Postmortem kinetic CT of the cervical spine and an objective index for diagnosing anterior disc space widening: A retrospective utility analysis.

Postmortem CT has limitations in identifying cervical spine injuries. Injuries at the level of the intervertebral disc (anterior disc space widening), such as rupture of the anterior longitudinal ligament or intervertebral disc, may be difficult to distinguish from normal images depending on the imaging position. We performed postmortem kinetic CT of the cervical spine in the extended position in addition to CT in the neutral position. The difference in intervertebral angles between the neutral and extended positions was defined as the intervertebral range of motion (ROM), and the utility of postmortem kinetic CT of the cervical spine for the diagnosis of anterior disc space widening and its objective index were examined based on the intervertebral ROM. Of 120 cases, 14 had anterior disc space widening: 11 had one lesion and 3 had two lesions. The intervertebral ROM for the 17 lesions was 11.85° ± 5.25° and that for the normal vertebrae was 3.78° ± 2.81°, with a significant difference between the two. ROC analysis of the intervertebral ROM between vertebrae with anterior disc space widening and the normal vertebral spaces showed an AUC of 0.903 (95 % confidence interval 0.803-1) and a cutoff value of 8.61° (sensitivity 0.96, specificity 0.82). Postmortem kinetic CT of the cervical spine revealed that the intervertebral ROM of the anterior disc space widening was increased, which facilitated identification of the injury. An intervertebral ROM that exceeds 8.61° facilitates a diagnosis of anterior disc space widening.