title: Substantia nigra neuromelanin magnetic resonance imaging in de novo Parkinson's disease patients.
abstract: BACKGROUND
  Depigmentation of the substantia nigra (SN) and locus coeruleus (LC) is a conspicuous pathological feature of Parkinson's disease (PD) and is related to the loss of neuromelanin, whose paramagnetic properties result in high signal on specific T1-weighted magnetic resonance imaging (MRI). Recent studies have suggested that neuromelanin decrease in the SN and LC of PD patients may emerge as a possible diagnostic biomarker. The SN neuromelanin signal in de novo and early stage PD patients was studied to assess its diagnostic accuracy. This is the first study based on a semi-automated MRI analysis of the neuromelanin signal in de novo PD patients.
  
  
  METHODS
  The inclusion criteria were untreated de novo PD and a 2-5 year disease duration; in addition, age matched healthy controls were enrolled. These were studied with a high-resolution T1-weighted MRI sequence at 3 T to visualize neuromelanin. The primary outcome was SN high signal area, length and neuromelanin/midbrain ratio obtained with semi-automated methods.
  
  
  RESULTS
  A total of 12 de novo PD patients and 10 PD patients with a 2-5 year disease duration were evaluated. The area, length of the SN T1 high signal and the SN neuromelanin/midbrain ratio were markedly decreased in the PD groups compared with age-matched controls, with a substantial overlap between the two PD groups.
  
  
  CONCLUSIONS
  Neuromelanin-sensitive MRI techniques can discriminate PD patients from healthy individuals with high sensitivity and specificity. Our findings are consistent with recent findings showing that PD neuromelanin changes remain stable during the course of the disease.
authors.affiliation: Neurological Imaging Department, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Lisbon, Portugal; Clinical Pharmacology Unit, Instituto de Medicina Molecular, Lisbon, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Reimão
authors.forename: P
authors.initials: P
authors.lastname: Pita Lobo
authors.forename: D
authors.initials: D
authors.lastname: Neutel
authors.forename: L
authors.initials: L
authors.lastname: Correia Guedes
authors.forename: M
authors.initials: M
authors.lastname: Coelho
authors.forename: M M
authors.initials: MM
authors.lastname: Rosa
authors.forename: J
authors.initials: J
authors.lastname: Ferreira
authors.forename: D
authors.initials: D
authors.lastname: Abreu
authors.forename: N
authors.initials: N
authors.lastname: Gonçalves
authors.forename: C
authors.initials: C
authors.lastname: Morgado
authors.forename: R G
authors.initials: RG
authors.lastname: Nunes
authors.forename: J
authors.initials: J
authors.lastname: Campos
authors.forename: J J
authors.initials: JJ
authors.lastname: Ferreira
mesh_terms: D000368:Aged; D015415:Biomarkers; D005260:Female; D006801:Humans; D008125:Locus Coeruleus / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D008543:Melanins / Q000378:metabolism*; D008875:Middle Aged; D010300:Parkinson Disease / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013378:Substantia Nigra / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D008543:Melanins; C014121:neuromelanin
keywords: Parkinson's disease; locus coeruleus; magnetic resonance imaging; neuromelanin; substantia nigra