Fetal/Pediatric Head and Neck Ultrasound: Approach for the Radiologist - HD

Introduction

Okay.
Thank you very much for the kind invitation.
This is definitely something very different than was discussed earlier during this session.
This is the outline of our talk.
We're gonna be talking a little bit about embryology and some ultrasound techniques in children, a little bit about normal anatomy and touch on the topics of congenital hypothyroidism, thyroid gland, topia masses, primarily thyroid gloss duct cyst, not the thyroid nodules that were discussed in beautiful detail on prior portions of this session, we'll talk about thyroid teratoma, and a little bit about inflammation, which includes, by the way, my very favorite ever diagnosis.
So we'll get to that. We, again, will not be discussing primarily thyroid nodules, which was beautifully covered previously.

Embryology

Just a word or two about embryology.
The anatomists tell us that the glands of the head and neck are essentially all buds of endoderm, with the one exception that the parotid gland is a bud of ectoderm.
I'm not sure why that is, but it's an interesting point.
It is important also to note that some of these buds have a very long way to go, particularly the bud that creates the thyroid gland and the bud that creates the thymus.
So both of these have a tendency to either go not far enough or to dive too far down into the mediastinum.
And these are important points to remember as you're analyzing your ultrasound findings.

Ultrasound Techniques and Normal Anatomy

This is an ancient slide, and for the older people in the room, you will recognize the black XP transducer of many, many years ago.
This is my son, Christopher, who's now 29 years old and would be absolutely mortified to know he's still being shown in this session.
But I show it on purpose because I actually think this is a very important part of this talk.
It's all about position of the baby or child.
So the neck has to be hyperextended.
You wanna roll or a pad behind their neck, and more importantly, behind their shoulders, so that you can actually have a flat surface to scan.
And in the old days, a standoff pad was more important than it is today.
But nonetheless, it can be helpful because it can allow you to really get a sense for the contour of the area of interest.
So in this case, I am pointing out the hyoid bone.
So here you can see the curvy linear calcified bone with a nice sharp posterior acoustic shadow.
And you know that this area represents the submental region, and this is more the anterior neck.
And I always consider the hyoid bone the point of reference when I'm doing a head and neck ultrasound in a child.
Of course, sonography, we're all ultrasound fans.
Sonography provides unbelievable anatomic detail.
You can just get out your axial anatomy references and see all the fancy layers of muscles cartilage around the larynx.
We have the advantage of real realtime observation, showing the vocal cords move in and out.
Sometimes symmetrically, sometimes asymmetrically.
If there's been laryngeal nerve injury during a prior operation, we always take a moment to scan up and down in the transverse plane and look for areas of asymmetry you cannot beat.
Ultrasound for definition of anatomy and motion.
Previous speakers beautifully described the anatomy of the thyroid gland.
Remember that sometimes the connecting isthmus is a skinny little thing.
Sometimes it's broader and thicker, and it's something you should observe as you're doing your scan.
The esophagus is most commonly to the left of the airway.
But in our patients who may have had esophageal surgery, maybe esophageal atresia, the esophagus might be on the right side.
Don't let that fool you into thinking it's something else.
Just watch the child swallow. You can see air go down.
You know right away what you're dealing with.
Here I am privileged to get to do some fetal ultrasound, particularly in fetus's thought to have some serious problem.
And this is a fetus with congenital diaphragmatic hernia.
And we, our goal was to really assess the anatomy of the chest to see what was up and what was down in the wrong place.
And I was struck in this situation.
Here's the heart that you could unbelievably well see the thymus, which has a glandular appearance at 25 weeks gestation.
So it's amazing what ultrasound can do for head and neck anatomy in the fetus.
And indeed, you can really even see the thyroid gland if you look hard enough, you can see portions of the laryngeal apparatus.
So if you happen to have the privilege of doing fetal ultrasound, I urge you to do so.
The thyroid actually looks relatively large in a normal fetus.
If you're able to see it.
And I showed this, you'll see why later on.
But you can see fluid in the oropharynx defining the piriform sinuses and extending down into the airway.
Remember, this is all fluid because the fetus is swallowing and breathing amniotic fluid at this point, but pretty amazing detail for a 21 week gestation.
Alright, so that was a little bit about how we make our pictures, what we focus on.

