title: Localized N20 Component of Somatosensory Evoked Magnetic Fields in Frontoparietal Brain Tumor Patients Using Noise-Normalized Approaches.
abstract: OBJECTIVE
  To localize sensorimotor cortical activation in 10 patients with frontoparietal tumors using quantitative magnetoencephalography (MEG) with noise-normalized approaches.
  
  
  METHODS
  Somatosensory evoked magnetic fields (SEFs) were elicited in 10 patients with somatosensory tumors and in 10 control participants using electrical stimulation of the median nerve via the right and left wrists. We localized the N20m component of the SEFs using dynamic statistical parametric mapping (dSPM) and standardized low-resolution brain electromagnetic tomography (sLORETA) combined with 3D magnetic resonance imaging (MRI). The obtained coordinates were compared between groups. Finally, we statistically evaluated the N20m parameters across hemispheres using non-parametric statistical tests.
  
  
  RESULTS
  The N20m sources were accurately localized to Brodmann area 3b in all members of the control group and in seven of the patients; however, the sources were shifted in three patients relative to locations outside the primary somatosensory cortex (SI). Compared with the affected (tumor) hemispheres in the patient group, N20m amplitudes and the strengths of the current sources were significantly lower in the unaffected hemispheres and in both hemispheres of the control group. These results were consistent for both dSPM and sLORETA approaches.
  
  
  CONCLUSIONS
  Tumors in the sensorimotor cortex lead to cortical functional reorganization and an increase in N20m amplitude and current-source strengths. Noise-normalized approaches for MEG analysis that are integrated with MRI show accurate and reliable localization of sensorimotor function.
authors.affiliation: Center for Intelligent Signal & Imaging Research (CISIR), Department of Electrical & Electronic Engineering, University Technology PETRONAS, Bandar Seri Iskandar, 31750, Tronoh, Perak, Malaysia.
authors.forename: Nor Safira
authors.initials: NS
authors.lastname: Elaina
authors.affiliation: Center for Intelligent Signal & Imaging Research (CISIR), Department of Electrical & Electronic Engineering, University Technology PETRONAS, Bandar Seri Iskandar, 31750, Tronoh, Perak, Malaysia. aamir_saeed@petronas.com.my.
authors.forename: Aamir Saeed
authors.initials: AS
authors.lastname: Malik
authors.affiliation: Center for Intelligent Signal & Imaging Research (CISIR), Department of Electrical & Electronic Engineering, University Technology PETRONAS, Bandar Seri Iskandar, 31750, Tronoh, Perak, Malaysia.
authors.forename: Wafaa Khazaal
authors.initials: WK
authors.lastname: Shams
authors.affiliation: Center for Intelligent Signal & Imaging Research (CISIR), Department of Electrical & Electronic Engineering, University Technology PETRONAS, Bandar Seri Iskandar, 31750, Tronoh, Perak, Malaysia.
authors.forename: Nasreen
authors.initials: N
authors.lastname: Badruddin
authors.affiliation: Department of Neurosciences, Universiti Sains Malaysia (USM), 15160, Kubang Kerian Kelantan, Malaysia.
authors.forename: Jafri Malin
authors.initials: JM
authors.lastname: Abdullah
authors.affiliation: Department of Neurosciences, Universiti Sains Malaysia (USM), 15160, Kubang Kerian Kelantan, Malaysia.
authors.forename: Mohammad Faruque
authors.initials: MF
authors.lastname: Reza
mesh_terms: D000328:Adult; D001931:Brain Mapping; D001932:Brain Neoplasms / Q000000981:diagnostic imaging*; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D060526:Magnetic Fields; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D013003:Somatosensory Cortex; D055815:Young Adult
keywords: Brodmann area 3b; Frontoparietal tumor; Magnetoencephalography; Noise-normalized approach; Somatosensory evoked magnetic fields