Can recumbent magnetic resonance imaging replace myelography or computed tomography myelography for detecting lumbar spinal stenosis?

CT myelography by intrathecal injection of contrast medium though percutaneous administration route visualizes compressed cervical spinal cord in a mouse

BACKGROUND

Chronic compressive myelopathy (CCM) is a major cause of spinal cord disorders in the elderly, in which the spinal cord is compressed by bony or soft tissue structures. Although computed tomography myelography (CTM) has been clinically used for the diagnosis of CCM, a method of CTM in rodents remains to be developed.

NEW METHOD

A 50 μl Hamilton syringe attached to a disposable needle was percutaneously inserted into the subarachnoid space (cisterna magna) between the occipital bone and C1 lamina in an anesthetized adult mouse, followed by the injection of contrast medium and CT imaging.

RESULTS

CTM clearly visualized the shape of the spinal cord of intact mice and tiptoe-walking Yoshimura (Twy) mice without any health issues.

COMPARISON WITH EXISTING METHOD(S)

Unlike histology, the current method functions in live mice, directly depicts the compressed spinal cord, and provides clinically related image information. Furthermore, the intrathecal administration of contrast medium through the percutaneous route makes CTM less invasive and takes less time than a conventional intrathecal injection method.

CONCLUSIONS

The CTM method used in the present study enables clear visualization of the shape of the dural sac and spinal cord and is useful when conducting experiments on CCM and other spinal diseases in rodents.

Automatic segmentation of dura for quantitative analysis of lumbar stenosis: A deep learning study with 518 CT myelograms

BACKGROUND

The diagnosis of lumbar spinal stenosis (LSS) can be challenging because radicular pain is not often present in the culprit-level localization. Accurate segmentation and quantitative analysis of the lumbar dura on radiographic images are key to the accurate differential diagnosis of LSS. The aim of this study is to develop an automatic dura-contouring tool for radiographic quantification on computed tomography myelogram (CTM) for patients with LSS.

METHODS

A total of 518 CTM cases with or without lumbar stenosis were included in this study. A deep learning (DL) segmentation algorithm 3-dimensional (3D) U-Net was deployed. A total of 210 labeled cases were used to develop the dura-contouring tool, with the ratio of the training, independent testing, and external validation datasets being 150:30:30. The Dice score (DCS) was the primary measure to evaluate the segmentation performance of the 3D U-Net, which was subsequently developed as the dura-contouring tool to segment another unlabeled 308 CTM cases with LSS. Automatic masks of 446 slices on the stenotic levels were then meticulously reviewed and revised by human experts, and the cross-sectional area (CSA) of the dura was compared.

RESULTS

The mean DCS of the 3D U-Net were 0.905 ± 0.080, 0.933 ± 0.018, and 0.928 ± 0.034 in the five-fold cross-validation, the independent testing, and the external validation datasets, respectively. The segmentation performance of the dura-contouring tool was also comparable to that of the second observer (the human expert). With the dura-contouring tool, only 59.0% (263/446) of the automatic masks of the stenotic slices needed to be revised. In the revised cases, there were no significant differences in the dura CSA between automatic masks and corresponding revised masks (p = 0.652). Additionally, a strong correlation of dura CSA was found between the automatic masks and corresponding revised masks (r = 0.805).

CONCLUSIONS

A dura-contouring tool was developed that could automatically segment the dural sac on CTM, and it demonstrated high accuracy and generalization ability. Additionally, the dura-contouring tool has the potential to be applied in patients with LSS because it facilitates the quantification of the dural CSA on stenotic slices.

Machine Learning Predicts Decompression Levels for Lumbar Spinal Stenosis Using Canal Radiomic Features from Computed Tomography Myelography

BACKGROUND

The accurate preoperative identification of decompression levels is crucial for the success of surgery in patients with multi-level lumbar spinal stenosis (LSS). The objective of this study was to develop machine learning (ML) classifiers that can predict decompression levels using computed tomography myelography (CTM) data from LSS patients.

METHODS

A total of 1095 lumbar levels from 219 patients were included in this study. The bony spinal canal in CTM images was manually delineated, and radiomic features were extracted. The extracted data were randomly divided into training and testing datasets (8:2). Six feature selection methods combined with 12 ML algorithms were employed, resulting in a total of 72 ML classifiers. The main evaluation indicator for all classifiers was the area under the curve of the receiver operating characteristic (ROC-AUC), with the precision-recall AUC (PR-AUC) serving as the secondary indicator. The prediction outcome of ML classifiers was decompression level or not.

