Systematic review of radiological cervical foraminal grading systems

Detection of Cervical Foraminal Stenosis from Oblique Radiograph Using Convolutional Neural Network Algorithm

PURPOSE

This study was conducted to develop a convolutional neural network (CNN) algorithm that can diagnose cervical foraminal stenosis using oblique radiographs and evaluate its accuracy.

MATERIALS AND METHODS

A total of 997 patients who underwent cervical MRI and cervical oblique radiographs within a 3-month interval were included. Oblique radiographs were labeled as "foraminal stenosis" or "no foraminal stenosis" according to whether foraminal stenosis was present in the C2-T1 levels based on MRI evaluation as ground truth. The CNN model involved data augmentation, image preprocessing, and transfer learning using DenseNet161. Visualization of the location of the CNN model was performed using gradient-weight class activation mapping (Grad-CAM).

RESULTS

The area under the curve (AUC) of the receiver operating characteristic curve based on DenseNet161 was 0.889 (95% confidence interval, 0.851-0.927). The F1 score, accuracy, precision, and recall were 88.5%, 84.6%, 88.1%, and 88.5%, respectively. The accuracy of the proposed CNN model was significantly higher than that of two orthopedic surgeons (64.0%, p<0.001; 58.0%, p<0.001). Grad-CAM analysis demonstrated that the CNN model most frequently focused on the foramen location for the determination of foraminal stenosis, although disc space was also frequently taken into consideration.

CONCLUSION

A CNN algorithm that can detect neural foraminal stenosis in cervical oblique radiographs was developed. The AUC, F1 score, and accuracy were 0.889, 88.5%, and 84.6%, respectively. With the current CNN model, cervical oblique radiography could be a more effective screening tool for neural foraminal stenosis.

Cervical Spondylosis Diagnosis Based on Convolutional Neural Network with X-ray Images

The increase in Cervical Spondylosis cases and the expansion of the affected demographic to younger patients have escalated the demand for X-ray screening. Challenges include variability in imaging technology, differences in equipment specifications, and the diverse experience levels of clinicians, which collectively hinder diagnostic accuracy. In response, a deep learning approach utilizing a ResNet-34 convolutional neural network has been developed. This model, trained on a comprehensive dataset of 1235 cervical spine X-ray images representing a wide range of projection angles, aims to mitigate these issues by providing a robust tool for diagnosis. Validation of the model was performed on an independent set of 136 X-ray images, also varied in projection angles, to ensure its efficacy across diverse clinical scenarios. The model achieved a classification accuracy of 89.7%, significantly outperforming the traditional manual diagnostic approach, which has an accuracy of 68.3%. This advancement demonstrates the viability of deep learning models to not only complement but enhance the diagnostic capabilities of clinicians in identifying Cervical Spondylosis, offering a promising avenue for improving diagnostic accuracy and efficiency in clinical settings.

Radiology Reports Do Not Accurately Portray the Severity of Cervical Neural Foraminal Stenosis

STUDY DESIGN

Retrospective study.

OBJECTIVE

(1) To compare cervical magnetic resonance imaging (MRI) radiology reports to a validated grading system for cervical foraminal stenosis (FS) and (2) to evaluate whether the severity of cervical neural FS on MRI correlates to motor weakness or patient-reported outcomes.

BACKGROUND

Radiology reports of cervical spine MRI are often reviewed to assess the degree of neural FS. However, research looking at the association between these reports and objective MRI findings, as well as clinical symptoms, is lacking.

PATIENTS AND METHODS

We retrospectively identified all adult patients undergoing primary 1 or 2-level anterior cervical discectomy and fusion at a single academic center for an indication of cervical radiculopathy. Preoperative MRI was assessed for neural FS severity using the grading system described by Kim and colleagues for each level of fusion, as well as adjacent levels. Neural FS severity was recorded from diagnostic radiologist MRI reports. Motor weakness was defined as an examination grade <4/5 on the final preoperative encounter. Regression analysis was conducted to evaluate whether the degree of FS by either classification was related to patient-reported outcome measure severity.

RESULTS

A total of 283 patients were included in the study, and 998 total levels were assessed. There were significant differences between the MRI grading system and the assessment by radio-logists (P< 0.001). In levels with moderate stenosis, 28.9% were classified as having no stenosis by radiology. In levels with severe stenosis, 29.7% were classified as having mild-moderate stenosis or less. Motor weakness was found similarly often in levels of moderate or severe stenosis (6.9% and 9.2%, respectively). On regression analysis, no associations were found between baseline patient-reported outcome measures and stenosis severity assessed by radiologists or MRI grading systems.

