Imaging the cervical spine: a comparison of MR with myelography and CT myelography

Clinical usefulness of CT-myelogram comparing with the MRI in degenerative cervical spinal disorders: is CTM still useful for primary diagnostic tool?

STUDY DESIGN

A radiographic review of 50 patients (29 radiculopathy and 21 myelopathy) who had undergone the anterior cervical discectomy and fusion was performed by 3 observers retrospectively.

OBJECTIVE

To compare the accuracy between magnetic resonance imaging (MRI) and postmyelographic computed tomography (CTM) in degenerative cervical spine disease by assessing the degree of interobserver and intraobserver agreement.

SUMMARY OF BACKGROUND DATA

The assessment of degenerative cervical spinal disease is still demanding. Now MRI is accepted as a primary diagnostic tool for degenerative cervical spine disease. Compared with MRI, usage of CTM has diminished, but it is usually reserved for the patients for whom MRI results were ambiguous or technically suboptimal.

METHODS

We retrospectively reviewed MRIs and CTMs of 50 patients (29 radiculopathy and 21 myelopathy) who had undergone the anterior cervical discectomy and fusion procedure. Using an assessment scale, 3 observers examined 5 parameters: spinal canal narrowing, foraminal stenosis, bony abnormality, intervertebral disk herniation, and nerve root compression. The degree of severity was graded using a 4-point scale for each item. Intraobserver, interobserver agreement, and the accentuation of each image were analyzed.

RESULTS

Intraclass correlation coefficiency statistical analysis showed moderate intraobserver agreement (Cronbach's alpha=0.63) and interobserver agreement (0.52). There was no significant difference in intraobserver, interobserver agreement between MRI (0.58) and CTM (0.57). Compared between MRI and CTM, disc abnormality and nerve root compression on MRI and foraminal stenosis and bony lesion on CTM showed better agreement.

CONCLUSIONS

CTM was still useful in diagnosis of the foraminal stenosis and bony lesion comparing with MRI but showed limitation in disc abnormality and nerve root compression. So even though CTM may provide valuable additional information in difficult or ambiguous cases, it also requires universal standards and sound experience for constant and objective information.

False Negative Magnetic Resonance Imaging Results: A Report of 2 Cases

OBJECTIVES

The purpose of this study is to present 2 clinical case studies in which large herniated disks were not detected on magnetic resonance imaging (MRI), leading to false negative results, and discuss some issues regarding potential shortcomings of MRI.

CLINICAL FEATURES

Cases of cervical and lumbar herniated nucleus pulposus (HNP) are presented. Each patient had severe pain and neurological deficit. The patients had positive physical examination findings suggestive of HNP despite the negative MRI scans. Both subsequently underwent myelography and computed tomography to arrive at the final and definitive diagnosis of HNP.

INTERVENTION AND OUTCOME

Both patients failed a course of conservative care that included manual and mechanical traction, manual mobilization, myofascial release techniques, epidural steroid injections, oral steroid and narcotic medications, and rehabilitative exercises. Both patients eventually required surgical decompression.

CONCLUSION

False negative MRI results in these cases of large HNPs emphasize the importance of case history and physical examination findings as the basis for ordering diagnostic tests. The conclusion of this article is simple; no single diagnostic test should be considered as 100% accurate, as false negative studies may occur that may mislead the patient and clinician.