The MRI two-perfusion IVIM model improves understanding of SARS-CoV-2 virus impact on placental tissue

Introduction: Diffusion-weighted imaging (DWI) has been adopted to study placentas of women infected by SARS-CoV-2, highlighting the microstructural deterioration of the tissues using the Intravoxel Incoherent Motion model (IVIM). However, unlike the results obtained on placental histology, no perfusion impairment was observed. We used the Two-perfusion IVIM model to investigate the placenta's perfusion compartments. Methods: DWIs of n = 12 patients affected by SARS-CoV-2 and n = 20 gestational age-matched pre-pandemic healthy subjects were acquired at 1.5 T scanner with 10 b values. The maternal and fetal placentae were investigated. Differences in the two groups were evaluated using Welch’s t test. Results: The placental fetal side showed higher values of D and lower values of f2 (relative to the trophoblast compartment) in SARS-CoV-2 patients. D2* was higher on the maternal side of SARS-CoV-2 patients. Discussion: Higher values of D reflect damage to the tissue, while the lower f2 parameter suggested an impairment of the exchange between mother and fetus. The higher values of D2* in the maternal side of SARS-CoV-2 placentas may be due to a decreased capillaries’ size caused by the infiltration of lymphocytes in the decidua basalis. These results further confirm the potential of the two-perfusion IVIM model in detecting placental dysfunction.