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The value of MR in differentiating subligamentous from supraligamentous lumbar disk herniations
C S Silverman1, L Lenchik, P M Shimkin
1Department of Radiology, Bridgeport Conn. Hospital 06610, USA.
Purpose:
To determine the value of MR criteria in differentiating subligamentous from supraligamentous lumbar disk herniations.
Methods:
A retrospective review of surgical reports and MR images of 50 patients undergoing first-time lumbar surgery was performed. Three MR imaging criteria were assessed: the presence and integrity of a low-signal-intensity line posterior to the disk herniation, the size of the disk herniation in comparison with the size of the spinal canal, and the presence of disk fragments. Correlation was made with surgical findings to determine the value of these MR criteria in differentiating subligamentous from supraligamentous disk herniations.
Results:
For determining subligamentous disk herniations: the presence of a continuous low-signal-intensity line posterior to the disk herniation was 29% sensitive, 65% specific, and 42% accurate; disk herniation size less than 50% of the size of the spinal canal was 64% sensitive, 47% specific, and 58% accurate; and the absence of disk fragments was 88% sensitive, 12% specific, and 62% accurate. Combinations of individual MR criteria did not improve diagnostic accuracy.
Conclusions:
For differentiating subligamentous from supraligamentous lumbar disk herniations, none of the MR imaging criteria assessed was reliable.
Insights
Magnetic resonance (MR) imaging criteria are not reliable for distinguishing between subligamentous and supraligamentous lumbar disc herniations. Further research is needed to improve diagnostic accuracy for these specific herniation types.
Area of Science:
- Radiology
- Neurosurgery
- Orthopedics
Background:
- Lumbar disc herniations can occur above or below the ligamentum flavum.
- Accurate differentiation is crucial for surgical planning and outcomes.
- Current MR imaging criteria require further validation.
Purpose of the Study:
- To evaluate the diagnostic value of specific MR imaging criteria in differentiating subligamentous from supraligamentous lumbar disc herniations.
- To assess the reliability of MR imaging findings in surgical decision-making for lumbar disc herniations.
Main Methods:
- Retrospective review of surgical reports and MR images from 50 patients with lumbar disc herniations.
- Assessment of three MR imaging criteria: posterior low-signal line, herniation size relative to spinal canal, and presence of disc fragments.
- Correlation of MR findings with intraoperative surgical observations.
Main Results:
- The presence of a posterior low-signal line showed 29% sensitivity and 65% specificity.
- Herniation size <50% of the spinal canal had 64% sensitivity and 47% specificity.
- Absence of disc fragments had 88% sensitivity and 12% specificity; combinations did not improve accuracy.
Conclusions:
- None of the assessed MR imaging criteria reliably differentiate subligamentous from supraligamentous lumbar disc herniations.
- The evaluated MR criteria have limited diagnostic value for this specific differentiation.
- Improved MR imaging techniques or additional criteria may be necessary.