0:00

Okay, so MRI considerations, um, in babies, right?

0:03

You ha they have to be stable

0:04

before they can go down for MRI.

0:06

So if they're, you know, difficult delivery,

0:08

they have all this like support devices

0:09

that are m MRI incompatible.

0:11

Uh, maybe they're preterm

0:12

and they have this, you know, huge surface area

0:14

to volume ratio, so they're losing heat, right?

0:16

So you need to incubate them.

0:18

Uh, they also sometimes like

0:20

to move like any patient, right?

0:21

So you might have to do the so-called

0:23

feed and swaddle, right?

0:24

So that they get postprandial

0:25

and then you can like, wrap 'em up real tight.

0:28

Um, sometimes if they're still moving

0:29

and it's important that you get the detail, you might need

0:31

to do sedation or even, um,

0:33

general anesthesia depending on how suspicious you are.

0:35

Obviously, we don't love to give general anesthesia, uh,

0:39

to kids below two or three years of age, uh,

0:41

because there's some literature showing

0:43

that there's long-term, uh,

0:44

neurodevelopmental effects, right?

0:46

But again, it's all about the risk benefit ratio. Okay?

0:50

So then imaging wise, right?

0:51

You have to decide what kind

0:52

of scanner you you wanna use, right?

0:54

The standard ones are three T and 1.5 T, of course.

0:57

Uh, and three T gives you much nicer brain detail.

1:00

You can do more, uh, with the advanced imaging.

1:02

Uh, but there are a number of emerging platforms, low field,

1:06

more accessible, mrs.

1:07

Uh, which, uh, slightly, slightly, uh, lower image quality,

1:11

uh, less capability for advanced imaging.

1:13

Uh, but some of these are self shielded, right?

1:15

So they can actually be on the floor, uh,

1:17

in the nicu, right?

1:18

And, um, even if they have some lines

1:20

and tubes, they may still be, um, safe enough to not,

1:24

you know, deviate within the scanner.

1:25

But obviously you need to, uh, work

1:27

with your MRI safety people and do testing and all of this

1:30

because, uh, these are more non-standard devices.

1:32

But the idea is that if you're not sta the baby's not stable

1:34

enough to be taken all the way down to radiology.

1:37

And MRI, some of these units are kind of more point of care

1:40

and may allow for, for more, uh, realtime scanning.

1:44

Um, and then obviously devices, if they have support lines

1:47

and things like ECMO is a big no-no, right?

1:49

You have a lot of deviation in the, in the vessel and stuff.

1:53

Uh, but some of the other lines

1:54

and tubes depending on, uh, screening

1:56

and compatibility, you know,

1:57

gold EEG leads can be scanned, uh, in MR mri.

2:00

So, uh, it just depends on what they have

2:02

and whether those things can be taken out

2:04

or switched out for MRI compatible or conditional ones.

2:07

And then what sequences are you just doing like a basic

2:10

screening and rule out, uh,

2:11

or you're looking for high level migrational anomalies,

2:14

you know that you need like that really good, uh,

2:16

good advanced imaging.

2:18

You wanna run some advanced sequences.

2:20

So again, that all kind of relates back to sedation,

2:22

anesthesia, and then contrast again,

2:25

like a gadolinium deposition in children.

2:27

Even the macrocyclic agents have a little bit of that,

2:29

and the babies have a very

2:31

immature blood brainin barrier, right?

2:33

So we don't know what the long-term effects are.

2:34

So typically we are not gonna give contrast

2:36

unless there's a tumor or infection, uh, concern, right?

2:40

And then of course, in those cases,

2:41

you can, um, and then timing.

2:43

So that's the kind of the biggest pitfall, right?

2:45

Is that the, the findings

2:47

of the neonatal brain imaging depend very much on the timing

2:51

after birth or after the insult.

2:54

So, um, some places, uh,

2:55

not too many a minority do immediate imaging within the

2:58

first one, one or two days after birth.

