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Intramedullary penetrance of metrizamide in the dog spinal cord
Abstract:
Metrizamide computed tomography (CT) myelography is clinically useful in the detection of syringohydromyelia. The mechanism by which intrathecally injected metrizamide migrates into the intramedullary cavity is unknown, although reflux into the central canal of the cord via the obex has been postulated. Since intrathecally injected metrizamide has been shown to penetrate normal brain, similar penetrance of the spinal cord might be expected. Five anesthetized mongrel dogs were examined with sequential CT scanning of the cervical spine for 24 hr after intrathecal introduction of metrizamide. The attenuation values of the specified subarachnoid space and the spinal cord at the level of the atlantoaxial joint were recorded. A significant and reproducible increase with time in attenuation values within the cervical spinal cord accompanied by a progressive decrease in attenuation values of the subarachnoid space was observed. The proposed mechanism of cord enhancement, the implication for cord imaging, and the analysis of patients with syringohydromyelia are discussed.
Insights
Metrizamide computed tomography (CT) myelography helps detect syringohydromyelia. Studies show metrizamide penetrates the spinal cord, aiding in imaging analysis.
Area of Science:
- Neuroradiology
- Spinal Cord Imaging
Background:
- Metrizamide computed tomography (CT) myelography is a valuable tool for diagnosing syringohydromyelia.
- The exact mechanism of metrizamide migration into the spinal cord's intramedullary cavity remains unclear, with reflux via the obex being a proposed theory.
Observation:
- This study investigated metrizamide's spinal cord penetration in dogs using sequential CT scans over 24 hours.
- Attenuation values in the cervical spinal cord and subarachnoid space were measured at the atlantoaxial joint.
Findings:
- A significant, time-dependent increase in cervical spinal cord attenuation values was observed.
- Concurrently, a progressive decrease in subarachnoid space attenuation values indicated contrast agent migration into the cord.
Implications:
- The findings suggest direct spinal cord penetration by metrizamide, offering a potential mechanism for intramedullary cavity enhancement.
- This understanding is crucial for interpreting CT myelography in syringohydromyelia diagnosis and for advancing spinal cord imaging techniques.