Health Care Today is a series of programs in continuing medical
education and is presented by the Faculty of Health
Sciences mcmaster University,
the Ontario Medical Association
Mohawk College,
the Ontario Chapter of the Canadian College of Family
Physicians,
the Hamilton Academy of Medicine and
CHCH TV.
Here is Doctor Michael Moot,
assistant professor of radiology at the Faculty of
Health Sciences mcmaster University.
Our subject for tonight's program is
computerized tomography of the head.
This method was first introduced approximately two
years ago and it has since revolutionized the
investigation of
diseases of the brain and its surrounding
structures.
It combines an X ray tube with a
computer and allows the radiologist
or physician to assess the inter cranial
structures which conventional
radiologic invasive and non
invasive methods have.
Heretofore been unable to provide
at the Hamilton General Hospital.
We have in the past two years carried out
almost 3500 such examinations
and have founded an invaluable method in the
investigation of patients who present with
problems related to the brain and its
surrounding structures.
Perhaps to better illustrate the
capabilities of the scanner and the method
involved Dr Joseph Homer,
a family practitioner from Hamilton will
present us with the case of a patient that came to
him in September of last year.
Thank you.
This was a 49 year old male who presented
with a history of weight loss in hems.
A routine chest X ray was ordered during investigation,
we can see on the chest X ray that the
patient had a large mass in the left.
Harlem and Joe,
the answer was this turned out to
be a proven carcinoma of the lung.
However,
the patient was also confused and complaining of left sided
headache.
A consultation was sought from a neurosurgeon
and a cerebral angiogram was performed.
We did carry out the angiogram and
surprisingly,
it showed a solitary lesion in the
left high frontal region.
Question arose,
Mike whether this was a single lesion,
a solitary metastasis or whether it was a
coincidental primary cerebral tumor or
whether in fact,
there may be multiple lesions in the cerebra in
which the angiogram failed to demonstrate,
the CT scan was therefore requested.
But perhaps before discussing those results,
you might give us a brief explanation of
how the CT information is obtained.
If we look at the
diagrammatic representation,
we see an X ray tube and the X
rays enter the head and
those leaving the head are picked up by two detectors.
These are sodium iodide detectors
which emit light
rays and these light rays are then
converted into an
analog or voltage.
And in turn into a digital
value or binary number.
These numbers are then stored temporarily in
a magnetic disk unit.
And the computer calculates these digits
for final values which are then returned to the
magnetic disk unit for permanent
storage.
These numbers are then
reconverted back to a voltage system.
And the voltage system then allows us to
view the image of the brain
with a cathode ray display
tube.
We then take a polaroid picture of
the display for our own permanent records.
This is a representation of the head encased in
a rubber bag and further
encased in a water sealed
box.
This is called the scanning gantry and it
consists of the X ray tube and the
detectors.
The gantry passes the head in
one movement.
As we see here,
it rotates one degree,
makes another pass a further degree and another
pass and we get a total of 180 degrees
over 4.5 minutes.
The levels of scan that we
do use are basal scans
at 25 degrees to the orbital
metal line and we carry out four
scans at 4.5 minutes each or 18 minutes in
total.
The first scan is basal and then just
moving up.
So we cover approximately 12 centimeters which
in the vast majority of patients will include their
entire brain and the intercranial structures.
Perhaps we might see the scanner in action by
reviewing a film clip.
Here is Mr Walton,
our technician who has just
turned on the computer and is now
giving information to the computer with regard
to the patient.
She is now marking the patient's head in order to
have the basal skin at the appropriate
level and she'll know,
get the patient set.
And it's extremely important that the patient
be immobilized in as comfortable a
position as possible because any movement at
all will interfere with our skin
and cause many artifacts.
So the patient is immobilized and
held relatively firmly by means of
the immobilizing
bans.
It's very important that we calm the patient
down and make them realize that this is not a painful
procedure.
It is not invasive in any way.
These crossing bands are
merely to hold the head in position and
it's just,
they're just velcro bands if you
can visualize the water.
Now encasing or increasing,
I should say around the rubber bag and this holds the
patient in place.
The X ray X
rays are then turned on.
And here we are viewing the patient from the control
room and now we're within the control room itself or within the
scanning room itself.
This is what the Cathode ray display looks
like.
And the Polaroid camera,
which Mrs Walton is now
using,
she'll take a film,
assess it and depending on what we see
on this scan as well as the other basal
scans,
we may or may not go further.