CONCLUSION

Radiology reports on the severity of cervical neural FS are not consistent with a validated MRI grading system. These radiology reports underestimated the severity of neural foraminal compression and may be inappropriate when used for clinical decision-making.

LEVEL OF EVIDENCE

Level III.

How Does the Severity of Neuroforaminal Compression in Cervical Radiculopathy Affect Outcomes of Anterior Cervical Discectomy and Fusion

STUDY DESIGN

This study is a retrospective cohort study.

PURPOSE

This study aims to determine whether preoperative neuroforaminal stenosis (FS) severity is associated with motor function patient-reported outcome measures (PROMs) following anterior cervical discectomy and fusion (ACDF).

OVERVIEW OF LITERATURE

Cervical FS can significantly contribute to patient symptoms. While magnetic resonance imaging (MRI) has been used to classify FS, there has been limited research into the impact of FS severity on patient outcomes.

METHODS

Patients undergoing primary, elective 1-3 level ACDF for radiculopathy at a single academic center between 2015 and 2021 were identified retrospectively. Cervical FS was evaluated using axial T2-weighted MRI images via a validated grading scale. The maximum degree of stenosis was used for multilevel disease. Motor symptoms were classified using encounters at their final preoperative and first postoperative visits, with examinations ≤3/5 indicating weakness. PROMs were obtained preoperatively and at 1-year follow-up. Bivariate analysis was used to compare outcomes based on stenosis severity, followed by multivariable analysis.

RESULTS

This study included 354 patients, 157 with moderate stenosis and 197 with severe stenosis. Overall, 58 patients (16.4%) presented with upper extremity weakness ≤3/5. A similar number of patients in both groups presented with baseline motor weakness (13.5% vs. 16.55, p =0.431). Postoperatively, 97.1% and 87.0% of patients with severe and moderate FS, respectively, experienced full motor recovery (p =0.134). At 1-year, patients with severe neuroforaminal stenosis presented with significantly worse 12-item Short Form Survey Physical Component Score (PCS-12) (33.3 vs. 37.3, p =0.049) but demonstrated a greater magnitude of improvement (Δ PCS-12: 5.43 vs. 0.87, p =0.048). Worse stenosis was independently associated with greater ΔPCS-12 at 1-year (β =5.59, p =0.022).

CONCLUSIONS

Patients with severe FS presented with worse preoperative physical health. While ACDF improved outcomes and conferred similar motor recovery in all patients, those with severe FS reported much better improvement in physical function.

The imaging of cervical spondylotic myeloradiculopathy

This review provides a detailed description of the imaging features of cervical spondylotic myelopathy and radiculopathy, with a focus on MRI. Where relevant, we will outline grading systems of vertebral central canal and foraminal stenosis. Whilst post-operative appearances of the cervical spine are outside the scope of this paper, we will touch on imaging features recognised as predictors of clinical outcome and neurological recovery. This paper will serve as a reference for both radiologists and clinicians involved in the care of patients with cervical spondylotic myeloradiculopathy.

Preoperative Radiographic Simulation for Partial Uncinate Process Resection during Anterior Cervical Discectomy and Fusion to Achieve Adequate Foraminal Decompression and Prevention of Vertebral Artery Injury

STUDY DESIGN

Retrospective radiographic study.

PURPOSE

This study aims to demonstrate the proper resection trajectory of a partial posterior uncinate process resection combined with anterior cervical discectomy and fusion (ACDF) and evaluate whether foraminal stenosis or uncinate process degeneration increases the risk of vertebral artery (VA) injury.

OVERVIEW OF LITERATURE

Appropriate resection trajectory that could result in sufficient decompression and avoid vertebral artery injury is yet unknown.

METHODS

We retrospectively reviewed patients who underwent cervical magnetic resonance imaging and computed tomography angiography for preoperative ACDF evaluation. The segments were classified according to the presence of foraminal stenosis. The height, thickness, anteroposterior length, horizontal distance from the uncinate process to the VA, and vertical distance from the uncinate process baseline to the VA of the uncinate process were measured. The distance between the uncinate anterior margin and the resection trajectory (UAM-to-RT) was measured.

