title: Proximal nerve magnetization transfer MRI relates to disability in Charcot-Marie-Tooth diseases.
abstract: OBJECTIVE
  The objectives of this study were (1) to develop a novel magnetization transfer ratio (MTR) MRI assay of the proximal sciatic nerve (SN), which is inaccessible via current tools for assessing peripheral nerves, and (2) to evaluate the resulting MTR values as a potential biomarker of myelin content changes in patients with Charcot-Marie-Tooth (CMT) diseases.
  
  
  METHODS
  MTR was measured in the SN of patients with CMT type 1A (CMT1A, n = 10), CMT type 2A (CMT2A, n = 3), hereditary neuropathy with liability to pressure palsies (n = 3), and healthy controls (n = 21). Additional patients without a genetically confirmed subtype (n = 4), but whose family histories and electrophysiologic tests were consistent with CMT, were also included. The relationship between MTR and clinical neuropathy scores was assessed, and the interscan and inter-rater reliability of MTR was estimated.
  
  
  RESULTS
  Mean volumetric MTR values were significantly decreased in the SN of patients with CMT1A (33.8 ± 3.3 percent units) and CMT2A (31.5 ± 1.9 percent units) relative to controls (37.2 ± 2.3 percent units). A significant relationship between MTR and disability scores was also detected (p = 0.01 for genetically confirmed patients only, p = 0.04 for all patients). From interscan and inter-rater reliability analyses, proximal nerve MTR values were repeatable at the slicewise and mean volumetric levels.
  
  
  CONCLUSIONS
  MTR measurements may be a viable biomarker of proximal nerve pathology in patients with CMT.
authors.affiliation: From the Department of Radiology and Radiological Sciences (R.D.D., J.C.G., S.A.S.), Vanderbilt University Institute of Imaging Science (R.D.D., L.M.D., J.C.G., S.A.S.), and the Departments of Biomedical Engineering (R.D.D., J.C.G., S.A.S.), Physics and Astronomy (J.C.G., S.A.S.), Molecular Physiology and Biophysics (J.C.G.), and Neurology (J.L.), Vanderbilt University, Nashville, TN. richard.dortch@vanderbilt.edu.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Dortch
authors.affiliation: From the Department of Radiology and Radiological Sciences (R.D.D., J.C.G., S.A.S.), Vanderbilt University Institute of Imaging Science (R.D.D., L.M.D., J.C.G., S.A.S.), and the Departments of Biomedical Engineering (R.D.D., J.C.G., S.A.S.), Physics and Astronomy (J.C.G., S.A.S.), Molecular Physiology and Biophysics (J.C.G.), and Neurology (J.L.), Vanderbilt University, Nashville, TN.
authors.forename: Lindsey M
authors.initials: LM
authors.lastname: Dethrage
authors.affiliation: From the Department of Radiology and Radiological Sciences (R.D.D., J.C.G., S.A.S.), Vanderbilt University Institute of Imaging Science (R.D.D., L.M.D., J.C.G., S.A.S.), and the Departments of Biomedical Engineering (R.D.D., J.C.G., S.A.S.), Physics and Astronomy (J.C.G., S.A.S.), Molecular Physiology and Biophysics (J.C.G.), and Neurology (J.L.), Vanderbilt University, Nashville, TN.
authors.forename: John C
authors.initials: JC
authors.lastname: Gore
authors.affiliation: From the Department of Radiology and Radiological Sciences (R.D.D., J.C.G., S.A.S.), Vanderbilt University Institute of Imaging Science (R.D.D., L.M.D., J.C.G., S.A.S.), and the Departments of Biomedical Engineering (R.D.D., J.C.G., S.A.S.), Physics and Astronomy (J.C.G., S.A.S.), Molecular Physiology and Biophysics (J.C.G.), and Neurology (J.L.), Vanderbilt University, Nashville, TN.
authors.forename: Seth A
authors.initials: SA
authors.lastname: Smith
authors.affiliation: From the Department of Radiology and Radiological Sciences (R.D.D., J.C.G., S.A.S.), Vanderbilt University Institute of Imaging Science (R.D.D., L.M.D., J.C.G., S.A.S.), and the Departments of Biomedical Engineering (R.D.D., J.C.G., S.A.S.), Physics and Astronomy (J.C.G., S.A.S.), Molecular Physiology and Biophysics (J.C.G.), and Neurology (J.L.), Vanderbilt University, Nashville, TN.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
mesh_terms: D000328:Adult; D002607:Charcot-Marie-Tooth Disease / Q000150:complications* / Q000235:genetics; D015331:Cohort Studies; D004185:Disability Evaluation; D006233:Persons with Disabilities; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009185:Myelin Proteins / Q000235:genetics; D020426:Sciatic Neuropathy / Q000175:diagnosis* / Q000209:etiology*; D013223:Statistics as Topic; D055815:Young Adult
chemical_list: D009185:Myelin Proteins; C073687:PMP22 protein, human