Tissue oxygen monitoring by photoacoustic lifetime imaging (PALI) and its application to image-guided photodynamic therapy (PDT)

Qi Shao, Ekaterina Morgounova, Shai Ashkenazi

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

4 Scopus citations


The oxygen partial pressure (pO2), which results from the balance between oxygen delivery and its consumption, is a key component of the physiological state of a tissue. Images of oxygen distribution can provide essential information for identifying hypoxic tissue and optimizing cancer treatment. 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 on small animals to identify hypoxia area. We also showed that PALI is able monitor changes of tissue oxygen, in an acute ischemia and breathing modulation model. Here we present our work on developing a treatment/imaging modality (PDT-PALI) that integrates PDT and a combined ultrasound/photoacoustic imaging system. The system provides real-time feedback of three essential parameters namely: tissue oxygen, light penetration in tumor location, and distribution of photosensitizer. Tissue oxygen imaging is performed by applying PALI, which relies on photoacoustic probing of oxygen-dependent, excitation lifetime of Methylene Blue (MB) photosensitizer. Lifetime information can also be used to generate image showing the distribution of photosensitizer. The level and penetration depth of PDT illumination can be deduced from photoacoustic imaging at the same wavelength. All images will be combined with ultrasound B-mode images for anatomical reference. We expect that PDT efficacy can be improved by applying PALI imaging feedback in real-time to determine, and individually optimize, O2-enriched gas breathing parameters and PDT light-dose during treatment.

Original languageEnglish (US)
Title of host publicationPhotons Plus Ultrasound
Subtitle of host publicationImaging and Sensing 2015
EditorsAlexander A. Oraevsky, Lihong V. Wang
ISBN (Electronic)9781628414134
StatePublished - 2015
EventPhotons Plus Ultrasound: Imaging and Sensing 2015 - San Francisco, United States
Duration: Feb 8 2015Feb 10 2015

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


OtherPhotons Plus Ultrasound: Imaging and Sensing 2015
Country/TerritoryUnited States
CitySan Francisco

Bibliographical note

Publisher Copyright:
© 2015 SPIE.


  • Hypoxia
  • Photoacoustic lifetime
  • Photodynamic therapy
  • Po<inf>2</inf>
  • Tissue oxygen
  • Tumor


Dive into the research topics of 'Tissue oxygen monitoring by photoacoustic lifetime imaging (PALI) and its application to image-guided photodynamic therapy (PDT)'. Together they form a unique fingerprint.

Cite this