title: The value of novel MRI techniques in Parkinson-plus syndromes: diffusion tensor imaging and anatomical connectivity studies.
abstract: Conventional MRI is a well-described, highly useful tool for the differential diagnosis of degenerative parkinsonian syndromes. Nevertheless, the observed abnormalities may only appear in late-stage disease. Diffusion tensor imaging (DTI) can identify microstructural changes in brain tissue integrity and connectivity. The technique has proven value in the differential diagnosis of multiple system atrophy (MSA), progressive supranuclear palsy (PSP) and Parkinson's disease (PD). Here, we performed a systematic review of the literature on the main corticosubcortical DTI abnormalities identified to date in the context of the diagnosis of MSA and PSP with diffusion-weighted imaging, diffusion tensor imaging and anatomical connectivity studies. In good agreement with the histological data, increased diffusivity in the putamen (in MSA and PSP), in the middle cerebellar peduncles (in MSA) and in the upper cerebellar peduncles (in PSP) has been reported. Motor pathway involvement is characterized by low fraction anisotropy (FA) in the primary motor cortex in MSA-P and PSP, a high apparent diffusion coefficient (ADC) and low FA in the supplementary motor area in PSP. We then outline the value of these techniques in differential diagnosis (especially with respect to PD). Anatomical connectivity studies have revealed a lower number of fibers in the corticospinal tract in MSA and PSP (relative to PD and controls) and fewer tracked cortical projection fibers in patients with PSP or late-stage MSA (relative to patients with early MSA or PD and controls). Lastly, we report the main literature data concerning the value of DTI parameters in monitoring disease progression. The observed correlations between DTI parameters on one hand and clinical scores and/or disease duration on the other constitute strong evidence of the value of DTI in monitoring disease progression. In MSA, the ataxia score was correlated with ADC values in the pons and the upper cerebellar peduncles, whereas both the motor score and the disease duration were correlated with putaminal ADC values. In conclusion, DTI and connectivity studies constitute promising tools for differentiating between "Parkinson-plus" syndromes.
authors.affiliation: Service de neurologie et pathologie du mouvement, hôpital Salengro, CHRU de Lille, EA 1046, département de pharmacologie médicale, université Lille Nord de France, 1, place de Verdun, 59045 Lille cedex, France; Service de neurologie, CHU d'Amiens, EA 4559, SFR CAP-Santé (FED 4231), université de Picardie-Jules-Verne, chemin du Thil, 80000 Amiens, France. Electronic address: Tir.melissa@chu-amiens.fr.
authors.forename: M
authors.initials: M
authors.lastname: Tir
authors.affiliation: Service de neuroradiologie, hôpital Salengro, CHRU de Lille, EA 4559, université Lille Nord de France, rue Prof.-Émile-Laine, 59037 Lille cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Delmaire
authors.affiliation: Service de neuroradiologie, hôpital Salengro, CHRU de Lille, EA 4559, université Lille Nord de France, rue Prof.-Émile-Laine, 59037 Lille cedex, France.
authors.forename: P
authors.initials: P
authors.lastname: Besson
authors.affiliation: Service de neurologie et pathologie du mouvement, hôpital Salengro, CHRU de Lille, EA 1046, département de pharmacologie médicale, université Lille Nord de France, 1, place de Verdun, 59045 Lille cedex, France.
authors.forename: L
authors.initials: L
authors.lastname: Defebvre
mesh_terms: D001921:Brain / Q000473:pathology; D003937:Diagnosis, Differential; D056324:Diffusion Tensor Imaging / Q000379:methods*; D018450:Disease Progression; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009434:Neural Pathways / Q000473:pathology*; D020734:Parkinsonian Disorders / Q000473:pathology*
keywords: Connectivity; Connectivité; Diffusion tensor imaging; Imagerie du tenseur de diffusion; Parkinson-plus syndrome; Parkinsonian syndromes; Syndromes parkinsoniens plus; Tractographie; Tractography