Oblique sagittal images improve quality of cervical spine MRI

Magnetic resonance imaging (MRI) plays a key role in the assessment of spinal cord and root impingement responsible for chronic neck pain. It supplements standard anteroposterior (AP) and lateral x-rays for patients experiencing neurological symptoms or not responding to conservative treatment.

A cervical spine MRI should include oblique sagittal images (OSIs) in addition to standard sagittal images (SSIs), radiologists from the University Hospital Heidelberg in Germany advise in the June 2018 edition of the German medical imaging e-journal, Röfo. The radiologists argue that compared to OSIs, standard sagittal images tend to underestimate neuroforaminal stenosis grades, and are therefore less reliable in evaluating disc herniations in the cervical spine.

For their comparative analysis, lead author Laurent Kintzelé, MD, of the Diagnostic and Interventional Radiology Department of University Hospital Heidelberg, and colleagues hypothesized that OSIs can improve the assessment of neuroforaminal stenosis resulting from disc herniation. They identified 29 patients with 45 disc herniations that compromised the cervical neural foramen on axial T2-weighted images who received treatment at the hospital from January 2014 through June 2017.

The exams were independently reviewed by two radiologists experienced in musculoskeletal imaging who graded neuroforminal stenosis on a four-point classification system.¹ Grading of SSIs seemed more prone to error than the grading of OSIs, the authors found, noting that grading differed significantly between the two techniques. Both radiologists underestimated the neuroforminal stenosis grade (NSG) by 2 units in seven cases. Forty-seven percent of neuroforminal stenoses were identified by at least one radiologist as at least one grade lower in SSIs compared to OSIs. Mean neuroforaminal grades of 2.36 were obtained in SSIs compared to 2.91 in OSIs. Significant differences were also obtained for the levels C3-4, C5-6, and C6-7.

“MRI plays a key role in the assessment of spinal cord and root impingement,” the authors wrote. “However, the neural foramen which contains the spinal root is poorly depicted on standard sagittal and axial images, which is the reason why oblique sagittal images were introduced... . This study was able to demonstrate that OSIs are valuable sequences in cervical spine MRI and can prevent underestimation of the severity of neuroforaminal stenoses caused by disc herniations.”

REFERENCES

1. Park HJ, Kim SS, Lee SY, et al. A practical MRI grading system for cervical foraminal stenosis based on oblique sagittal images. Br J Radiol. 2013 86: 1-7.
2. Kintzelé L, Rehnitz C, Kauczor HU, et al. Oblique sagittal images prevent underestimation of the neuroforaminal stenosis grade caused by disc herniation in cervical spine MRI. Röfo. Published online June 6, 2018. doi: 10.1055/a-0612-8205.