Magnetic resonance imaging of cognition in Parkinson’s disease

Parkinson;;s disease;Magnetic Resonance Imaging;Cognition;Arterial Spin Labelling;Diffusion Tensor Imaging

Melzer, Tracy Robert ; Anderson, Tim J ; MacAskill, Michael R ; Watts, Richard

University of Otago

关键词: Parkinson;    ;    s disease;    Magnetic Resonance Imaging;    Cognition;    Arterial Spin Labelling;    Diffusion Tensor Imaging;   

Others  :  https://ourarchive.otago.ac.nz/bitstream/10523/1719/1/MelzerTracyR2011PhD.pdf

美国|英语

来源: Otago University Research Archive

【 摘 要 】

Parkinson’s disease (PD) is a debilitating neurodegenerative movement disorder characterized by tremor, rigidity, bradykinesia, and postural instability. Additionally, a large portion of those with Parkinson’s disease will experience cognitive decline, with up to 80% developing dementia. In patients without dementia, cognitive impairment of a lesser severity, or mild cognitive impairment, is also frequent. The identification and characterization of mild cognitive impairment in the early stages of cognitive decline would allow clinicians to better assess the patient’s prognosis and facilitate informed disease management. No robust biochemical or genetic markers have emerged, but recent neuroimaging work shows promise. Magnetic resonance imaging (MRI) is one such technique that may be employed to identify quantitative biomarkers of cognitive decline in PD. Ninety-six patients with PD and 34 healthy controls matched for mean age, years of education, and sex ratio participated in this study. Comprehensive neuropsychological testing was used to classify PD patients as either cognitively normal (PD-N, n = 59), with mild cognitive impairment (PD-MCI, n = 22), or with dementia (PD-D, n = 15). Each participant completed a magnetic resonance imaging scanning session on a 3 T machine that included conventional structural imaging (sensitive to atrophy), arterial spin labelling perfusion imaging (sensitive to cerebral blood flow), and diffusion tensor imaging (sensitive to tissue microstructural integrity). All three MRI modalities were analysed using a general linear model in order to compare underlying brain differences associated with cognitive impairment in PD. Relative to controls, those with Parkinson’s disease and mild cognitive impairment and those with dementia showed significant grey matter atrophy, hypoperfusion, and loss of microstructural integrity in extensive brain regions. A dissociation of severe hypoperfusion and minimal atrophy in the PD-MCI group was also identified, a finding that holds promise as a biomarker of cognitive status in PD. Furthermore, distinct regions of atrophy, hypoperfusion, and microscopic damage significantly correlated with cognitive status. Principal component analysis was used to identify a characteristic pattern of abnormal perfusion associated with Parkinson’s disease. Absolute perfusion values were used to interpret the identified network as one of cortical hypoperfusion. Both motor and cognitive statuses were significant factors related to the expression of the PD-related perfusion pattern. In this thesis, I have identified promising cross sectional biomarkers of cognitive status in PD using structural, diffusion, and perfusion MRI. To provide maximum utility to the Parkinson’s disease community, these markers should describe progression as well. A longitudinal study—currently underway—will provide the opportunity to test whether these encouraging imaging findings can faithfully track progression of PD-related cognitive decline.