Abstract:
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Purpose: Imaging the cortical plaques of multiple sclerosis which has until now been impossible using conventional imaging at 1.5 T. The improved signal-to-noise ratio of imaging at 8T provided an opportunity to examine these plaques.
Methods and Materials: Postmortem formalin-fixed brain slices from an MS patient were examined for cortical pathology using 8T and 1.5 T imaging techniques. A transverse electromagnetic (TEM) coil was used for acquisition of the images. The slices in saline was placed in the coil for tuning with a HP 4195A spectrum analyzer. A 4 msec sinc RF pulse was used to determine the required RF power for a 90 degree flip angle. Axial spin-echo and gradient-echo images were acquired using the following typical parameters: TR=700ms, TE = 11ms, slice thickness = 2 mm, FOV = 15cmx15cm, Matrix = 1024 x 1024,NEX = 1. Standard sequences were used for imaging the same slices at 1.5 T. All slices were examined by standard H&E staining as well as stains with luxol-fast-blue PAS to confirm the cortical pathology.
Results: Numerous cortical plaques not seen by imaging at 1.5 T were evident using imaging at 8T. Lesions were easily identified using gradient echo, spin echo as well as diffusion images. The superior resolution of the 8T not only identified numerous cortical lesions, but also subtle disorganization of the cytoarchitectural organization of the cortical layers. As to whether the cortical disorganization is a manifestation of pathology of multiple sclerosis is not known. Additionally, it is also not clear whether the cortical grey-matter pathology is a primary event or alternately a consequence of the overwhelming white matter pathology in this patient, who suffered from severe disabilities (KEDSS 8.0) consequent to secondary progressive multiple sclerosis. Our present efforts are directed at quantitation of the relative involvement of the cerebral cortex in MS and white matter in MS, by imaging and corroborating the lesions by pathology.
Conclusion: It would appear that MS is not merely a disorder of myelin but also a disorder of the axons and neurons. Until imaging techniques can visualize involvement in all 3 domains, the correlation of imaging with clinical disability and clinical course will remain incomplete. The ability to image plaques at 8T during life should enhance our understanding of this disorder and help with choice of patients in clinical trials.
Kangarlu PhD, A,
Detection of Cerebral Cortical Lesions in Multiple Sclerosis Using High Field MRI at 8T. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3102914.html
