title: Magnetic resonance correlation of iron content with neuromelanin in the substantia nigra of early-stage Parkinson's disease.
abstract: OBJECTIVE
  Magnetic resonance (MR) studies have demonstrated a significant reduction of neuromelanin in the substantia nigra (SN) of Parkinson's disease (PD) patients with high accuracy for differential diagnosis compared to non-PD controls and essential tremor. However, studies state that not knowing how paramagnetic effects of iron influence neuromelanin signal is a limitation. In this study a neuromelanin-sensitive MR sequence was combined with T2* relaxometry iron quantification analysis to study the SN of early-stage PD patients to investigate the correlation between these parameters.
  
  
  METHODS
  The inclusion criteria were untreated de novo PD patients and a 2-5 year disease duration (early PD); in addition, age-matched controls were enrolled. These were studied at 3.0 T with a high-resolution T1-weighted MR sequence to visualize neuromelanin and a relaxometry sequence for iron quantification. The primary outcome was the correlation of the width of the neuromelanin high signal region and the T2* values in the lateral, central and medial segments of the SN.
  
  
  RESULTS
  Very weak correlations of T2* values with neuromelanin width, positive for global and negative for the medial and lateral SN segments, were found in both PD groups and control subjects. The SN neuromelanin width was markedly reduced in the de novo and early PD groups compared with controls in all SN segments, but no significant difference in T2* values was found between the groups.
  
  
  CONCLUSIONS
  The SN neuromelanin signal does not have a significant correlation with iron content in PD patients or controls. The neuromelanin MR signal reduction in PD does not seem to be significantly influenced by paramagnetic iron effects.
authors.affiliation: Neurological Imaging Department, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Lisbon, Portugal.|Clinical Pharmacology Unit, Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Lisbon, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Reimão
authors.affiliation: Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Ferreira
authors.affiliation: Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: R G
authors.initials: RG
authors.lastname: Nunes
authors.affiliation: Clinical Pharmacology Unit, Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Lisbon, Portugal.|Neurology Department, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Lisbon, Portugal.|CNS - Campus Neurológico Sénior, Torres Vedras, Portugal.
authors.forename: P
authors.initials: P
authors.lastname: Pita Lobo
authors.affiliation: Clinical Pharmacology Unit, Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Lisbon, Portugal.|Neurology Department, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Lisbon, Portugal.
authors.forename: D
authors.initials: D
authors.lastname: Neutel
authors.affiliation: Clinical Pharmacology Unit, Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Lisbon, Portugal.
authors.forename: D
authors.initials: D
authors.lastname: Abreu
authors.affiliation: Clinical Pharmacology Unit, Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Lisbon, Portugal.
authors.forename: N
authors.initials: N
authors.lastname: Gonçalves
authors.affiliation: Neurological Imaging Department, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Lisbon, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Campos
authors.affiliation: Clinical Pharmacology Unit, Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Lisbon, Portugal.|Neurology Department, Hospital de Santa Maria - Centro Hospitalar Lisboa Norte, Lisbon, Portugal.|CNS - Campus Neurológico Sénior, Torres Vedras, Portugal.|Laboratory of Clinical Pharmacology and Therapeutics, Faculty of Medicine, University of Lisbon, Lisbon, Portugal.
authors.forename: J J
authors.initials: JJ
authors.lastname: Ferreira
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007501:Iron / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008543:Melanins / Q000378:metabolism*; D008875:Middle Aged; D010300:Parkinson Disease / Q000378:metabolism*; D013378:Substantia Nigra / Q000378:metabolism*
chemical_list: D008543:Melanins; C014121:neuromelanin; D007501:Iron
keywords: MRI; Parkinson's disease; iron; neuromelanin; substantia nigra