Contributions
Abstract: EP1440
Type: ePoster
Abstract Category: Pathology and pathogenesis of MS - Imaging
Background: Loss of tissue coherency is well recognized in MS patients following changes in myelin and axonal property. Recent evidence show that extensive pathological damage also exists in the normal appearing white matter (NAWM) of the central nervous system, and that is associated with the continuing progression of patient disability. Current measurement of tissue coherency relies on advanced MRI, which however is not part of the standard imaging protocol in MS. In this study, we developed a new image-processing method for assessing tissue coherency through measurement of the alignment in white matter structure using T2-weighted MRI.
Methods: This is based on Fourier transform power spectrum, a verified approach in histological studies. We calculated NAWM alignment of the corpus callosum in axial T2-weighted MRI obtained from a 3T scanner. These images were obtained from 19 patients (10 RRRMS; 9 SPMS) and 19 matched controls. Six regions of interest were examined from the left, central, and right aspects of the genu and splenium of corpus callosum. To assess tissue alignment, we performed the following steps: 1) Fourier transform power spectrum of the ROIs; 2) power spectrum normalization and thresholding; and 3) polar conversion and angle extraction of the spectrum. The highest peak of an angular spectrum is considered the dominant direction of a structure, and angular entropy of the spectrum was calculated to characterize the alignment complexity of the structure; larger entropy reflects greater complexity.
Results: The dominant directions derived from our method were highly consistent with the observed alignment in each ROI (p < 0.05). Tissue angular entropy was greater in patients than in controls, and tended to be greater in SPMS than in RRMS in the splenium. When considering all ROIs per group, the peak location of angular entropy was found increasing from -10 in controls, to -3 in RRMS, and to -2 in SPMS.
Conclusions: Our new method suggests that Fourier transform power spectrum has the potential to identify tissue coherency using clinical MRI. Outcomes of angular entropy reflect the degree of tissue injury that increases from controls to RRMS and then to SPMS. This method may become a new way of studying subtle pathologies of MS subjects in a clinical setting and deserves further verification.
Disclosure: Sharma S is funded by the Queen Elizabeth II graduate scholarship from the University of Calgary and the graduate scholarship from NSERC I3T Create Scholarship, Canada.
This project was funded by the operating grants (Zhang Y) from MS Society of Canada, Natural Sciences and Engineering Council of Canada, and Alberta Innovates - Health Solutions, Canada.
Abstract: EP1440
Type: ePoster
Abstract Category: Pathology and pathogenesis of MS - Imaging
Background: Loss of tissue coherency is well recognized in MS patients following changes in myelin and axonal property. Recent evidence show that extensive pathological damage also exists in the normal appearing white matter (NAWM) of the central nervous system, and that is associated with the continuing progression of patient disability. Current measurement of tissue coherency relies on advanced MRI, which however is not part of the standard imaging protocol in MS. In this study, we developed a new image-processing method for assessing tissue coherency through measurement of the alignment in white matter structure using T2-weighted MRI.
Methods: This is based on Fourier transform power spectrum, a verified approach in histological studies. We calculated NAWM alignment of the corpus callosum in axial T2-weighted MRI obtained from a 3T scanner. These images were obtained from 19 patients (10 RRRMS; 9 SPMS) and 19 matched controls. Six regions of interest were examined from the left, central, and right aspects of the genu and splenium of corpus callosum. To assess tissue alignment, we performed the following steps: 1) Fourier transform power spectrum of the ROIs; 2) power spectrum normalization and thresholding; and 3) polar conversion and angle extraction of the spectrum. The highest peak of an angular spectrum is considered the dominant direction of a structure, and angular entropy of the spectrum was calculated to characterize the alignment complexity of the structure; larger entropy reflects greater complexity.
Results: The dominant directions derived from our method were highly consistent with the observed alignment in each ROI (p < 0.05). Tissue angular entropy was greater in patients than in controls, and tended to be greater in SPMS than in RRMS in the splenium. When considering all ROIs per group, the peak location of angular entropy was found increasing from -10 in controls, to -3 in RRMS, and to -2 in SPMS.
Conclusions: Our new method suggests that Fourier transform power spectrum has the potential to identify tissue coherency using clinical MRI. Outcomes of angular entropy reflect the degree of tissue injury that increases from controls to RRMS and then to SPMS. This method may become a new way of studying subtle pathologies of MS subjects in a clinical setting and deserves further verification.
Disclosure: Sharma S is funded by the Queen Elizabeth II graduate scholarship from the University of Calgary and the graduate scholarship from NSERC I3T Create Scholarship, Canada.
This project was funded by the operating grants (Zhang Y) from MS Society of Canada, Natural Sciences and Engineering Council of Canada, and Alberta Innovates - Health Solutions, Canada.