Musculoskeletal Imaging: When is Ultrasound Enough? - SD

Introduction

My name is John Jacobson.

I'm a radiologist at the University of Michigan working in the musculoskeletal division.

My talk today will be musculoskeletal imaging.

When is ultrasound enough?

It turns out that ultrasound is being used more and more over the past decade.

That's primarily due to the improved resolution of transducers.

With proper training, ultrasound can rival MRI.

What I'm going to talk about are some indications where ultrasound can perform as equal as MRI.

My name is John Jacobson and I'll be discussing musculoskeletal imaging.

When is ultrasound enough?

Disclosures

A few disclosures I need to mention.

I'm a consultant for Sono site Phillips BioClinca and Tesson.

I receive a book honorarium from Elsevier.

Objectives

The objectives of this lecture are to demonstrate examples of musculoskeletal sonography, reviewing those applications that have been proven at least equal to MR Imaging and include Mr. Correlation when possible.

Advantages of Ultrasound and MRI

One compares ultrasound MRI.

There are some advantages of ultrasound.

For example, it's inexpensive.

You can examine multiple joints.

It's better tolerated by the patient.

It's higher resolution than conventional MRI.

You can guide needle aspiration and it really has improved evaluation of the distal extremities.

Keep in mind however, that the deeper structures in the adult, such as the hip and the pelvis are limited with regard to ultrasound evaluation.

Now there are some advantages of MRI over ultrasound.

Of course, with MRI, you can examine the entire joint, you can look within the joint at the cartilage, you can look within the bone at all the deep structures and one of the main areas, it's less operator dependent.

Indications for Ultrasound

Here's a list of accept indications where ultrasound has been proven to be at least as effective as MRI and I'll be going through these examples in this lecture.

Tendon Abnormalities

First I'll be talking about tendon abnormalities.

If we look at the accuracy of ultrasound compared to MRI, there are several research articles which give us some promising results.

Both rotator cuff ultrasound and MRI are fairly accurate at 87%.

Looking at the tibials posterior tendon in the ankle ultrasound, 93% MRI, at least 90%.

Looking at perineal subluxation, ultrasound is a hundred percent.

The reason why MRI is questionable because many times subluxation is only present with specific foot placement or movement and therefore is not truly assessed in MRI.

It's also been shown looking at ligaments that ultrasound can be quite effective.

Now looking more closely at rotator cuff ultrasound, full thickness tears, accuracies can be approximately 96%.

Partial thickness tear is up to 94%.

It's also been shown that it can be equal to MRI With regard to accuracy and size of tear, and again, patients prefer ultrasound over MRIs.

There are plenty of advantages of ultrasound versus MRI.

How do we diagnose the rotator cuff tear?

Most tears are hypo coic or anti coic filling defect within the tendon.

As the tear becomes larger, the OID dips into the torn tendon gap and at the end of the spectrum a massive tear.

There's non visualization of the tendon.

Keep in mind that there's an important indirect sign of a supraspinatus tear in patients over the age of 40 and that is cortico irregularity of the greater tuberosity.

Here's the appearance of a normal supraspinatus.

This is a long axis view where we see the hyper coic in fibrillar or fiber like architecture of normal tendon.

Note that this normal appearance is best appreciated when the sound beam is perpendicular to the tendon fibers.

As the tendon moves more oblique away from the sound beam, it becomes artifactually hypo coac, which is called anisotropy.

Note that on MRI, the goal is to look at each structure in long and short axis and basically we duplicate that with ultrasound with this long axis view of the supraspinatus.

Now to correctly classify a rotator cuff tear or pathology, it's important to understand the anatomy of the rotator cuff.

If we look more closely at the supraspinatus, there are three surfaces.

There's the bursal surface, the articular surface, and the greater tuberosity.

The extent of the abnormality and wet surface it touches will determine how we categorize a rotator cuff tear.

For example, looking at these illustrations, if you look here, this is a partial articular side of tear.

The defect is in black.

Note that it touches the articular surface, also touching the greater tuberosity surface with bone irregularity.

Note that it does not extend to the bursal surface, therefore we exclude full thickness tear.

This type of tear is also called a rim rent tear.

The example on the right is a partial thickness bursal side tear.

Again, the defect in black note that is predominantly touching the bursal surface with some greater tuberosity extension with bone irregularity, but again, not going to the articular surface and therefore not a full thickness tear.

Uncommonly you can have a tear or a defect within the tendon or just touching the greater tuberosity surface.

