Multiparametric Quantitative MRI of the Cervical Spinal Cord to Measure Microstructure and Tissue Injury
Author | : Allan Russell Martin |
Publisher | : |
Total Pages | : |
Release | : 2017 |
Genre | : |
ISBN | : |
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An array of spinal cord (SC) quantitative MRI (qMRI) techniques can measure aspects of microstructure and tissue injury. This research develops a clinically feasible multiparametric MRI protocol, including diffusion tensor imaging (DTI) fractional anisotropy (FA), magnetization transfer ratio (MTR), and measurement of SC cross-sectional area (CSA). A novel biomarker of white matter (WM) injury is also introduced, normalizing T2*WI WM signal intensity by grey matter (T2*WI WM/GM). A study of 40 healthy subjects establishes methods, normalization procedures, normative values, and reliability. 58 patients with degenerative cervical myelopathy (DCM) are studied, showing significant differences in 10 metrics. Combining these measures using multivariate methods overcomes the limitations of each technique, achieving good diagnostic accuracy and clinical correlation. T2*WI WM/GM shows strong potential as a novel biomarker, comparing favourably with established biomarkers FA and MTR. Our study of healthy subjects identifies an alarming rate of asymptomatic SC compression (ASCC) at 50%. Objective criteria and automated shape analysis are developed to create a new definition of SC compression, and qMRI demonstrates significant tissue injury in this group. This finding suggests the potential for pre-symptomatic diagnosis of DCM and other spinal pathologies. Finally, a longitudinal study compares multiparametric qMRI with clinical measures for monitoring disease progression in DCM, indicating that modified Japanese Orthopedic Association (mJOA) score is insensitive to detect progression, whereas qMRI showed tissue progression more often than comprehensive clinical assessments. These results suggest that natural history studies employing mJOA underestimate progression, due to neuroplasticity and behavioural adaptation. Combined qMRI and clinical data are now being used to inform surgical decision-making for individual patients. Reliable multiparametric assessment of SC microstructure is possible using clinically suitable methods. This approach shows strong clinical utility for individual patients, including good diagnostic accuracy, correlations with impairment, detection of tissue injury in asymptomatic individuals, and detection of progressive tissue injury in DCM patients.