Overview of Musculoskeletal Ultrasound - SD

Overview of Musculoskeletal Ultrasound

I'm Nevita here.
I'm from the Maning History of Radiology, which is a part
of the Washington University in St.
Louis. We do a lot of musculoskeletal work,
and today's lecture is gonna be about the overview
of musculoskeletal ultrasound.
Today we are gonna talk about an overview
of the musculoskeletal ultrasound.
As musculoskeletal ultrasound has gained
more acceptance in the community, I think it's important
to understand what are the main areas
we can focus on When we attempt
to do a musculoskeletal ultrasound, generally
you can pretty much look at everything,
but the focus usually is on muscles, tendons, joints,
ligaments, nerves, soft tissues, and bone.
We'll go through the basic techniques, the equipment
image optimization, a recognition of artifacts
that is important in musculoskeletal ultrasound,
the normal sonographic appearances,
and then some abnormal appearances.
The musculoskeletal ultrasound is
always targeted and interactive.
You have to ask the patient the questions,
how long are the symptoms?
Was the onset of symptoms sudden or insidious?
Was there any causative event?
Are there any aggravating factors? Is it age-related change?
Is it related to remote trauma
and always compare with the other side.

Basic Techniques and Equipment

We use linear arrays, which are of high frequency,
so good resolution.
Although the depth may be compromised, we have
to make sure we have good elevation.
Plane focus, use a wide dynamic range
and decrease the power.
Multiple vendors have multiple post-processing tools
that can also help in making the image better.
Here is a transducer that shows the elevation plane
and the long axis.
This illustration shows
how if you have a narrow elevation plane focus,
you can see a lesion much clearly.
If that red dot represents a cyst in the soft tissue,
the part of the image on the left side shows
that the beam thickness goes through that entire cyst
and so will form a clear image.
The illustration on the right shows
that the beam is much thicker than the red dot, which means
that even though the red dot may be a cyst, there is going
to be a significant partial volume averaging
and there will not be anti coic cyst seen on the
ultra sonographic imaging.
This is partial volume averaging.
One way to get over it if you do not have dedicated
musculoskeletal ultrasound transducers is
to increase the depth or the distance the sound travels
before it reaches its focal point.
You could use a gel pad for that.
Once you have a gel pad of an appropriate thickness,
then you are attempting to visualize the lesion
at the point of minimum
or maximum narrowing or maximum focus.
Here are two examples of linear transducers.
The second transducer with the gel pad is a 3D transducer.
Now the scan techniques involves apart from the standoff
pads, the heel and toe manure.
This is where you rock the transducer back
and forth, making sure that you are imaging the tendons
and the muscles in an orthogonal plane.
Make sure two orthogonal planes are visualized
and comparisons are done on split screens.
This is a dynamic examination, so
examining the patient while doing the movements
is extremely important.
Record the exam on C loops for reviewing later on.
Here is an illustration showing the HU
and the toe effect of the transducer.
The transducers on the top are rocking back and forth
and you can see here how you tilt them forward
or tilt them backward such that they can be perpendicular
to the tendon.
This is the view of the transfuser from the side,
which means a transverse view even when you do a
transverse examination.
This rocking motion is important to get rid of an isotropy.
Apart from an optimum dynamic range,
make sure you use a gray map
that does not oversaturate the image.
Use time gain compensation to avoid over gain
and use high contrast.

Artifacts: Anisotropy

We've talked about the varying angle
of insulation which leads to the artifact of an isotropy.
This is also important for the same reason.
It is also important
that tendons are best seen when they are stretched.
A stretched tendon is going to show its normal echo pattern
and will be hyper coic.
Here is the illustration showing the artifact of anisotropy.
When the source sends a sound beam
that gets reflected completely back by a structure
that runs at 90 degrees to the insulation angle,
then you get a very good reflection.
However, if that structure
or that tendon is going at an angle,
then you lose a large part of your sound beam
as it comes back as an echo.
This leads to us seeing that tendon as a dark structure.
This reflector appears dark,
and this is the principle of an isotropy.

Normal Sonographic Appearances

Muscles

Muscle fibers are range in bundles called sles
and each fassal is surrounded
by a stronger connective tissue layer.
Term permium.
Each muscle consists of multiple fas eye on ultrasound.
The muscle has this normal appearance.
This is a penate pattern
of multiple hypoechoic lines converging
to the central penate.
This is a zoomed up view of the muscle.
Again, a normal view of the muscle
with multiple fascial planes separating the muscle bundles.
This is an extended field
of view showing the entire length of the muscle.

