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This is an MRI of the abdomen and pelvis

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in a patient who presented at 28 weeks

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gestation after having an abnormal ultrasound

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in the maternal-fetal medicine clinic.

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There was suspicion raised for placenta

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accreta spectrum on the ultrasound,

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and the MRI was ordered for further

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clarification of the placental anatomy.

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We have axial T2-weighted images of the pelvis.

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These are steady-state free precession,

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and these are turbospin echo images.

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As we scroll inferiorly, we begin to

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see the gravid uterus and we can clearly

0:34

see the heterogeneous myometrium, which

0:38

is indicative of the uterine wall.

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Notice the difference in the appearance of

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the myometrium between these two sequences.

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On the turbospin echo, the myometrium

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will look much brighter on the T2

0:51

weighted sequences than it does on the

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steady-state free precession images.

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As we scroll inferiorly, we

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begin to see the placenta.

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And, if you recall the normal pregnancy

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MRI case that we looked at earlier,

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some of the features that are present in

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that case of a normal placenta include

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homogeneous signal, relatively uniform

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thickness, and intact overlying myometrium.

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As we evaluate this placenta, one

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of the first things that I notice

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about it is that it's low-lying.

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We're down here near the level

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of the bladder and the cervix.

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And we can see that we are encountering

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a lot of placental tissue in this region.

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So this is all placenta here.

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This is all placenta in these images as well.

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Another feature that I'd like

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to point out about this placenta is

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the relative heterogeneity of it.

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You can see some increased placental

1:47

heterogeneity, particularly in the

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third trimester of pregnancy, but

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it should not be to this degree.

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A feature that's present here is this

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wedge-shaped area of T2 hypointensity,

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which we can identify on both sequences.

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This is what's known as a placental band.

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These are thought to be areas of fibrous

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change within the placenta at sites of infarct

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or hemorrhage, and they're a reflection of

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the abnormal microvascular environment in

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patients with placenta accreta spectrum.

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Another feature of this placenta

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is that it has rounded contours

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and it's not uniform in thickness.

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It has sort of a lumpy, bumpy appearance

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to it which we can really appreciate on

2:30

the steady-state free precession images.

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Next, let's look at the sagittal images

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of the placenta for this patient.

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Again, the steady-state free precession

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images are on this side, and the

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turbospin echo images are over here.

2:45

We can see that the placenta

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is low-lying for this patient.

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The patient has a marginal placenta previa,

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meaning that the placenta abuts but does not

2:54

entirely cover the internal cervical os.

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Again, this placenta is lumpy,

2:59

bumpy; it's heterogeneous.

3:01

We see a nice example of a placental

3:03

band here, and there's really a bulging

3:05

appearance of the placenta in this patient.

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In patients with suspected placenta accreta

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spectrum, it is important to trace the

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myometrium all the way around the uterus

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to determine if there is still myometrium

3:19

covering the placenta, which would exclude

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a diagnosis of placenta percreta.

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And so knowing that the myometrium has a

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T2 heterogeneous appearance, we can trace

3:30

it all the way around in this patient.

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And although it gets very thin, we can

3:35

still see a very thin T2 heterogeneous

3:39

myometrial layer in this patient.

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On the steady-state free precession images,

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again, this is T2 heterogeneous myometrium.

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And although the myometrium

3:48

is thin, it is still intact.

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Lastly, these are coronal T2-weighted

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images of the placenta in this patient.

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In this plane, we again see features of placenta

4:00

accreta spectrum, including an irregular

4:02

placental contour, placental heterogeneity

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with multiple placental bands present, and a

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thin but still present intervening layer of

4:11

T2 heterogeneous myometrium for this patient.

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This patient was taken for cesarean hysterectomy

4:19

at 32 weeks gestation, and this was a

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pathology-proven case of placenta accreta.