Radiological research methods and radiological semiotics of acute cerebrovascular accident

ACUTE CEREBROVASCULAR ACCIDENT(CVA, STROKE)
– acute and severe brain disease. Blood may be interrupted or stop moving through an artery, because the artery is blocked (ischaemic stroke) or bursts (haemorrhagic stroke).

Types of stroke
Ischemic-20%
Hemorrhagic-80%

CT and MRI

Neuroimaging tasks
Define:
Intracerebral hemorrhage/infarction
Localization and size of the lesion
Time from the beginning progression infaction
The state of intracranial vessels and collateral blood flow
Penumbra zone
The effectiveness of the therapy

CT or MRI?
Exclude ICH

CT and MRI in the dynamics

EVOLUTION OF INTRACEREBRAL HEMATOMA
stage of hematoma
transformation of blood elements
oxyhemoglobin
Hyperacute
(4 to 12 hours)
deoxyhemoglobin Acute
(1 to 3 days)
intracellular methemoglobin
Early subacute
(3 to 7 days)
extracellular methemoglobin
Late subacute
(7 to 28 days)
ferritin in the form of hemosiderin
Chronic
(more than a month)
isointensive
isointensive
hyperintensive
isointensive with a hyperintensive rim
hypointensive
hyperintensive
hypointensive
hypointensive
hyperintensive
hyperintensive with a pronounced hypointensive rim

Hemorrhagic strokes
CT - is a “gold standard” of diagnosis.
Hemorrhage is a focus of increased density of matter (hyperdense zone) of the brain of a rounded or oval shape, sometimes there are signs of a volumetric effect on the cerebrospinal fluid spaces and the ventricular system of varying degrees of severity, depending on the size and localization of the hemorrhage.
In the dynamics of the hemorrhage focus, there is a gradual decrease in the density of the hemorrhage focus in the brain tissue – the phenomenon of a "melting sugar cube".

SUBARACHNOID HEMORRHAGE
The sensitivity of CT to the presence of blood in the subarachnoid spaces is associated with the amount of blood and the time elapsed since the hemorrhage.
The diagnosis is suspected in the presence of high-density staining of subarachnoid spaces.
In most cases, it is observed near the Willisian circle, since most sac aneurysms are localized in this area (~65%), or in the sylvian fissure (~30%). Small hemorrhages in terms of the amount of blood can sometimes be detected due to accumulation in the medullary cistern or in the form of a hyperdensive triangle in the occipital horn of the lateral ventricle.

Subarachnoid hemorrhage

CT or MRI?
Types of ischemic edema
Cytotoxic edema (CBF < 30 ml/ 100 g x min) - reversible changes
Ionic edema (CBF < 10 ml/ 100 g x min) - irreversible changes
Vasogenic edema is the result of a violation of HEB and the penetration of blood plasma into the intercellular space
capillary intercellular fluid neuron

CT or MRI?
Types of ischemic edema
Cytotoxic edema (CBF < 30 ml/ 100 g x min) - reversible changes
Ionic edema (CBF < 10 ml/ 100 g x min) - irreversible changes
Vasogenic edema is the result of a violation of HEB and the penetration of blood plasma into the intercellular space
capillary intercellular fluid neuron
capillary intercellular fluid neuron

CT or MRI?
Types of ischemic edema
Cytotoxic edema (CBF < 30 ml/ 100 g x min) - reversible changes
Ionic edema (CBF < 10 ml/ 100 g x min) - irreversible changes
Vasogenic edema is the result of a violation of HEB and the penetration of blood plasma into the intercellular space
capillary intercellular fluid neuron

CT or MRI?
Types of ischemic edema
Cytotoxic edema (CBF < 30 ml/ 100 g x min) - reversible changes
Ionic edema (CBF < 10 ml/ 100 g x min) - irreversible changes
Vasogenic edema is the result of a violation of HEB and the penetration of blood plasma into the intercellular space
capillary intercellular fluid neuron

Early СТ signs CVA
Arterial hyperdensity (a sign of intravascular thrombosis: hyperdensive middle cerebral artery, a "point" symptom)
Loss of differentiation of gray and white matter
Edema of brain tissue with smoothness of cortical furrows, convolutions, subcortical nuclei
Decrease in the density of brain matter
Loss of the ability to visualize the insula of the brain
Disappearance of the normal outlines of the lenticular nucleus
Mass effect with dislocation
The presence of a clear demarcation line of the ischemic focus on the RCT indicates the limitation period of a stroke-outside the "therapeutic window"!

