title: A detailed analysis of functional magnetic resonance imaging in the frontal language area: a comparative study with extraoperative electrocortical stimulation.
abstract: BACKGROUND
  Functional magnetic resonance imaging (fMRI) is a less invasive way of mapping brain functions. The reliability of fMRI for localizing language-related function is yet to be determined.
  
  
  OBJECTIVE
  We performed a detailed analysis of language fMRI reliability by comparing the results of 3-T fMRI with maps determined by extraoperative electrocortical stimulation (ECS).
  
  
  METHODS
  This study was performed on 8 epileptic patients who underwent subdural electrode placement. The tasks performed during fMRI included verb generation, abstract/concrete categorization, and picture naming. We focused on the frontal lobe, which was effectively activated by these tasks. In extraoperative ECS, 4 tasks were combined to determine the eloquent areas: spontaneous speech, picture naming, reading, and comprehension. We calculated the sensitivity and specificity with different Z score thresholds for each task and appropriate matching criteria. For further analysis, we divided the frontal lobe into 5 areas and investigated intergyrus variations in sensitivity and specificity.
  
  
  RESULTS
  The abstract/concrete categorization task was the most sensitive and specific task in fMRI, whereas the picture naming task detected eloquent areas most efficiently in ECS. The combination of the abstract/concrete categorization task and a 3-mm matching criterion gave the best tradeoff (sensitivity, 83%; specificity, 61%) when the Z score was 2.24. As for intergyrus variation, the posterior inferior frontal gyrus showed the best tradeoff (sensitivity, 91%; specificity, 59%), whereas the anterior middle frontal gyrus had low specificity.
  
  
  CONCLUSIONS
  Despite different tasks for fMRI and extraoperative ECS, the relatively low specificity might be caused by a fundamental discrepancy between the 2 techniques. Reliability of language fMRI activation might differ, depending on the brain region.
authors: Department of Neurosurgery, University of Tokyo, Tokyo, Japan.
authors: Naoto
authors: N
authors: Kunii
authors: Kyousuke
authors: K
authors: Kamada
authors: Takahiro
authors: T
authors: Ota
authors: Kensuke
authors: K
authors: Kawai
authors: Nobuhito
authors: N
authors: Saito
mesh_terms: D000328:Adult; D001307:Auditory Perception; D001931:Brain Mapping; D032882:Comprehension; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D017034:Epilepsy, Frontal Lobe / Q000473:pathology / Q000503:physiopathology* / Q000523:psychology; D004833:Epilepsy, Temporal Lobe / Q000473:pathology / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance; D012372:ROC Curve; D011932:Reading; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013060:Speech; D013355:Subdural Space; D014796:Visual Perception; D055815:Young Adult