Amniotic Fluid and Fetal Organ Volume on MRI in Late Gestation

Bansal S.1

, Uus A. 1, Neves Silva S. 1

, Waheed H. 2

, Kyriakopoulou V.1

, Siassakos D.2, David AL.2, Chandiramani M. 1, Story L.1, Rutherford M.1

1 King’s College London , 2 University College London

Aims

1. To calculate an MRI-derived amniotic fluid volume (MR-AFV)

2. To calculate fetal lung, stomach, kidney and bladder volumes

3. To compare ultrasound amniotic fluid index (US-AFI) with MRI

amniotic fluid volume (MR-AFV)

4. To correlate MR-AFV with fetal organ volumes

Background

• US-AFI is a 2D measure of a 3D parameter

• MRI provides volume measurements from reconstructed 3D

models of amniotic fluid and fetal body organs

Method

• Pregnant women at 35-41w gestation planning vaginal birth had an

MRI for the MiBirth study (n=129)

• MRI was performed on a low field (0.55T) Freemax scanner

T2-weighted ssFSE

sequences were

reconstructed

Results

• MR-AFV is correlated with US AFI (r=0.43, p<0.001)

• MR-AFV tended to decrease with GA; this approached significance

(p=0.08)

• Total amniotic fluid volume, including

stomach and bladder volumes,

decreased with GA (r=-0.19, p=0.02)

• MR-AFV increased with fetal lung (p=0.03) and fetal body (p=0.02)

volumes

In-house networks were

trained to automatically

segment amniotic fluid,

fetal body, lungs,

stomach, kidneys and

bladder

3D models were

generated from

segmentation

and volumes

were estimated

MRI reconstruction

3D model fetus,

amniotic fluid and

placenta

3D model

amniotic fluid

• Amniotic fluid in the stomach and bladder are not accounted for in

current estimates

• A total amniotic fluid volume can be estimated by including fetal

stomach and bladder volumes to the amniotic fluid volume