0:00

Okay, so imaging modality.

0:01

So in the neonate, um, we often start with head ultrasound

0:04

because it's, um, you know, there's no ionizing radiation.

0:07

It's fast bedside exam.

0:09

And so, uh, they can go through various fontanels,

0:11

which are essentially these know, like open, uh, you know,

0:14

non ossified, uh, fibrous things, um, in the skull, uh,

0:17

that actually the sutures and fontanels are there

0:21

because they can mold as the baby goes

0:23

through the birth canal, right?

0:24

So you have some level of plasticity,

0:26

and then as the brain grows, it keeps the sutures open

0:28

and they start to, uh, narrow

0:30

and fuse over time, depending on age.

0:32

So the anterior fontanel actually stays open, you know,

0:35

till about 14, 18 months of age.

0:36

So obviously throughout the infancy you can

0:38

still intonate through it.

0:40

And so you can see in the coronal

0:42

and the satchel plane, um, the ventricles,

0:44

nice gray white distinction here, the corpus callosum, uh,

0:47

the cerebellum, if you're lucky as well.

0:51

We don't typically do ct, you know,

0:52

because of the ionizing radiation,

0:53

but let's say if there's a trauma, right?

0:56

Accidental or, um, non-accidental, um, any concern for, um,

1:00

you know, uh, hemorrhage, for fracture, um, rapid screening,

1:04

if, uh, MR is not immediately available,

1:06

that might be within the risk benefit ratio.

1:08

And so here, uh, you can see that the neonates have, uh,

1:11

water or brains in adults, right?

1:13

Because they're not myelinated yet.

1:15

And so it is, uh,

1:16

a little bit more hypodense here, and that's normal.

1:19

And the overall volumes are fuller too, right?

1:21

So unlike the, the atrophy you see the adult brain, right?

1:23

You, you actually have a relatively smaller, uh,

1:26

ventricle subarachnoid spaces for, for much

1:29

of the infancy childhood.

1:30

Now you can have the, uh, so-called benign enlargement

1:33

of subarachnoid spaces, transiently in around nine months

1:36

or so in self resolving around two or three years,

1:39

but, uh, not in the neonate.

1:40

And then you have these sutures, right, the sutures

1:42

and fontanels that I mentioned.

1:43

So these are gonna, um, gonna be pretty open and,

1:47

and maybe a little overlapping if, uh,

1:49

they had a vaginal burst, right, going

1:50

through the canal there.

1:51

Uh, and then they, they actually narrow pretty rapidly in

1:54

the first like month or so.

1:55

So then you have like a couple millimeters,

1:57

and then they steadily, uh, narrow over time

1:59

and have different, uh, age related times of closure.

2:03

So for example, the atopic suture in the frontier, uh,

2:05

closes earliest, uh, it can be, you know, four months

2:08

or sometimes even a little bit earlier.

2:11

And then we have mr, which is really the workhorse

2:13

for all of our problem solving.

2:14

So I wanna show you this, uh,

2:16

because this is what a normal, uh,

2:19

term neonatal Mr should look like, right?

2:21

So I have these arrows here on

2:23

what are called the posterior limbs of internal capsules.

2:25

If you've got the, you know, anterior limb,

2:26

the Gen U, the posterior limb.

2:28

And so you see that that's pretty much the only part

2:30

of the neonatal brain that's myelinated, right?

2:32

Because what do you have to do when you're born?

2:33

You have to cry and reach out for mom,

2:35

and that's pretty much it.

2:37

So, uh, this T one shortening myelin is fat

2:39

and protein, right?

2:40

So you're gonna get T one bright,

2:43

T two dark, uh, kind of signal here.

2:45

And so it's pretty much that, uh, posterior third

2:48

to posterior half of the IC

2:50

or the click, uh, should be myelinated.

2:51

If you're a full term infant.

2:53

Obviously if you're preterm, it might be a little less,

2:56

but if you're not seeing it at all or barely, then

2:58

You, you have to be suspicious that maybe there's

3:00

something obscuring it, right?

3:01

Like, um, maybe an edema from an, uh,

3:04

hypoxic ischemic injury.

3:06

And so here, this is the,

3:07

the apparent diffusion coefficient map from the diffusion.

3:10

Um, and so there's nothing restricted

3:11

that's as it should be, right?

3:13

This is a perfusion, uh,

3:14

what we call arterial spin labeling.

3:16

And so you see that again, right?

3:18

The basal ganglia are the most robust, um,

3:21

and the corticospinal tract.

3:22

So they have good flow

3:23

because they're actively developing as a result

3:26

because they have more flow.

3:27

Normally, if you have a hypoxic ischemic insult,

3:30

they will be selectively vulnerable to a severe, um, HII

3:34

because they are taking more blood flow baseline,

3:38

but still the rest of the brain does have,

3:40

you know, a reasonable flow.

3:41

It's just not as much as the actively

3:43

developing myelinating areas.

3:45

So that's important too. And then Mr.

3:48

Spectroscopy another advanced tool, right?

3:50

So we can do voxels,

3:51

usually they'll do one over the basal ganglia,

3:53

like a single voxel one over the, uh, white matter.

3:56

Um, and then you can basically get

3:58

the different metabolites.

4:00

This here is a long echo MRS,

4:02

and so we're just cleaning up the baseline here.

4:04

Essentially just looking at the major metabolites.

4:06

And so again, in contradistinction to adults where they have

4:09

that hunter angle that's supposed to go up, right?

4:11

So your NAA from your neurons is higher than your

4:15

choline from your cell membranes.

4:16

Well, the infants are still, you know,

4:18

they have some anaerobic metabolism, even more

4:20

of their preterm, but basically at term age, right,

4:24

they still are undergoing a combination

4:26

of aerobic and anaerobic.

4:27

So the NAAP, uh, area under the curve of the NAA peak,

4:31

right, is around like two thirds of the choline.

4:33

And that's actually normal to have that slight down slope.

4:36

They can have a little bit of lactate

4:37

and lipid again because of that.

4:38

Um, some of that physiologic immature in heric metabolism.

4:42

So that's actually what a normal MRS looks like,

4:44

and that'll be important for us later on.