Claudia
Angela Michela Wheeler-Kingshott1, Olga Ciccarelli2,
Torben Schneider1, Daniel C. Alexander3, Mara
Cercignani4
1NMR Unit, Department of
Neuroinflammation, UCL Institute of Neurology, London, United Kingdom; 2NMR
Unit, Department of Brain Repair and Rehabilitation, UCL Institute of
Neurology, London, United Kingdom; 3Dept. Computer Science, UCL,
Centre for Medical Image Computing, London, United Kingdom; 4Neuroimaging
Laboratory, Fondazione Santa Lucia, Rome, Italy
A
new definition of projected-axial (dp-ax) and radial (dp-rad)
diffusivities in standard space has been tested in multiple sclerosis and healthy
subjects using VBM. For each subject, dp-ax and dp-rad
are defined as the components of the diffusion tensors (DTs) along the most
probable direction of healthy tracts as defined by the eigenvectors of a
super-DT dataset in standard space (calculated as the average of the DTs of
a reference group of healthy subjects). The results show that in a patient
with moderate disability there are areas of reduced dp-ax not
revealed by the principal eigenvalue of the DT.