0:01

You can guesstimate the gestational age

0:02

of your infant based on the appearance of the brain, um,

0:06

as long as it's a normal infant

0:07

with without a ational abnormality.

0:10

So, um, prior to about 24, 25 weeks of gestational age, um,

0:15

the two things we'll be able to see to help you out

0:18

to know this is an extremely premature infant

0:21

that you're imaging is number one,

0:22

you won't have your cingulate sulcus,

0:25

so along the fox you won't have any sort of soci.

0:28

The other thing is your sylvan fissure will look box-like

0:31

prior to 25 weeks of gestational age.

0:34

You can see in this 27 week gestational age infant,

0:36

our sylvan fissure starts to look like a whale's tail.

0:38

It has that sort of curved appearance, um,

0:41

unlike the boxy appearance of an extremely premature infant.

0:44

And then our cingulate sulcus starts to form as well

0:47

around 26, 27 weeks gestational age.

0:50

And as you go through gestation,

0:51

of course you get increasing.

0:53

Uh, sulfation, we can image infants through about one year

0:58

of life as long as they have an open anterior fontanel.

1:01

Of course, this is a beautiful example.

1:03

Most of the time in one year olds the anterior fontanel is

1:07

either completely closed

1:08

or very tiny, so we can't see this level of detail.

1:11

Um, most of the time this,

1:12

this infant was a former very premature infant,

1:15

so they had delayed closure of their anterior fontanel.

1:19

A reminder of one

1:21

of the big reasons why we are imaging these premature

1:23

infants is the germinal matrix.

1:25

So, uh, it bleeds

1:27

because it is, it is a super vascular area.

1:30

So the germinal matrix is a transient area of proliferation

1:34

and migration of neuronal and glial, uh, cell precursors.

1:39

Most of the hemorrhages that we see are going

1:41

to be venous in etiology,

1:43

and these images, uh, show how tiny these blood vessels are

1:47

and how vascular that area is.

1:50

Don't forget that if you are looking at a premature,

1:53

an extremely premature infant, the germinal matrix, um,

1:56

involutes posterior to anterior.

1:59

So if you have an extremely premature infant,

2:01

you will still see the germinal matrix

2:03

because it doesn't mature

2:05

and involute until 34 weeks gestational age.

2:08

So this white arrow is showing you the germinal matrix

2:12

that is the anterior aspect right here.

2:14

Um, and we see this all the time on fetal MRI.

2:17

It is this low signal structure on a T two

2:20

weighted, um, sequence.

2:22

It parallels the caudate head, kind

2:24

of underlies the lateral ventricle.

2:26

So this is it in the axial plane.

2:28

You can see this low signal structure here in the coronal

2:31

plane and at ultrasound we can see it as well.

2:33

It is this hypo coic structure, um, paralleling the caudate

2:38

and underlying the lateral ventricle.

2:40

So this is the posterior germinal matrix.

2:43

So it's this hypo coic focus again,

2:46

paralleling your lateral ventricles symmetry is your friend.

2:50

So typically a normal germinal matrix will be hypoechoic.

2:54

You shouldn't have gular echogenic foci

2:57

within the germinal matrix.

2:59

We traditionally think of germinal matrix hemorrhages

3:01

as occurring at the coth thalamic groove.

3:04

But if you have an extremely premature infant

3:07

who still has a posterior germinal matrix,

3:10

you can also get germinal matrix hemorrhages at the

3:13

posterior germinal matrix.

3:15

So be sure to look both anteriorly and posteriorly.