Diffusion-Weighted MRI of the placenta in normal pregnancies and in pregnancies complicated by Fetal Growth Restriction

Haals, Caroline Frederike

5. Term (Master thesis)

Medicine, Master

2015

2015-12-21

59

Formål: At vurdere moderkagens apparente diffusionskoefficient (ADC) målt med diffusionvægtet MR (DWI) i normale graviditeter og graviditeter med føtal væksthæmning (FGR, hvor barnet vokser for lidt i livmoderen). Metode: Vi gennemgik retrospektivt 1,5T MR-skanninger af moderkagen fra 38 enkeltgraviditeter. I DWI-sekvensen (b-værdier 200, 400 og 1000 s/mm2) blev interesseområder tegnet, så fem snit dækkede hele moderkagen, og et gennemsnitligt ADC blev beregnet. I graviditeter med nyfødt fødselsvægt ≥ 2,3-percentilen blev sammenhængen mellem ADC og gestationsalder ved MR estimeret med lineær regression. I FGR-forløb blev ADC z-scorer beregnet i forhold til normalområdet. Resultater: 31 graviditeter (20–37 uger) endte med nyfødte ≥ 2,3-percentilen. Her lå moderkagens ADC mellem 1,33 og 1,76 x10-3 mm2/s og var omvendt korreleret med gestationsalderen (p=0,001). I syv FGR-graviditeter (27–37 uger) lå ADC z-scorer mellem 1,10 og -2,80; i tre tilfælde var ADC tydeligt nedsat, mens det i fire lå inden for normalområdet. Konklusion: I normale graviditeter falder moderkagens ADC med stigende gestationsalder. Ved FGR påvirker forandringer i den svigtende moderkage ikke ADC-værdien konsekvent.

Objective: To evaluate placental apparent diffusion coefficient (ADC) values measured by diffusion-weighted imaging (DWI) in uncomplicated pregnancies and in pregnancies with fetal growth restriction (FGR, when the baby grows too little in the womb). Methods: We retrospectively reviewed 1.5T placental MRI from 38 singleton pregnancies. On the DWI sequence (b-values 200, 400, and 1000 s/mm2), regions of interest were drawn to cover the whole placenta across five slices, and a mean ADC was calculated. In pregnancies delivering neonates ≥ 2.3rd percentile, the relationship between ADC and gestational age at MRI was assessed with linear regression. In FGR pregnancies, ADC z-scores were calculated relative to the normal range. Results: Thirty-one pregnancies (20–37 weeks) resulted in neonates ≥ 2.3rd percentile. In these, placental ADC ranged from 1.33 to 1.76 x10-3 mm2/s and showed a significant inverse correlation with gestational age (p=0.001). In seven FGR pregnancies (27–37 weeks), ADC z-scores ranged from 1.10 to -2.80; in three cases ADC was markedly reduced, while in four it was within the normal range. Conclusion: In normal pregnancy, placental ADC decreases as gestation advances. In FGR, placental abnormalities did not consistently affect ADC values.

[This abstract was generated with the help of AI]

Download
View record in AAU Student Projects