If we're at all concerned,
we inject a contrast medium which is
very similar to an intravenous plog gram or an
angiogram and we then repeat the
appropriate scans.
And this is a scan following
the injection of
contrast.
Perhaps it might be a good idea to
illustrate what the normal scan looks like.
And the first
one we have is a basal scan showing the
Petri bones,
the cerebellum and the temporal
horns as well as the frontal horns more anteriorly.
And you can see the slice of the brain at
the same level with
the same anatomical features.
A slightly higher
slice illustrates well,
the ventricular system,
the pineal gland,
the right ch choroid plexus.
And here is the right choroid plexus and
the ventricular structures.
It's quite obvious that the cerebral spinal fluid
pathways are very well illustrated
with this investigation and don't
require injection of
air or contrast media
again,
just a little bit higher showing the ventricular
system.
And the interhemispheric fissure.
A very high scan illustrates the
many superficial cerebral palsy over the
convexity of the skull.
And this of course is very important in assessing a patient
with
significant dementia or atrophy of
the brain.
This slide is to illustrate
how well we can see the eyes.
In fact,
if you look very closely,
you can see the lens of each eye.
This is these are the paris bones,
the fourth ventricle,
the sphenoid sinus.
And just by playing with our
measure,
we are now able to better visualize the optic
nerves.
This is exactly the same scan as the one
we've just seen,
but we've highlighted the
orbits like what were the
results of the scan on my patient?
Well,
Joe,
it's very interesting if
we look at the
injection or sorry,
the scan prior to injection,
there is a suspicious area of high
density in the
left posterior parietal region.
And when we gave contrast,
it became evident that it was an obvious tumor.
However,
there's also other areas of concern
which would suggest to us that we're dealing with multiple
metastases as we go up
higher.
Again,
you can see just sort of a
modeling look or modeled appearance which
isn't normal.
But once we gave the contrast,
it became evident that there were many,
many metastases in the brain and
unfortunately,
a very poor prognosis mike,
can you expand a little bit on the advantages and value of
scanning in more specific disease
entities?
For instance,
it must be of tremendous value in assessing abnormalities of
the CSF pathways.
It certainly is Joe
just a few illustrations here is an example of a
patient with a very significant atrophy of the
brain.
The ventricles are quite enlarged and as
you saw in the normal,
they were in no way close to this
size,
the frontal horns are grossly enlarged and on a
higher cut,
we can see how the occipital poles
themselves are large as well.
The superficial cerebral palsy are widened.
And what we can
say from this is that this is a non
obstructive atrophy of the
brain.
As opposed to that.
Here is a case where again,
we have relative enlargement of the ventricles,
but we don't see any superficial sulfide.
And this is most likely a case
of normal pressure hydrocephalus where we have a
block to absorption of cerebral spinal fluid at the
level of the tentorium or the superior sain
sinus.
And here's one more example of
the spinal fluid pathways.
But in this case,
we have an obstructive hydrocephalus,
presumably at the level of the aqueduct of
Silvius with gross enlargement of the third
and the lateral ventricles.
And this patient would have required shunting.
Mike is the scanner uh valuable in cases of head
trauma.
Yes,
it certainly is Joe and perhaps I
can show you a few illustrations of
this.
The major problem we have in dealing
with patients who have had trauma is
immobilizing them.
And in certain instances,
it may be necessary to sedate them
and very rarely
give them a general anesthetic.
This is an example of a of a,
a woman in her mid 50 s who
was on anticoagulants for deep vein
thrombosis and unfortunately fell out of
bed while in hospital and hit her
head on the wall.
She lost consciousness and was brought to our
hospital where a scan was carried out immediately.
And here is a typical
large subdural hematoma in the right
posterior parietal region at a level,
a little bit higher.
We can see that not only is there an extra cerebral
lesion but also an intracerebral hemorrhage as
well,
which required aspiration.
It becomes quite evident that
this is a significant lesion or both
are in that there's complete compression of
the right lateral ventricle.
We don't even see it and displacement of the left lateral
ventricle as opposed to the
acute type.
We can also see the sub acute form and
these are diagnosed primarily by the
the secondary changes that they
cause the subdural
hematoma itself.
In the sub acute stage has the same density as
brain.
So that we don't see the lesion as such,
but we do see the gross displacement of the
ventricular system to the
contralateral side.
This is a patient who we followed
after surgery,
she did have a left subur hematoma
and following it up.
Several months later,
we showed the ventricles returning almost to normal
and even later,
the ventricles are quite normal.
