title: Visualization of nigrosome 1 and its loss in PD: pathoanatomical correlation and in vivo 7 T MRI.
abstract: OBJECTIVE
  This study assessed whether high-resolution 7 T MRI allowed direct in vivo visualization of nigrosomes, substructures of the substantia nigra pars compacta (SNpc) undergoing the greatest and earliest dopaminergic cell loss in Parkinson disease (PD), and whether any disease-specific changes could be detected in patients with PD.
  
  
  METHODS
  Postmortem (PM) midbrains, 2 from healthy controls (HCs) and 1 from a patient with PD, were scanned with high-resolution T2*-weighted MRI scans, sectioned, and stained for iron and neuromelanin (Perl), TH, and calbindin. To confirm the identification of nigrosomes in vivo on 7 T T2*-weighted scans, we assessed colocalization with neuromelanin-sensitive T1-weighted scans. We then assessed the ability to depict PD pathology on in vivo T2*-weighted scans by comparing data from 10 patients with PD and 8 age- and sex-matched HCs.
  
  
  RESULTS
  A hyperintense, ovoid area within the dorsolateral border of the otherwise hypointense SNpc was identified in the HC brains on in vivo and PM T2*-weighted MRI. Location, size, shape, and staining characteristics conform to nigrosome 1. Blinded assessment by 2 neuroradiologists showed consistent bilateral absence of this nigrosome feature in all 10 patients with PD, and bilateral presence in 7/8 HC.
  
  
  CONCLUSIONS
  In vivo and PM MRI with histologic correlation demonstrates that high-resolution 7 T MRI can directly visualize nigrosome 1. The absence of nigrosome 1 in the SNpc on MRI scans might prove useful in developing a neuroimaging diagnostic test for PD.
authors.affiliation: Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, UK.
authors.forename: Anna I
authors.initials: AI
authors.lastname: Blazejewska
authors.forename: Stefan T
authors.initials: ST
authors.lastname: Schwarz
authors.forename: Alain
authors.initials: A
authors.lastname: Pitiot
authors.forename: Mary C
authors.initials: MC
authors.lastname: Stephenson
authors.forename: James
authors.initials: J
authors.lastname: Lowe
authors.forename: Nin
authors.initials: N
authors.lastname: Bajaj
authors.forename: Richard W
authors.initials: RW
authors.lastname: Bowtell
authors.forename: Dorothee P
authors.initials: DP
authors.lastname: Auer
authors.forename: Penny A
authors.initials: PA
authors.lastname: Gowland
mesh_terms: D000328:Adult; D000368:Aged; D064026:Calbindins; D004298:Dopamine / Q000502:physiology; D006801:Humans; D007501:Iron; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008543:Melanins; D008875:Middle Aged; D010300:Parkinson Disease / Q000378:metabolism / Q000473:pathology*; D064030:S100 Calcium Binding Protein G; D013378:Substantia Nigra / Q000378:metabolism / Q000473:pathology*
chemical_list: D064026:Calbindins; D008543:Melanins; D064030:S100 Calcium Binding Protein G; C014121:neuromelanin; D007501:Iron; D004298:Dopamine