Endocavity ultrasound and photoacoustic system for fetal and maternal imaging: Design, implementation, and ex-vivo validation

Yan Yan, Edgar Hernandez-Andrade, Maryam Basij, Suhail S. Alshahrani, Sirisha Kondle, Barrington O. Brown, Juri Gelovani, Sonia Hassan, Chaur Dong Hsu, Mohammad Mehrmohammadi

Research output: Contribution to journalArticlepeer-review


Purpose: Transvaginal ultrasound (TVUS) is a widely used real-time and non-invasive imaging technique for fetal and maternal care. It can provide structural and functional measurements about the fetal brain, such as blood vessel diameter and blood flow. However, it lacks certain biochemical estimations, such as hemoglobin oxygen saturation (SO2), which limits its ability to indicate a fetus at risk of birth asphyxia. Photoacoustic (PA) imaging has been steadily growing in recognition as a complement to ultrasound (US). Studies have shown PA imaging is capable of providing such biochemical estimations as SO2 at relatively high penetration depth (up to 30 mm). Approach: In this study, we have designed and developed a multi-modal (US, PA, and Doppler) endocavity imaging system (ECUSPA) around a commercialized TVUS probe (Philips ATL C9-5). Results: The integrated system was evaluated through a set of in-vitro, ex-vivo, and in-vivo studies. Imaging of excised sheep brain tissue demonstrated the system's utility and penetration depth in transfontanelle imaging conditions. The accuracy of using the spectroscopic PA imaging (sPA) method to estimate SO2 was validated by comparing sPA oximetry results with the gold standard measurements indicated by a blood gas analyzer. The ability of US and Doppler to measure moving blood volume was evaluated in-vivo. Spectral unmixing capabilities were tested using fluorophores within sheep brains. Conclusion: The developed system is a high resolution (about 200 μm at 30 mm depth), real-time (at 30 Hz), and quantitative (SO2 estimation error <10 %) imaging tool with a total diameter less than 30 mm, making it suitable for intrapartum applications such as fetal and maternal diagnostics.

Original languageEnglish (US)
Article number066001
JournalJournal of Medical Imaging
Issue number6
StatePublished - Nov 1 2021
Externally publishedYes


  • delivery
  • Doppler
  • endocavity
  • fetal
  • maternal
  • photoacoustic
  • ultrasound

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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