Clinical application of brain MRI in parkinsonism. From basic to advanced imaging

Parkinson’s disease is a neurodegenerative disorder with increased prevalence at raising age, and the most frequent cause of parkinsonism. In clinical practice, differentiating Parkinson’s disease from the various forms of neurodegenerative atypical parkinsonism can be difficult, especially in the early stages of the disease. For adequate patient treatment and counseling, it is important to establish the correct diagnosis in early disease stages. The main objective of the studies presented in this thesis is to evaluate the (added) diagnostic value of brain MR imaging in early stage parkinsonism. The current state of literature concerning brain MR imaging in Parkinson’s disease and atypical parkinsonism is discussed, both for conventional and advanced MR imaging sequences. Next, the diagnostic value of brain MR imaging in the diagnostic work-up of early stage parkinsonism is evaluated, both for a conventional MR protocol performed at 1 or 1.5 Tesla magnetic field strength, and for a standardized 3 Tesla MR scanning protocol extended with a Susceptibility Weighted Imaging (SWI) and Diffusion Tensor Imaging (DTI) sequence. Brain MR imaging proves to be of added value for the diagnostic work-up of early stage parkinsonism, mainly when there is uncertainty about the clinical diagnosis. To further enhance the diagnostic yield, an optimized MR imaging scanning protocol is advised, which includes a T2* or SWI sequence. We demonstrate that severe hypo-intensity of the putamen on SWI is indicative of MSA-P, and this improves the diagnostic accuracy of brain MRI. High-resolution SWI could possibly provide a new diagnostic marker specific for Parkinson’s disease, though further research is needed to evaluate its diagnostic work-up of early stage parkinsonism. Clinical application of quantitative DTI is more complex, as it requires dedicated post-processing, and quantitative measures are dependent on the scanning parameters and magnetic field strength used