Our major emphasis in imaging is three-fold. First, we have developed a rapid neuroimaging protocol to study oxygen saturation in the fetal brain and susceptibility weighted imaging of the fetal brain. Second, we are evaluating the entire vascular system of the placenta from the mother’s side to the fetus via the umbilical cord. Third, we are developing other novel imaging methods to study the fetus and fetal brain.

Our goal is to create 3D images mapping the iliac, uterine, arcuate,  radial and spiral arteries on the mother’s side to the stem, chorionic and umbilical vessels on the fetal side. We plan to study vascular function by examining both flow and oxygenation levels in the maternal, placental, umbilical, and fetal vessels to evaluate fetal development and to assess intrauterine growth restriction. We display below some of this work in reverse chronological order.

1) Mapping Placental Abnormalities in Intrauterine Growth Restriction

Feifei Qu, Hernandez-Andrade Edgar, Marin-Concha Julio, Swati Mody, Pavan Jella, Roberto Romero, and E Mark Haacke. Relationship between Placenta T2* and Gestational Age at 3.0 T. 2020 ISMRM (2569)

(Submitted to European Radiology).

• In this study, we collected T2* maps for both healthy pregnancy (appropriate for gestational age) and pregnancy complicated by fetal growth restriction at different gestational ages at 3T.
• The experiments were performed on 11 healthy controls and 4 fetal growth restriction patients.
• We found that the fetal growth restriction cases had regions of abnormally low signal in T2W, T2*W, and T2* map data (Figures 1)
• Placental T2* values were higher in appropriate for gestational age versus fetal growth restriction cases with a similar gestational age as expected (Figure 2).
• The placental T2* value of appropriate for gestational age cases linearly decreased with gestational age (Figure 2).
• This abnormal loss of signal is likely a result of an increase in deoxyhemoglobin in placental blood over time.

2) Mapping the Vasculature of the Placenta

Feifei Qu, Taotao Sun, Sanjay Patwardhan, Manasi Patwardhan, Sunil Jaiman, Pavan Jella, Swati Mody, Julio Marin-Concha, Ling Jiang, Zhaoxia Qian, Brijesh Kumar Yadav, Roberto Romero, E. Mark Haacke. Magnetic Resonance Angiography and T2* Mapping of Placenta. 2020SPR(106).

• In this study, we acquired magnetic resonance (MR) angiograms and T2* maps to evaluate placental vasculature and oxygenation.
• The experiments were performed on two subjects.
• For both subjects, the MR angiograms of the entire placenta were well displayed (Figure 3). It is easy to identify the umbilical vessels, chorionic vessels, and stem vessels.
• The umbilical vein can be distinguished from umbilical arteries for Subject A. Chorionic vessels and stem vessels can be identified for both subjects in the target cotyledons.
• This study sheds light on estimating in vivo placental vasculature and oxygenation.

3) Mapping T2* of Fetal Liver

Marin-Concha Julio, Feifei Qu, Hernandez-Andrade Edgar, Pavan Jella, Swati Mody, Karthikeyan Subramanian, Kiarash Ghassaban, Roberto Romero, and E Mark Haacke. Fetal Liver T2* Values using 3.0 T MRI. 2020SPR (SCI-006).

T2* can be used as a noninvasive means to study fetal liver iron content. In this study, we evaluated prenatal fetal liver T2* at 3T. This data could provide a quantitative standard reference value for the assessment of chronic fetal liver conditions. The experiments were performed on 8 singleton pregnant women without chronic disease. No significant variation between gestational ages was found.

4) Fetal blood oxygenation levels and perfusion

Brijesh Kumar Yadav, Sagar Buch, Uday Krishnamurthy, Pavan Jella, Edgar Hernandez-Andrade, Anabela Trifan, Lami Yeo, Sonia S. Hassan, E. Mark Haacke, Roberto Romero, and Jaladhar Neelavalli. Quantitative susceptibility mapping in the human fetus to measure blood oxygenation in the superior sagittal sinus. European Radiology 29, no. 4 (2019): 2017-2026.

• In these studies, we used quantitative susceptibility mapping at 3T in the human fetus to evaluate the oxygenation (S_vO₂) of cerebral venous blood in vivo.
• Twenty-one healthy pregnant subjects were recruited in the study.
• S_vO₂ was measured in the superior sagittal sinus (Figure 4).
• The average susceptibility in the superior sagittal sinus quantified across all gestational ages was 0.42 ± 0.03 ppm and the average putative S_vO₂ in the superior sagittal sinus  across all the fetuses was 67% ± 7%.

Brijesh Yadav, Edgar  Hernández-Andrade, Uday   Krishnamurthy, Sagar  Buch, Pavan  Jella, Anabela  Trifan, Lami   Yeo, Sonia S Hassan, E. Mark  Haacke, and Roberto  Romero. Dual-imaging modality approach to evaluate cerebral hemodynamics in growth-restricted fetuses: oxygenation and perfusion.  Fetal Diagnosis and Therapy. 2020;47(2):145-55.

Oxygen saturation was measured using quantitative susceptibility mapping and blood perfusion by power Doppler ultrasound (PDU) and fractional moving blood volume (FMBV) of the frontal lobe. We studied 33 healthy fetuses and 10 abnormal fetuses with fetal growth restriction. S_vO₂ decreased in healthy controls and increased in fetal growth restriction fetuses as FMBV increased (Figure 5).

5) Mapping the Vasculature of the Fetus

Jaladhar Neelavalli, Uday Krishnamurthy, Pavan Jella, Swati Mody, Brijesh Yadav, Kelly Hendershot, Edgar Hernandez-Andrade, Lami Yeo, Maria Cabrera, E Mark Haacke, Sonia Hassan and Roberto Romero.. Magnetic resonance angiography of fetal vasculature at 3.0 T. European radiology. 2016:26(12): 4570-4576.

• In this study, we acquired MR angiograms of fetal vasculature without contrast at 3T.
• The experiments were performed on five healthy subjects
• The great vessels of the fetal heart were clearly visualized (Figure 6b).
• Fetal neck vessels, the common carotids arising from the subclavian branches of the aorta, the internal carotids joining to form the circle of Willis, the transverse sinus, jugular veins, and the vertebral arteries joining to form the basilar artery were also clearly visualized (Figure 6c and Figure 6d).

This study reports the feasibility of using an appropriately modified clinical time-of-flight MRI sequence for non-contrast angiography of the human fetal vessels at 3.0 T.