Study design: A cohort study.
Objective: The aim of this study was to evaluate the clinical utility of Zero-Echo-Time (ZTE) magnetic resonance imaging (MRI) for the assessment of cervical neural foraminal stenosis (CNFS) through the comparison of inter-modality [computed tomography (CT) and ZTE-MRI] CNFS grade severity agreements.
Summary of background data: Conventional MRI limited in its ability to provide direct visualization of cortical bone. The highly organized tissue structure of cortical bone results in very short T2 values that preclude acquisition of sufficient signal intensity and positive image contrast. ZTE imaging permits visualization of tissues with very short transverse relaxation times, and is capable of displaying images with CT-like contrast.
Methods: Thirty-four subjects were recruited from a clinical cohort of patients undergoing standard of care MRI and CT imaging for evaluation of CNFS. Standard of care CT imaging studies were obtained on all subjects within 6 months of their ZTE-MRI acquisition (mean time interval: 25.3 ± 54.1 days; median: 0 days). ZTE-MRI and CT imaging studies were evaluated and severity of CNFS was graded on a scale from 0 to 5 (0 = none; 5 = severe). Weighted-kappa statistics were used to assess agreement between ZTE and CT grades of CNFS on both sides (right and left) of each motion segment. Ordinal logistic mixed-effects regression analyses evaluated the effects of inter-modality position differences (flexion-extension curvature) on inter-modality differences in CNFS grade.
Results: Substantial agreement (κ = 0.72) was found between ZTE- and CT-based grades of CNFS. Significant inter-modality differences in cervical spine curvature were found for all motion segments, except C2-3 and C3-4 (P < 0.05). However, no significant relationship was found between inter-modality differences in curvature, and inter-modality differences in CNFS grade for any motion segment (P = 0.28).
Conclusion: Results of the current study suggest that ZTE-MRI is well-suited for the evaluation of CNFS and may have the potential to obviate the need for concurrent CT scans in some cases.
Level of evidence: 2.