Tendons

Tendons usually attached tuberosity ate recant
processes and ridges.
Most of the time. Ultrasound evaluation
of a tendon is either to look at a tear
or a degenerative change.
On ultrasound, the description of a tendon,
a normal tendon echo pattern is known
as a fibrillar echo pattern.
These are fine echogenic lines which correspond
to interfaces between the collagen and the endo kenon.
On a transverse section, a fine punctate pattern is noted.
Tendons are mobile and the synovial sheath might appear
as hypoechoic area around the tendon.
On ultrasound, as you can see on these two images,
the tendon shows a normal fibrillar pattern.
On the image at the top, the focal zone is relatively lower.
After putting a pad of gel above interior to the skin,
you can see that the tendon is much better visualized
with a good fibrillar pattern
and the focal zone is appropriately located.
This is a view of the biceps tendon in the bicep groove.
You can see a good fibrillar pattern
as the beam is coming at 90 degrees to the
axis of the tendon.
If the tendon is not insolated at 90 degrees,
then you see a tendon that is much darker
and this phenomena is known as an isotropy.
As we have discussed previously,
here is a demonstration on the transverse plane
of the phenomena of an isotropy.
You have the Es tendon seen on two images.
The one on the left is a hypoechoic tendon,
the one on the right, the one on the left is a
hypoechoic tendon.
The one on the right is a hypoechoic tendon.
The one on the left is when the sound is 90
degrees to the tendon.
The one on the right is when the transducer in transverse
plane had an abnormal angle and thus there was an ope.

Abnormal Appearances

Muscle Injuries

The most common injuries you would see are muscular.
A grade one injury is a mild injury in which on ultrasound
you may not see any appreciable distortion of fibers.
A grade two is a partial tear.
A grade three is a complete tear of the tendon.
On the left side is the normal echo pattern of the muscle.
On the right side, you can see that the normal echo pattern
of the muscle is destroyed
because there is some infiltrative hemorrhage
within the myo fis.
Here again, the left side
of the image shows grade one injury.
The right side of the image shows normal muscle.
This is a transverse view
of the quad recept muscle showing an internal area
of altered echo pattern.
The rest of the muscle is intact around that area.
This is how a partial tear is seen.
A complete rupture of the muscle leads to retraction
of the muscle and the muscle itself appears bunched
up or bulky head is a retracted quadriceps
muscle after a rupture.
The other part of muscular injuries deals
with muscular hematomas.
This is a demonstration of the intramuscular hematoma.
You can see this is a lobulated hypo E COE lesion within the
muscular planes on colored doppler.
There is no increase in vascularity
or no vascularity within the lesion.
This is consistent with a hematoma.
Given the background of history of injury,
you have to remember while investigating the muscles,
multiple incidental tumors
or pseudo tumors can also be visualized.
Going in depth for each one of them is beyond the scope
of this talk, but as a part of the overview, it is important
to differentiate between lesions that are solid
and lesions that are cystic.
Air is a lesion which shows which is seen to be hypoechoic
and well-defined and seems to show a little bit of
through transmission initially concerning for a hematoma
On color dopplar examination,
there was internal vascularity noted within this lesion
consistent with a solid tumor,
this is the image of a muscle herniation
from a fascial defect.
This is a pseudo
tumor tendons.

Tendons

When you deal with tendons, it's important to understand
that the inflammation of the sheath
around the tendon can lead to teno synovitis.
Hypoechoic area around the tendon itself
represents the synovial sheath.
There is one important aspect
to a musculoskeletal interpretation of 10 synovitis,
and that is the understanding of the myo tendonous junction
or the muscular tendonous junction.
If that is a musculo tenderness junction,
then on ultrasound you can see that central tendon enveloped
by the muscle fibers as a decrease in thickness
and towards the insertion only the tendon remains.
If an ultrasound beam does a transverse section short
of the myo tendons junction,
then you can get an appearance like this
in which there is a hypoechoic area around the tendon.
This simulates a sheath.
However, these are normal muscle fibers
and not a thickened synovial sheath.
A synovial sheath is seen much later down,
further down close to the insertion of the tendon itself.
Here's an example of posterior tial Tino.
The tendon appears hyper coic
and fibrillar on colored doppler.
There is intense increase in vascularity within the
sheath surrounding the tendon.
The other aspect of tendons is tears.
Here's an example of a tendon AEs tear.
This is the normal tendon AEs.
On the other side, this is an MRI
and A 3D cornal reconstruction
of the same tear of the tendon.