Hyperdensive MCA
It is manifested by an increase in the density of the proximal sections of the MCA , and is associated with thrombosis of the M1 segment of the MCA.
The same pathological mechanism in the distal parts of the MCA gives a point increase in the density of MCA .
Hyperdensity of MCA is visible after ~90 minutes from the moment of ischemia development

ASPECTS SCORE
The Alberta stroke programme early CT score (ASPECTS) 1 is a 10-point quantitative topographic CT scan score used for patients with CVA
The need for the ASPECTS scale:
the assessment of early ischemic changes is important in the assumption of a response to thrombolysis
thrombolysis increases the chances of a good functional outcome in patients with small (less than 1/3 of the MCA) sizes of the hypodensive zone on non-amplified CT scans, and quantifying the volume of one third of the territory is inconvenient for routine practice
ASPECTS was developed to standardize the identification of changes and the compilation of descriptions (reports) of the degree of hypodensiveness of ischemia ​​

The assessment on the ASPECTS scale is carried out by determining changes in the MCA territory at two standard levels::
basal ganglia level - the level at which the thalamus, basal and caudate nucleus are visualized,
rostral level, the level at which the radiant crown and semioval centers are visualized.

C - caudate nucleus,
I - insular cortex,
IC - internal capsule,
L- nucleus lentiformis,
M1 - anterior cortex of the MCA ,
M2 - cortex lateral to the insular,
M3- posterior cortex of the MCA ,
M4, M5, M6 - anterior, lateral and posterior area of the MCA

Results:
The basal ganglia are estimated at 3 points (C, L, and IC).
The crust of the MCA territoty is estimated at 7 points (the crust of the island, M1, M2, M3, M4, M5 and M6).
A score of 7 points or less indicates an extensive hypodensive zone in the MCA territory and correlates with the prognosis of a poor functional outcome, as well as with the risk of intracerebral hemorrhage.
According to the studies of R. I Aviv et al, patients with a score of less than 8 points on the ASPECTS scale did not have a good clinical outcome from the use of thrombolysis.

PATHOPHYSIOLOGY AND MR-PICTURE OF CEREBRAL ISCHEMIC STROKE
I
acute stage(0-3 days).
Pathoanatomically-focal cytotoxic edema, macroscopically-thickening of the brain gyrus and loss of clear distinctions between gray and white matter.
MRI: the focus or zone of a sufficiently uniform increase in the signal for T2 and FLAIR, a moderate uniform decrease for T1. Compliance with the territory (according to the form) Violation of the differentiation of gray and white matter of the brain + mass effect of varying degrees of severity, depending on the volume of the lesion. .

THE FOCUS OF ACUTE ISCHEMIC CVA
THE TERRITORY OF THE LEFT SUPERIOR CEREBELLAR ARTERY. FLAIR Т1- weighted image

PATHOPHYSIOLOGY AND MR-PICTURE OF CEREBRAL ISCHEMIC STROKE
Subacute stage (3 days-10-14 days).
The combination of cytotoxic and vasogenic edema, the onset of encephalomalacia with the formation of necrotic zones in combination with reparative processes – the appearance of a symptom of "giral" amplification.
MRI: focus or zone of NON-UNIFORM increase in the signal for T2 and FLAIR, an indistinctly expressed NON-uniform decrease for T1 or isointensive MRS (a symptom of "veiling") . There is a violation of the differentiation of gray and white matter of the brain, a decrease in the mass effect or its absence.

Zone of the subacute ischemic stroke
Middle cerebral artery circulation . FLAIR Т1-weighted image

PATHOPHYSIOLOGY AND MR-PICTURE OF CEREBRAL ISCHEMIC STROKE
Chronic stage (end of the 2nd week and beyond).
resorption of necrotic masses, the formation of a cystic cavity with perifocal gliosis, may be accompanied by dilation of the ipsilateral ventricle. The decrease in the intensity of the MR signal corresponds to the prescription period of cyst formation, after 3-6 months it corresponds to the characteristics of the cerebrospinal fluid.
MRI: foci or zones of cystic-glious or infiltrative-glious transformation +local atrophy

Zone of the chronic ischemic stroke
Left posterior cerebral artery circulation . FLAIR Т1-weighted image

Direct signs(⅓ cases ):
Triangle sign – visualization of
a blood clot on the contrast-free part of
the study in the form of a dense
triangle or circle on the back of the SSS
The negative delta sign (empty
triangle, empty delta) is a triangular pattern
of contrast enhancement on the back of the SSS
Cord symptom, curved or linear hyperdensity on contrast enhancement,
visualizing a thrombosed cortical
vein
Indirect signs( 60-80%):
Hemorrhagic: ICH,SAH
Non-hemorrhagic: focus of
hypodensiveness caused by
edema or infarction of the brain,
usually not corresponding to the zones of
arterial circulation,
diffuse edema of the brain
Disappearing stroke in
serial research
CEREBRAL VENOUS THROMBOSIS
CT signs

CEREBRAL VENOUS THROMBOSIS

CT or MRI?
the state of intracranial vessels and collateral blood flow
Thrombus size > 8 mm-systemic thrombolysis is not effective
Detection of distal blood clots

CT or MRI?
The state of intracranial vessels and collateral blood flow
Advantages of SWI
The size of the hyperperfusion zone

Evaluation of the effectiveness of the conducted therapy
Reperfusion after thrombolic therapy
Patient A.
67 years
1 hour before stroke
24 hours