RESULTS

The embedding linear support vector (embeddingLSVC) was the optimal feature selection method. The feature importance analysis revealed the top 5 important features of the 15 radiomic predictors, which included 2 texture features, 2 first-order intensity features, and 1 shape feature. Except for shape features, these features might be eye-discernible but hardly quantified. The top two ML classifiers were embeddingLSVC combined with support vector machine (EmbeddingLSVC_SVM) and embeddingLSVC combined with gradient boosting (EmbeddingLSVC_GradientBoost). These classifiers achieved ROC-AUCs over 0.90 and PR-AUCs over 0.80 in independent testing among the 72 classifiers. Further comparisons indicated that EmbeddingLSVC_SVM appeared to be the optimal classifier, demonstrating superior discrimination ability, slight advantages in the Brier scores on the calibration curve, and Net benefits on the Decision Curve Analysis.

CONCLUSIONS

ML successfully extracted valuable and interpretable radiomic features from the spinal canal using CTM images, and accurately predicted decompression levels for LSS patients. The EmbeddingLSVC_SVM classifier has the potential to assist surgical decision making in clinical practice, as it showed high discrimination, advantageous calibration, and competitive utility in selecting decompression levels in LSS patients using canal radiomic features from CTM.

Japanese Orthopaedic Association (JOA) clinical practice guidelines on the management of lumbar spinal stenosis, 2021 - Secondary publication

BACKGROUND

The Japanese Orthopaedic Association (JOA) guideline for the management of lumbar spinal stenosis (LSS) was first published in 2011. Since then, the medical care system for LSS has changed and many new articles regarding the epidemiology and diagnostics of LSS, conservative treatments such as new pharmacotherapy and physical therapy, and surgical treatments including minimally invasive surgery have been published. In addition, various issues need to be examined, such as verification of patient-reported outcome measures, and the economic effect of revised medical management of patients with lumbar spinal disorders. Accordingly, in 2019 the JOA clinical guidelines committee decided to update the guideline and consequently established a formulation committee. The purpose of this study was to describe the formulation we implemented for the revision of the guideline, incorporating the recent advances of evidence-based medicine.

METHODS

The JOA LSS guideline formulation committee revised the previous guideline based on the method for preparing clinical guidelines in Japan proposed by the Medical Information Network Distribution Service in 2017. Background and clinical questions were determined followed by a literature search related to each question. Appropriate articles based on keywords were selected from all the searched literature. Using prepared structured abstracts, systematic reviews and meta-analyses were performed. The strength of evidence and recommendations for each clinical question was decided by the committee members.

RESULTS

Eight background and 15 clinical questions were determined. Answers and explanations were described for the background questions. For each clinical question, the strength of evidence and the recommendation were both decided, and an explanation was provided.

CONCLUSIONS

The 2021 clinical practice guideline for the management of LSS was completed according to the latest evidence-based medicine. We expect that this guideline will be useful for all medical providers as an index in daily medical care, as well as for patients with LSS.

When does CT myelography add value beyond MRI for lumbar degenerative disease?

BACKGROUND CONTEXT

In patients with lumbar spinal stenosis, it is crucial for clinicians to identify all symptomatic levels. Prior studies have demonstrated that CT myelography has a greater sensitivity in revealing stenosis (94.4%) compared to MRI (75.9%). However, this is an invasive test that should be used judiciously. No study has identified subgroups of patients that do or do not benefit from this additional invasive testing.

PURPOSE

The objective of this study was to identify subgroups of patients with lumbar stenosis for whom CT myelogram could be expected to provide additional information following an MRI scan.

STUDY DESIGN

Retrospective chart review.

PATIENT SAMPLE

Consecutive series of patients with lumbar degenerative disease seen at a single multisurgeon tertiary spine center.

OUTCOME MEASURES

Degree of stenosis on MRI or CT myelo.

METHODS

Medical records were reviewed to collect standard demographic and surgical data and patient diagnoses. MRI and CT myelo obtained within 6 months of each other in patients >45 years old with a diagnosis of central stenosis, spondylolisthesis or degenerative scoliosis were reviewed. Each lumbar level was recorded as mild, moderate, or severe based on the radiologist's report. Fisher exact test was performed with change in recorded severity of stenosis from MRI to CT myelo as the primary outcome of interest.