We use the term intrasubstance tear or interstitial tear in this situation.

Note that because it does not touch the articular surface or the bursal surface, it will not be seen at either arthroscopy or bursoscopy.

At the end of the spectrum we have the ous tear where the defect obviously extends from the bursal to the articular surface.

Note that there's retraction of the tendon.

If the gap is filled with fluid, it would be an coic.

If the fluid was reabsorbed, you'd have dipping of deltoid muscle into this torn tendon gap.

You here are some examples of this type of pathology.

Here's an example of an articular sided partial thickness tear of the supraspinatus.

The defect is well-defined, it's hypo coic, it's touching the articular surface.

There's bone irregularity.

It's not touching the bursa, so it is not a full thickness tear, although it is an extensive articular sided partial tear.

Note that on this T two weighted image that the ultrasound image is almost a mirror image where the pathology is bright on T two and it's dark or black on ultrasound.

Here's an example of a partial thickness tear involving the bursal surface.

Here what we see is that the defect is involving the bursal aspect, it's touching the greater tuberosity.

Note that it's filled with fluid and there's dipping of deltoid in bursa into the torent tendon gap.

Note that it does not extend to the articular surface, therefore excluding a full thickness tear in short axis.

We can also see this defect, which is hypoechoic with bone irregularity.

Incidentally, there is increased flow on color doppler imaging.

This should not be equated with inflammation.

Many times this is neovascular as the tendon defect is trying to heal itself.

It is uncommon, however, to see increased flow within a tendon abnormality in the rotator cuff.

As we look now to a full thickness tear here we can see the end of the tendon is completely detached from the greater tuberosity.

The defect is filled with anti coic fluid.

This bright line here is called the cartilage interface sign where the fluid is touching the hylan cartilage.

Note that the normal convexity superiorly is now quite flattened because there is no tendon tissue there to keep that same contour and the altoid and the bursa is really flattened out where the tendon used to reside.

Here we have even a more extensive large foist tear where the tendon is really, we can't even see it, it's off view.

Note the significant dipping of the deltoid into the torn tendon gap where the tendon used to reside.

Note on the samurai image that there's muscle atrophy.

The tendons retracted underneath the acromion and that's why we cannot see it.

Basically it's because of the degree of traction.

Tendinosis

We talked about rotator cuff tears.

Let's briefly talk about tendinosis.

And this applies to any tendon throughout the body.

We use the term tendinosis and not tendonitis because it's been shown that there are really no inflammatory cells after the abnormalities has been present at least 14 days.

Tendinosis typically is hypo coic.

It may be focal or diffuse.

Now one problem exists because sometimes a tear may not be anti coic, but hypo coic as well.

How do we differentiate tear from tendinosis?

These are some guidelines that you may follow.

The more anti coic well-defined in homogeneous the abnormality, the more likely it's a tear.

The more hypo ill-defined and heterogeneous, the more likely it's tendinosis.

The examples I showed, many of the tears had tendon thinning.

That's a nice and direct sign with tendinosis, the tendon may actually be swollen.

Another important indirect sign is bone irregularity.

As I mentioned earlier, if you see bone irregularity at the site of the hypo coic defect, that would imply tear.

But usually with tendinosis the bone is relatively smooth.

Here's a case of tendinosis of the supraspinatus tendon.

Note. The tendon is abnormal, it's hypoechoic.

But note how it's really ill-defined.

We cannot really trace the exact border of the abnormality and we see tendon fibers traversing the abnormality throughout.

Also note the tendon is swollen and also note the smooth cortex, which would be different from what we would see with a tendon tear.

Soft Tissue Infection and Joint Effusion

Let's move on to talk about soft tissue infection and joint effusion.

Another indication where ultrasound can be quite effective.

How do we diagnose a joint effusion while we're looking for distension of the joint recess?

Typically anti coic or hypo coic, be aware that if the fluid is complex the echoes can be quite bright and be hyper coic.

Also, keep in mind that ultrasound including power and colored doppler imaging cannot distinguish between septic and a septic effusion.

If you worry about infection, you must put a needle into the joint recess.

Here's an example of an elbow effusion.

It's been shown that the most sensitive place to look for fluid in the elbow is posteriorly with the elbow flex.

And here what we see is anti coic fluid and the reon recess distending and displacing the fat pad posteriorly.

Here's an MRI where we have fluid within the joint.

It's T one weighted where fluid is more intermediate.

