Main imaging methods for spinal cord vessels
Two main modalities are used to evaluate the vascular bed of the spinal canal, each with its own technical features:
- Digital subtraction angiography (DSA / DSA). This technique provides the best visualization quality of small vessels compared to any other method. However, it is a complex, time-consuming, and invasive intervention. Due to the high risk of complications (morbidity / morbidity) and significant cost, the procedure should be performed exclusively in specialized medical centers by experienced specialists.
- CT angiography (CTA / CTA). A less invasive alternative requiring strict technical parameters. To adequately opacify the spinal arteries and the vascular network of the spinal cord itself, a high-concentration radiopaque agent must be used. In addition, a high intravenous injection rate—at least 6 mL/s—is critically important.
Indications for the study
DSA is considered justified only when the study results have high therapeutic value, meaning they can directly influence the patient's further management. During diagnostic spinal angiography, a therapeutic intervention—embolization (embolisation)—can be performed immediately.
Key indications include:
- Suspected arteriovenous malformations (AVMs / AV malformations).
- Diagnosis of spinal aneurysms.
- Visualization of vascular tumors located in the spinal cord, its meninges, or the structures of the spinal column.
- Preoperative vascular mapping, in particular locating the artery of Adamkiewicz (Adamkiewicz artery), before planned extensive aortic or spinal surgeries.
Differential diagnosis challenges
When performing magnetic resonance imaging (MRI), specialists frequently encounter slow-flow artifacts (small-flow artefacts). Visually, such artifacts can closely mimic a vascular malformation, leading to overdiagnosis.
To avoid unjustifiably subjecting a patient to a complex and risky invasive DSA, it is necessary to properly differentiate the artifact from true pathology. To achieve this, thin-slice scanning and mandatory intravenous contrast administration with gadolinium-based agents (Gd) are used during the MRI protocol.
Role of CT in spinal cord assessment
Computed Tomography (Computed Tomography) is traditionally the method of choice in the evaluation of trauma patients, as it has the highest sensitivity in detecting bone fractures.
Although MRI has become the more common standard for routine evaluation of intervertebral discs and spinal canal structures today, conventional spinal CT remains an entirely adequate method. It allows for high-quality visualization of the spinal cord and reliably rules out acute compression caused, for example, by a traumatic hematoma or a large disc herniation.
Review of clinical illustrations
The practical application of diagnostic imaging methods is best demonstrated by specific clinical examples:
Case 1: Arteriovenous malformation (AVM)
- On the T2-weighted sagittal MRI scan of the thoracic spine, an AVM is clearly visualized posterior to the spinal cord. An area of abnormal signal hyperintensity is identified within the spinal cord parenchyma, which is a sign of developing myelomalacia (myelomalacia).
- During selective DSA of the right lumbar artery at the T6 vertebral level, the pathological AVM network is contrasted with maximum clarity.
- Additional selective DSA of the left lumbar artery at the T8 level reveals the origin of the critically important artery of Adamkiewicz.
Case 2: Postoperative assessment (plain film myelography / Plain Film Myelography)
- A patient underwent plain radiography in anteroposterior and lateral projections following posterior lumbar intervertebral fusion (posterior lumbar intervertebral fusion) and placement of an artificial disc prosthesis at the L4-L5 level.
- The administered contrast agent (myelography) clearly demonstrates the free patency of the cerebrospinal fluid spaces and confirms the absence of spinal canal stenosis following the intervention.
Briefly: answers to topical questions
Which main arterial basins and branches form the blood supply to the spinal cord?
The blood supply to the spinal cord has a segmental character and is formed by several major vessels and their branches.
- Aorta (aorta) is the main source at the thoracic and lumbar levels.
- Brachiocephalic trunk (truncus brachiocephalicus) gives rise to the vessels of the right side of the neck.
- Common carotid artery (a. carotis communis).
- Thyrocervical trunk (truncus thyrocervicalis) supplies the cervical enlargement.
- Costocervical trunk (truncus costocervicalis) supplies the lower cervical and upper thoracic segments.
- Vertebral artery (a. vertebralis) is a vital source for the upper cervical segments.
Terminal branches of the subclavian, intercostal, lumbar, and internal iliac arteries also participate in the blood supply.
At which spinal segment levels does the artery of Adamkiewicz anatomically originate most frequently?
Anatomically, the artery of Adamkiewicz (artery of Adamkiewicz), or the great radicular artery (a. radicularis magna), most frequently originates at the level of the lower thoracic or upper lumbar vertebrae. In most cases, this largest vessel supplying the spinal cord originates from the aorta at the T9–L2 segments on the left side.
Which specific groups of radiopaque agents are used for CT angiography of the spinal cord vessels?
CT angiography of spinal cord vessels requires a high-concentration radiopaque agent and a high injection rate of 6 mL/s.
What MRI features, besides myelomalacia, are characteristic of spinal cord arteriovenous malformations?
In addition to myelomalacia, spinal cord arteriovenous malformations are characterized by the following MRI features:
- Flow voids (flow voids) — tortuous dilated intra- and/or perimedullary veins on T2-WI that enhance with contrast medium.
- Cord edema (cord oedema) — ill-defined hyperintense signal on T2-WI accompanied by spinal cord expansion (thickening) due to venous congestion.
- Hemosiderin deposition — visualized as a hypointense rim around the intramedullary lesion.
- Hemorrhage — signal intensity depends on age; subarachnoid hemorrhage or intranidal aneurysm may be present.
Class and exam questions
What is the main advantage of DSA over other methods?
Digital subtraction angiography provides the highest quality visualization of spinal vessels and allows for a simultaneous therapeutic intervention—embolization.
Why is a high-concentration contrast agent needed in spinal CT angiography?
Spinal arteries and spinal cord vessels have a very small caliber. Their adequate visualization requires not only a high-concentration agent but also its administration at a high rate (6 mL/s.
What is myelomalacia and how does it appear on MRI?
Myelomalacia is the softening of the spinal cord tissue (e.g., in the setting of vascular pathology). On T2-weighted images, it is visualized as an area of pathological signal hyperintensity.
How to distinguish a vascular malformation from an MRI artifact?
Slow-flow artifacts can mimic AVMs. Thin-slice scanning with gadolinium contrast is used for accurate differentiation.
What else to study on this topic
- Features of selective catheterization of intercostal and lumbar arteries during DSA
- Topographic anatomy of the artery of Adamkiewicz and its clinical significance
- Classification and hemodynamics of spinal arteriovenous malformations
- Endovascular embolization: materials used and technique
- MRI semiotics of myelomalacia and ischemic spinal cord lesions
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