hello everybody I'm very honored to be
part of the first little stroke
symposium and be part of distinguished
speakers of today my topic is emergency
brain imaging and stroke so I'm going to
talk about CT CT angiography and CT
perfusion why CT but for one you have
not heard about mobile stroke units with
an MRI on them so I'm going to try to
give you a bit broader perspective and
try to see what we want from acute
stroke imaging and basically I'm going
to limit is to three basic questions do
we wanna first we want to know if it's
an hemorrhagic stroke or an ischemic
stroke and to be able to quantify how
large it is ideally the question number
two that we have to answer from imaging
is to see is there or not a large
resolution that we can act on and limit
the stroke by opening the vessel and the
question number three which is whether
the first tool it would be good to know
how much brain is suffering but is
potentially salvageable
so the infra just remains as large as we
see it if we answer question number one
so I'm going to just start talking about
c.t non-contrast CT I will say is the
fundamental method of stroke imaging not
because it's been around for so long it
has an excellent track record
everybody's familiar with it is widely
available is rapidly available and the
non-contrast CT when we get it in acute
stroke we use it first and foremost to
rule out the hemorrhage so the only
thing that we need to know in order to
give patient IV thrombolysis in the
first three hours is the hemorrhagic
lesion or not so once we roll out
hemorrhage patient goes for IV TPA now
ideally the main image when tawny stroke
would also show you that there is a
stroke and there are some indirect signs
even in the hyper acute phase like in
this case this is a young patient
actually as she had right emissary
syndrome in the hospital so was imaged
within maybe 15 to 30 minutes from
stroke onset and City is normal with a
small exception there is the solid arrow
pointing to a hyper tense internal
carotid artery and middle cerebral
artery this was a sign that the vessel
is occluded the patient is indeed having
a stroke corresponding to her large
stroke scale and this is the
confirmation with CT angiography now if
we have a stroke this is another patient
that has a hyper dense I ca on the left
side if you have a stroke we start
seeing early schema changes and those
early schema changes are signs of
irreversible damage to the brain
parenchyma and the damage is caused by
accumulation of water in the dying
neurons and as the water accumulates the
differentiation between the gray and
white matter fades the brain starts
swelling so you have shortly Faceman and
as the story progresses we have a hypo
density and how do we quantify the
extent the state of the region's we can
use the in an MCA stroke the one-third
of the MCA rule we know the MCA
territory corresponds to about 220 250 a
mouse we can calculate a volume we can
use the aspect score and the aspect
scores assigns a number to various
regions in the middle cerebral artery so
in this case the aspects code is 5 which
the we see largely white matter
differentiation loss in the areas that
are outlined by the circles now if we go
back to first case and I'm going to try
to talk about question number 3 that I
told you the beginning we need to answer
from acute stroke imaging Eastern is a
virtual brain or not so you say Oct
cannot tell us that of course it can
because if the city is normal the brain
parenchyma is normal normal and we know
we have a large vessel occlusion all
that area that supplied by that vessel
is going to be salvageable brain so in
this case CT was normal we now have a la
right internal right internal carotid
artery occlusion patient underwent
geography mechanical turn back to me
with the recognization nearly perfusion
and I shall have a very good outcome
this is the MRI and this either enough
interaction is limited to the basal
ganglia which is always the case if you
have an m1 what an icy occlusion now CT
angiography is my next my next topic and
if we say that the CT without contrast
is the the main the fundamental modality
and was used for a long time CT
angiography I think is the current hot
imaging method in the era of
endovascular treatment because CT
angiography of the head in the neck will
allow us to identify the clot identify
this large vessel occlusion push the
patient to endovascular treatment it
will show us exactly where the clot is
how long it is what are the vessel that
get there how can you reach the clot how
does the arch look and also it will give
us information about the karate of law
this is an example where Lanka City was
not very helpful because the result
effect from a previous clip but this
patient has a right hemisphere syndrome
has a right middle cerebral artery
occlusion and right internal carotid
artery occlusion and if we look in the
neck which it interview we can see that
this R t2 artery amylose comes for
disease in the carotid bifurcation with
an occlusion and the tandem a tandem
occlusion in the carotid and
intracranial II so of course it helps
you plan this patient underwent
mechanical trabectome under general
anesthesia but also had the first
carotid stent placed and then we went
after intracranial occlusion and did the
trabectome and this is the ticket to be
reperfusion collateral flow collateral
flow is a very important topic and is
actually the answer by CTA to question
number three is the savage or brain or
not what keeps brain alive is the PL
collateral flow when the vessel is
occluded so sometimes it's difficult to
assess very accurately the pl quattro
flow but basically like a basic rule
would be if there is no vessels or less
vessels on
affected side the pier Tatas fall is
poured if there's equal vessels between
the two sides or more vessels on the
