Imaging description

Many patients undergoing spine evaluation in the emergency department are intubated or otherwise unable to hold still while undergoing CT. Misregistration is a CT artifact caused by patient or physiologic motion during helical or sequential image acquisition [1–3]. Slight movement may cause blurring on axial CT images (Figure 24.1). If greater physical displacement occurs, motion artifact can result in double edges on images or ghosting (Figure 24.2A). The cervical spine is the most mobile portion of the spinal column, and images of the cervical spine are prone to motion artifact.

CT images of the spine degraded by patient motion can be mistaken for fractures. When an equivocal fracture is suspected on axial views confirmation of the finding on multiplanar reformations (usually obtained in the sagittal and coronal planes) is advised. Multiplanar image reformations improve clinical accuracy for the detection of spine fractures [4, 5], intracranial hemorrhage [6], and pulmonary embolism [7]. In the spine, orthogonal image reformation in the sagittal and coronal plane increases sensitivity, when compared to axial image review alone [4]. Thin axial image reconstruction (1 mm) also improves sensitivity to 95% for the detection of spine fractures compared to thicker slice reconstruction in the osteoporotic patient [5].