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AJNR - American Journal of Neuroradiology

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American Journal of Neuroradiology 27:1952-1961, October 2006
© 2006 American Society of Neuroradiology

SPINE

A Preliminary Study of the Effects of Trigger Timing on Diffusion Tensor Imaging of the Human Spinal Cord

P. Summers^a, P. Staempfli^a,b, T. Jaermann^a,b, S. Kwiecinski^a and S. Kollias^a

^a Institute for Neuroradiology, University Hospital Zurich, Zurich, Switzerland
^b Institute for Biomedical Engineering, ETHZ, Zurich, Switzerland

Address correspondence to Spyros S Kollias, Institute of Neuroradiology, University Hospital of Zurich, Frauenklinikstr 10, 8091 Zurich, Switzerland; e-mail: spyros.kollias{at}usz.ch

BACKGROUND AND PURPOSE: Diffusion tensor and diffusion-weighted spinal cord imaging remain relatively unexplored techniques despite demonstrations that such images can be obtained and may yield clinically relevant findings. In this study, we examined the temporal dynamics of spinal cord motion and their impact on diffusion tensor image quality.

METHODS: Four healthy volunteers underwent phase contrast-based velocity mapping and segmented echo-planar diffusion tensor scans of the cervical spinal cord. Regions of interest in the cord were used to identify the temporal patterns of motion. The delay of data acquisition after the cardiac trigger was varied to correspond to either quiescence or motion of the cord.

RESULTS: The cervical spinal cord consistently displayed maximal velocities in the range of 0.5 cm/s and accelerations of up to 25 cm/s². In both these respects, the cervical cord values were greater than those of the medulla. Despite this pronounced motion, approximately 40% of the cardiac cycle can be described as relatively calm, with absolute velocities and accelerations less than 20% of the maximum values. Confining image acquisition to this window reduced ghosting artifacts and increased the consistency with which the dominant direction of diffusion was along the rostral-caudal axis in both gray and white matter of the spine. Preliminary clinical application and fiber tracking in pathologic cases was feasible, and alterations of the diffusion properties by multiple sclerosis lesions, tumor, and syringomyelia were seen.

CONCLUSIONS: Acquiring DTI data during the quiescent phase of spinal cord motion can reduce ghosting artifacts and improve fiber tracking.

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