affected side it's a good collateral
flow so here I just having two examples
these patients both presented with a
left hemispheric stroke in the same in a
similar time window when you see the
patient a on the left there are no basis
at all and on the patient me if I don't
show you where the accused at least you
can't even figure out which side is the
occluded side both patients underwent
angiography and thus proven mca
occlusion and underwent in the similar
time window the endovascular
recanalization with good reperfusion
tiki three reperfusion but his patient
on the right side has an excellent
outcome with the stroke just let me do
the basal ganglia which again is always
there but the patient on the left side
despite the successfully perfusion is
going to undergo a significant swelling
the so called malignantly perfusion with
early mass effect and despite
decompressive craniectomy didn't make it
so assessment of collateral flow is
extremely important has a prognostic
value this was shown in the studies now
what about the CT perfusion of the brain
so I think we talked about non-contrast
CT has been the fundamental method of
imaging in acute stroke we talked about
the CT angiography of the head and neck
showing us if there's a large vessel
occlusion and helping us indicating the
patient for endovascular treatment and
at that point is now we do CT interfere
the head and neck in every patient that
comes to the Hannaford system ER within
24 hours with any focal or global energy
deficit now let's talk about the CT
perfusion cinema fusion can be part of
your acute stroke protocol it it
required simultaneously with a CT and CT
angiography requires an additional bonus
of contrast of 14 or 50 cc's of contrast
require some post processing of the
images to generate the map the main
limitation would be motion artifact in
the restorable
in the interpretation of the map
depending on the commercial software so
what happens when we do CT perfusion a
bolus of contrast is injected it travels
from the arteries through the brain
parenchyma and to the veins and we are
trying to capture that bolus as it goes
to each elementary volume of brain
parenchyma by imaging about every second
and as we image every second we're
getting this curve of enhancement in the
brain parenchyma those curves are post
processed and the post processing will
result in the maps that you see this
nice colored maps and the map on the
left is the mean transit time which is
an assessment of how fast the blood
travels to the brain parenchyma and if
you have ischemia it's kind of intuitive
that the blood will go a little slower
the map on the bottom is the cerebral
blood volume map and it's kind of
related to the amount of blood that gets
there if you have in farty tissue blood
doesn't get there so it would be a loss
your blood volume the map on the right
is the zero blood flow and it's usually
calculated from the previous tool by
dividing the blood volume to the mean
transit time now how can a city
perfusion help us answer the questions
well it's very easy the core as we can
see it either on the cbv or on the
Shapiro blood flow map is the area that
does not get blood to it so it's the
so-called unsalvageable tissue and you
can use various thresholds to define it
but it will show on the CB V or the CBS
map the penumbra is the answer to
question number three so we identify the
salvageable tissue and we look at the
mean transit time map for that and we
have this penumbra and a core of the in
fact that will define us the concept of
mismatch so basically always the
penumbra is going to be larger than the
core if it's a significantly larger we
have a target mismatch where we can use
a ratio penumbra to core 1.8 which would
be an optimal ratio we can use a volume
difference subtracting the volume of the
core from the volume of the penumbra and
an accepted the target mismatch would be
fifteen a mouse now how does perfusion
help us in acute stroke management well
now that we're not talking only the time
window it kind of shifts the treatment
from the time window paradigm to the
imaging paradigm so if we have patients
that present with a large vessel
occlusion but outside the six hour
window or its wake up strokes that we
don't know exactly when the stroke
happened those are the patients that we
can image with perfusion and we can get
the accurate assessment of the core of
the infarct looking at an adequate
assessment of the savage will brain
volume and indicate treatment conversely
some patients that have no mismatch
where the area of ischemia overlaps with
the area of in fact those are the
patients that for which page treatment
will be futile so we don't want to treat
those patients will help us rule out
patients in same way it helps us rule in
patients now we can use commercial
software and this is an example for
patients with the target mismatch on the
left and they have a large green area of
hypo as a burr of hypo perfusion and a
small core on the right you have a
patient with comparable areas of
ischemia and in fact and this is this is
from a commercial software and kind of
makes it a green light red light
approach to to stroke imaging so you
have the green light there is no red
glove with treatment and if you have the
red light you don't read in brief here
at any for we do CT and CT angiography
in all patients that present with acute
technology deficit patients get riddled
with IV TPA in a foreign half hour
window and we indicate endovascular
treatment in all patients if there is a
large vessel occlusion on CT angiography
and if there is no there are no where is
chemic science on CT or less than one
third of the territory so a CT perfusion
we do it in selective patients in wakeup
strokes and officials present in over
the six hour land
so this is my talk and it's a camera
sticking to the fire thank you very much