RESULTS

There were no VA injuries or root injuries among the 101 patients who underwent ACDF (163 segments, mean age of 56.3±12.2). Uncinate anteroposterior length was considerably longer in foramens with foraminal stenosis, whereas uncinate process height, thickness, and distance between the uncinate process and VA were not significantly associated with foraminal stenosis. There were no significant differences in radiographic parameters based on uncinate degeneration. The UAM-to-RT distances for adequate decompression were 1.6±1.4 mm (range, 0-4.8 mm), 3.4±1.7 mm (range, 0-7.1 mm), 4.0±1.7 mm (range, 0-9.0 mm), and 4.5±1.2 mm (range, 2.5-7.5 mm) for C3-C4, C4-C5, C5-C6, and C6-C7, respectively.

CONCLUSIONS

More than half of the uncinate process in the anteroposterior plane should be removed for adequate neural foramen decompression. Foraminal stenosis or uncinate degeneration did not alter the relative anatomy of the uncinate process and the VA and did not impact VA injury risk.

Additional benefit of ultrasonography to evaluate nerve root condition of degenerative cervical spine disease

STUDY DESIGN

A cross-sectional explanatory study.

OBJECTIVES

To clarify the nerve root condition and the association between nerve root cross-sectional area (CA) on ultrasonography (US) and other examinations such as MRI or compound muscle action potentials (CMAPs) in degenerative cervical spine diseases.

SETTING

A university hospital in Japan.

METHODS

Fifty-one patients diagnosed with proximal cervical spondylotic amyotrophy (CSA) (13 patients), cervical radiculopathy of C5 or C6 nerve root (CR) (26 patients), or cervical spondylotic myelopathy (CSM) (12 patients), and twenty-nine healthy volunteers were included in this study. Neurological findings, US findings and CMAPs of deltoid and biceps muscles of all participants were evaluated. In addition, CSA, CR, and CSM patients underwent MRI.

RESULTS

A significant correlation was not observed between CA and CMAP amplitude or foraminal diameter on MRI (P > 0.05). In the US examination, the C6 CA of the affected side of the CR group was significantly larger than that of both the normal side and the other groups (P < 0.001). The C5 CA of the affected side of the CSA group clearly showed a bimodal distribution: enlarged and small CA groups. In the CMAP findings, CSA cases respectively showed the lower amplitude of deltoid and bicep CMAPs on both the normal and the affected side (P ≦ 0.01). CSM and healthy volunteers were nearly identical in CA and CMAPs.

CONCLUSION

Utilizing US in addition to NCS and MRI can contribute towards an evaluation of the nerve root condition of degenerative cervical spine disease.

SPONSORSHIP

no sponsorship.

Deep learning reconstruction for the evaluation of neuroforaminal stenosis using 1.5T cervical spine MRI: comparison with 3T MRI without deep learning reconstruction

PURPOSE

To compare image quality and interobserver agreement in evaluations of neuroforaminal stenosis between 1.5T cervical spine magnetic resonance imaging (MRI) with deep learning reconstruction (DLR) and 3T MRI without DLR.

METHODS

In this prospective study, 21 volunteers (mean age: 42.4 ± 11.9 years; 17 males) underwent cervical spine T2-weighted sagittal 1.5T and 3T MRI on the same day. The 1.5T and 3T MRI data were used to reconstruct images with (1.5T-DLR) and without (3T-nonDLR) DLR, respectively. Regions of interest were marked on the spinal cord to calculate non-uniformity (NU; standard deviation/signal intensity × 100), as an indicator of image noise. Two blinded radiologists evaluated the images in terms of the depiction of structures, artifacts, noise, overall image quality, and neuroforaminal stenosis. The NU value and the subjective image quality scores were compared between 1.5T-DLR and 3T-nonDLR using the Wilcoxon signed-rank test. Interobserver agreement in evaluations of neuroforaminal stenosis for 1.5T-DLR and 3T-nonDLR was evaluated using Cohen's weighted kappa analysis.

RESULTS

The NU value for 1.5T-DLR was 8.4, which was significantly better than that for 3T-nonDLR (10.3; p < 0.001). Subjective image scores were significantly better for 1.5T-DLR than 3T-nonDLR images (p < 0.037). Interobserver agreement (95% confidence intervals) in the evaluations of neuroforaminal stenosis was significantly superior for 1.5T-DLR (0.920 [0.916-0.924]) than 3T-nonDLR (0.894 [0.889-0.898]).