Congenital Hypothyroidism

Now, let's get to a bit of pathology.
We'll start with congenital hypothyroidism.
So luckily in our country, all babies in nurseries are screened for the possibility of hypothyroidism.
But occasionally something goes wrong, a specimen is lost, or you may be evaluating a baby who has come from another country where screening has not occurred.
Babies with congenital hypothyroidism have excessive sleeping, poor feeding, and muscle tone, a low horse cry, infrequent bowel movements, exaggerated jaundice, frequently and large ils.
So there are some clinical findings.
Why do ultrasound in this setting?
Well, what we're really looking for is to see whether or not we can see the tiny little abnormal appearing thyroid gland in the usual place.
Or is the problem because the gland never migrated in the usual way?
Is it up in the tongue?
Is there an associated mass that might potentially require some surgical intervention at a later date?
So we're mostly looking to see, can we see a small thyroid gland or is there something in an abnormal site of descent?
So here's an example of a two month old little boy who was screened for hypothyroidism, was shown to have congenital hypothyroidism.
And our sonographer came back and said, oh, look, I can see the margins of what looks like in a normal thyroid gland tomy.
And I said to her, gosh, I'm not really sure.
It doesn't have the edges that I'm used to seeing.
So we went in together and scanned, and this all turned out to be intervening connective tissue, sort of filling the spot where the thyroid sits.
And she said, oh, no, no, that this is what I'm talking about this stuff here, these hypoechoic triangular areas.
So we scanned a little further down and we could see that it was really rather asymmetric with the left side being larger than the right.
And then when we turn the probe into a sagittal plane, this is the same structure of interest.
I'll point out the cervical vertebrae here.
This is the esophagus that has some air and fluid within it.
And this in fact is the level of the thoracic inlet.
So I bet plenty of you in this audience know that this turns out to be a normal thymus, very commonly seen.
It's very soft. And you can see it bouncing up and down.
So if you're looking at a baby who has congenital hypothyroidism, don't let the thymus fool you as being a thyroid gland.
They have a characteristic appearance, very soft.
Here's another example, thymus.
They often have these sort of segments here within them.
They shouldn't be confused with other things.
Don't require a biopsy.
And if you look for them, even in a baby whose youth thyroid, you see them all the time.
Just one more example of a sagittal MRI showing the thymus that continues down into a substernal location.
Very classic appearance, often even more than this, extends up into the neck.
So normal variant thymus, if you are searching the neck in a patient with congenital hypothyroidism, do not forget to aim your probe superiorly to the level of the tongue base, because that is where your residual thyroid gland or cyst may occur.
So here we are again focusing on the level of the hyoid and then aiming superior to that.
You can see the midline of the tongue during real time scanning.
The you can see the muscles moving around in there.
There is no cys mass in this situation.
So your search is not done until you aim your transducer superiorly and document the appearance of the base of the tongue.

