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Cerebral vein thrombosis is an important cause of stroke, especially in children and young adults.
It is more common than previously thought, and is often overlooked in initial imaging.
This is a difficult diagnosis because of its nonspecific clinical presentation and subtle imaging presentation.
In this article, we will focus on:
1. The results of routine imaging should remind you of venous thrombosis that is not suspected.
2, how to image patients with suspected venous thrombosis.
3. Traps.
Cerebral venous thrombosis is arranged in descending order in the following venous structures:
Primary dural sinuses:
Superior sagittal, transverse, straight, and sigmoid sinuses.
Cortical veins:
Labbe vein, draining temporal lobes.
The Trolard vein, the largest cortical vein, flows into the superior sagittal sinus.
Deep veins:
Intra-cerebral veins and thalamic veins.
Cavernous sinuses
Patients with clinical cerebral venous thrombosis have a variety of symptoms, ranging from headache to epilepsy and severe coma.
In newborns, shock and dehydration are common causes of venous thrombosis.
In older children, it is usually a local infection, such as mastoiditis or coagulation disorders.
In adults, coagulation disorders are the cause in 70% and infection is the cause in 10% of cases.
In women, oral contraceptive use and pregnancy are serious risk factors.
Venous thrombosis has a nonspecific manifestation, so it is important to recognize subtle imaging findings and indirect signs that may indicate the presence of a thrombosis.
While these findings usually appear in initial scans, they are usually only found in retrospect.
Clinically, patients with venous thrombosis are often accompanied by seizures, which is not a symptom in patients with arterial infarction.
On a routine non-enhanced MR or CT, you should consider the possibility of venous thrombosis when you see:
A direct sign of a blood clot
Non-arterial infarction, especially bilateral and hemorrhagic infarction
Cortical or peripheral lobe hemorrhage
Cortical edema
Directly showing blood clots in the veins of the brain on a non-enhanced CT scan is called a densification sign.
This occurs in only one-third of cases.
Normally, the density of veins is slightly higher than that of brain tissue, and in some cases, it is difficult to say whether veins are normal or too dense (see Traps).
In this case, an enhanced scan is needed to solve this problem. The following figure shows the dense triangulation sign.
The figure below shows a high density of thrombotic cortical veins in the form of lines or ropes, also known as tight line signs.
The figure below shows temporal lobe hemorrhagic cerebral infarction (red arrow). Note the dense transverse sinuses (blue arrows) caused by thrombosis.
The null triangle was found on a CT enhanced scan (CECT) and was first described as superior sagittal sinus thrombosis.
The sign consists of a triangular strengthening area and a relatively low attenuation center, possibly explained by enhanced collateral circulation of the rich dural veins around the sinuses.
In early thrombosis, empty triangulation may not be present and you will have to rely on non-visualization of veins that are thrombotic on THEECT.
Symptoms may disappear after two months due to intrathrombotic recanalization.
The figure below shows thrombosis of the right and left transverse sinuses and sigmoid sinuses (arrows). There is reinforcement around the thrombus.
MR vascular vascular vascular voiding disappears
On spin echo images, unclosed brain veins usually exhibit low signal intensity because of empty flow.
Streaming voids are most common on T2-weighted images and FLAIR images, but can sometimes also be seen on T1-weighted images.
Thrombosis manifests as the disappearance of empty fluidity and an increase in signal.
While this isn't a completely reliable sign, it's often the first thing that makes you think about the possibility of venous thrombosis.
The next step must be a contrast enhancement check.
The figure below shows a T2-weighted image with normal blood flow (blue arrow) in the right sigmoid sinus and jugular vein.
There is an abnormally high signal on the left side, which is the result of thrombosis (red arrow).
The lower image shows an abnormally high signal due to thrombosis on a T1-weighted image.
Thrombosis extends from the deep veins and straight sinuses of the brain to the right transverse and sigmoid sinuses.
Notice the normal flow void of the transverse sinus on the left side of the lower right image.
Normal voiding on MR images is very helpful in detecting venous thrombosis, but there are also some defects that we will discuss later.
Slow blood flow may occur in the veins and lead to high T1 intensity.
Venous infarction
Another sign that can help you diagnose unidentified venous thrombosis is venous infarction.
Venous thrombosis leads to venous hypertension, which first leads to angioedema of the white matter of the affected area.
When this process continues, it may lead to the development of infarction and cytotoxic edema that immediately follows angioedema.
This is different from arterial infarction, in which there is only cytotoxic edema and no angioedema.
Due to venous hypertension, venous infarction is more common than arterial infarction.
Because we are less familiar with venous infarction, we generally consider venous infarction to be atypical sites or infarctions with non-arterial distribution.
