Using magnetic resonance imaging to accurately assess injury to the posterior ligamentous complex of the spine: a prospective comparison of the surgeon and radiologist

Clinical article

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Object

Magnetic resonance imaging has been proposed as a powerful technique for assessing the integrity of the posterior ligamentous complex (PLC) in spinal trauma. Because MR imaging is often used to determine appropriate treatment, it is important to determine the accuracy and reliability of MR imaging in diagnosing PLC disruption. The purpose of this study is to compare the ability of the radiologist and surgeon to assess disruption of the PLC in the setting of acute cervical and thoracolumbar trauma using MR imaging.

Methods

The components of the PLC in 89 consecutive patients with cervical or thoracolumbar fractures following acute spinal trauma were evaluated using MR imaging by both a musculoskeletal radiologist and an independent spine surgeon and assessed intraoperatively under direct visualization by the treating surgeon. The MR imaging interpretations of the musculoskeletal radiologist and surgeon were compared with the intraoperative report for accuracy, sensitivity, specificity, and positive and negative predictive values. A comparison between the radiologist's and spine surgeon's accuracy of MR imaging interpretation was performed.

Results

The agreement between both the spine surgeon's and radiologist's MR imaging interpretation and the actual intraoperative findings was moderate for most components of the PLC. Overall, the MR imaging interpretation of the surgeon was more accurate than that of the radiologist. The interpretation of MR imaging by the surgeon had negative predictive value and sensitivity of up to 100%. However, the specificity of MR imaging for both the surgeon and radiologist was lower, ranging from 51.5 to 80.5%.

Conclusions

Comparison of the MR imaging interpretations between surgeon and radiologist indicates that the surgeon was more accurate for some PLC components. The relatively low positive predictive value and specificity for MR imaging in assessing PLC integrity suggests that both the surgeon and radiologist tend to overdiagnose PLC injury using MR imaging. This can lead to unnecessary surgeries if only MR imaging is used for treatment decision making.

Abbreviations used in this paper: NPV = negative predictive value; PLC = posterior ligamentous complex; PPV = positive predictive value.

Article Information

Address correspondence to: Jeffrey A. Rihn, M.D., Department of Orthopaedic Surgery, The Rothman Institute, Thomas Jefferson University Hospital, 925 Chestnut Street, Philadelphia, Pennsylvania 19107. email: jrihno16@yahoo.com.

© AANS, except where prohibited by US copyright law.

Headings

Figures

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    Images obtained in a 40-year-old man who fell from a ladder from a height of 20 feet. A and B: Midline sagittal (left) and parasagittal (right) CT scan reconstruction (A), and consecutive axial CT images (B). These images demonstrate an L-1 burst fracture with involvement of the posterior column in the form of a right-sided lamina/facet fracture (arrows, B). C: Sagittal T2-weighted (left) and T1-weighted (right) MR images demonstrate the soft tissue structures. In this case, the radiologist read the interspinous ligament (dashed arrow) as intact and the supraspinous ligament (solid arrow) as disrupted. The surgeon, however, interpreted both the interspinous and supraspinous ligaments as intact. Intraoperatively, both the interspinous and supraspinous ligaments were noted to be intact. D: Axial MR image demonstrating the disrupted right facet capsule (solid arrow) and the intact thoracodorsal fascia (open arrows), both of which the radiologist and surgeon agreed upon and the intraoperative report confirmed.

  • View in gallery

    Images obtained in a 30-year-old man who was an unrestrained passenger in a head-on motor vehicle accident. A: Midline sagittal (left), parasagittal left (center), and parasagittal right (right) CT scan reconstructions demonstrate bilateral perched facets at the level of C5–6, with significant angulation and subluxation of the C-5 vertebral body on the C-6 vertebral body. B: Midline sagittal (left), parasagittal left (center), and parasagittal right (right) T2-weighted MR images demonstrating significant interspinous widening (between the dotted arrows) with disruption of all components of the PLC. The facet capsules are disrupted bilaterally (solid arrows). In this case, there was complete agreement between the radiologist and surgeon regarding interpretation of the MR imaging findings and the intraoperative findings.

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