Masses

Okay, masses, there are several possible explanations for a palpable mass involving the head and neck of a child.
The most common indication in, at least in our practice in Boston, is the presence of a thyroglossal duct cyst.
And I would argue that one can generally make this diagnosis with a fair degree of certainty.
These tend, these can occur anywhere along the track of descent of the thyroid gland.
Most of slight majority are in an infra hyoid position.
A larger majority are in the midline, but we've seen plenty that scoot off towards one side or the other.
They can appear as simple cysts or complex cysts.
We'll show an example.
And really the main differential is that of a dermoid cyst.
These tend to be more commonly located in a supra high location, and they tend to be centered in the subcutaneous fatty layer.
Those are important distinguishers.
So here's an example of a 13-year-old boy who presented with a neck mass.
He was a very good historian.
He was able to tell me that the thing came and went, got bigger and smaller, occasionally was a little bit red.
He's 13.
He's now starting to be embarrassed when other people can notice it.
So he finally points it out to his parent.
And in the transverse plane, you can see that the lesion is bi lobed.
They are sometimes like this, sometimes they're a simple round single cyst, sometimes bi lobed.
And really this is the most important picture in the sagittal plane.
You've localized the heavily calcified hyoid bone, a nice sharp posterior acoustic shadow, and the lesion itself touches the hyoid bone.
This really can be nothing else but a thyroglossal duct cyst.
Of course, one should turn on the color doppler.
You may have some internal echoes within the center of this thing, but you shouldn't have a central vascularity.
Occasionally the echoes can be a little bit confusing, but generally not.
And our ORL surgeons tell me that when they go in and resect these, which they generally do because of a tendency for recurrent infection, and because patients don't like to have a lump on their neck, they always make a point of resecting the contiguous portion of the hyoid bone.
If they don't, the lesion has a tendency to recur.
So remember that. Here's just another picture for those who who seem to need to go beyond ultrasound.
We don't usually, by the way, our ol ORL surgeons are very happy with an ultrasound diagnosis of thyroid gloss duct cyst.
But occasionally, cts are done first before we get a chance to give it a try.
And again, you can see the calcified hyoid bone.
Here's the cyst pointing up towards the base.
And here, in theory anyway, is your ultrasound probe.
You can see that if you didn't type orex extend the neck, it would be rather tricky to make a nice picture.
Hence it's so important to get your patient into a position that makes them more scannable.
It's probably worth saying that it's very helpful to have a child life helping you or a couple of parents who were cooperative, turning on a little tv, a little iPad entertainment, something to help distract the child goes a very long way.
Okay, this is a nine month old boy who presented with a palpable mass.
And the clinical impression at least on our requisition was that this is probably gonna end up being a thyroglossal duct cyst.
You can see, however, on our ultrasound, this structure is really a little bit lower than we would generally expect.
It's right next to the normal appearing thyroid gland.
And in the sagittal plane, there is no at least no documented connection up with the hyoid bone.
Unfortunately, this was interpreted as being consistent with a thyroglossal duct cyst.
So the patient did go to the operating room, however, in fact, this turned out to be necrotizing.
Granulomatous lymphadenitis probably didn't need to go to the operating room.
So we can really help in this situation by redirecting when appropriate.
Okay. So, you know, it's also important to remember that sometimes when you discover a thyroid gloss duct cyst, you may be looking at the only functioning thyroid tissue.
So that would imply that the usual bud did not descend in the appropriate manner.
Why am I bringing this up? You're not finished.
If you've documented a complex cyst in association with the hyoid bone, you have to also look for the thyroid gland and make sure that there's a normal appearing thyroid gland also present.
If there's not, you may be looking at the only functioning thyroid gland, and it may still need to be resected, but at least the child won't go through a period of being hypothyroid and suffer the complications of that.
So it's, the onus is on us to prove that there is a also a normal looking thyroid gland present goiter.

Goiter

Okay, well, certainly goiter can present as a mass.
We have several examples of fetal goiter, which I think is pretty amazing.
You can certainly document the enlarged thyroid lobes here.
Sometimes the thyroid gland is so big that it actually compresses the fetal airway.
And there have been reports of situations where the infant at the time of delivery had significant airway troubles.
I love this 3D rendering of fetal goiter.
This particular mom was on propofol uracil for treatment of her hyperthyroidism, and it was crossing the placenta at the time of delivery.
Luckily this baby had no particular trouble breathing, but I think at a glance you can notice that this is looks like a typical goiter you might see in an older patient.
The connecting isthmus has some bulk to it, happily over time, when no longer exposed to the material medications, that shrunk down and the baby did just fine.
Generally, of course in the world, the presence of goiter is usually simply a dietary problem.
Luckily, it's rarely seen in this country.
We do sometimes see patients particularly teenagers with goiter.
Most commonly, at least in our practice, this is due to an autoimmune condition.
The gland looks generally heterogeneous without any specific nodule identified.
Tends to be hyperemic.
I'm a big animal lover, so I love to learn about other things that they can get.
Indeed, many animals also can get goiters, horses, sheep, et cetera.

Thyroid Nodules

Alright, I mentioned we would not get into any detail here because it was so beautifully covered by previous speakers.
Maybe I'll show an example or two.
Here's a teenager who had a nodule, and indeed this did turn out to be a malignancy.
Yes, teens can get the typical forms of thyroid cancers that older patients can get.
It is rare.
So we don't wanna get too excited about every tiny little nodule we see.
But I did wanna make one point, and that is simply that history is tremendously important.
So you know, whether or not you grade this in one way or another.
Is the capsule intact? I'm not sure.
But when we learned a little bit more about this patient, important history was revealed.
So she's 20. Yes, we do see some young adults and it turns out that as an infant, she had neuroblastoma, she had a bone marrow transplant and total body radiation.
So I would argue that almost no matter what this thing looks like, she needs to have very careful follow up.
There's papers yet to be written about this, but I think we need to really dig a little bit deeper.
You know, she sort of forgot about her neuroblastoma.
She's a success story.
Luckily she was treated at our hospital, so we were able to dig a little deeper and find this out.
But knowing a good history, I think is relevant to the interpretation of these studies.
And just one more note, you know, sometimes disasters happen and remember that the young thyroid gland is particularly susceptible to radiation injury.
Patients may have been exposed at one point or another.
Patients travel around the world these days.
So if you see a nodule in a patient who was exposed as a child to one of these accidents, I think that's a very different group of patient than your average teen.
Oops. Okay. Okay, let's go. Yeah. Alright.
And yes, we do see familial forms of thyroid cancers.
Probably enough to be said.
This is something you could talk about for a couple of hours alone, but do look into family history.
It is important.

