CT vs Plain Film Radiography for Cervical Trauma
CT vs Plain Film Radiography for Cervical Trauma
By Michael A. Gibbs, MD, FACEP,
Chief, Department of Emergency Medicine, Maine Medical Center, Portland, ME
Source: Holmes AF, et al. Computed tomography versus plain radiography to screen for cervical spine injury: A meta-analysis. J Trauma 2005; 58:902-905.
The aim of this study was to compare the accuracy of plain film radiography and computed tomography (CT) for the detection of cervical injuries in blunt trauma patients. The authors conducted a MEDLINE review of all relevant studies published between 1995 and 2004. Articles were excluded for any of the following reasons: 1) plain films series failed at a minimum to include three views (e.g., anterior/posterior, lateral, open-mouth/odontoid); 2) CT scan did not extend from the occiput to the superior aspect of the first thoracic vertebrae; and 3) distance between cuts on the CT scan was more than 5 mm. Of 712 articles, seven met inclusion criteria and provided data for both plain films and CT in all study patients. These seven studies provided the substrate for the meta-analysis.
Patient entry criteria were highly variable for each study, and there were no randomized controlled trials. For identifying patients with cervical spine injury, the pooled sensitivity for cervical plain film radiography was 52% [95% CI, 47% to 56%], and for CT imaging was 98% [95% CI, 96% to 99%].
Commentary
So, is it time to jump on the CT-everyone bandwagon? Not so fast! At first glance, the results of this study are compelling. CT imaging provided outstanding anatomic definition and an overall diagnostic accuracy of nearly 100%—almost twice that seen with conventional plain film radiography. The question is: How do we apply this information to clinical practice?
The authors acknowledge that all seven studies in their meta-analysis were conducted at large trauma centers, with a high percentage of enrolled patients sustaining severe multisystem trauma. In this patient population, the incidence of cervical injury is expected to be high. Furthermore, these patients are likely to undergo coincident CT imaging of the head and torso. In this setting, it makes good clinical and logistical sense to forgo plain film imaging and to move directly to cervical tomography as part of a more comprehensive "trauma CT protocol."
However, it is not clear that the same logic can be applied to alert, stable, low-risk patients with a much lower pretest probability of cervical fracture. Mower and colleagues reviewed the NEXUS experience in a broader population of ED trauma patients (n=34,065; fractures in 818 [2.4%]).1 While CT imaging was not done in all patients, the performance of plain film imaging was reviewed carefully. Based upon the NEXUS data, the following generalities can be applied as a rule of 3s:
1. Inadequate plain films will miss approximately 30% of injuries. This is a sobering reminder that the emergency physician should never settle for inadequate films; if adequate films are unobtainable, cervical CT imaging is the mandatory next step.
2. Adequate plain films will miss roughly 3% of stable cervical fractures
3. Adequate plain films will miss about 0.3% of unstable cervical fractures.
The use of CT imaging as a primary screening test in low-risk patients has not been studied; based upon the NEXUS data, plain films likely will remain the appropriate first step in this population. CT imaging should be used to supplement inadequate or suspicious plain film findings. Like everything else in medicine: clinical judgment is essential.
References
1. Mower WR, et al. Use of plain radiography to screen for cervical spine injuries. Ann Emerg Med 2001;38:1-7.
The aim of this study was to compare the accuracy of plain film radiography and computed tomography (CT) for the detection of cervical injuries in blunt trauma patients. The authors conducted a MEDLINE review of all relevant studies published between 1995 and 2004.Subscribe Now for Access
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