title: MR imaging of the substantia nigra at 7 T enables diagnosis of Parkinson disease.
abstract: OBJECTIVE
  To evaluate the anatomy of the substantia nigra (SN) in healthy subjects by performing 7-T magnetic resonance (MR) imaging of the SN, and to prospectively define the accuracy of 7-T MR imaging in distinguishing Parkinson disease (PD) patients from healthy subjects on an individual basis.
  
  
  METHODS
  The 7-T MR imaging protocol was approved by the Italian Ministry of Health and by the local competent ethics committee. SN anatomy was described ex vivo on a gross brain specimen by using highly resolved proton-density (spin-echo proton density) and gradient-recalled-echo (GRE) images, and in vivo in eight healthy subjects (mean age, 40.1 years) by using GRE three-dimensional multiecho susceptibility-weighted images. After training on appearance of SN in eight healthy subjects, the SN anatomy was evaluated twice by two blinded observers in 13 healthy subjects (mean age, 54.7 years) and in 17 PD patients (mean age, 56.9 years). Deviations from normal SN appearance were described and indicated as abnormal, and both diagnostic accuracy and intra- and interobserver agreement for diagnosis of PD with 7-T MR imaging were calculated.
  
  
  RESULTS
  Three-dimensional multiecho susceptibility-weighted 7-T MR imaging reveals a three-layered organization of the SN allowing readers to distinguish pars compacta ventralis and dorsalis from pars reticulata. The abnormal architecture of the SN allowed a discrimination between PD patients and healthy subjects with sensitivity and specificity of 100% and 96.2% (range, 92.3%-100%), respectively. Intraobserver agreement (κ = 1) and interobserver agreement (κ = 0.932) were excellent.
  
  
  CONCLUSIONS
  MR imaging at 7-T allows a precise characterization of the SN and visualization of its inner organization. Three-dimensional multiecho susceptibility-weighted images can be used to accurately differentiate healthy subjects from PD patients, which provides a novel diagnostic opportunity.
authors.affiliation: From the IMAGO7 Foundation, Pisa, Italy (M. Cosottini, M. Costagli); Department of Translational Research and New Surgical and Medical Technologies (M. Cosottini) and Neurology Unit, Department of Clinical and Experimental Medicine (D.F., R.C., U.B.), University of Pisa, Pisa, Italy; Neuroradiology Unit, Department of Diagnostic and Interventional Radiology, Azienda Ospedaliero-Universitaria Pisana (AOUP), Pisa, Italy (I.P.); and Stella Maris Scientific Institute, Pisa, Italy (L.B., M.T.).
authors.forename: Mirco
authors.initials: M
authors.lastname: Cosottini
authors.forename: Daniela
authors.initials: D
authors.lastname: Frosini
authors.forename: Ilaria
authors.initials: I
authors.lastname: Pesaresi
authors.forename: Mauro
authors.initials: M
authors.lastname: Costagli
authors.forename: Laura
authors.initials: L
authors.lastname: Biagi
authors.forename: Roberto
authors.initials: R
authors.lastname: Ceravolo
authors.forename: Ubaldo
authors.initials: U
authors.lastname: Bonuccelli
authors.forename: Michela
authors.initials: M
authors.lastname: Tosetti
mesh_terms: D000328:Adult; D000368:Aged; D002102:Cadaver; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis / Q000473:pathology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013378:Substantia Nigra / Q000033:anatomy & histology / Q000473:pathology*