Introduction: Although diffusion tensor imaging (DTI) is used to detect spinal cord pathology, it is unclear if DTI performed on a standard clinical scanner produces data of sufficient quality to identify differences in DTI parameters throughout the cervical spinal cord (CSC). In this study, we performed DTI on neurologically intact subjects of different ages, and measured diffusivities of the gray matter and white matter tracts within individual segments of the CSC.
Methods: Twenty-five neurologically intact subjects (22 -85 years old) were studied. A single-shot, twice-refocused, spin-echo, echoplanar pulse sequence was used to obtain axial images throughout the CSC (C1–T1) on a 1.5T clinical MR scanner. DTI metrics were calculated for the whole CSC, GM and individual WM funiculi. Signal-to-noise ratios (SNRs) and mean DTI metrics were measured for segmental groups- upper (C1-3), middle (C4-6) and lower (C7-T1) CSC. Age-related changes in DTI measures were also analyzed.
Results: The FA, MD and tADC showed significant differences between GM and individual WM funiculi throughout the CSC. However, the median SNR was significantly decreased in the middle and lower segmental groups as compared to the upper levels (5.5 vs 10.7, p<0.001), contributing to poor spatial resolution of the cord structure in the lower CSC. DTI was sensitive to age-related changes in FA within the CSC- particularly in the upper and middle cord. The FA of the lower cord did not correlate with age, probably due to the poor SNR in this region.
Conclusions: This study is the first to systematically characterize changes in DTI metrics throughout the CSC in neurologically intact subjects using a standard clinical scanner. Although DTI reliably differentiates GM and individual WM funiculi across the CSC, technical issues limit lower CSC characterization and need to be refined. While DTI metrics may be used to define cord pathology, variations in metrics due to age and signal quality need to be accounted for before making definitive conclusions.
Patient Care: This research represents the first study of its kind in the application of DTI technology to evaluate the spinal cord in healthy volunteers. Refinement of this technique is likely to add an important new imaging modality to spinal disease diagnostic armamentarium in the future
Learning Objectives: After reviewing this abstract, participants should be able to
1. Understand the potential of DTI to better characterize spinal cord structure
2. Understand that DTI imaging may form an important future modality for clinical imaging for patients with spinal cord disorders, incluing injury, myelopathy etc