Direct tissue oxygen monitoring by in vivo photoacoustic lifetime imaging (PALI)

Qi Shao, Ekaterina Morgounova, Shai Ashkenazi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


Tissue oxygen plays a critical role in maintaining tissue viability and in various diseases, including response to therapy. Images of oxygen distribution provide the history of tissue hypoxia and evidence of oxygen availability in the circulatory system. Currently available methods of direct measuring or imaging tissue oxygen all have significant limitations. Previously, we have reported a non-invasive in vivo imaging modality based on photoacoustic lifetime. The technique maps the excited triplet state of oxygen-sensitive dye, thus reflects the spatial and temporal distribution of tissue oxygen. We have applied PALI on tumor hypoxia in small animals, and the hypoxic region imaged by PALI is consistent with the site of the tumor imaged by ultrasound. Here, we present two studies of applying PALI to monitor changes of tissue oxygen by modulations. The first study involves an acute ischemia model using a thin thread tied around the hind limb of a normal mouse to reduce the blood flow. PALI images were acquired before, during, and after the restriction. The drop of muscle pO 2 and recovery from hypoxia due to reperfusion were observed by PALI tracking the same region. The second study modulates tissue oxygen by controlling the percentage of oxygen the mouse inhales. We demonstrate that PALI is able to reflect the change of oxygen level with respect to both hyperbaric and hypobaric conditions. We expect this technique to be very attractive for a range of clinical applications in which tissue oxygen mapping would improve therapy decision making and treatment planning.

Original languageEnglish (US)
Title of host publicationPhotons Plus Ultrasound
Subtitle of host publicationImaging and Sensing 2014
ISBN (Print)9780819498564
StatePublished - Jan 1 2014
EventPhotons Plus Ultrasound: Imaging and Sensing 2014 - San Francisco, CA, United States
Duration: Feb 2 2014Feb 5 2014


OtherPhotons Plus Ultrasound: Imaging and Sensing 2014
Country/TerritoryUnited States
CitySan Francisco, CA


  • Ischemia
  • Methylene blue
  • Photoacoustic lifetime imaging
  • Tissue oxygen
  • Tumor hypoxia


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