CONCLUSION

By using DLR, image quality and interobserver agreement in evaluations of neuroforaminal stenosis on 1.5T cervical spine MRI could be improved compared to 3T MRI without DLR.

The value of magnetic resonance imaging and computed tomography in the study of spinal disorders

Computed tomography (CT) and magnetic resonance imaging (MRI) have replaced conventional radiography in the study of many spinal conditions, it is essential to know when these techniques are indicated instead of or as complementary tests to radiography, which findings can be expected in different clinical settings, and their significance in the diagnosis of different spinal conditions. Proper use of CT and MRI in spinal disorders may facilitate diagnosis and management of spinal conditions. An adequate clinical approach, a good understanding of the pathological manifestations demonstrated by these imaging techniques and a comprehensive report based on a universally accepted nomenclature represent the indispensable tools to improve the diagnostic approach and the decision-making process in patients with spinal pain. Several guidelines are available to assist clinicians in ordering appropriate imaging techniques to achieve an accurate diagnosis and to ensure appropriate medical care that meets the efficacy and safety needs of patients. This article reviews the clinical indications of CT and MRI in different pathologic conditions affecting the spine, including congenital, traumatic, degenerative, inflammatory, infectious and tumor disorders, as well as their main imaging features. It is intended to be a pictorial guide to clinicians involved in the diagnosis and treatment of spinal disorders.

A systematic review of validated classification systems for cervical and lumbar spinal foraminal stenosis based on magnetic resonance imaging

PURPOSE

Foraminal stenosis is commonly investigated with radiological methods in patients with radiating pain in extremities. However, there is a lack of consensus regarding the methodology to assess compression of the nerve roots. This systematic review was performed to identify validated classification systems for foraminal stenosis in the lumbar and cervical spine based on magnetic resonance imaging (MRI).

METHODS

A systematic search was conducted according to the PRISMA guidelines. The search included Cochrane, Embase, Medline and PubMed databases going back 30 years and up to September 2021. Three categories of words were used in different variations; foraminal stenosis, MRI and scoring. For inclusion, at least one word from each category had to be present. Articles suggesting classification systems or reporting on their validation were selected for inclusion.

RESULTS

A total of 823 articles were identified and all abstracts were reviewed. Subsequently, a full-text review of 64 articles was performed and finally 14 articles were included. A total of three validated classification systems were found for the cervical and lumbar spine. The remaining 11 articles reported on validation or suggested modifications of the classification systems.

CONCLUSION

The three classification systems demonstrated moderate to good reliability and have all been shown feasible in the clinical setting. There is however a need for further studies testing the validity of these classifications in relation to both clinical findings and to surgical outcome data.

Nerve root morphological and functional changes after degenerative cervical myelopathy surgery: preliminary study using ultrasound and electrophysiology

STUDY DESIGN

A prospective observational study.

OBJECTIVES

To depict morphological and functional changes in the cervical nerve roots before and after spinal cord decompression surgery for degenerative cervical myelopathy (DCM).

SETTING

A general hospital in Japan.

METHODS

Thirteen DCM patients who underwent posterior spinal cord decompression surgery, laminoplasty or laminectomy, were included in this study. The neural foramen shown on MRI and the cross-sectional area (CSA) of the nerve roots on ultrasound were used to evaluate the C5 and C6 nerve roots. The compound muscle action potentials (CMAPs) of deltoid and biceps muscle were also recorded.

RESULTS

All patients showed sensorimotor functional improvement without the postoperative C5 palsy after surgery. Foraminal stenosis and preoperative CSA of the nerve root: C4/5 foramen and C5 nerve root, C5/6 foramen and C6 nerve root, had no significant correlation (P = 0.53 and 0.08). CSA of the C5 nerve root displayed no significant change before and after surgery (P = 0.2), however, that of the C6 nerve root reduced significantly after surgery (P = 0.038). The amplitude of the deltoid and biceps CMAPs displayed no significant change before and after surgery (P = 0.05 and 0.05).

CONCLUSION

The C6 nerve root CSA change was observed after spinal cord decompression surgery with functional recovery. However, deltoid and biceps CMAPs amplitude showed no significant change. Independent CSA changes on ultrasound might be useful when conducting a functional evaluation of the postoperative nerve root.

SPONSORSHIP

The Grant of Japan Orthopaedics and Traumatology Research Foundation No. 395.