CT Evaluation of Cervical Spine Unwarranted in Asymptomatic Children

The objective of a recent study was to estimate the excess relative risk from CT in patients aged <9 years after radiographic evaluation for CSI.

The retrospective study has concluded that due to the significant increase in relative risk for thyroid cancer in those children exposed to radiation via CT, the use of CT for evaluation of cervical spine injury (CSI) in young children who are asymptomatic is unwarranted.

Methodology
Children who underwent radiographic evaluation for CSI after blunt trauma were identified over a two-year period. The children were divided into three groups: group 1 consisted of children aged 0 to 4 years; group 2 included patients aged 5 to 8 years; and, group 3 consisted of patients aged >8 years.

Data extracted from the patient records included age, gender, type of trauma, physical findings, Glasgow Coma Scale, and radiographic studies performed as well as findings.

Anthropomorphic mannequins or phantoms were used to estimate the radiation dose. This measurement was then used to estimate excess relative risk of thyroid cancer for cohorts after exposure to the common radiographic modalities for CSI evaluation.

The total radiation dose for radiographic evaluation, including conventional x-ray and CT, was calculated and matched to the cases.

Results of the Study
992 patients were identified, of which 557 patients (56.0%) were evaluated for CSI using CT. The mean ages in groups 1, 2, and 3 were 2.3, 6.7, and 12.6 years, respectively. Only 32.0% of the patients evaluated for CSI were evaluated by conventional radiography prior to CT. The distributions of positive CT scans for CSI were similar in each group, ranging from 4.3% to 4.7%.

Conclusions
Excess relative risk for developing thyroid cancer calculated by the phantoms and based on the data from Sadetaki et al, revealed a 0.7 excess relative risk associated with exposure to the radiation from cervical spine CT. There was no associated relative risk for developing thyroid cancer associated with conventional radiography of the cervical spine in any group.

Reviewer’s Comments
The use of CT for the evaluation of the cervical spine has become increasingly popular among emergency department staff to clear the cervical spine effectively and in a short amount of time.

We, as radiologists and the professionals who best understand the risk of ionizing radiation, have been remiss in our duty to limit over utilization and subsequent increased exposure to sensitive populations.

Here is a remarkable article that directly compares the risks and benefits. Clearly, without clinically significant suggestions of CSI, the use of CT in imaging the cervical spine in children should be limited.

Author: Basil Hubbi, MD

Reference
Jimenez RR, DeGuzman MA, et al. CT Versus Plain Radiographs for Evaluation of C-Spine Injury in Young Children: Do Benefits Outweigh Risks?
Pediatr Radiol; 2008, online edition.