Nerves

Ultrasound can also look at nerves.
Hair is an example of a normal median nerve
in the wrist joint.
This is a transverse view of the media of the median nerve,
and you can see it has small hypoechoic
and punctate areas interspersed.
The nerves are less amenable
to an phy sometimes that can help them
to be differentiated well from the tendons.
Here's an example of a nerve in long section
and a tendon together at the wrist joint.
This is the ulnar nerve seen close to the
elbow.
Al neuropathy can lead to thickening of the ulnar nerve.
Here you can see this is a relatively thick
segment of the ulnar nerve.
In such cases, an extended field
of view can show a greater length of the nerve.
Here you can see this is a normal caliber.
Other nerve becomes thicker as it crosses the elbow
and then tries to regain its normal caliber.
This is an example of a peroneal nerve neuroma.
This patient came with classic symptoms
and we focused our search for a Mortons.
Neuroma can see a small nerve ending exiting from this
neuroma and entering nerve was difficult to visualize.

Ligaments

Ultrasound can also look at ligaments.
A ligament almost looks like a tendon
with a normal hyper echoic appearance
with a fibrillar texture pattern.
Here is an example showing the rupture
of a collateral ligament at the knee joint with a hematoma.
It is a thick plantar fasciitis insertion.
You can see it's hypoechoic
and thickened compared to the normal.
On the opposite side, this is a case of plantar fasciitis.
Although MRI is the choice for diagnosing meniscal tears
in some rare cases if the patient cannot have an MRI
ultrasound can look at the meniscus at the peripheral
part of the knee joint.
Here you can see this hyper echo triangular area
is the meniscus Is one case
which showed a meniscal tear on ultrasound.
Ultrasound is also being more
and more used in evaluation of rheumatoid arthritis.
This is a good slide from Radiographics
to look at the concept of subc chondral erosion
because of the inflammation of the synovium.
If you look at a zoomed up image of the portion, you see
that small area where the synovium,
the blue plaque like area is the synovium inserts onto the
subc chondral portion of the bone.
Ultrasound is very sensitive at picking up the subc chondral
erosions,
synovial hypertrophy seen here at the joint space.
It represents a case of rheumatoid arthritis.
Here is another case which shows subcon erosion.

Bursae

After we've looked at the tendons
and ligaments, we will look at the bur se.
Bur SE are virtual spaces which allow
for fluid movement of the tendons.
Sometimes if there is fluid collection within the bursal
space, a patient can be symptomatic
and an inflammation of that area can lead to bursitis.
Bursitis can be secondary to trauma, hemorrhage, infection
and also may be seen in inflammatory arthropathy
or dialysis related Amy amyloid arthropathy.
This is a small amount
of fluid seen in the subdeltoid bursal space.
Here's an example of a patient with frozen shoulder.
You can see that this is the tendon.
On the top is a subdeltoid bursa, which appears to be thick.
Here's a case of intra patal bursitis. This is the patella.
This is the infra patal ligament at its insertion on the
tibia and there is inflamed bursa with fluid.

Cystic Lesions

Ultrasound is very good at looking at cystic
lesions near joints.
A few examples would include looking at a ganglion cyst,
a baker cyst, and a para articular cyst.
Here's an example of a ganglion cyst at the scaffold
unit joint.
This is a large cyst, which was more on the radial aspect.
However, head and neck that was leading towards
the scaffold unit ligament.
This is a complex multi septated ganglion cyst.
Here's an example of a baker cyst in the Popal fossa.

Foreign Bodies

Ultrasound is very good
for looking at foreign bodies in the soft tissues,
especially related to penetrating injuries.
If you have a radiopaque foreign body,
which might even be seen on a plain film,
a radiolucent foreign body is more likely to be seen.
Well on ultrasound glass, metal
or stone would be seen as hypoechoic structures with
or without shadowing,
but wood would be seen as a hypoechoic structure
with shadowing In terms of glass and metal.
Apart from shadowing, you might even see
a common tail artifact.
This is a picture of foreign body demonstrating small specs
of glass within the soft tissue.
Two of these specs are very close to the tendon.
There are two pictures showing the appearance
of a foreign body that is made of wood.
These are essentially thorns
of splinters within the soft tissue.
One of them seems to be showing a good shadow.
Here's one example of a splinter in the soft tissue
with surrounding vascularity implying there is some
inflammation around this joint, around this,
foreign body.

Conclusion

In conclusion, musculoskeletal ultrasound has
got a very wide spectrum.
You are pretty much limited by your learning curve.
It takes some time to get a hang of the normal appearance
of the tendons, the ligaments, and the other structures.
However, if you practice on normal volunteers,
that can decrease the learning curve.
A targeted interactive approach is important
and equipment specific to MSK imaging,
which might include specialized transducers like the hockey
stick probe might have to be used.
Always remember that this is a dynamic examination, so try
and simulate the movements which might be increasing the
symptoms of the patient and do not forget to do comparisons
with the normal side.