Note the bright fat pad, which is pushed away because of the fluid in the radon fossa.

A similar finding that we see in radiography where we have the sail sign and the fat pads displaced out of the joint recesses because of distension of the joint recess.

Now keep in mind that if a joint recess is not anti coic but rather contains echoes, there's a differential.

It could either be complex fluid or perhaps synovium.

How does one differentiate between these two?

These are the finds that suggest that it's a complex effusion.

If you push the with the transducer and you see displacement, if you see the compressibility of the fluid movement of echoes within, that all indicates complex fluid.

Also, negative flow on color power doppler imaging indicates that it's likely a fusion, as I mentioned, swirling within the recess.

That also implies that it's complex fluid.

Here are two cases, the ex, the case on the left is synovitis.

The case on the right is complex fluid.

Here on the left we see that the, that the posterior recess of the elbow is markedly distended.

It's not an coic, so it's not simple fluid.

There are a number of echoes in here. This did not compress.

There was no swirling.

There was flow un uncolored opular imaging all indicating synovitis.

And the right is an example of complex fluid with a septic joint.

Here there are echoes as well within this recess, but in a real time we saw a movement in swirling of the echoes and this compressed with transducer pressure and joint movement.

Synovitis and Erosions

So looking more closely at synovitis, ultrasound and MRI have been compared in literature, although many studies are limited.

It has been shown however that both ultrasound and MRI are more sensitive compared to radiography.

Both can show activity of disease ultrasound with the use of color and power doppler imaging and MRI with the use of gadolinium enhancement.

An additional article has shown that ultrasound indeed is more sensitive compared to MRI.

Here's a case of synovitis in the dorsal recesses of the wrist.

Here's the radius, the lunate and the capitate.

In long axis in the sagittal plane we see hypo coic, distension of the radiocarpal and mid carpal joint recesses.

We can see with the color of doppler imaging marked increased flow, these findings indicating synovitis.

If you see cytovitis within a joint recess, the next thing we need to look for is the result of the synovitis.

That being an erosion.

The cortex in the SubCal bone plate is normally smooth and echogenic with ultrasound.

To identify an erosion, we're looking for disruption in the cortex seen in two planes.

Typically with adjacent cytovitis it has been shown that ultrasound per is better than radiography in the detection of erosions.

Here's a case of rheumatoid arthritis.

Note the normal smooth cortex of the ulna now is quite irregular and even throughout this whole area very irregular.

Now keep in mind that this irregularity, which in this case represents erosions, is quite non-specific.

Osteophytes at times can simulate erosions and that is why we're looking for the adjacent hypo coic synovitis to indicate that this is truly an erosion.

And here we see Tino synovitis of the extensor carpe all narrows tendon.

Bursitis

Another inflammatory condition you can see is bursitis and what we're looking for is distension of a bursa, typically anti coic or hypo coic.

The keys to know where the various bursa in the body exists to differentiate a bursal fluid collection from a non-specific fluid collection.

Now remember that just because the bursa is filled with fluid, it doesn't imply it's always inflamed.

If you see hyperemia or if there's symptoms with transducer pressure that would indicate that the bursa fluid is truly inflamed.

Of course the more heterogeneous and the more synovitis within the bursa, again the more likely it will be truly inflamed.

Some meteorologies foric include infection, rheumatologic disorders and gout.

Here's a case of SLE with trocanter bursitis over the greater trocanter, we see this area of abnormality in the expected location of a bursa.

We've see an ncoic area and a more hypo coic area.

Now with transer pressure, note that the fluid area is compressible with the synovial area is not.

This will help when we're trying to put our needle into this area.

We would target the fluid component and not the synovial component if we're injecting steroids into this inflamed versa.

We can see how dynamic imaging can help differentiate synovitis from fluid based on compressibility.

Soft Tissue Foreign Bodies

Moving on to soft tissue foreign bodies, this is one area where ultrasound really is preferable over MRI primarily due to the high resolution of ultrasound.

Fortunately, all foreign bodies look the same by ultrasound.

They're initially hyper coic.

However, keep in mind that organic matter becomes less echogenic over time.

Also, the foreign body will be more echogenic if you're perpendicular to the surface of the foreign body and lemme show what that looks like.

Here's a a splinter that's in the hand.

Now if we center over the puncture site, the form body is very difficult to see, but as we move the transducer around the finger and we're now we're getting the form body more perpendicular to the sound beam, we now truly appreciate the hyper co nature of the form body and there's a little bit of abscess formation around it.

