title: Combined Diffusion Tensor Imaging and Apparent Transverse Relaxation Rate Differentiate Parkinson Disease and Atypical Parkinsonism.
abstract: OBJECTIVE
  Both diffusion tensor imaging and the apparent transverse relaxation rate have shown promise in differentiating Parkinson disease from atypical parkinsonism (particularly multiple system atrophy and progressive supranuclear palsy). The objective of the study was to assess the ability of DTI, the apparent transverse relaxation rate, and their combination for differentiating Parkinson disease, multiple system atrophy, progressive supranuclear palsy, and controls.
  
  
  METHODS
  A total of 106 subjects (36 controls, 35 patients with Parkinson disease, 16 with multiple system atrophy, and 19 with progressive supranuclear palsy) were included. DTI and the apparent transverse relaxation rate measures from the striatal, midbrain, limbic, and cerebellar regions were obtained and compared among groups. The discrimination performance of DTI and the apparent transverse relaxation rate among groups was assessed by using Elastic-Net machine learning and receiver operating characteristic curve analysis.
  
  
  RESULTS
  Compared with controls, patients with Parkinson disease showed significant apparent transverse relaxation rate differences in the red nucleus. Compared to those with Parkinson disease, patients with both multiple system atrophy and progressive supranuclear palsy showed more widespread changes, extending from the midbrain to striatal and cerebellar structures. The pattern of changes, however, was different between the 2 groups. For instance, patients with multiple system atrophy showed decreased fractional anisotropy and an increased apparent transverse relaxation rate in the subthalamic nucleus, whereas patients with progressive supranuclear palsy showed an increased mean diffusivity in the hippocampus. Combined, DTI and the apparent transverse relaxation rate were significantly better than DTI or the apparent transverse relaxation rate alone in separating controls from those with Parkinson disease/multiple system atrophy/progressive supranuclear palsy; controls from those with Parkinson disease; those with Parkinson disease from those with multiple system atrophy/progressive supranuclear palsy; and those with Parkinson disease from those with multiple system atrophy; but not those with Parkinson disease from those with progressive supranuclear palsy, or those with multiple system atrophy from those with progressive supranuclear palsy.
  
  
  CONCLUSIONS
  DTI and the apparent transverse relaxation rate provide different but complementary information for different parkinsonisms. Combined DTI and apparent transverse relaxation rate may be a superior marker for the differential diagnosis of parkinsonisms.
authors.affiliation: From the Departments of Neurology (G.D., M.M.L., N.W.S., L.H., X.H.) guangweidu@hmc.psu.edu xuemei@psu.edu.
authors.forename: G
authors.identifier: http://orcid.org/0000-0002-8267-0301
authors.initials: G
authors.lastname: Du
authors.affiliation: From the Departments of Neurology (G.D., M.M.L., N.W.S., L.H., X.H.).|Pharmacology (M.M.L., X.H.).
authors.forename: M M
authors.identifier: http://orcid.org/0000-0002-1375-689X
authors.initials: MM
authors.lastname: Lewis
authors.affiliation: Radiology (S.K., X.H.).
authors.forename: S
authors.identifier: http://orcid.org/0000-0002-4192-7414
authors.initials: S
authors.lastname: Kanekar
authors.affiliation: From the Departments of Neurology (G.D., M.M.L., N.W.S., L.H., X.H.).
authors.forename: N W
authors.identifier: http://orcid.org/0000-0001-6240-0892
authors.initials: NW
authors.lastname: Sterling
authors.affiliation: From the Departments of Neurology (G.D., M.M.L., N.W.S., L.H., X.H.).|Department of Public Health (L.H.), Shanxi Medical University, Taiyuan, China.
authors.forename: L
authors.identifier: http://orcid.org/0000-0003-2220-7347
authors.initials: L
authors.lastname: He
authors.affiliation: Public Health Sciences (L.K.), Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, Pennsylvania.
authors.forename: L
authors.identifier: http://orcid.org/0000-0001-6098-9445
authors.initials: L
authors.lastname: Kong
authors.affiliation: Department of Statistics (R.L.), Pennsylvania State University, University Park, Pennsylvania.
authors.forename: R
authors.identifier: http://orcid.org/0000-0002-0154-2202
authors.initials: R
authors.lastname: Li
authors.affiliation: From the Departments of Neurology (G.D., M.M.L., N.W.S., L.H., X.H.) guangweidu@hmc.psu.edu xuemei@psu.edu.|Radiology (S.K., X.H.).|Pharmacology (M.M.L., X.H.).|Neurosurgery (X.H.).|Kinesiology (X.H.).|Bioengineering (X.H.).
authors.forename: X
authors.identifier: http://orcid.org/0000-0003-3583-5502
authors.initials: X
authors.lastname: Huang
mesh_terms: D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging / Q000379:methods*; D020734:Parkinsonian Disorders / Q000000981:diagnostic imaging*; D012372:ROC Curve