Function and Safety of SlowflowHD Ultrasound Doppler in Obstetrics

Lior Drukker, Richard Droste, Christos Ioannou, Lawrence Impey, J. Alison Noble, Aris T. Papageorghiou*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


SlowflowHD is a new ultrasound Doppler imaging technology that allows visualization of flow within small blood vessels. In this mode, a proprietary algorithm differentiates between low-speed flow and signals attributed to tissue motion so that microvessel vasculature can be examined. Our objectives were to describe the low-velocity Doppler mode principles, to assess the bone thermal index (TIb) safety parameter in obstetric ultrasound scans and to evaluate adherence to professional guidelines. To achieve the latter goals, we retrospectively reviewed prospectively collected ultrasound images and video clips from pregnancy ultrasound scans at >10 wk of gestation over 4 mo. We used a custom-built optical character recognition-based software to automatically identify all images and video clips using this technology and extract the TIb. Overall, a total of 185 ultrasound scans performed by three fetal medicine physicians were included, of which 60, 54 and 71 scans were first-, second- and third-trimester scans, respectively. The mean (highest recorded) TIb values were 0.32 (0.70), 0.23 (0.70) and 0.32 (0.60) in the first, second, and third trimesters, respectively. Thermal index values were within recommended values set by the World Federation for Ultrasound in Medicine and Biology American Institute of Ultrasound in Medicine and British Medical Ultrasound Society in all scans.

Original languageEnglish
Pages (from-to)1157-1162
Number of pages6
JournalUltrasound in Medicine and Biology
Issue number6
StatePublished - Jun 2022


FundersFunder number
Intelligent Ultrasound Ltd.
National Institute for Health and Care Research


    • Doppler ultrasound
    • Safety index
    • SlowflowHD
    • Superb Microvascular Imaging
    • Thermal index
    • Ultrasound safety


    Dive into the research topics of 'Function and Safety of SlowflowHD Ultrasound Doppler in Obstetrics'. Together they form a unique fingerprint.

    Cite this