title: Challenges in Identifying the Foot Motor Region in Patients with Brain Tumor on Routine MRI: Advantages of fMRI.
abstract: OBJECTIVE
  Accurate localization of the foot/leg motor homunculus is essential because iatrogenic damage can render a patient wheelchair- or bed-bound. We hypothesized the following: 1) Readers would identify the foot motor homunculus <100% of the time on routine MR imaging, 2) neuroradiologists would perform better than nonradiologists, and 3) those with fMRI experience would perform better than those without it.
  
  
  METHODS
  Thirty-five attending-level raters (24 neuroradiologists, 11 nonradiologists) evaluated 14 brain tumors involving the frontoparietal convexity. Raters were asked to identify the location of the foot motor homunculus and determine whether the tumor involved the foot motor area and/or motor cortex by using anatomic MR imaging. Results were compared on the basis of prior fMRI experience and medical specialty by using Mann-Whitney U test statistics.
  
  
  RESULTS
  No rater was 100% correct. Raters correctly identified whether the tumor was in the foot motor cortex 77% of the time. Raters with fMRI experience were significantly better than raters without experience at foot motor fMRI centroid predictions (13 ± 6 mm versus 20 ± 13 mm from the foot motor cortex center, P = 2 × 10(-6)) and arrow placement in the motor gyrus (67% versus 47%, P = 7 × 10(-5)). Neuroradiologists were significantly better than nonradiologists at foot motor fMRI centroid predictions (15 ± 8 mm versus 20 ± 14 mm, P = .005) and arrow placement in the motor gyrus (61% versus 46%, P = .008).
  
  
  CONCLUSIONS
  The inability of experienced readers to consistently identify the location of the foot motor homunculus on routine MR imaging argues for using fMRI in the preoperative setting. Experience with fMRI leads to improved accuracy in identifying anatomic structures, even on routine MR imaging.
authors.affiliation: From the Functional MRI Laboratory, Department of Radiology (R.A.F., R.X.J., C.S., N.M.P.B., K.K.P, A.I.H.).
authors.forename: R A
authors.initials: RA
authors.lastname: Fisicaro
authors.affiliation: From the Functional MRI Laboratory, Department of Radiology (R.A.F., R.X.J., C.S., N.M.P.B., K.K.P, A.I.H.).
authors.forename: R X
authors.initials: RX
authors.lastname: Jiao
authors.affiliation: From the Functional MRI Laboratory, Department of Radiology (R.A.F., R.X.J., C.S., N.M.P.B., K.K.P, A.I.H.).
authors.forename: C
authors.initials: C
authors.lastname: Stathopoulos
authors.affiliation: From the Functional MRI Laboratory, Department of Radiology (R.A.F., R.X.J., C.S., N.M.P.B., K.K.P, A.I.H.).
authors.forename: N M
authors.initials: NM
authors.lastname: Petrovich Brennan
authors.affiliation: From the Functional MRI Laboratory, Department of Radiology (R.A.F., R.X.J., C.S., N.M.P.B., K.K.P, A.I.H.) Department of Medical Physics (K.K.P.).
authors.forename: K K
authors.initials: KK
authors.lastname: Peck
authors.affiliation: From the Functional MRI Laboratory, Department of Radiology (R.A.F., R.X.J., C.S., N.M.P.B., K.K.P, A.I.H.) the Brain Tumor Center (A.I.H.), Memorial Sloan-Kettering Cancer Center, New York, New York. holodnya@mskcc.org.
authors.forename: A I
authors.initials: AI
authors.lastname: Holodny
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology*; D009462:Neurology; D011871:Radiology