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.

Fig. 1

Anatomic features of the cervical foramen. a Axial T₂-weighted images at the C4–5 disc level. The cervical foramen is directed anterolaterally at approximately a 45° angle with respect to the coronal plane through the foramen. b Anteroposterior image of 3D reconstructive CT. The cervical foramina are directed downward 10–15° with respect to the axial plane

Fig. 2

Comparison of conventional MRI and angled sagittal MRI. The images were obtained in a 27-year-old woman who has not been diagnosed with cervical disease. a Identification of the lateral aspects of the cervical canal and foramen is difficult because the routine parasagittal images are not optimally oriented. b Angled sagittal MRI images are oriented perpendicular to the true course of the neural foramen. As compared with conventional MRI, a clearer foraminal contour and nerve root can be seen using angled sagittal MRI. The circle indicates the intervertebral foramen between C4 and C5

Fig. 3

Case 6. A 52-year-old woman complained of right arm pain and neck pain. a Conventional T2-weighted MRI showed a low-intensity mass and suspected stenosis in the right foraminal space of C5–6. However, the presence of a herniated disc in the foramen could not be established. b The herniated disc and stenosis were visible clearly in the foraminal space using angled sagittal MRI

Fig. 4

Case 13. A 46-year-old man complained of left arm pain and neck pain. a Although conventional MRI showed what was suspected to be herniated disc in the left foraminal space of C6–7, other pathology was not documented in the left foramina. b Angled sagittal MRI definitely revealed C5–6 and C6–7 lesions with foraminal herniated disc and stenosis