If you're looking for a foreign body, don't just put the transo over the puncture site but interrogate the area at different angles so that we can catch the foreign body perpendicular to make it brighter.

This effect here is basically an atrophy similar to what we see with the tendon, meaning that if we're not perpendicular, the echoes actually decrease in the structure that we're imaging.

In addition to looking for the bright foreign body, we wanna see what happens around it to help identify the foreign body.

What we look for is a hypo halo surrounding the foreign body, which is a foreign body response with granulation tissue and inflammation.

Also, there's often an artifact deep to the foreign body.

If the foreign body is smoothing flat, we tend to see reverberation artifact deep to it.

If it's irregular with a small race of curvature, we tend to see shadowing.

Here's an example of a rose thrown in the foot.

I was interpreting this MRI.

We did indeed see abnormal increased signal in this T two weighted image indicating fluid or inflammation.

However, we did not see a foreign body.

The patient returned for an ultrasound and what we see here is this echogenic linear rose thorn with this halo around it representing inflammation looking short axis of the foreign body.

There it is with this small abscess forming around it, it's unclear if this was the foreign body or this basically the resolution of ultrasound is the key, which is the advantage for ultrasound in this situation.

Soft Tissue Masses

Let's move on to soft tissue mass.

Ultrasound is primarily used in musculoskeletal imaging with regard to soft tissue masses to distinguished cyst versus solid.

And where this comes into play is when a clinician suspects a benign cyst and they simply want to confirm it.

We're gonna look at baker cyst and risk ganglia.

A ular cyst is basically distension of the semiosis menial gastric bursal, which resides in the posterior medial aspect of the knee or half the patients of 50 and eight years and older have communication between this bursa and the knee joint.

And that's why we tend to see distension of this cyst in patients over the age of 50.

And keep in mind that we must see this communication between the bursa and the joint, between the semiosis and the media gastric tendons to exclude other fluid collections.

This is a very important finding which I'll demonstrate on the slide here.

Here's a typical baker cyst.

They tend to curve around the medial head of the gastroc anemia, but this is the channel here, the connection between the knee joint and the bursa that you must see between the semi member analysis and the medial head of the gastro anemia.

Now here's an MRI of the same patient.

I've turned this upside down to simulate what we see on ultrasound.

Here's the bursa, the baker cyst, there's that channel or connection moving toward the knee joint.

If we see this, we know it's definitively a baker cyst.

When someone has pain other than looking for the presence of a baker cyst, we need to look for a complication of a baker cyst.

That being rupture.

Normally the baker cyst is smooth at the bottom.

If you see hypoechoic fluid tracking over the muscle of the medial head of the gastroc anemia also shown on the mr.

That indicates that the baker cyst has ruptured and this can cause significant pain and swelling down to the ankle and at times simulate venous thrombosis.

The other mass or cyst that we look at with ultrasound commonly is the wrist ganglion.

Most wrist masses are ganglion cyst.

70% occur over the skin lane ligament.

The rest occur between the radi artery and the flexor carpi radial tendon.

These are two very important areas to screen for ganglion cyst.

When you're imaging the wrist with ultrasound or even MRI, so by ultrasound you'll see an coic or hypoechoic cyst or mass like area tends to be well-defined.

Another important finding, it tends to be lobular, almost a multiple loles or vesicular and that's a very important indirect sign.

You may see joint or tendency communication.

Keep in mind that when they're small they won't be anticoag so they don't fulfill the criteria for a simple cyst, but that's because they have, they're composed of small vesicles rather than a large single fluid collection.

Here's a typical dorsal ganglion cyst over the S ligament area, not in the MRI.

We appreciate the vesicular, the multilobular appearance and this is classic, we see the same thing by ultrasound with the septations and lobular.

This is the scaphoid bone on this image on the right.

If you look at the volar aspect of the wrist, again they tend to occur around the radial artery.

Here we can see one between the radial artery and the flexor carpe radialis.

They tend to come from the wrist joint and as you can see on this ultrasound image, they can wrap around the radial artery and they can simulate a pseudo aneurysm.

Peripheral Nerves

Let's move to the next accepted indication.

That being peripheral nerves, this is one area of my practice that has dramatically increased over the last four years.

And again, that's predominantly due to the higher resolution probes that can really show the intrinsic anatomy of a peripheral nerve.

