Detection of multiple pathways in the spinal cord using q-ball imaging

Magnetic resonance diffusion tensor imaging (DTI) has been extensively applied to the spinal cord for depicting its architecture and for assessing its integrity following spinal lesions. However, DTI is limited in representing complex white matter architecture, notably in the presence of crossing fibres. Recently, q-ball imaging (QBI) has been proposed as a new method for recovering complex white matter architecture. We applied this technique to both ex vivo and in vivo spinal cords of cats using a 3T scanner. For the purpose of comparison, gradients have been applied in 55 and 100 encoding directions and b-values varied from 800 to 3000 s/mm2. As a result, QBI was able to retrieve crossing fibre information, where the DTI approach was constrained in a unique diffusion direction. To our knowledge, this is the first study demonstrating the benefits of QBI for detecting the presence of longitudinal, commissural and dorso-ventral fibres in the spinal cord. It is a first step towards in vivo characterization of the healthy and injured human spinal cord using high angular resolution diffusion imaging and QBI.