The Utility of MRI for Measuring Hematocrit in Fetal Anemia

Doppler ultrasound measurements of the peak systolic velocity of the middle cerebral artery (MCA) can be used to non-invasively diagnose fetal anemia but are less precise following fetal blood transfusion and in late gestation. We have previously demonstrated the feasibility of estimating fetal hematocrit in vitro using MRI relaxation times. The objective of this thesis is to report the use of MRI as a non-invasive tool to accurately detect fetal anemia in vivo. MRI- estimated hematocrit of the umbilical vein of fetuses undergoing fetal blood sampling or transfusion was compared against MCA Doppler and fetal blood sampling measurements. Excellent correlation and low systematic bias were found between MRI and laboratory measurements. MRI had higher specificity than MCA Doppler for detecting fetal anemia. Our results suggest there may be a role for fetal MRI as an adjunct to ultrasound in fetuses with suspected anemia, particularly following previous transfusion and in late gestation.M.Sc