Normal Pediatric Prevertebral Soft-Tissue Thickness on MDCT

OBJECTIVE. The thickness of the prevertebral soft tissue (PVST) is instrumental in helping detect cervical spine injuries in the pediatric population. Current parameters for normal PVST thickness in that population are based on lateral radiographs because there have been no studies to date defining age-dependent normal measurements on MDCT. With the increasingly important role of MDCT in the evaluation of pediatric trauma patients, it is necessary to establish normal values for pediatric PVST thickness on MDCT images. Thus, the purpose of this study is to establish the normal thickness of PVST on MDCT of the pediatric population from 0 to 15 years old. MATERIALS AND METHODS. The thickness of the PVST was measured in 139 pediatric trauma patients (age range 0-15 years) who presented to the pediatric emergency department between 2005 and 2008. Patients included in the study were not intubated, had no congenital or acquired osseous abnormality detected on CT, and were discharged from the hospital without a diagnosis of cervical spine or soft-tissue injury. Exclusion criteria included patients with concurrent injury found on head CT or nontraumatic causes of PVST thickening, such as lymphadenopathy or retropharyngeal internal carotid arteries. Patients who were diagnosed with cervical injuries within 1 year after the initial CT examination were also excluded. Each patient was scanned with a cervical collar placing the cervical spine in a neutral or near-neutral position. RESULTS. The smallest variability and calculated SD were at C2 and C6. The upper limits of normal for PVST thickness at C2 were 7.6 mm in patients from 0 to 2 years old, 8.4 mm in patients from 3 to 6 years old, and 6.8 mm in patients from 7 to 10 years old and in those from 11 to 15 years old. At the C6 level, the upper limits were 9.0 mm in patients from 0 to 2 years old, 9.8 mm in patients from 3 to 6 years old, 12.1 mm in patients from 7 to 10 years old, and 14.5 mm in patients from 11 to 15 years old. The upper limit of normal had the highest variability at C3 and C4 for all age groups. CONCLUSION. The thickness of the PVST is important in the detection of underlying injuries to the cervical spine. MDCT is playing an increasingly important role in the evaluation of pediatric trauma patients. We propose the obtained values as the upper limits of normal for PVST thickness on MDCT images in the pediatric population from 0 to 15 years old.