A non-invasive tool to detect oxygenation level changes in the placenta and fetal organs; useful for detection of placental insufficiency for intra-uterine growth restriction (IUGR) cases, and for characterization of placenta share and blood transfusion between twin fetuses for twin-to-twin transfusion syndrome (TTTS) cases.
Adequate oxygen transport across the placenta from mother to fetus is critical for fetal growth and development. Currently, there is no way to directly measure placental transport to assess placental insufficiency in vivo because spatial separation of functionally heterogeneous placental regions, such as maternal blood containing intervillous space and fetal blood containing villous trees, is difficult with existing technology. Physicians primarily rely on indirect measures of umbilical artery flow by Doppler ultrasound as an indication of placental function.
This invention presents a novel blood-oxygen-level-dependent (BOLD) magnetic resonance imaging (MRI) analysis technique to characterize placental regions and placental fetal interactions. Hemoglobin in the blood changes its magnetic state when combined with oxygen and alters the MRI signal. Fetal blood ranges from 80% oxygenated in the umbilical vein to 60% oxygenated in the umbilical artery during normoxia; therefore, alternating the oxygen supply from room air (21% O2) to >90% oxygen and back to room air (a normoxic-hyperoxic-normoxic maternal oxygenation cycle) offers a large dynamic range for changes in the BOLD MRI signal. At maternal hyperoxia, maternal blood is saturated with oxygen before fetal blood. After 30 minutes of echo planar imaging BOLD acquisition in 4D, signal activities in the placenta and fetal organs are mapped by their gradients of increase and decrease in different temporal segments, showing distinct regions of oxygen uptake in the placenta especially after the first minute of increased maternal oxygenation. This spatially differentiates maternal blood containing intervillous space from fetal blood containing villous trees in placenta.
Offers a map that characterizes how placental regions respond to sudden increases in maternal oxygen
Can differentiate healthy and pathological placental tissues such as an infarct, avascular villi, and thrombosis by their differential response to oxygen exposure
Shows oxygen intake correlations between placental regions and fetal organs; helps to determine whether fetus’ oxygen supply is heavily influenced by pathological parts of the placenta and whether the placental function is sufficient for the fetus’ demand
Measures effective placenta reserve (oxygen clearance of placenta after switching oxygen back to room air)