So that by the final examination,
we had a normal scan
and this is a case of a chronic subdural
hematoma.
Bilateral.
As a matter of fact,
in the frontal regions,
this was picked up by means of an
isotope scan and the
C TT scan was carried out to confirm
the findings and
certainly it showed the bilateral
subdurals and it saved this patient and geography.
He was over 80 years old and at high risk for
catheter studies,
a dramatic problem that we sometimes face is a patient
who suddenly loses unconsciousness
and it's imperative that an accurate diagnosis be made
as quickly as possible.
In order to institute proper and effective treatment,
can the scanner help in this type of patient?
Yes.
As you know,
Joe,
these patients are,
are usually ones who have had a
significant intercranial catastrophe.
And it's this type of patient who has had
an intracerebral hemorrhage of some kind or a
stroke due to
thrombosis or embolism.
And it's very important that we be able to
distinguish the two because the intercranial
hemorrhage can will
require some form of surgical therapy as opposed to
the stroke where conventional medical therapy
is needed.
Here is an example of a young woman
who developed a severe sudden headache and
collapsed when she came to the hospital.
A lumbar puncture was carried out and the spinal fluid was
grossly bloody.
We carried out an angiogram immediately on
this lady and on the left side,
we demonstrated a moderately large cellular
aneurysm of the internal carotid artery.
The right carted angiogram
illustrated or demonstrated three,
surprisingly an anterior communicating aneurysm
and two of the right internal carotid artery
at the origins of the posterior communicating and
anterior choroidal vessels.
In most cases of multiple aneurysms,
one would expect that the
larger or largest of the
aneurysms will have a
bled,
but in this case,
we couldn't be sure with four of them.
So a scan was requested and carried out.
And here we have a
large sub frontal hematoma
indicating that it was the anterior communicating
artery or aneurysm that had
bled and surgically,
they were able to aspirate
the hematoma and clip that
aneurysm.
This is an unfortunate illustration of a
young 12 year old boy who
came home from school at lunch time,
not feeling very well and suddenly collapsed
on his way to hospital by ambulance,
he had two respiratory arrests
and we carried out a scan immediately
on this youngster and we demonstrated a
massive hemorrhage involving the
fourth ventricle,
the third,
the lateral ventricles,
as well as a left parietal occipital
intracerebral hematoma.
Unfortunately,
this patient died very soon after the
skin.
Here's another example of
an intraventricular hemorrhage this time.
However,
in a man in his sixties who had high blood pressure,
and again,
we do see evidence of the intracerebral
component of the bleed involving
primarily the right lateral ventricle and to some
degree the third ventricle.
Unlike what we've all been taught in medical school where
we were always told that
intraventricular hemorrhage meant
death.
This man,
this man proved us wrong.
And here we
have a follow up scan three weeks later and for
all intents and purposes,
the hemorrhage has resolved and this
patient is doing quite well.
Here we have a patient who has had an embolus
or a thrombus with occlusion of one of the
middle cerebral branches and a resultant
wedge shaped zone of low density,
which is very classical of an infarct.
And in this instance,
the patient would not have required any surgery as
opposed to the others that did.
Obviously,
the CT scanner plays an important
role in diagnosing,
expanding in inter cranial lesions.
And at probably a lesser risk than some of
the past techniques,
we have used things such as tumors,
abscesses.
Could you give us some examples of these
problems,
Joe He,
here's an example of a youngster
that um had a tumor.
Um The scan
looks so bleak and the reason it is is that this
little girl was unable to hold her head straight.
As soon as her head was held straight,
she would vomit.
And so we were still able to carry out the scan in
spite of the rotation of our head.
And as you know,
no other examination could theoretically be
carried out in this position.
Here,
we have the basal scan
showing no significant abnormality,
although we don't see 1/4 ventricle and this clued
us into giving her a contrast medium and
unfortunately,
a high density lesion became
enhanced and this turned out to be a
glioma of the left cerebellar hemisphere.
This is the case of a 20 or
21 year old boy who complained of
deafness in his left ear.
This was his only problem and a scan
being the least invasive of procedures to investigate
deafness was carried out in our
department.
Again,
we don't the fourth ventricle in the posterior fossa.
And we therefore gave this young
man contrast material.
And we showed a large
circumscribed tumor mass in the left
cerebellopontine angle cistern.
And this turned out to be a classical acoustic
neuroma.
This is a case to illustrate a
large glioma
of the left frontal lobe.
