Today, a wide range of traumatic and non-traumatic emergency conditions can be rapidly and accurately diagnosed by helical CT. Many traditional emergency imaging procedures have been replaced by novel helical CT techniques that can be performed quickly and with great accuracy, causing less patient discomfort and at lower costs [1,6,9
]. The pooled sensitivity for cervical spine plain radiography is 52%, and that for CT is 98% [9
] in the identification of patients with cervical spine injury. Daffner et al. [10
] reviewed the CT and plain radiographic images of 245 patients, and reported that radiography detected injuries in 108 patients (44.1%) whereas CT detected injuries in 243 patients (99.2%). If a patient experiences complete or incomplete paralysis in four limbs, we always request CT and MRI assessment. Minor fractures, such as tear drop or transverse foramen fractures, can be clearly detected by CT, while cervical spinal cord injury without fracture and dislocation can be detected by MRI.
Helical CT has limitations. The first is motion artifacts [5,6
]. Sciubba et al. [5
] reported that CT reconstruction artifacts can mimic cervical spine subluxation. Daffner  showed motion artifact mimicking vertebral offset at C3/4. Voluntary or involuntary patient movements can cause such artifact mimicking cervical injury.
The second limitation is difficulty detecting fracture line parallel to the plane of the scan [6,10
]. The third limitation is beam hardening or scatter artifacts [5
]. Daffner et al. [10
] reviewed the CT images of 245 patients with cervical injury. Two fractures not detected by CT occurred at C2: one fracture was obscured by dental artifacts and the other was in the horizontal plane of the scan [10
In our patient, motion artifacts mimicked dens fracture, and special caution should be exercised when assessing reconstructed CT. Assessment using other imaging techniques, such as plain radiographs and MRI, is helpful in detecting motion artifacts on CT [6