Angiography of the brain and spinal cord

Angiography is a method of examining the vascular system of the brain and spinal cord by injecting a contrast agent into the arteries supplying blood to the brain. It was first proposed by Monitz in 1927, but its widespread use in clinical practice began only in the 1940s.

Improvement of X-ray equipment, creation of intravascular catheter systems, appearance of X-ray surgical and new X-ray contrast agents allowed to switch to isolated contrasting of basins first of the main and then of the intracranial arteries. It became possible to conduct selective angiography - a method in which a catheter after puncture and catheterization of a large artery (usually the femoral) is inserted under fluoroscopic X-ray control into a certain vascular basin of the brain (selective angiography) or a separate vessel (superselective angiography), after which a contrast agent is injected intra-arterially with serial filming of the skull in the corresponding projection. Modern angiographic installations are television systems in which the registration of the X-ray beam is performed using an electron-optical converter and a television camera or a position-charge system. The recorded video signals are digitized with high resolution, and the computer performs mathematical processing of the entire series of digital images, consisting of subtracting from each serial image the so-called mask - the first image in the series, obtained before the introduction of the contrast agent. After subtracting the "mask", only the contours of the vessels filled with the contrast agent as it passes through the vascular system remain on the images. Bone structures are practically invisible. This method is called "digital subtraction angiography".

Currently, cerebral angiography is used mainly when arterial or arteriovenous aneurysm of the cerebral vessels is suspected, as a method of preoperative diagnostics and postoperative monitoring, as well as in determining thrombosis or stenosis of the main vessels in the neck. The use of cerebral angiography in determining the sources of blood supply and relationships with large arteries of various brain tumors, primarily those located basally at the base of the skull, is still important, which allows planning surgical access and the volume of removal (meningiomas, pituitary adenomas, etc.). Indications for digital subtraction angiography include planning radiation therapy for small arteriovenous malformations.

New possibilities in visualization of vascular pathology of the central nervous system have opened up with the introduction of 3D reconstruction methods into clinical practice. It has become possible to combine high-resolution angiography and the construction of three-dimensional models of brain vessels.

The digital subtraction angiography method is the basis of interventional endovascular methods of treating vascular diseases of the brain and spinal cord, which in neurosurgery are considered minimally invasive. This direction is currently singled out as a separate specialty - interventional neuroradiology.

Spinal angiography is used to examine the vessels that supply the spinal cord. The technique used is similar to cerebral angiography. Through a catheter in the femoral artery, catheterization of the artery in the basin of which vascular pathology is suspected is performed (usually, these are intercostal arteries). Selective spinal angiography is the main method for diagnosing arteriovenous malformations of the spinal cord, which allows identifying both afferent and efferent vessels of the malformations. Less often, it is used to determine the blood supply of certain types of tumors of the spine and spinal cord, such as hemangiomas and hemangioblastomas. Catheterization of the vessels that supply the spinal cord and spine allows not only to identify vascular pathology, but also to simultaneously perform embolization of arteriovenous malformations and large vessels involved in the blood supply of the tumor.

In modern neuroradiological practice, methods with positive contrasting of the subarachnoid spaces and the ventricular system of the brain are still preserved. Currently, contrasting of cerebrospinal fluid in brain structures is used with the help of radiocontrast agents based on iodine. Since the appearance of the first contrast agent in 1925, work on reducing the toxicity of such substances has not ceased.

Ventriculography with non-ionic radiopaque agents is an invasive diagnostic method, now used extremely rarely and for strict clinical indications. The method involves the introduction of a contrast agent into the cavity of the lateral ventricles by puncturing, as a rule, one of the anterior horns. Indications for the study include determining the patency of the interventricular openings, the state of the cerebral aqueduct, the third and fourth ventricles, mainly in complex congenital malformations of the cerebrospinal fluid spaces and the brain itself. As a modification of the method, cystography is distinguished (the introduction of contrast agents into the cavity of an intracranially located cyst, less often into a craniopharyngioma cyst, to determine its relationship with the cerebrospinal fluid spaces of the brain). In a modern neurosurgical hospital equipped with CT, a combination of a lateral ventricle puncture with the introduction of a contrast agent into it and CT capabilities is most often used - CT ventriculography.

Myelography is a method for examining the cerebrospinal fluid system of the spinal cord. It is performed by puncturing the subarachnoid space of the spinal cord and introducing a water-soluble contrast agent into it. The method is classified as invasive and is not used in outpatient settings. A distinction is made between descending myelography, when the puncture of the subarachnoid spaces is performed at the level of the large occipital cistern (currently almost never used), and ascending myelography - the puncture is performed at the level of the lower lumbar region. This method was widely used earlier, but with the advent of MRI, it has been virtually eliminated from everyday practice. In modern conditions, it is used mainly to determine the degree of compression of the subarachnoid spaces of the spinal cord in complex herniated discs, in the diagnosis of inflammatory changes in the membranes of the spinal cord (arachnoiditis), in the postoperative period, to resolve the issue of the patency of the subarachnoid spaces in case of a relapse of a herniated disc or tumor, postoperative cicatricial adhesive process. The indication for myelography remains a suspicion of a malformation of the cerebrospinal fluid spaces of the spinal cord (meningocele). In the presence of CT, myelography, as a rule, is only the primary stage for further CT myelography or its variety - CT cisternography (for visualization of cerebrospinal fluid fistulas in the cranial cavity).

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