And these two upper
slices are prior to the contrast
medium.
We do see a relative high density lesion
which would suggest that this is the tumor
core surrounded by a lot of
edema or perhaps necrosis of the surrounding
brain.
We then gave contrast medium and you can
see that the core of the tumor
becomes considerably enhanced,
suggesting that the contrast medium has been
able to pool in the tumor and indicating to some
degree the vascularity of the lesion.
This is the patient postoperatively a month or two
later.
And with the exception of a residual
defect and presumably a surgical defect in the left
frontal lobe,
the tumor itself has been removed
and the ventricular system is in normal
position,
even with enhancement,
we don't show any evidence
of tumor recurrence.
So it illustrates the point not only of
the capabilities of the scanner to show tumor
but also as follow up investigations.
Here,
we have another case of a patient
with a suspicious high density
mass lesion at the level of the sanatorium on the
left Conray was given.
And here we have a huge
homogeneously dense lesion,
which is characteristic of a meningioma.
This is a very interesting case of a
young man who had had a mastoidectomy.
One month prior to the scan had gone
home.
But two or three days prior to being admitted to our
hospital,
he developed a fever confusion
and became almost
comatose.
By the time he was admitted here is an
excellent example of a,
of a fluid level.
We can see gas and we can see blood below it.
And this was a
fairly typical abscess
containing gas as well
as I don't know why,
but it did contain blood and this was aspirated
and the young man did relatively well.
We can see that initially,
one might consider that this is the whole size of
the abscess.
But when we gave Conray a huge ring
density appeared
illustrating the size of the abscess in the left
temporal lobe mike.
It's apparent that with the advent of C TT
scanning,
this has revolutionized the investigation of
inter cranial diseases.
Do you think you might give us a brief summary of some of its
advantages?
Sure,
Joe,
first and foremost,
it's essentially a non invasive examination.
Certainly,
we may have to give contrast medium and we do
so in perhaps 60 to 70% of cases.
But we don't consider the injection of contrast
medium an invasive procedure as such.
But it does have the
advantage of providing us with so much
information that
plain skull examinations,
skull,
sorry,
angiograms and pneumoencephalogram don't,
in fact,
it's done away with many of the
invasive procedures that we carried out in the
past,
the accuracy is in the 90 to
98% range.
And this has been shown in many papers
that have been written in the past few years.
Scanning allows us to assess the subarachnoid
spaces and the ventricular system.
And as you know,
in the past,
only the injection of air or
contrast medium into the
into the CSF pathway system
would have allowed us to assess the spinal
fluid pathways.
Uh It's certainly uh a great advantage in
the assessment of trauma patients and in
not,
uh and not uncommonly saves us doing a
geography.
As you know,
as we've discussed,
it's tremendous in assessing the patient who
has become suddenly unconscious and particularly
to see if this patient has had an
intracerebral hemorrhage,
which would require aspiration.
The the scanner allows us
to carry out serial studies either
post operatively or just post
treatment and we can follow
patients weekly,
daily,
monthly or yearly.
It really doesn't matter,
but it is a way of assessing the patient.
Once we have a baseline.
As we noted very early in the
program,
the scanner is capable
of allowing assessment of
the orbit and the eye and the optic nerves.
And we have picked up a number of tumors and there have been
reports of many ophthalmologic
lesions being picked up by other
institutions.
Of course,
economically,
it's a tremendous advantage in that we are
now saving admission of patients to
hospital for investigation of
their possible brain
lesions.
We save perhaps three or four days of hospital
admission and we also
save the patient having to undergo a geography
or pneumoencephalography.
There are perhaps a few disadvantages in
that it is a relatively time consuming
procedure which requires if we give
contrast medium,
probably a total of an hour,
which limits us in doing perhaps a
maximum of 10 to 11 patients in any
10 hour day.
The other thing of course is that it requires a
maximum immobilization and
without it,
the patient can move around.
And so we therefore just might have to
sedate the patient or give
him a general anesthetic.
But I think you can see from all of the
cases we presented that these
disadvantages are far outweighed by the
capabilities and the advantages
of the CT scanner.
If you're interested in participating in the evaluation of the
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Health Sciences mcmaster University,
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Today was produced in cooperation with
TB,
the Faculty of Health Sciences mcmaster University,
the Ontario Medical Association,
Mohawk College,
the Ontario Chapter of the Canadian College of Family
Physicians and the Hamilton Academy of Medicine.