title: Transcallosal diffusion tensor abnormalities in predominant gait disorder parkinsonism.
abstract: BACKGROUND
  There have been no previous diffusion tensor imaging (DTI) studies comparing Parkinson's disease (PD) with postural instability and gait disorder (PIGD) parkinsonism.
  
  
  OBJECTIVE
  Utilizing DTI with 2-region tractography, we conducted a case control study to determine if different brain regions representing the neural network of the motor system are differentially affected in PIGD compared to PD and controls.
  
  
  METHODS
  On a 3 T MR machine, using manual ROI (regions of interest) we determined the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values on DTI in anatomical brain regions representing the extrapyramidal, pyramidal, and transcallosal tracts, aided by 2-region tractography. FA and ADC were correlated with the Tinetti score (measure of gait and balance).
  
  
  RESULTS
  Sixty-five subjects (21 PD, 25 PIGD, 19 controls) were included in the analysis. We demonstrated greater ADC abnormalities in the extrapyramidal, pyramidal and transcallosal motor systems in PIGD compared to controls. Multivariate analysis taking into consideration various clinical variables showed that the FA (p = 0.02) and ADC (p = 0.001) values in the corpus callosum body differentiated PIGD from PD. PIGD with low Tinetti score had a lower FA (p = 0.02) and a higher ADC value (corpus callosum body) (p = 0.03) compared to those with a high score.
  
  
  CONCLUSIONS
  We demonstrated for the first time that DTI abnormalities along the transcallosal motor tract in the body of the corpus callosum, but not the substantia nigra, differentiated PIGD from PD, and the degree of corpus callosum body abnormality correlated with the Tinetti score (a measure of risk of falls).
authors.affiliation: Department of Diagnostic Radiology, Singapore General Hospital, Republic of Singapore.
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Chan
authors.affiliation: Department of Diagnostic Radiology, Singapore General Hospital, Republic of Singapore; Duke-NUS Graduate Medical School, Republic of Singapore.
authors.forename: Kia-Min
authors.initials: KM
authors.lastname: Ng
authors.affiliation: Department of Diagnostic Radiology, Singapore General Hospital, Republic of Singapore.
authors.forename: Helmut
authors.initials: H
authors.lastname: Rumpel
authors.affiliation: Department of Clinical Research, Singapore General Hospital, Republic of Singapore.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Fook-Chong
authors.affiliation: Department of Clinical Research, Singapore General Hospital, Republic of Singapore.
authors.forename: Hui-Hua
authors.initials: HH
authors.lastname: Li
authors.affiliation: Department of Neurology, Singapore General Hospital, Republic of Singapore; Department of Clinical Research, Singapore General Hospital, Republic of Singapore; National Neuroscience Institute, Republic of Singapore; Duke-NUS Graduate Medical School, Republic of Singapore. Electronic address: gnrtek@sgh.com.sg.
authors.forename: Eng-King
authors.initials: EK
authors.lastname: Tan
mesh_terms: D000368:Aged; D016880:Anisotropy; D016022:Case-Control Studies; D003337:Corpus Callosum / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D010300:Parkinson Disease / Q000473:pathology*; D020734:Parkinsonian Disorders / Q000150:complications / Q000473:pathology*; D012372:ROC Curve; D012680:Sensitivity and Specificity
keywords: Diffusion tensor imaging; Gait disorder; Parkinson's disease; Postural instability