RESULTS

Of 269 patients, 207 (80%) had at least one level of moderate or severe central stenosis on MRI and 62 had mild or no stenosis on MRI. Of the 207, 139 (67%) had multilevel stenosis and 68 (33%) had single level stenosis. CT myelo identified a greater proportion of additional stenotic levels in patients with multilevel stenosis (80/139, 58%) compared to patients with single-level stenosis (27/68, 40%, p=.018). In 62 patients with a clinical diagnosis of lumbar stenosis but no moderate to severe stenosis on MRI, CT myelogram identified three additional stenotic levels (3/65, 5%, p=.836).

CONCLUSIONS

CT myelography is not as useful in providing additional information in patients with no stenosis or single level stenosis as compared to patients with multilevel stenosis.

Resurgence of the Role of Computed-Tomography Myelogram in the Era of MRI for Surgical Decision-Making of Lumbar Degenerative Disc Disorder

BACKGROUND

Since the introduction of magnetic resonance imaging (MRI) into clinical practice in the mid-1980s, the role of computed tomography myelography (CTM) has become less important in spinal diagnostics but remains a method that is probably even superior to MRI for special clinical issues. The study aims to report the diagnostic utility of CTM as an adjunct to MRI in lumbar degenerative disc disorder (DDD).

METHODS

Included were 20 patients who presented with symptomatic DDD but with MRI findings that did not correlate with the clinical features. These patients underwent CTM as an additional imaging technique to aid preoperative surgical decision-making. Both imaging modalities were compared for the identification of the impinging pathology as well as the number of levels of compression.

RESULTS

MRI revealed compression and/or impingement at 38 levels, whereas CTM revealed these at 29 levels. Of 20 patients, 18 underwent surgery, and a total of 29 levels were decompressed as localized in the CTM. The visual analog scale (VAS) score for back pain and leg pain at baseline were 6 ± 0.7 and 7 ± 0.4, respectively, and at 6 months postintervention (surgical/conservative) were 2 ± 0.8 and 0.3 ± 0.1, respectively. The Oswestry Disability Index scores at baseline and 6 months postintervention were 56 ± 6.9 and 18 ± 4.2, respectively (P < .0001). There was agreement on the number of levels between MRI and CTM in 10 patients (50%). MRI overestimated the number of involved levels in 9 patients (45%), whereas in the remaining 1 patient (5%), MRI underestimated the number of involved levels. The weighted κ value for agreement between MRI and CTM on the number of levels involved necessitating decompression was 0.4 (95% CI, 0.18-0.77; P = .0009).

CONCLUSIONS

CTM has a role as an adjunct imaging modality to formulate an effective management plan in patients presenting with symptomatic lumbar DDD in cases where MRI findings are inconclusive and ambiguous.

LEVEL OF EVIDENCE

4.

The Role and Contribution of Lumbar Myelography in the Diagnosis and Treatment of Patients With Lumbar Degenerative Disorders: Clinical and Statistical Evaluation of Post-Myelography Treatment of 63 Patients

Introduction

Myelography is a radiological examination method that has been used for the diagnosis of spinal canal pathologies for a long time. More than 90 years of experience has been improved by the development of increasingly less toxic contrast agents. Nowadays, although there are many advanced diagnostic tools, lumbar myelography is a direct imaging technique and so it is a powerful diagnostic method for patients whose treatment has not been decided. The aim of our study is to evaluate the effect of lumbar myelography as a diagnostic method and its contribution to treatment.

Materials and methods

Between January 2016 and April 2018, 63 patients who were admitted to our neurosurgery clinic due to lumbar degenerative disorders and underwent myelography were included in our study. Patients over 30 years of age with lumbar disc disease, narrow spinal canal, and spinal instability, but for whom a surgical decision could not be made, were included in this study.

Results

After lumbar myelography, 55 of 63 patients underwent a surgical procedure and 8 were directed to non-surgical treatment options. The results of the patients were evaluated by Roland-Morris Low Back Pain and Disability Questionnaire (RMQ). Results showed that the contribution of selected treatment protocols to the recovery after myelography was statistically significant.

Conclusion

Nowadays, myelography is not the first choice for the diagnosis of lumbar degenerative disorders. However, according to the results of our study, lumbar myelography is an effective diagnostic tool for specific purposes.

Analysis of radiological parameters associated with decreased fractional anisotropy values on diffusion tensor imaging in patients with lumbar spinal stenosis

PURPOSE

Previous studies have indicated that decreased fractional anisotropy (FA) values on diffusion tensor imaging (DTI) are well correlated with the symptoms of nerve root compression. The aim of our study is to determine primary radiological parameters associated with decreased FA values in patients with lumbar spinal stenosis involving single L5 nerve root.

