title: Diffusivity measurements differentiate benign from malignant lesions in patients with peripheral neuropathy or plexopathy.
abstract: OBJECTIVE
  Peripheral nerve disorders caused by benign and malignant primary nerve sheath tumors, infiltration or compression of nerves by metastatic disease, and postradiation neuritis demonstrate overlapping features on conventional MR imaging but require vastly different therapeutic approaches. We characterize and compare diffusivities of peripheral nerve lesions in patients undergoing MR neurography for peripheral neuropathy or brachial or lumbosacral plexopathy.
  
  
  METHODS
  Twenty-three patients, referred for MR neurography at our institution between 2003 and 2009 for a peripheral mononeuropathy or brachial or lumbosacral plexopathy and whose examinations included DWI, received a definitive diagnosis, based on biopsy results or clinical and imaging follow-up, for a masslike or infiltrative peripheral nerve or plexus lesion suspicious for tumor. Mean ADC values were determined within each lesion and compared across 3 groups (benign lesions, malignant lesions, and postradiation changes).
  
  
  RESULTS
  Both ANOVA and Kruskal-Wallis tests demonstrated a statistically significant difference in ADC values across the 3 groups (P = .000023, P = .00056, respectively). Post hoc pair-wise comparisons showed that the ADC within malignant tumors differed significantly from that within benign tumors and postradiation changes. ADC within benign tumors and postradiation changes did not differ significantly from each other.
  
  
  CONCLUSIONS
  DWI may be highly effective for the differentiation of benign from malignant peripheral nerve masslike or infiltrative lesions.
authors.affiliation: From the Departments of Radiology and Biomedical Imaging (E.L.Y., C.T.C.).
authors.forename: E L
authors.initials: EL
authors.lastname: Yuh
authors.affiliation: San Leandro Medical Center (S.J.P.), The Permanente Medical Group, San Leandro, California.
authors.forename: S
authors.initials: S
authors.lastname: Jain Palrecha
authors.affiliation: Department of Radiology (G.M.L.), University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: G M
authors.initials: GM
authors.lastname: Lagemann
authors.affiliation: Department of Neurosurgery (M.K.), Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: M
authors.initials: M
authors.lastname: Kliot
authors.affiliation: Neurological Surgery (P.R.W.), University of California at San Francisco, San Francisco, California.
authors.forename: P R
authors.initials: PR
authors.lastname: Weinstein
authors.affiliation: Goodman Campbell Brain and Spine (N.M.B.) Department of Neurological Surgery (N.M.B.), Indiana University, Indianapolis, Indiana.
authors.forename: N M
authors.initials: NM
authors.lastname: Barbaro
authors.affiliation: From the Departments of Radiology and Biomedical Imaging (E.L.Y., C.T.C.) cynthia.t.chin@ucsf.edu.
authors.forename: C T
authors.initials: CT
authors.lastname: Chin
mesh_terms: D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018317:Nerve Sheath Neoplasms / Q000150:complications / Q000175:diagnosis*; D010523:Peripheral Nervous System Diseases / Q000209:etiology*