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MR Based Blood Oxygen Level Dependent (BOLD) and Intravoxel Incoherent Motion (IVIM) Imaging of the Human Placenta

Y Zhou1*, Y Le1 , R Kedar2 , A Odibo3 , (1)Department of Radiology, Mayo Clinic at Arizona, Phoenix, AZ, United States (2) Department of Radiology, University of South Florida, Tampa, FL, United States,(3) Department of Obstetrics & Gynecology, University of South Florida, Tampa, FL, United States

Presentations

(Sunday, 7/14/2019) 2:00 PM - 3:00 PM

Room: 221CD

Purpose: The goal of this study was to implement MRI based blood oxygen level dependent (BOLD) and intravoxel incoherent motion (IVIM) techniques to study the perfusion fraction, diffusion coefficient, pseudo diffusion coefficient, and local variations in oxygenation in the human placenta.

Methods: 5 singleton pregnancies between 30 and 36 weeks gestational age (mean 34.2, range 31.7-35.5, SD of 1.5) were included in the study. All the subjects were scanned while breathing air followed by pure medical oxygen at a flow rate of 15 L/min with a face-mask. The IVIM sequence used in this study was a standard diffusion weighted spin echo EPI sequence with 10 different b values acquired the whole placenta volume. The BOLD acquisition protocol consisted of a multi-echo GRE sequence with 16 echoes. Maps of diffusion coefficient & pseudo diffusion coefficient, and T2* map were generated using the multi-b DWI and multi-echo GRE images. The changes of T2* between air-on and pure oxygen-on were derived. Also, diffusion coefficient, pseudo diffusion coefficient were calculated on a selected ROI in the normal placental area.

Results: The mean value of T2* change (ΔT2*),across all subjects was about 14.6 ms between normoxia and hyperoxia. The diffusion coefficient, pseudo diffusion coefficient values are 0.00142 mm2/s and 0.0184 mm2/s, respectively. There were no strong correlations between the change of T2 star and gestational age, diffusion coefficient and gestational age, and pseudo diffusion coefficient and gestational age.

Conclusion: BOLD MRI is a technology that can detect local variations in oxygenation using hemoglobin as an endogenous contrast agent. Also, IVIM has been demonstrated as a sensitive method of measuring blood movement in the placental intervillous spaces. Our studies demonstrating no change in ΔT2*, D, and D* with gestational age in normal placental area are consistent with previous results.

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