title: Is intraoperative diffusion tensor imaging at 3.0T comparable to subcortical corticospinal tract mapping?
abstract: BACKGROUND
  Primary brain tumors in motor eloquent areas are associated with high-risk surgical procedures because of potentially permanent and often disabling motor deficits. Intraoperative primary motor cortex mapping and corticospinal tract (CST) monitoring are well-developed and reliable techniques. Imaging of the CST by diffusion tensor tractography (DTT) is also feasible.
  
  
  OBJECTIVE
  To evaluate the practical value of 3.0T intraoperative MRI (iMRI) with intraoperative DTT (iDTT) in surgery close to the CST, and to compare high-field iDTT with intraoperative neurophysiological CST mapping during glioma and metastasis resection in a routine setting.
  
  
  METHODS
  Twenty-five patients (13 males, 12 females, median 47 years) were enrolled prospectively from June 2010 to June 2012. Patients were included if they had a solitary supratentorial intracerebral lesion compressing or infiltrating the CST according to preoperative MRI. Subcortical CST mapping was performed by monopolar (cathodal) stimulation (500 Hz, 400 μs, 5 pulses). CST DTT was made both at preoperative and intraoperative 3.0T MRI. Subcortical motor-evoked potential threshold current and probe-CST distance were recorded at 155 points before and at 103 points after iMRI. Current-distance correlations were performed both for pre-iMRI and for post-iMRI data.
  
  
  RESULTS
  The correlation coefficient pre-iMRI was R = 0.470 (P < .001); post-iMRI, the correlation coefficient was R = 0.338 (P < .001). MRI radical resection was achieved in 17 patients (68%), subtotal in 5 (24%), and partial in 3 (12%). Postoperative paresis developed in 8 patients (32%); the paresis was permanent in 1 case (4%).
  
  
  CONCLUSIONS
  The linear current-distance correlation was found both in pre-iMRI and in post-iMRI data. Intraoperative image distortion appeared in 36%. Neurophysiological subcortical mapping remains superior to DTT. Combining these 2 methods in selected cases can help increase the safety of tumor resection close to the CST.
authors.affiliation: *Department of Neurosurgery, First Medical Faculty, Charles University in Prague, Central Military Hospital-Military University Hospital Prague, Czech Republic; ‡Department of Radiology, Central Military Hospital-Military University Hospital Prague, Czech Republic; and §Department of Developmental Epileptology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Svatopluk
authors.initials: S
authors.lastname: Ostrý
authors.forename: Tomáš
authors.initials: T
authors.lastname: Belšan
authors.forename: Jakub
authors.initials: J
authors.lastname: Otáhal
authors.forename: Vladimír
authors.initials: V
authors.lastname: Beneš
authors.forename: David
authors.initials: D
authors.lastname: Netuka
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D001932:Brain Neoplasms / Q000175:diagnosis / Q000601:surgery; D056324:Diffusion Tensor Imaging; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D053580:Muscle Strength / Q000502:physiology; D019635:Neurosurgical Procedures; D011712:Pyramidal Tracts / Q000473:pathology*; D055815:Young Adult