Magnetic resonance imaging signal changes of alar and transverse ligaments not correlated with whiplash-associated disorders
PURPOSE To analyse and classify structural changes in the transverse ligament in the late stage of whiplash injury by use of high-resolution MRI, and to evaluate the reliability of our classification. MATERIAL AND METHODS Ninety-two whiplash-injured (2-9 years previously, mean 6 years) and 30 non-injured individuals underwent proton-weighted MR imaging of the craniovertebral junction in three orthogonal planes. Structural changes in the transverse ligaments were graded twice (grades 1-3) based on increased signal, independently by 3 radiologists with a 4-month interval. Inter- and intraobserver statistics were calculated by ordinary and weighted kappa (K). RESULTS Image quality was excellent in 109 cases and slightly reduced in 13. Twenty-two out of 30 ligaments in the control group were classified as normal (73%) compared with only 32 out of 92 in the injured group (36%). Two or all 3 observers agreed in their grading in 101 out of 122 ligaments (83%). Intraobserver agreement (weighted K) was fair to good (0.33-0.73). Pair-wise interobserver agreement was fair (0.24-0.39). Reasons for divergent grading were insufficient knowledge of normal variations, low signal intensity in the peridental soft tissue obscuring the ligament and interpretation flaw. CONCLUSION Whiplash trauma can damage the transverse ligament. By use of high-resolution proton-weighted MR images such lesions can be detected and classified. The reliability of this classification still needs improvement.