Thyroid Teratoma

Thyroid teratoma.
This is a mass that we see with some frequency because of referral patterns in newborns or even fetuses who are present to our hospital.
And here's an example of a fetus who was found to have a mass at 32 weeks gestation.
So if you just do your midline, sagittal view, all is good.
No particular suspicions other than maybe there's a little bit of polyhydramnios this late in pregnancy.
But if you turn your probe into a coronal plane, oh my goodness, there is indeed something going on.
This is a primarily solid lesion with a few little cysts within it.
And there's also this tube kind of squished over to the side, which proves to be the fluid filled trachea, which is squished over by the presence of this large mass.
It's something that you can document fairly readily by ultrasound.
Of course, you'll wanna use your color doppler to help you discover what is a vast vessel and what is a fluid-filled trachea, excuse me.
But ultrasound can go a long way to identify the airway and help determine whether or not there may be a problem getting an airway at the time of delivery.
In this particular case, the patient did go on to have a fetal MRI and I, the fetus was extraordinarily cooperative, was scanned in both flexion and extension.
And in the flexed position you could see the column of T two bright fluid going through the trachea.
A little bit of compression here, but in the hyper extended position, which is often the position assumed when a baby is being intubated, the compression was greater.
So this made us determined that we needed to have all of the experts to achieve a newborn airway in the delivery room at the time of delivery.
And indeed that happened.
They struggled a little, but were able to intubate without doing any sort of fancy tracheotomy.
You can see the soft tissue mass over here, and I'm not sure people in the back can see, but there are definitely some linear calcifications, which help us know that we're dealing with a teratoma as opposed to something else.
So what other things might we see these?
This is the patient that I just showed you and this is a different patient.
So with gray scale assessment of the mass, you can see that it's essentially mostly solid with many echogenic foci, some of which cast posterior acoustic shadows, who are probably frank calcifications.
And when you turn on the color doppler, the solid appearing portions are highly vascularized.
So that really tells you in this situation, in a newborn, in a mass growing from the neck, almost certainly the thyroid as its origin, this is a teratoma.
The alternate possibility is this, which is a primarily fluid containing lesion with intervening septations.
And of course this represents a lymphatic malformation.
On physical examination, assuming there's been no complications, no bleeding, the LMS tend to be very soft and boggy, therefore very rarely interfere with the airway, whereas the teratomas tend to be firm and certainly can interfere with the airway.

Lymphatic Malformations

Okay, so just a word or two about lymphatic malformations.
Don't use the term Cystic Hy Roma. This is out of vogue.
These are comprised of lakes of echo free fluid separated by Fin septi.
They are fragile so they can bleed.
So you may see some fluid debris levels within them.
They tend to be located in the posterior triangle, but can go anywhere.
They may have a beard like distribution underneath the chin, and they of course can be inter parotid as well.

Fibromatosis Colli

Alright. All right. This is a different patient, not a brand newborn, but pretty darn young.
22 days old, presenting to ultrasound with a painless firm neck mass.
And I've given you a clue here.
This is on the right side as opposed to midline.
There's no hyoid in our field of view.
Our sonographer has put the cursors on the mass itself here and there is some blood flow within it.
I'll tell you, it primarily comes from the posterior aspect of this focus or lesion.
Some of you may already know what this is.
This is a diagnosis made based on location and one can be very confident.
So on the opposite side that didn't have the mass, this is the sternal colleto mastoid muscle shown in the sagittal plane.
This is on the symptomatic side where you have a bulge in the body of the sternal colleto mastoid.
So what is this? This is an example of fibromatosis colie.
This is a poorly understood disorder of the neonate tends to be associated with de developmental dysplasia of the hip.
More commonly seen in girls and on the right for some reason it may not be evident of birth, but usually within a couple weeks after birth you start to feel this firm mass.
And an experienced pediatrician is very good at making this diagnosis.
Clinically, we don't often see them referred to ultrasound, but it's important for us to recognize and reassure the referring pediatrician when we see it.
The term cli comes from the Latin for neck column.
So it's fibromatosis cli with two Ls, not coli, otherwise you're talking about fecal stuff.

