I. Aneurysm (AN)
DSA images show an abnormal bulge in the arterial wall.
DSA can show the size, number, shape, spasm and bleeding of aneurysm. Wan Zou, Department of Brain Surgery, Nanchang Third Hospital
Gross outline of aneurysm or small spike-like protrusion and displacement of nearby vessels are signs of ruptured aneurysm and bleeding.
The size and shape of intracranial aneurysms are very different, but they generally have a “neck” connected to the artery. Those with a wide neck are called saccular aneurysms, while those with a narrow neck are called “berry-shaped” aneurysms. There is also a type of aneurysm without a neck, which appears as a localized enlargement of the artery in the shape of a shuttle or S-shaped aneurysm. Some aneurysms may have one or more sacs protruding from the aneurysm wall, called lobulated aneurysms, which are more likely to rupture and bleed. The part of the aneurysm opposite the neck is called the “base”.
Aneurysms between 2 and 2.5 cm in diameter are called large aneurysms, and those exceeding 2.5 cm are called giant aneurysms.
The main points of DSA examination are summarized as follows.
1.Multi-angle confirmation – two or more angles.
2.Aneurysm stagnation confirmation – limited to narrow carotid aneurysms.
3, morphological confirmation – saccular, berry-shaped, lobulated, spindle-shaped, etc.
4.Location confirmation – mostly seen in (1) anterior communicating artery, (2) posterior communicating artery, (3) middle cerebral artery, (4) vertebral artery.
II. Arteriovenous malformation (AVM)
The malformed vascular masses are mostly located in the subcortical area, and the lesions may be mass-like, earthworm-like, or densely packed into spheres of blood sinusoidal form. Some small lesions are seen with only one blood supply artery and one draining vein, similar to AVF, mostly located in the brain parenchyma, with little microvascular component on pathological examination. In the occult type, one or two vessels are thickened or one draining vein is seen.
The blood supplying artery is coarse and tortuous and enters the lesion, and some of the lesions near the convex surface of the brain are seen to be supplied by the meningeal artery.
The draining vein is thick and tortuous and is often seen together with the malformation mass, which is a characteristic manifestation of AVM. Sometimes the veins are spherically dilated.
Blood theft: Due to short-circuiting of the malformation lesion, blood flow is injected into the vein in large quantities, so the blood supply artery, malformation mass and draining vein are early and intense, while other vessels are poorly visualized or not visualized.
Hemorrhagic signs: The vessels of the malformation mass lack elastic layer, and the vessel wall is thin and prone to rupture, resulting in intracerebral hematoma causing occupational effect. The period of acute hemorrhage can affect the visualization of AVM.
The basic pathological change of meningeal AVM is cerebral AVM and also combined with meningeal AVM. In terms of DSA manifestation, the dual supply of internal and external carotid arteries is the characteristic feature of this disease. The external carotid artery can be seen as a “dangerous anastomosis” of the occipital spine. The venous drainage may appear as intracranial or extracranial venous drainage or dual drainage. Other manifestations are similar to AVM.
DSA features are summarized as follows
1. arteries supplying blood – thick and tortuous.
2, presence of aberrant masses (Nidus).
3. the reflux vein – early manifestation, coarse.
III. Carotid cavernous fistula (CCF)
It is a cavernous sinus vasculopathy due to trauma or various causes, so that the internal and external carotid arteries and/or their branches communicate with the cavernous sinus.
Separate imaging of the internal and external carotid arteries should be performed to determine, in addition to the location of the fistula, the arterial “steal”, venous drainage, development of the venous sinus and intercavernous sinus, whether there is drainage to the contralateral side, dilatation of the cavernous sinus, entry into the pterygoid sinus, and the presence of draining venous aneurysm-like dilatation and pseudoaneurysm.
DSA features are summarized as.
1, internal carotid artery trunk or branches communicating with the cavernous sinus, with or without external carotid artery blood supply.
2, early manifestation of the cavernous sinus.
3, premature manifestation of the veins associated with the cavernous sinus.
4. “Blood theft” phenomenon.
According to the hemodynamics of DSA, they can be divided into high-flow fistulas (most traumatic CCF and ruptured internal carotid aneurysms of the cavernous sinus) and low-flow fistulas (DAVF of the cavernous sinus), also known as Parkinson type I and II.
Barrow classifies them into four types based on the relationship of the diseased arterial vessels to the cavernous sinus on DSA as follows.
Type A: Internal carotid artery trunk with cavernous sinus traffic
Type B: Internal carotid artery branches communicating with the cavernous sinus
Type C: External carotid artery and cavernous sinus traffic
Type D: Type B+C, in which both the internal carotid artery branches and the external carotid artery traffic with the cavernous sinus.