However, venous infarction does have a typical distribution, as shown in the figure below.
Since many veins are midline structures, venous infarction is often bilateral.
This is seen in superior sagittal sinuses, straight sinuses, and intra-cerebral venous thrombosis.
The most common venous thrombosis is the superior sagittal sinus. Infarction is seen in 75% of cases.
Abnormalities are parasural and mostly bilateral. Bleeding occurs in 60% of cases.
Figure 1 below is bilateral infarction in a patient with superior sagittal sinus thrombosis.
Figure below Sagittal CT image of a patient with bilateral sagittal sinus hemorrhage due to upper sagittal sinus thrombosis.
The red arrow on the enhancement image shows an filling defect due to a thrombosis.
Another typical venous infarction is due to Labbe venous thrombosis.
In the figure below, the white matter density of the temporal lobe on the left is low, and the temporal lobe on the right is not obvious.
A wide range of differential diagnoses include arterial infarction, infection, and tumor.
Note that there is some linear high density in the infarct area, which is caused by bleeding.
The subtle density of the left transverse sinus (arrow) area is key to diagnosis.
This is a direct sign of thrombosis, the next step is CECT, confirming the diagnosis (not shown).
Image below of a patient with temporal lobe bleeding.
When the hemorrhagic component of an infarction is large, it may look like any other intracranial hematoma with angioedema.
The diagnostic cues of this case are seen on the enhanced image, which shows well the filling defect (blue arrow) of the sigmoid sinus.
The figure below has angioedema (red arrow), cytotoxic edema, and bleeding (blue arrow).
These findings, and the location of the temporal lobe, should remind you of venous infarction caused by Labbe's venous thrombosis. The next test should be an enhanced MR or CT to prove the diagnosis.
Deep cerebral vein embolism
The figure below shows the high signal of the left thalamus on the left side.
When you look closely, there is also a high signal in the right basal node area.
These bilateral findings should raise suspicion of deep cerebral vein thrombosis.
Sagittal CT reconstruction shows filling defects in the straight sinuses and Galen veins (arrows).
The figure below shows young patients with bilateral basal ganglion abnormalities.
Depending on the imaging presentation, there is a broad distinction, including small blood vessel disease, demyelinating, intoxication and metabolic disorders.
Note the abnormal hyperintensity of the veins and straight sinuses in the brain on the T1-weighted image.
Bilateral basal ganglia infarction is diagnosed with deep vein thrombosis.
In some cases of venous thrombosis, imaging findings can disappear completely.
The figure below is of a patient with a high signal under the cortex.
The first impression is that this may be a low-grade glioma.
After follow-up scans, the anomaly was completely resolved.
Retrospectively, one of the cortical veins shows dense vascular signs and diagnoses venous thrombosis.
Hyperintensity can be attributed to angioedema due to high venous pressure due to thrombosis.
CTV
CT venography is a simple and direct technique for showing venous thrombosis.
In the early stages of thromboembolism there is no strengthening of the veins, in the later stages there is no strengthening of the thrombus, peripheral strengthening is called the empty triangle, as discussed earlier.
Unlike MR, CT phlebography is hardly any defective.
The only thing you don't want to do is scan too early, i.e. before or too late for the veins to be enhanced, when the contrast disappears.
Some advocate doing a scan like CT angiography with just a 5-10 second delay.
To be on the safe side, we advocate a 45-50 second delay after the start of the injection contrast agent. We use at least 70 ml of contrast medium.
In the figure below, some CT vein imaging shows many venous sinus thrombosis.
Figure below of patients with infarction in the Labbe venous region.
On non-enhanced images, you can see bleeding in tight clots and infarct areas within the transverse sinuses.
Enhanced images show filling defects visible in the transverse sinuses.
MRV on magnetic resonance venography
Mr techniques used to diagnose cerebral vein thrombosis are:
Time Leap (TOF), Phase Contrast (PC) and Enhanced Magnetic Resonance Ivy.
When you view the reconstructed image, always look at the source image.
Figure below is a transverse MIP image of phase contrast angiography.
The right transverse sinuses and jugular veins are signalless due to thrombosis.
The figure below shows lateral and oblique MIP images of normal contrast-enhanced MR venography.
Note the protruding veins of Trolard (red arrows) and Labbe (blue arrows).
Each technology has its own flaws, which we'll discuss later.
Contrast-enhanced MR intravenography has a disadvantage, you need intravenous contrast media, but there are fewer defects.
DSA
Angiography is performed only in severe cases when intervention is planned.
Left image of a patient with venous thrombosis, with thrombosis of the superior sagittal sinus (red arrow), straight sinus (blue arrow) and transverse and sigmoid sinuses (yellow arrows).
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