title: Basal Ganglia Iron in Patients with Multiple Sclerosis Measured with 7T Quantitative Susceptibility Mapping Correlates with Inhibitory Control.
abstract: OBJECTIVE
  T2 hypointensity in the basal ganglia of patients with MS has been associated with clinical progression and cognitive decline. Our objectives were the following: 1) to compare signal in T2WI, R2 (ie, 1/T2), and R2* (ie, 1/T2*) relaxation rates and quantitative susceptibility mapping; and 2) to investigate the associations among MR imaging, clinical scores, and cognitive measures of inhibitory control linked to basal ganglia functioning.
  
  
  METHODS
  Twenty-nine patients with MS underwent a battery of neuropsychological tests including the Flanker and Stroop tasks. 7T MR imaging included 3D gradient-echo and single-echo multishot spin-echo EPI. Quantitative susceptibility mapping images were calculated by using a Wiener filter deconvolution algorithm. T2WI signal was normalized to CSF. R2 and R2* were calculated by log-linear regression. Average MR imaging metrics for the globus pallidus, putamen, and caudate were computed from manually traced ROIs including the largest central part of each structure.
  
  
  RESULTS
  Marked spatial variation was consistently visualized on quantitative susceptibility mapping and T2/T2*WI within each basal ganglia structure. MR imaging metrics correlated with each other for each basal ganglia structure individually. Notably, caudate and putamen quantitative susceptibility mapping metrics were similar, but the putamen R2 was larger than the caudate R2. This finding suggests that tissue features contribute differently to R2 and quantitative susceptibility mapping. Caudate and anterior putamen quantitative susceptibility mapping correlated with the Flanker but not Stroop measures; R2 did not correlate with inhibitory control measures. Putamen quantitative susceptibility mapping and caudate and putamen R2 correlated with the Expanded Disability Status Scale.
  
  
  CONCLUSIONS
  Our study showed that quantitative susceptibility mapping and R2 may be complementary indicators for basal ganglia tissue changes in MS. Our findings are consistent with the hypothesis that decreased performance of basal ganglia-reliant tasks involving inhibitory control is associated with increased quantitative susceptibility mapping.
authors.affiliation: From the Departments of Radiology (P.S., G.K.Y., M. Russell, M.V.K.) petra.schmalbrock@osumc.edu.
authors.forename: P
authors.identifier: http://orcid.org/0000-0002-4898-9984
authors.initials: P
authors.lastname: Schmalbrock
authors.affiliation: Psychology (R.S.P., B.S., A.J.).
authors.forename: R S
authors.initials: RS
authors.lastname: Prakash
authors.affiliation: Psychology (R.S.P., B.S., A.J.).
authors.forename: B
authors.initials: B
authors.lastname: Schirda
authors.affiliation: Psychology (R.S.P., B.S., A.J.).
authors.forename: A
authors.initials: A
authors.lastname: Janssen
authors.affiliation: From the Departments of Radiology (P.S., G.K.Y., M. Russell, M.V.K.).
authors.forename: G K
authors.initials: GK
authors.lastname: Yang
authors.affiliation: From the Departments of Radiology (P.S., G.K.Y., M. Russell, M.V.K.).
authors.forename: M
authors.initials: M
authors.lastname: Russell
authors.affiliation: From the Departments of Radiology (P.S., G.K.Y., M. Russell, M.V.K.).
authors.forename: M V
authors.initials: MV
authors.lastname: Knopp
authors.affiliation: Neurology (A.B., J.A.N., M. Racke), The Ohio State University, Columbus, Ohio.
authors.forename: A
authors.initials: A
authors.lastname: Boster
authors.affiliation: Neurology (A.B., J.A.N., M. Racke), The Ohio State University, Columbus, Ohio.
authors.forename: J A
authors.initials: JA
authors.lastname: Nicholas
authors.affiliation: Neurology (A.B., J.A.N., M. Racke), The Ohio State University, Columbus, Ohio.
authors.forename: M
authors.initials: M
authors.lastname: Racke
authors.affiliation: Department of Neurology (D.P.), Yale School of Medicine, New Haven, Connecticut.
authors.forename: D
authors.initials: D
authors.lastname: Pitt
mesh_terms: D000328:Adult; D000368:Aged; D001479:Basal Ganglia / Q000473:pathology* / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007501:Iron / Q000032:analysis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology* / Q000503:physiopathology
chemical_list: D007501:Iron