings but not for perioral and tongue mappings. The cortical representation of the perioral showed a broad overlap with the tongue area in both assessments.
Conclusions: CoGs were similarly reproducible by fMRI and nTMS. Both methods seem sufficiently reliable for clinical application. In terms of spatial reliability, nTMS seems to be superior to map the primary motor areas of hand and foot but less accurate for lips and tongue. Thus, both methods may well complement each other in the clinical routine.