Evaluation of voxel-based group-level analysis of diffusion tensor images using simulated brain lesions |
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| Institution: | 1. Brain Research Unit, Low Temperature Laboratory, Aalto University School of Science, P.O. Box 15100, 00076-AALTO, Finland;2. Advanced Magnetic Imaging Centre, Aalto University School of Science, P.O. Box 13000, 00076-AALTO, Finland;1. Institute for Neuroscience and Muscle Research, The Children''s Hospital at Westmead, Sydney, Australia;2. Brain Dynamics Centre, Westmead Institute for Medical Research and University of Sydney Medical School, Sydney, Australia;3. Murdoch Childrens Research Institute, Melbourne, Victoria, Australia;4. The Children''s Hospital Education Research Institute, The Children''s Hospital at Westmead, Sydney, Australia;1. Beijing Friendship Hospital Affiliated to the Capital Medical University, Beijing 100050, China;2. Beijing Anding Hospital Affiliated to the Capital Medical University, Beijing 100088, China;1. Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland;2. Department of Neurology, Kuopio University Hospital, PO Box 1777, FI-70211 Kuopio, Finland;1. Neurology department, Military hospital Avicenne, Marrakech, Morocco;2. Anesthesiology department, Military hospital Avicenne, Marrakech. Morocco;3. Neurology department, Mohamed VI hospital, Marrakech, Morocco;4. Neuroscience research laboratory, Marrakech Medical school, Cadi Ayyad university, Marrakesh, Morocco;5. Radiology department, Military hospital Avicenne, Marrakech, Morocco;1. Department of Psychiatry, University of Cambridge, Addenbrooke''s Hospital, Cambridge, United Kingdom;2. Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, United Kingdom;3. Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge, United Kingdom |
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| Abstract: | We simulated brain lesions in mean diffusivity (MD) and fractional anisotropy (FA) images of healthy subjects to evaluate the performance of voxel-based analysis (VBA) with SPM2. We increased MD and decreased FA, simulating the most typical abnormalities in brain pathologies, in the superior longitudinal fasciculus (SLF), corticospinal tract (CST), and corpus callosum (CC). Lesion sizes varied from 10 to 400 voxels (10.5 mm3 each) and intensity changes from 10 to 100%. The VBA contained eddy current correction, spatial normalization, smoothing, and statistical analysis.The preprocessing steps changed the intensities of MD and FA lesions from the original values, and many lesions remained undetected. The detection thresholds varied between the three brain areas, and between MD and FA images. Although spatial smoothing often improved the sensitivity, it also markedly enlarged the estimated lesion sizes.Since conventional VBA preprocessing significantly affected the outcome and sensitivity of the method itself, the impact of analysis steps should be verified and considered before interpreting the findings. Our results provide insight into the sizes and intensity changes of lesions that can be detected with VBA applied to diffusion tensor imaging (DTI) data. |
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