A peripheral nerve will actually show the individual hypo coic nerve sles and you'll see surrounding hyper coic connective tissue.

If you look at the peripheral nerve and transverse, it has a honeycomb appearance.

Here we're looking at the median nerve in the carpal tunnel.

Here's the flexor carpi radialis, here's the ER's longus, there's the Retin ocular.

As I rock the transducer along the long axis of these structures, we can appreciate the hypo coic individual nerve fascicle and the bright connective tissue surrounding it.

That's the median nerve.

Note that the tendons actually become dark and that's due to anisotropy.

That's one trick to differentiate a tendon from a peripheral nerve.

We predominantly look at peripheral nerves with ultrasound to evaluate for entrapment.

And the ultrasound findings of nerve entrapment are the same regardless of where in the body we're looking.

Basically as a peripheral nerve goes into a tight space, typically a fibrosus canal we'll see swelling of the nerve and this is usually best appreciated transverse to the nerve.

Moving proximal, the distal you'll see swelling.

The nerve may also be hypo coic because of edema, especially the connective tissue layers.

Then as it goes into the entrapment site, there's a variable enlargement or flattening.

The most common entrapment neuropathy is carpal tunnel syndrome.

And there are different ways of diagnosing this by ultrasound.

This described in 2009 is a very effective way where they measure the median nerve more proximal of the pronator qua quadratus looking distally in the carpal tunnel.

If the nerve area increases by two millimeters or more, that indicates carpal tunnel syndrome with 99 s percent sensitivity and 100% specificity.

Also note the significant hypo coic edema of this enlarged median nerve.

Here's a companion case again contrasting with the normal appearance, the median nerve is enlarged and it's globally hypo coic because the individual connected tissue right areas are now hypoechoic corresponding to significant increased signal on the T two 80 image.

On this MRI, we can also look for cubital tunnel syndrome again looking for enlargement.

One study has shown that if it's greater than 9.5 millimeter square in area in cross-section that's abnormal, there are a number of causes for the ulnar nerve to be swollen in the elbow.

It could be from overuse, an adjacent joint process or a normal variation muscle called the ENC conus epi petroli areas.

Here's a cross section of the ulnar nerve within the cubital tunnel.

The cubital tunnel is enclosed because it the arcuate ligament, the humeral head and the ulnar head of the flexor carpi omas.

This is markedly enlarged in hypo coic.

If we look in long axis, you can see the nerve is enlarged, markedly enlarged in hypo coic at the cubital entrance.

And then there's a transition among normal size within the cubital tunnel.

This is a finding of entrapment that we see and if you push on this area at the transducer, the patient will experience symptoms and give you that immediate feedback.

Another peripheral nerve pathology that we look with ultrasound is Morton's neuroma.

In length that nerve imp the name implies neuroma is not a tumor but it's really edema, fibrosis and necrosis due to digital nerve entrapment.

In this situation the nerve will be enlarged more than five millimeters will be hypo coic and ultrasound is quite effective in this diagnosis with a 100% sensitivity.

It's important when you see this hypo coic mass between the metatarsal heads in the foot that you look for the digital nerve to go into the mass, which excludes other causes for mass in this area.

Here between the metatarsal heads we see an enlarged hypo coic area that's over a centimeter and here it is on MRI.

And this is a Morton's neuroma again classically between the metatarsal heads.

If we look under long axis, we can see this mass like area again.

And there's the emmis peripheral nerve going into this area of nerve entrapment.

Another important indirect sign is when you push on this with a transducer with your hand on the other side of the foot, the palpation and pressure will cause significant symptoms experienced by pushing on the Morton's neuroma.

More recently the molars maneuver has been described.

The molars sign is a clinical sign that when you squeeze the foot from side to side, there'll be a popping sensation and pain where the Morton's neuroma pops in and out from between the metatarsal heads.

We can do this with ultrasound and here we see the metatarsal heads and we're gonna look here for the Morton's neuroma.

It's located here right now, but as we squeeze the foot from side to side, there'll be a click in the Morton's neuroma will snap out.

Here we can see the Morton's neuroma snapping into into view.

This is the plantar aspect of the foot.

This is the normal inter menstrual space which does not demonstrate this finding.

And with this maneuver the patient experiences symptoms, which again is more indirect evidence.

Dynamic Imaging

The next area is dynamic imaging.

This is one area where ultrasound really is affected effective compared to MRI Ns because the patient has pain or symptoms in a certain joint movement or position that's difficult to recreate in the magnet, but that's easy to do with ultrasound.

