Measurement of Prevertebral Cervical Soft Tissue Thickness on Lateral Digital Radiographs

Abstract

Widening of the prevertebral soft tissues is one of several significant indirect signs of cervical spine trauma. This paper provides pediatric radiographic reference measurements for prevertebral soft tissues at C2 and C6, and for the ratio of soft tissue to vertebral width at C6. We reviewed 327 radiographs of consecutive patients under 14 years of age presenting at a trauma unit and obtained the relevant measurements using a software tool. Patients included in the study had no clinical features of cervical spine injury. Interobserver reliability of the measurements was assessed using the intraclass correlation coefficient of reliability. The effect of age category on the measurements was tested. Interobserver reliability was high for all measurements. The mean soft tissue width at C6 was significantly different across 3 age categories, whereas there was no significant difference for the soft tissue at C2 or the C6 ratio. The highest C2 soft tissue measurement was 10.6 mm, whereas the mean was 4.3 mm. The highest ratio at C6 was 1.2, with a mean ratio of 0.69. We present prevertebral soft tissue measurements from a larger sample of subjects than published previously, which allows our values to be used with more confidence as a tool in screening for cervical spine injury.