Correct Estimation of Neuroforaminal Stenosis Grade Caused by Disc Herniation in Cervical Spine MRI by Using Oblique Sagittal MR Sequences

Purpose: Identify whether sagittal MRI images (SMI) result in underestimation of neuroforaminal stenosis grade (NSG) compared to oblique sagittal MRI images (OSMI) in patients with cervical spine disc herniation.

Patients and Methods: 74 patients with 104 cervical disc herniations compromising the corresponding nerve root were evaluated. NSGs were evaluated in SMI and OSMI by one senior and one resident radiologist. OSMI were angled 30° towards the standard sagittal plane. NSGs were classified from 0 (no stenosis) to 3 (high-grade stenosis).

Results: Average NSG of both readers was significantly lower in SMI compared to OSMI (2.41 ± 0.65 and 2.92 ± 0.27). For 49 of 104 disc herniations (47.1%), one or both readers found a NSG which was at least 1 grade lower in SMI compared to OSMI. Significant difference maintained looking at patients who had neurological symptoms (2.50 ± 0.55 and 2.88 ± 0.32) or underwent cervical spine surgery subsequently (2.58 ± 0.49 and 2.90 ± 0.31). Based on location, a significant difference between SMI and OSMI was observed for foraminal herniations (2.36 ± 0.67 and 2.91 ± 0.27). In contrast, no significant difference was observed for recessal herniations (2.68 ± 0.46 and 2.91 ± 0.30) or herniations which caused myelopathy (2.74 ± 0.45 and 2.91 ± 0.29). Kappa values showed a very good inter-reader reliability for SMI (0.88) and OSMI (0.94).

Conclusion: Since SMI tend to underestimate NSG compared to OSMI for disc herniations in cervical spine MRI, OSMI should be considered as a valuable option for selected patients.