We can look at a number of structures that show pathology with dynamic maneuvers we can look at dislocation of the biceps subluxation and the triceps snapping of Ilia sous the perineal.

And we can use this to help differentiate partial from fo thickness achilles tendon tears.

We can move the shoulder and look for bursal impingement.

We can put stress across the elbow and look for ulnar collateral ligament tear for nerves.

You can look for dislocation of the ulnar nerve.

We already showed Morton's neuroma and then inal hernias and muscle hernias.

Again, using dynamic imaging is imperative in making these diagnosis.

Just to show a couple examples, here's an example of snappy ilio sous uh tendon syndrome.

Here's a transverse oblique view over the anterior hip.

Here's the ileum, there's the muscle and there's the tendon.

Normally when the patient goes from frog leg view to a straight view, there's a smooth motion of the muscle and tendon if you're snapping or popping.

If that is seen, that implies it's abnormal.

Lemme start the video clip right now in frog leg position as the leg is straightened, keep an eye on the tendon and there's the snap.

Basically it's moving abruptly, it's snapping down onto the ileum.

You can feel the snap through the transducer send.

Sometimes you can hear the snap and the patient will tell you, yes, I'm feeling pain when this maneuver is happening.

All this feedback together gives you the diagnosis.

There it is again, a snapping hip syndrome.

Here's an example of muscle hernia.

This is a patient who had ankle pain.

We scanned her ankle and it was completely normal.

At the end of the exam I asked, could you point to where the problem is?

And she said, when I stand up and move my foot around, I see a mass or a bulge.

We had the patient stand up and do a specific maneuver that created that symptom and what we saw was this bulging of the muscle because of the weakened fascia.

This representing a muscle hernia.

Why we're scanning The patient explained that she was feeling some symptoms going down her leg and what we saw in addition to the hernia was this hypo coic swelling of the superficial perineal nerve.

Ultrasound with dynamic imaging allowed us to make the muscle hernia diagnosis.

The resolution of ultrasound allowed us to see the superficial perineal nerve entrapment, which coexisted with the muscle hernia.

Another cause of elbow pain where dynamic imaging is very helpful is snapping tricep syndrome.

Normally the ulnar nerve and the tricep stays behind the media epicondyle when you go from extension to flexion.

And some people, especially those with large muscle bulk, if you flex the elbow, the ulnar nerve can dislocate and part of the medial head of the triceps will subluxate.

As well note, first of all, how enlarged this ulnar nerve is.

There's already evidence for neuritis as we flex the elbow, the nerve comes out and look at the medial head of the triceps.

Both of these are abnormally moving medial and anterior to the medial epicondyle causing the patient's symptoms.

And this only occurs when the patient is flexed.

Here's an MRI of the same patient with the elbow extended.

Indeed we can see some edema in the NAR nerve.

Although this can be a normal variation, we have no clue to why there's a problem here because in neutral position we do not see the dislocation of the ulnar nerve and we do not appreciate subluxation of the medial head of the triceps muscle.

Contraindications for MRI

The last area where ultrasound can always be considered is when a patient can have mr.

And there are a number of situations where this comes into play.

Perhaps when a patient has metal formed bodies near critical organs or a certain fair of magnetic devices or implants.

Some people just don't like being the magnet because of claustrophobia and some people just can't fit in the magnet.

In these situations we need another alternative and that's where ultrasound can be quite helpful.

Summary

Just to summarize, what I tried to accomplish is to review some accepted indications where ultrasound can perform equal to at least MRI tendon abnormalities.

By far the most common indication that being the shoulder, rotator cuff ultrasound, soft tissue infection, and joint effusion form bodies.

And again, here because of the high resolution, it really is the imaging method of choice, soft tissue masses cyst versus solid.

That being baker's and risk ion peripheral nerves, again because of resolution allows us to really appreciate all the entrapment neuropathies.

Also with ultrasound, we can examine entire extremity in a fraction of the time that MRI would examine an extremity.

Dynamic imaging, definitely one area where ultrasound performs much better than MRI and I showed a number of examples of that.

And lastly, when there are contraindications for MRI, one last point to keep in mind the accuracies of ultrasound MRI really depend on the education and the training of the person doing the ultrasound.

As I mentioned and all these indications, ultrasound can perform equal if not better than MRI, but that also depends on the training and experience of the person performing the ultrasound.

Thank you very much.