Computed tomography versus magnetic resonance imaging for evaluation of the cervical spine: How many slices do you need?

Controversy exists regarding the correlation between CT and MRI for evaluation of the cervical spine. We hypothesize that newer-generation CT scanners will improve diagnostic accuracy and may obviate the need for MRI in patients with a normal CT. We compared the missed injury rate of four-slice CT and 64-slice CT performed to evaluate the cervical spine. We conducted a retrospective study from January 2004 to June 2008 of all blunt trauma patients who underwent both a CT and MRI to evaluate the cervical spine. One hundred six blunt trauma patients underwent both CT and MRI, including 43 with four-slice and 63 with 64-slice CT. CT missed three injuries (3%), all of which were clinically significant ligamentous injuries seen only on MRI. The 64-slice CT missed no injuries (0%), whereas the four-slice CT missed all three (7%) of the ligamentous injuries (P = 0.03). Older-generation CT scanners miss clinically significant injuries in blunt trauma patients and should not be independently relied on to evaluate the cervical spine. The newer 64-slice CT scan does not appear to miss clinically significant cervical spine injuries and may allow clearance of the cervical spine in blunt trauma patients without the addition of an MRI.