Inflammation

Okay, great. And then we'll finish up with just a couple of words about inflammation.
Yes, Hashimoto thyroiditis does appear occur in the pediatric population.
This is a chronic lymphocytic thyroiditis and autoimmune condition.
Very often though not always associated with a known family history of the condition.
The cause is likely genetic and there's a very long growing list of specific genetic abnormalities known to be associated with Hashimoto thyroiditis.
Amazingly. This was originally described way back in 1912 by Dr.
Hashimoto. And patients will clinically present with bouts of hypothyroidism and hyperthyroidism.
We've got a couple families where, you know, all the little kids come in and everybody gets their thyroid scan and you compare them to prior and they're generally treated with thyroid replacement.
You know, the trouble can come if you suspect there may be a nodule within this.
Luckily our patients tend to be a little lower, where the risk of malignancy is lower too.
So here's an example of an 11-year-old girl who has a clinical and a genetic diagnosis of Hashimoto thyroiditis with a diffusely enlarged heterogeneous thyroid gland, which is hyperemic a rather big connecting isthmus.
Her little brother had a tiny little fibrotic burnt out thyroid gland.
And we are very confident what we're dealing with here.

Suppurative Thyroiditis

Okay, I mentioned earlier I have a favorite, favorite diagnosis.
This is it. At a glance you might say, well you know what, what is this?
We got a big thyroid gland with a big canes connecting isus, but I've told you this child has a fever, they are acutely ill, their neck is red and tender and swollen and not usually, usually like this.
And it popped up fairly quickly.
You can see that on the left side there's some hypoechoic material, maybe with some air with dirty shadowing within it.
And when you turn on the color, the edges of this thing are hyperemic.
But we weren't able to detect anything within the central portion of this focus.
Whenever I see this, chroma or B mode technique, I know which sonographer this is.
You know, some of them are just is favorite, right?
They're looking for the edges. Sometimes it helps.
But you know, it almost looks solid here.
I wonder if ultrasound contrast may have a role in this situation.
It was not given here.
I'm gonna keep going here. Okay. A little movie.
You do get the sense for edges here. Okay?
This is a different child with the same diagnosis.
This is a little bit more hypoechoic perhaps than the other example that I showed you, but otherwise has similar features.
Fever, acute neck swelling, localized on one side, in this case the left side.
And here's a little movie from that same patient scrolling through ill defined part of the thyroid gland looks abnormal and part of it looks as though it may be mass.
Like, alright, so does anybody know what this is?
So this is an example of separative thyroiditis due to a congenital piriform sinus fistula.
And this is thought to be a remnant of the third or fourth pharyngeal pouch.
The fistula may be from the pouch to the peri thyroidal space, as is seen on the CT scan.
You have lots of inflammation and an abscess.
I love this artist rendering.
It always makes it look so much more simple.
And in the old days we used to always do a barium swallow to see if we could see a connection from the point of the piriform sinus down into that abscess cavity with a caveat that you shouldn't do that study in the acute phase because the inflammation will prevent flow of contrast into the abscess cavity.
And I come back to this little thyroid.
This is a fetal picture here showing the piriform sinus and where these things that can occur.
I've never seen this diagnosis made in the fetus, but who knows if we know about it and look for this kind of detailed anatomy that may be possible in future.
In this case, I see that goal raises here.
I don't know if you did this or not, but our interventional radiologist saved the day, did a percutaneous drainage procedure.
The patient felt much better right away and then later on had a formal surgical excision of the abnormal fistula.

Quiz

This is our quiz, location, location, location.
This patient is a 21 month old kid.
We can see the hyoid bone here is a cystic mass connecting up to it.
So sure enough, that is a slam dunk thyroglossal duct cyst.
And I'll point out, there's a second tiny little lesion that's centered in the subcutaneous fatty layer in a super sternal location.
And that turned out to be a dermoid cyst.
So you can have several things in the same patient.
You know, don't be fooled by satisfaction of search.
So that was a long list of topics covered.
Thank you very much.