The effect of maternal hyperoxygenation on placental perfusion in normal and Fetal Growth Restricted pregnancies using Intravoxel Incoherent Motion

Purpose: To evaluate the effect of maternal hyperoxygenation on placental perfusion in normal and Fetal Growth Restricted (FGR) pregnancies using Intravoxel Incoherent Motion (IVIM). Methods: Ten FGR pregnancies and twenty-five normal pregnancies underwent IVIM examinations before and after maternal hyperoxygenation (95% O-2, 5% CO2) using a 1.5T MR scanner. The IVIM parameters (f(p), D-t, D-p) were determined for the placentas of both groups. The IVIM parameters within and between groups and their correlations with Doppler findings were statistically analyzed. ROC analysis was performed to evaluate the diagnostic power of IVIM derived parameters. Results: Before maternal hyperoxygenation, the perfusion fraction f(p) was significantly lower in the FGR group than that in the normal group ((%) vs. 36.28 +/- 9.70 (%), p = 0.000). After maternal hyperoxygenation, f(p) decreased significantly in the normal group (36.28 +/- 9.70 (%) vs. 29.93 +/- 10.25 (%), p = 0.032), whereas it remained relatively stable in the FGR group ((%) vs. 24.38 +/- 13.67 (%), p = 0.508). An increase of D-t was found only for the normal group and D-p did not changed significantly after maternal hyperoxygenation. There existed a negative correlation between f(p pre) and umbilical artery pulsatility index (PI) (r = -0.385, p < 0.05) as well as D-t post and PI (r = -0.574, p < 0.01). The f(p pre) displayed a best diagnostic power of all parameters with the area under curve (AUC) of 0.912. Conclusion: The perfusion fraction, f(p), is able to distinguish FGR from normal pregnancies by its value pre and by its change (or lack thereof) post maternal hyperoxygenation. IVIM may potentially help improve the diagnosis of placenta function as it relates to disease.