J Korean Neurosurg Soc.  2017 Sep;60(5):540-549. 10.3340/jkns.2016.0809.008.

Comparison of Root Images between Post-Myelographic Computed Tomography and Magnetic Resonance Imaging in Patients with Lumbar Radiculopathy

• Park CK
• Lee HJ
• Ryu KS

• KMID: 2457961
• DOI: http://doi.org/10.3340/jkns.2016.0809.008

Abstract

OBJECTIVE
To evaluate the diagnostic value of computed tomography-myelography (CTM) compared to that of magnetic resonance imaging (MRI) in patients with lumbar radiculopathy.
METHODS
The study included 91 patients presenting with radicular leg pain caused by herniated nucleus pulposus or lateral recess stenosis in the lumbar spine. The degree of nerve root compression on MRI and CTM was classified into four grades. The results of each imaging modality as assessed by two different observers were compared. Visual analog scale score for pain and electromyography result were the clinical parameters used to evaluate the relationships between clinical features and nerve root compression grades on both MRI and CTM. These relationships were quantified by calculating the receiver-operating characteristic curves, and the degree of relationship was compared between MRI and CTM.
RESULTS
McNemar's test revealed that the two diagnostic modalities did not show diagnostic concurrence (p<0.0001). Electromyography results did not correlate with grades on either MRI or CTM. The visual analog pain scale score results were correlated better with changes of the grades on CTM than those on MRI (p=0.0007).
CONCLUSION
The present study demonstrates that CTM could better define the pathology of degenerative lumbar spine diseases with radiculopathy than MRI. CTM can be considered as a useful confirmative diagnostic tool when the exact cause of radicular pain in a patient with lumbar radiculopathy cannot be identified by using MRI. However, the invasiveness and potential complications of CTM are still considered to be pending questions to settle.

Keyword

Radiculopathy; Myelography; Magnetic resonance imaging

MeSH Terms

Constriction, Pathologic
Electromyography
Humans
Leg
Magnetic Resonance Imaging*
Myelography
Pain Measurement
Pathology
Radiculopathy*
Spine
Visual Analog Scale

Figure

• 

  Fig. 1 Grading of nerve root images on magnetic resonance imaging. Gr: grade.

• 

  Fig. 2 Grading of nerve root images on computed tomography-myelography. Gr: grade.

• 

  Fig. 3 Grading of nerve root images in the herniated nucleus pulposus and lateral recess stenosis. A: No compromise of the nerve root (grade 0). B: The nerve root is abutted but does not show any signs of deviation or deformation (grade I). C: The nerve root is displaced (deviated) and deformed by compression (grade II). D: Definite nerve root compression with the nerve root completely nonvisualized (grade III). E: No compromise of the nerve root in the lateral recess (grade 0). F: Trefoil-shape change of the lateral recess (grade I). G: Early acute angular narrowing of the lateral recess (grade I). H: Trefoil-shape narrowing of the lateral recess, and displaced (deviated) and deformed nerve root (grade II). I: Angular pinch-like narrowing of the lateral recess, and displaced (deviated) and deformed nerve root (grade II). J: Severe angular pinch-like narrowing of the lateral recess and flattened nerve root (grade III). K: The root image is completely nonvisualized in the lateral recess (grade III).

• 

  Fig. 4 A: Receiver-operating characteristic (ROC) curve for electromyography (EMG)-computed tomography-myelography (CTM) grading; the area under the curve (AUC) is 0.497, indicating no association between the EMG results and grades on CTM. B: ROC curve for EMG-magnetic resonance imaging (MRI) grading; the AUC is 0.567, indicating no association between the EMG results and grades on MRI.

• 

  Fig. 5 A: Receiver-operating characteristic (ROC) curve for visual analog scale (VAS) score-computed tomography-myelography (CTM) grading; the area under the curve (AUC) was 0.691, indicating an moderate association between VAS score and grade on CTM. B: The ROC curve for VAS score-magnetic resonance imaging (MRI) grading; the AUC is 0.598, indicating less association between VAS score and grade on MRI.

• 

  Fig. 6 A: Preoperative magnetic resonance imaging (MRI) T2 and computed tomography-myelography (CTM) axial scans showing differences in root compression finding. While the finding is grade I on the MRI axial scan, the finding is grade III on CTM. Grade I on MRI generally means less significant radicular pain that does not require surgical intervention. However, grade III on CTM generally means severe root compression that requires decompressive surgery. B: CTM axial scan showing severe left L5 root compression by obliteration of the nerve root not detectable on MRI axial scan. While grade II on MRI generally indicates a moderate degree of root compression, grade III on CTM generally means severe root compression that requires decompressive surgery. Grade III on CTM is congruent with the patients’ clinical symptoms (severe radicular pain with a VAS score of 8).

Reference

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