3:00

The reason that a lot of places don't do this is

3:02

because I'll get to it later,

3:03

but, uh, they often will do cooling

3:05

or other, you know, uh, supportive therapies.

3:07

And so that kind of gets the baby outta circulation

3:09

for MRI compatibility.

3:11

So, uh, there are places that do early scans, uh,

3:14

within the first, let's say three to five days.

3:16

There are places that do later scans within the first,

3:19

like one or two plus weeks, right?

3:22

Or at the time of discharge, some do both.

3:24

Uh, and then of course, follow up

3:26

after discharge when the, when the, uh, baby's older.

3:30

And, uh, each of these has pros and cons, right?

3:32

So it's actually incredibly heterogeneous practice

3:35

variations across the country and across the world.

3:38

And so I'm gonna just talk about all

3:39

of the different possibilities kind of at a high level.

3:42

Um, but if you look at, uh, the major, um, you know,

3:46

clinical trials and, uh, landmark publications, most

3:48

of them are talking about either early and or late imaging

3:50

and comparing the two, okay?

3:53

So normal myelination, we have to know about normal

3:55

before we can diagnose a abnormal.

3:57

So I talked about this a little bit in that other slide,

3:59

but essentially myelination happens starting in the fifth,

4:02

about the fifth fetal month.

4:04

Um, and it starts in the peripheral nervous system,

4:05

and then it goes, um, in kind of, um, stereotype direction.

4:09

So it'll actually, uh, go up from inferior to disappear.

4:11

So we will go from the peripheral

4:13

to the spinal cord brainstem, right?

4:15

Brain stem cerebellum, and then starts to get into, uh,

4:18

the super tentorial just at the time of birth.

4:21

It tends to go from central to peripheral, right?

4:23

And then also generally speaking, posterior to anterior, uh,

4:26

so that the frontal lobes,

4:28

the executive areas myelinate last,

4:29

but also the eloquent tracts while myelinate earlier.

4:32

So like I said, those corticospinal tracts

4:34

and the, the clicks, um,

4:36

visual cortex sensor motor cortex areas

4:38

that you really need to use, right?

4:39

The babies are gonna mature those faster.

4:42

Um, and so myelin is fat and protein, right?

4:45

So again, at birth, right, you just have the clicks

4:47

that are involved, T one bright, T two dark,

4:49

and then over time.

4:52

So by, uh,

4:53

there's a saying T one at one T two at two, right?

4:56

So the idea is that by one year

4:58

of H you have essentially inverted the contrast.

5:01

So you have enough male island on board

5:02

to have white matter being white, uh, on the T one,

5:06

just like you'd seen an adult,

5:07

even though it's not complete yet.

5:09

And then it takes another year.

5:10

So about two years of age where you actually get the,

5:13

the full, uh, T two hypo, uh, intensity out

5:16

to the periphery, uh, to have the kind of adult pattern.

5:19

So you can date, you know, myelination on T one up

5:22

to one year of age, and then T two up to two,

5:24

assuming they don't have some kind of genetic or epilepsy

5:27

or something that would slow myelination, um, flare.

5:31

So that's kind of like macroscopic suppression of fluid.

5:34

And so when you have intra myelin edema

5:36

that you're looking at, so the why is it T two dark?

5:38

Basically you're forcing out as you mil it,

5:40

you force out the free water

5:41

between the layers of the myelin sheet.

5:43

So it looks dark on T two.

5:45

Um, but flares looking more like

5:47

macroscopic collections, right?

5:49

So the picture is actually very confusing in

5:52

neonates in young children.

5:53

And so, um, I can always tell if a place is like a serious

5:57

Children's hospital by whether they ran flare on kids less

6:00

than two or three years of age, it's just not helpful.

6:02

Um, in most cases, maybe like tumor infection if you wanted

6:05

to do a post contrast flare to look at, you know,

6:07

superimposed edema, leptomeningeal disease.

6:09

But in general, like doing a pre contrast flare in young

6:13

children really, uh, is, is kind of a waste

6:15

and can actually cause more confusion.