0:00

This is an MRI of the abdomen and

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pelvis in a patient in the early third

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trimester of pregnancy who was referred

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from the maternal fetal medicine clinic

0:08

for an abnormal obstetric ultrasound.

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Again, we've placed our steady-state

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free precession images on the left-hand

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side of the screen and the turbo spin

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echo sequences on the right-hand side.

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We begin to see the gravid uterus and the

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fetus again with a classic T2 heterogeneous

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appearance of the myometrium in both.

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As we scroll inferiorly, we

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have not yet seen the placenta.

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It just starts to come into view here.

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And I want to point out a relatively normal

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relationship between the myometrium and

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the placenta along the superior aspect.

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And so we just see the placenta

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resting against the myometrium.

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It's relatively uniform in thickness and signal.

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And we can see a clear relationship with

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the myometrium with a thick, generous

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amount of overlying muscular tissue.

0:59

As we scroll inferiorly for this patient,

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we start to see some of those classic

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features of placenta accreta spectrum.

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Again, this placenta is low-lying,

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it's lumpy-bumpy, and in this case, we

1:12

see a lot of placental heterogeneity.

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We see very extensive and dark placental bands

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for this patient in addition to some abnormal

1:23

vascularity in the periphery of the placenta.

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Another thing that I want to point out for

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this patient is that if we keep an eye on

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the amount of T2 heterogeneous myometrium

1:34

that's overlying the placenta here.

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As we scroll inferiorly, it becomes really

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difficult to follow the myometrium and

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continue to visualize it as we reach

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these areas where the placenta is bulging

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and lobular and irregular in appearance.

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There's probably a very thin 2 to 3 millimeter

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layer of myometrium present in this patient.

1:58

And we can see that the placenta extends

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fairly far inferiorly in this patient.

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These are coronal T2-weighted images of the

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abdomen and pelvis for the same patient.

2:09

We have a cephalic presentation fetus

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and a low-lying anterior placenta,

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as we saw on the axial images.

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I think the coronal images are very

2:19

demonstrative in this case, as in pointing out

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the irregularity and the abnormal contour of

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this placenta, in addition to the parenchymal

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heterogeneity and all of the abnormal

2:30

vascularity in the periphery of this placenta.

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Again, as we try to follow the

2:36

uterine myometrium, we can trace

2:37

it very clearly, superiorly on the

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steady-state free precession images.

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But as we come inferiorly toward the

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region of this abnormal low-lying

2:46

placenta, the myometrium becomes very

2:49

thin in this region of placental bulge.

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And we see similar findings on

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the turbo spin echo sequences.

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There is marked thinning of the myometrium, and

2:59

in some places, it's difficult to see it at all.

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Finally, these are the sagittal

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steady-state free precession and

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turbo spin echo images for this patient.

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Both are T2-weighted.

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And we can see again this low-lying,

3:14

heterogeneous, lumpy, bumpy placenta

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with multiple placental bands.

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This is probably the largest one.

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There is a placental mass with overlying

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myometrial thinning and occasionally difficult

3:27

to discern the myometrium in this patient.

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The other thing that I'll point out is that in

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this patient, there is a T2 hypointense area

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that is posterior to the placenta and is sitting

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directly on top of the internal cervical os.

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We can also see this triangular area

3:46

where the placenta has separated

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from the underlying myometrium.

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And so in this patient with evidence

3:53

of placenta accreta spectrum, there's

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also a focal placental abruption with

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a fairly large retroplacental hematoma.

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This patient was also taken

4:02

for a cesarean hysterectomy

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with pathology-proven placenta increta.

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And what I'd like to point out is that on

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MRI, we are not able to reliably distinguish

4:12

placenta accreta from placenta increta.

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But what we can say is I see features

4:17

of placenta accreta spectrum without

4:20

evidence of placenta percreta.