Evaluating Fetoplacental Response to Hypercapnia in Pregnant Rats: A comparison between T2* MRI and Photoacoustic Imaging

Motivation: T2* MRI and photoacoustic imaging (PAI) offer non-invasive oxygenation measures, but their comparative effectiveness for placental study remains untested. Goal(s): Our goal was to directly compare T2* MRI and PAI's ability and effectiveness to assess placental and fetal organ oxygenation responses under normoxic hypercapnia challenge. Approach: Using pregnant rats, the study involved sequential scans of fetoplacental units with T2* MRI and PAI under normoxic hypercapnia challenge. Results: We found discrepancies between MRI and PAI in detecting oxygenation changes. MRI displayed a marked response in placental oxygenation, not as prominently reflected in PAI measurements. Impact: T2* MRI could accurately captures fetoplacental responses to hypercapnia, outperforming photoacoustic imaging. Investigating this performance gap is essential before combining these techniques in preeclampsia and fetal growth restriction studies.