According to the characteristics of venous drainage on DSA, it can be further divided into 5 types as follows.
1, anterior drainage: DSA shows more than 90% thickening of the ophthalmic veins, impaired venous blood return to the face and orbit, and corresponding clinical symptoms.
2, superior drainage: pterygoid parietal sinus (including superficial lateral fissure vein) or deep lateral fissure vein drainage. It often shows a lake-like dilatation of the cavernous sinus.
3.Healthy side drainage: through the intercavernous sinus (anterior and posterior) can drain to the healthy side of the vein.
4.Inferior drainage: mainly the pterygoid plexus.
5.Mixed drainage: the most common.
Dural arteriovenous fistula (DAVF)
DAVF is a type of vascular disease in which the arterioles and veins communicate directly with the dura mater and its appendages, the falx and the cerebellar curtain, and the extracranial blood supply arteries communicate directly with the intracranial venous sinuses.
In addition to bilateral internal and external carotid arteries, bilateral vertebral arteries, bilateral thyrocervical trunk and cribriform trunk angiograms should be performed to fully understand the arteries supplying the fistula, the specific site, size and type of the fistula, the draining veins, the flow rate of the fistula, the intracranial “blood theft” and the possible The fistula is a dangerous anastomosis.
DSA shows varying degrees of tortuous dilatation of both the supply artery and the draining vein in DAVF. When the venous sinus pressure is high and cortical venous reflux is poor, especially in DAVF with direct cortical venous drainage, diffuse cortical venous dilatation, tortuous earthworm-like or tumor-like dilatation is seen. Dangerous anastomoses and other branches of the blood supply arteries are often not visualized due to “blood theft” from the fistula, but these vessels can be visualized after fistula occlusion.
DSA features are summarized as follows.
1. the supplying artery is the dural artery – the internal carotid artery, the external carotid artery, and the meningeal branches of the vertebral artery.
2, absence of aberrant vascular masses.
3, the fistula is located on the dura mater.
Herber classified DAVF into four categories according to the site of fistula on DSA.
1, posterior cranial fossa DAVF: the blood supplying artery is mainly the occipital artery.
2. middle cranial fossa DAVF: the blood supplying artery is mainly the posterior branch of the middle meningeal artery.
3, anterior cranial fossa DAVF: the blood supplying artery is mainly the anterior branch of the middle meningeal artery.
4, paracavernous DAVF: the blood supplying artery is mainly the middle meningeal artery and internal maxillary artery branches.
According to the extent of the lesion, it can be divided into simple DAVF which is limited to the dura mater and mixed DAVF which is more extensive.
Cognard classifies DAVF according to the type of draining vein.
Type I: blood flow converging in a prograde direction into the main venous sinus.
Type II: blood flows retrograde into the sinuses (IIa); blood flows retrograde into the cortical veins (IIb); or both (IIa+b).
type III: blood draining directly from the cortical veins, without venous dilatation
type IV: direct drainage from cortical veins with venous dilatation
Type V: blood is drained by spinal veins.
V. Cerebral venous malformation (developmental venous anomaly)
Cerebral venous malformation is also called cerebral venous hemangioma and cerebral venous tumor. It is also called developmental venous anomaly because it is abnormal in shape but still provides functional venous drainage to the corresponding tissues. Venous malformations can be divided into superficial and deep types. The superficial type refers to the deep medullary venous region that drains into the cortical veins through the superficial medullary veins; the deep type refers to the subcortical region that drains into the deep venous system. It is most commonly associated with cavernous hemangiomas. The literature reports that 20% to 30% of cavernous hemangiomas are associated with venous malformations. The histological criteria for differentiating the two are the presence of normal brain tissue between the diseased vessels and the size of the vascular lumen. Cerebral venous malformations can also be associated with other vascular or nonvascular lesions, such as tumors, demyelinating diseases, aneurysmal AVMs, dural arteriovenous fistulas, smoker’s disease, and vascular lesions of the head, face, and eyes. Venous malformations often drain back blood from normal brain tissue away from these lesions and, in rare cases, from the lesions themselves.
The angiogram shows no lesions in the arterial phase, but in the capillary phase there is a “staining” of the lesion, which is clarified in the venous phase and replaced by an enlarged vein with some small branches into its lumen, showing a characteristic “jellyfish head-like” vein This vein eventually leads into the venous sinus. There is no sign of occupancy and it can be differentiated from glioma.
The cerebral circulation time is normal. The lesion lacks a supply artery, and there is no “blood theft” to distinguish it from an AVM.
DSA features are summarized as follows
1, no supply artery.
2. No aberrant vascular mass.
3, the presence of anomalous vessels in the venous phase.
4. “Jellyfish head”-like changes.