Assessment of Apparent Diffusion Coefficient and Perfusion Values of the Placenta in Intrauterine Growth Restriction by Using 3Tesla Magnetic Resonance Imaging (MRI) in an Indian Population: A Pilot Study.

BACKGROUND

Intrauterine growth restriction (IUGR) is defined as an estimated fetal weight below the 10th percentile for gestational age and is commonly associated with placental insufficiency and abnormal fetoplacental oxygenation. This study aimed to assess placental apparent diffusion coefficient (ADC) and perfusion values in IUGR using 3T magnetic resonance imaging (MRI).

METHODS

Sixty pregnant women (30 with IUGR and 30 controls; gestational age 20-38 weeks) underwent placental MRI on a 3T system. The imaging protocol included T2-weighted anatomical sequences, diffusion-weighted imaging (b-values: 0 and 700 s/mm2; NEX = 3), and three-dimensional pseudo-continuous arterial spin labeling (3D pCASL) perfusion imaging (TR/TE = 5000/50 ms, labeling duration = 1500 ms, post-labeling delay = 1525 ms, 30 label/control pairs). ADC and perfusion maps were generated, and multiple elliptical regions of interest (ROIs; 40-60 mm2) were placed throughout the placenta. Mean values were calculated for each subject.

RESULTS

Mean placental perfusion was significantly lower in the IUGR group compared with controls (102.5 ± 18.7 vs. 120.2 ± 23.7 ml/100 g/min, p = 0.002). ADC values were also significantly reduced in IUGR placentas (1.83 ± 0.10 × 10-3 mm2/s vs. 2.02 ± 0.10 × 10-3 mm2/s, p = 0.001). Receiver operating characteristic (ROC) analysis demonstrated fair diagnostic performance for perfusion (AUC = 0.703) and excellent performance for ADC (AUC = 0.919).

CONCLUSION

Both placental ADC and perfusion values were reduced in IUGR. However, because ADC is influenced by perfusion bias, the most clinically relevant finding is the direct quantification of reduced placental perfusion using 3D pCASL at 3T. This technique provides absolute perfusion values in physiological units and may serve as a valuable non-invasive biomarker of placental dysfunction in IUGR.