title: MRI of pathology-proven peripheral nerve amyloidosis.
abstract: OBJECTIVE
  To highlight the MRI characteristics of pathologically proven amyloidosis involving the peripheral nervous system (PNS) and determine the utility of MRI in directing targeted biopsy for aiding diagnosis.
  
  
  METHODS
  A retrospective study was performed for patients with pathologically proven PNS amyloidosis who also underwent MRI of the biopsied or excised nerve. MRI signal characteristics, nerve morphology, associated muscular denervation changes, and the presence of multifocal involvement were detailed. Pathology reports were reviewed to determine subtypes of amyloid. Charts were reviewed to gather patient demographics, neurological symptoms and radiologist interpretation.
  
  
  RESULTS
  Four men and three women with a mean age of 62 ± 11 years (range 46-76) were identified. All patients had abnormal findings on EMG with mixed sensorimotor neuropathy. All lesions demonstrated diffuse multifocal neural involvement with T1 hypointensity, T2 hyperintensity, and variable enhancement on MRI. One lesion exhibited superimposed T2 hypointensity. Six of seven patients demonstrated associated muscular denervation changes.
  
  
  CONCLUSIONS
  Peripheral nerve amyloidosis is rare, and the diagnosis is difficult because of insidious symptom onset, mixed sensorimotor neurologic deficits, and the potential for a wide variety of nerves affected. On MRI, peripheral nerve involvement is most commonly characterized by T1 hypointensity, T2 hyperintensity, variable enhancement, maintenance of the fascicular architecture with fusiform enlargement, multifocal involvement and muscular denervation changes. While this appearance mimics other inflammatory neuropathies, MRI can readily detect neural changes and direct-targeted biopsy, thus facilitating early diagnosis and appropriate management.
authors.affiliation: Department of Musculoskeletal Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA. mckenzie.gavin@mayo.edu.
authors.forename: Gavin A
authors.initials: GA
authors.lastname: McKenzie
authors.affiliation: Department of Musculoskeletal Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Broski
authors.affiliation: Department of Musculoskeletal Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Howe
authors.affiliation: Department of Musculoskeletal Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Spinner
authors.affiliation: Department of Musculoskeletal Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Amrami
authors.affiliation: Department of Musculoskeletal Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Angela
authors.initials: A
authors.lastname: Dispenzieri
authors.affiliation: Department of Musculoskeletal Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Ringler
mesh_terms: D000368:Aged; D000686:Amyloidosis / Q000000981:diagnostic imaging* / Q000473:pathology; D003287:Contrast Media; D005260:Female; D006801:Humans; D061705:Image-Guided Biopsy; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010523:Peripheral Nervous System Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D012189:Retrospective Studies; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging* / Q000473:pathology
chemical_list: D003287:Contrast Media
keywords: Amyloid; Amyloidoma; Amyloidosis; MRI; Peripheral nerve