Placental baseline conditions modulate the hyperoxic BOLD-MRI response

3D mapping of the placenta during early gestation using free‐breathing multiecho stack‐of‐radial MRI at 3T

“…One previous study found significantly higher placental T * 2 for normal pregnancies versus IUGR pregnancies. 12 Another study showed an improvement in the receiver operating characteristic curve using T * 2 mapping for the detection of IUGR, compared to the uterine artery pulsatility index. 10 Based on these studies, we expected a higher R * 2 to be associated with hypoxia, but in one preeclampsia subject whom we studied, a lower mean placental R * 2 compared to normal subjects was observed.…”

“…2 In addition, most investigations of R * 2 or T * 2 mapping in the placenta were performed using 1.5T MRI. [9][10][11][12] Some of these studies showed a significant decrease in nominal placental T * 2 as GA increased 9,10,12 but in one study quantifying R * 2 , this trend was not significant. 11 Compared to 1.5T, 3T MRI may provide higher sensitivity to changes in R * 2 for detecting IPD.…”

“…Thus, R * 2 is higher (or T * 2 is lower) in hypoxic tissues than in normoxic tissues. [9][10][11][12] Despite the potential of MRI as a diagnostic tool to detect IPD via R * 2 mapping, there is limited understanding of the range of placental R * 2 across gestational age (GA), within the structure of the placenta, and among normal and abnormal pregnancies.…”

“…Previous investigations of R * 2 or T * 2 mapping in the placenta have been performed typically at later GAs from 20-40 weeks using a 2D breath-hold (BH) Cartesian R * 2 mapping technique [9][10][11] ; with only one very recent study including earlier GAs of 16-40 weeks. 12 If IPD is detected at later GA, intervention may not be possible or may have limited effectiveness. 2 In addition, most investigations of R * 2 or T * 2 mapping in the placenta were performed using 1.5T MRI.…”

“…[9][10][11][12] However, in pregnant patients involuntary motion can occur during the scan, such as uterine contractions and fetal motion. 11,12,15,16 In addition, a BH may not be possible for all patients, such as sick or mentally impaired patients. Even for patients who can perform a BH, requiring a BH may reduce patient comfort during the scan.…”