Rapid In Vivo Detection of Rat Spinal Cord Injury With Double-Diffusion-Encoded Magnetic Resonance Spectroscopy

Purpose: Diffusion-weighted imaging is a common experimental tool for evaluating spinal cord injury (SCI), yet it suffers from complications that decrease its clinical effectiveness. The most commonly used technique, diffusion tensor imaging (DTI), is often confounded by effects of edema accompanying acute SCI, limiting its sensitivity to the important functional status marker of axonal integrity. The purpose of this study is to introduce a novel diffusion-acquisition method with the goal of overcoming these limitations. Methods: A double diffusion encoding (DDE) pulse sequence was implemented with a diffusion-weighted filter orthogonal to the spinal cord for suppressing nonneural signals prior to diffusion weighting parallel to the cord. A point-resolved spectroscopy readout (DDE-PRESS) was used for improved sensitivity and compared with DTI in a rat model of SCI with varying injury severities. Results: The DDE-PRESS parameter, restricted fraction, showed a strong relationship with injury severity (P < 0.001, R-2 = 0.67). Although the whole-cord averaged DTI parameter values exhibited only minor injury relationships, a weighted region of interest (ROI) based DTI analysis improved sensitivity to injury (P < 0.001, R-2 = 0.66). Conclusions: In a rat model of SCI, DDE-PRESS demonstrated high sensitivity to injury with substantial decreases in acquisition time and data processing. This method shows promise for application in rapid evaluation of SCI severity. Magn Reson Med 77: 1639-1649, 2017. (C) 2016 International Society for Magnetic Resonance in Medicine