Degenerative disk disease was not an exclusion criterion. The subjects selected for this study were 20 years of age and older (average age, 42 years range, 20–98 years) and had no known prior cervical spine injury, congenital or acquired anomaly of the PVST such as retropharyngeal internal carotid artery, retropharyngeal lymphadenopathy, mass, abscess, or fluid collection. The patient population consisted of 192 trauma patients (119 men and 73 women) who presented to the hospital emergency department between January 2007 and April 2007 and underwent MDCT of the cervical spine with multiplanar reconstructions as part of a trauma protocol. The purpose of this study was to determine the normal thickness of the PVST on neutral position MDCT images in the adult population. Furthermore, the lack of abnormal PVST thickness does not exclude an underlying injury. 11 All of these methods have their own limitations. Hay et al proposed a ratio method in which they compared the thickness of the PVST with the width of the C5 vertebral body, therefore taking into consideration differences in radiographic technique and a patient's body habitus. 11 Others, such as Harris, 1 found the contour of the PVST at the craniocervical junction to be a more reliable method of detecting underlying injury in this region. In the past, many authors have measured the PVST thickness on lateral cervical spine radiographs and obtained results that have a large overlap between normal and abnormal findings in patients. To our knowledge, an up-to-date evaluation of the PVST thickness on MDCT images has not been published. With the widespread replacement of standard radiographic evaluation of the cervical spine by MDCT, 4, 7– 10 it is necessary to establish normal values for the thickness of the PVST on MDCT images. In our experience, the normal values based on radiographic studies are commonly used in multidetector CT (MDCT) images, despite the fact that differences in the acquisition of these images could account for significant differences in their normal values. 1– 6 Analysis of the PVST is helpful in detecting subtle osseous or ligamentous injuries that might go unrecognized. The thickness of the prevertebral soft tissue (PVST) has long been considered a valuable radiographic measurement in evaluating possible injury to the cervical spine. We propose the obtained values as the upper limits of normal for PVST thickness on MDCT images in the adult population. The smallest variability and calculated SDs were found at C2 and C3.ĬONCLUSIONS: The thickness of the PVST is important in the detection of underlying injuries to the cervical spine. The upper limit of normal was not determined for C4 and C5 levels due to variable position of the esophagus and larynx. RESULTS: The upper limits of normal for the thickness of the PVST were 8.5 mm at C1, 6 mm at C2, 7 mm at C3, 18 mm at C6, and 18 mm at C7. Exclusion criteria included patients with a congenital or acquired (nondegenerative) abnormality of the cervical spine or PVST. Patients included in the study were not intubated, had an immobilized cervical spine, had normal findings on cervical spine CT, and did not have a diagnosis of osseous or soft-tissue cervical injury. MATERIALS AND METHODS: Thickness of the PVST was measured in 192 patients undergoing screening cervical spine MDCT with multiplanar reconstructions as part of a trauma protocol. Because the standard of care has shifted from radiographs to multidetector CT (MDCT), a re-examination of the PVST on MDCT images is needed to establish normal values for thickness appropriate for this imaging technique. BACKGROUND AND PURPOSE: Analysis of the prevertebral soft tissue (PVST) is helpful in detecting osseous and ligamentous injuries of the cervical spine.
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