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PT  - JOURNAL ARTICLE
AU  - Guttuso, T.
AU  - Bergsland, N.
AU  - Hagemeier, J.
AU  - Lichter, D.G.
AU  - Pasternak, O.
AU  - Zivadinov, R.
TI  - Substantia Nigra Free Water Increases Longitudinally in Parkinson Disease
AID  - 10.3174/ajnr.A5545
DP  - 2018 Mar 01
TA  - American Journal of Neuroradiology
PG  - 479--484
VI  - 39
IP  - 3
4099  - http://www.ajnr.org/content/39/3/479.short
4100  - http://www.ajnr.org/content/39/3/479.full
SO  - Am. J. Neuroradiol.2018 Mar 01; 39
AB  - BACKGROUND AND PURPOSE: Free water in the posterior substantia nigra obtained from a bi-tensor diffusion MR imaging model has been shown to significantly increase over 1- and 4-year periods in patients with early-stage idiopathic Parkinson disease compared with healthy controls, which suggests that posterior substantia nigra free water may be an idiopathic Parkinson disease progression biomarker. Due to the known temporal posterior-to-anterior substantia nigra degeneration in idiopathic Parkinson disease, we assessed longitudinal changes in free water in both the posterior and anterior substantia nigra in patients with later-stage idiopathic Parkinson disease and age-matched healthy controls for comparison.MATERIALS AND METHODS: Nineteen subjects with idiopathic Parkinson disease and 19 age-matched healthy control subjects were assessed on the same 3T MR imaging scanner at baseline and after approximately 3 years.RESULTS: Baseline mean idiopathic Parkinson disease duration was 7.1 years. Both anterior and posterior substantia nigra free water showed significant intergroup differences at baseline (P &amp;lt; .001 and P = .014, respectively, idiopathic Parkinson disease versus healthy controls); however, only anterior substantia nigra free water showed significant longitudinal group × time interaction increases (P = .021, idiopathic Parkinson disease versus healthy controls). There were no significant longitudinal group × time interaction differences found for conventional diffusion tensor imaging or free water–corrected DTI assessments in either the anterior or posterior substantia nigra.CONCLUSIONS: Results from this study provide further evidence supporting substantia nigra free water as a promising disease-progression biomarker in idiopathic Parkinson disease that may help to identify disease-modifying therapies if used in future clinical trials. Our novel finding of longitudinal increases in anterior but not posterior substantia nigra free water is potentially a result of the much longer disease duration of our cohort compared with previously studied cohorts and the known posterior-to-anterior substantia nigra degeneration that occurs over time in idiopathic Parkinson disease.aSNanterior substantia nigraFWfree waterHChealthy controlIPDidiopathic Parkinson diseaseIPD-NMsubjects with IPD not receiving any MAOI at baselineIPD-Rsubjects with IPD receiving rasagiline at baselineMAOImonoamine oxidase inhibitorMMSEMini-Mental State ExaminationMoCAMontreal Cognitive AssessmentMNIMontreal Neurological InstituteNODDIneurite orientation dispersion and density imagingpSNposterior substantia nigraSNsubstantia nigra pars compacta