METHODS

Patients confirmed with single L5 nerve root compression by transforaminal nerve root blocks were included in this study. FA values of L5 nerve roots on both symptomatic and asymptomatic side were obtained. Conventional radiological parameters, such as disc height, degenerative scoliosis, dural sac cross-sectional area (DSCSA), foraminal height (FH), hypertrophic facet joint degeneration (HFJD), sagittal rotation (SR), sedimentation sign, sagittal translation and traction spur were measured. Correlation and regression analyses were performed between the radiological parameters and FA values of the symptomatic L5 nerve roots. A predictive regression equation was established.

RESULTS

Twenty-one patients were included in this study. FA values were significantly lower at the symptomatic side comparing to the asymptomatic side (0.263 ± 0.069 vs. 0.334 ± 0.080, P = 0.038). DSCSA, FH, HFJD, and SR were significantly correlated with the decreased FA values, with r = 0.518, 0.443, 0.472 and - 0.910, respectively (P < 0.05). DSCSA and SR were found to be the primary radiological parameters related to the decreased FA values, and the regression equation is FA = - 0.012 × SR + 0.002 × DSCSA.

CONCLUSIONS

DSCSA and SR were primary contributors to decreased FA values in LSS patients involving single L5 nerve root, indicating that central canal decompression and segmental stability should be the first considerations in preoperative planning of these patients. These slides can be retrieved under Electronic Supplementary Material.

Myelography in the Assessment of Degenerative Lumbar Scoliosis and Its Influence on Surgical Management

Objective

Myelography has been shown to highlight foraminal and lateral recess stenosis more readily than computed tomography (CT) or magnetic resonance imaging (MRI). It also has the advantage of providing dynamic assessment of stenosis in the loaded spine. The advent of weight-bearing MRI may go some way towards improving assessment of the loaded spine and is less invasive, however availability remains limited. This study evaluates the potential role of myelography and its impact upon surgical decision making.

Methods

Of 270 patients undergoing myelography during 2006–2009, a period representing peak utilisation of this imaging modality in our unit, we identified 21 patients with degenerative scoliosis who fulfilled our inclusion criteria. An operative plan was formulated by our senior author based initially on interpretation of an MRI scan. Subsequent myelogram and CT myelogram investigations were scrutinised, with any additional abnormalities noted and whether these impacted upon the operative plan.

Results

From our 21 patients, 18 (85.7%) had myelographic findings not identified on MRI. Of note, in 4 patients, supine CT myelography yielded additional information when compared to supine MRI in the same patients. The management of 7 patients (33%) changed as a result of myelographic investigation. There were no complications of myelography of the total 270 analysed.

Conclusion

MRI scan alone understates the degree of central and lateral recess stenosis. In addition to the additional stenosis displayed by dynamic myelography in the loaded spine, we have also shown that static myelography and CT myelography are also invaluable tools with regards to surgical planning in these patients.

Intraoperative Myelography in Transpsoas Lateral Lumbar Interbody Fusion for Degenerative Lumbar Spinal Stenosis: A Preliminary Prospective Study

Aim

To investigate the feasibility and effectiveness of intraoperative myelography in determining adequacy of indirect spinal canal decompression during transpsoas lateral lumbar interbody fusion (LLIF).

Methods

Seven patients diagnosed with degenerative lumbar spinal stenosis (DLSS) were prospectively included to this study. All patients underwent LLIF and subsequently received intraoperative myelography to determine the effect of indirect spinal canal decompression, which was visualized in both anterior-posterior and lateral images. Those patients with insufficient indirect canal decompression were further resolved by microendoscopic canal decompression (MECD). Radiological parameters, including stenosis ratio and dural sac area of operated levels, were measured and compared before and after operation. Besides, all patients were followed up for at least one year using visual analogue scale (VAS) for back and leg, Japanese Orthopaedic Association score (JOA), and Oswestry disability index (ODI).

Results

Seven patients with 8 operated levels underwent LLIF safely and demonstrated significant symptom relief postoperatively. Five operated levels showed adequate indirect canal decompression intraoperatively, while the remaining three levels did not achieve the adequacy, and their residual stenosis was resolved following MECD. Radiological parameters were improved statistically when compared with preoperation (P < 0.05). Furthermore, neurological symptoms of all patients were also improved significantly (P < 0.05), shown by improved VAS (back and leg), JOA, and ODI at both two-week and one-year follow-up.

Conclusions

Intraoperative myelography during LLIF is able to assess adequacy of indirect canal decompression for DLSS, thus promising favorable clinical outcomes.