A comparison of angled sagittal MRI and conventional MRI in the diagnosis of herniated disc and stenosis in the cervical foramen

Abstract

The object of this study is to demonstrate that angled sagittal magnetic resonance imaging (MRI) enables the precise diagnosis of herniated disc and stenosis in the cervical foramen, which is not available with conventional MRI. Due to both the anatomic features of the cervical foramen and the limitations of conventional MR techniques, it has been difficult to identify disease in the lateral aspects of the spinal canal and foramen using only conventional MRI. Angled sagittal MRI oriented perpendicular to the true course of the foramina facilitates the identification of the lateral disease. A review of 43 patients, who underwent anterior cervical discectomy and interbody fusion, is presented with a herniated disc and/or stenosis in the cervical foramen. They all had undergone conventional MRI and angled sagittal MRI. Fifty levels were surgically explored for evidence of foraminal herniated disc and stenosis. The results of each test were correlated with what was found at each explored surgical level. The sensitivity, specificity, and accuracy of both examinations for making the diagnosis of foraminal herniated disc and stenosis were compared. During the diagnosis of foraminal herniated disc, the sensitivity, specificity, and accuracy of angled sagittal MRI were 96.7, 95.0, and 96.0%, respectively, compared with 56.7, 85.0, and 68.0% for conventional MRI. In making the diagnosis of foraminal stenosis, the sensitivity, specificity, and accuracy of angled sagittal MRI were 96.3, 95.7, and 96.0%, respectively, compared with 40.7, 91.3, and 66.0% for conventional MRI. In the above groups, the difference between the tests for making the diagnosis of both foraminal herniated disc and stenosis was found to be statistically significant in sensitivity and accuracy. Angled sagittal MRI was a more accurate test compared to conventional MRI for making the diagnosis of herniated disc and stenosis in the cervical foramen. It can be utilized for the precise diagnosis of foraminal herniated disc and stenosis difficult or ambiguous in conventional MRI.

A practical MRI grading system for cervical foraminal stenosis based on oblique sagittal images

“…Oblique sagittal images provide much more information about the foramen than routine sagittal images because oblique images are oriented perpendicular to the course of the cervical neural foramen [5]. Facet overgrowth, herniated lateral discs and uncinate process osteophytes that may induce foraminal stenosis are more easily detectable in the oblique sagittal view [8]. A major disadvantage of the oblique sagittal view is that its use increases examination time.…”

“…A major disadvantage of the oblique sagittal view is that its use increases examination time. Shim et al [8] reported that the total scan time on the oblique sagittal view was 5 min. In the present study, we required 3.25 min for the acquisition of both oblique sagittal views, whereas the acquisition time for the routine T 2 weighted sagittal view alone was 2.5 min.…”

“…In the present study, we required 3.25 min for the acquisition of both oblique sagittal views, whereas the acquisition time for the routine T 2 weighted sagittal view alone was 2.5 min. These differences might result from the fact that Shim et al [8] made four time signal acquisitions and averaged them, while we averaged only triple signal acquisitions. We used T 2 weighted images for the acquisition of oblique sagittal views because T 2 weighted images provide the high tissue contrast required to easily distinguish bone from soft tissue.…”

Clinical anatomy and clinical significance of the cervical intervertebral foramen: a review

“…In other words, the intervertebral foramen is located anteriorly to the vertebral canal at an angle of 45 o relative to the coronal plane [19]. Therefore, the oblique or axial views have greater confidence rates than the sagittal views, in order to evaluate the presence of foraminal stenosis or of a disc herniation [17,25,36,37,44]. CT -computed tomography; MRI -magnetic resonance imaging…”

Oblique MR Imaging in Cervical Spine Surgery

“…Natural aging process outcrops imminent degenerative changes in the cervical spine (CS) consisting instability, disc herniation, and spinal stenosis [1]. The neural foramen of the CS has an almost elliptical shape and is oriented in an oblique position [2,3]. Conventional plain radiographs at an oblique view show the neural foramen of the CS, however they are of limited value in evaluating neural foraminal pathology.…”