Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published April 2015 | Published
Journal Article Open

Ultrasonic-heating-encoded photoacoustic tomography with virtually augmented detection view


Photoacoustic (PA) imaging of arbitrarily shaped or oriented objects may miss important features because PA waves propagate normal to structure boundaries and may miss the acoustic detectors when the detection view has a limited angular range. To overcome this long-standing problem, we present an ultrasonic thermal encoding approach that is universally applicable. We exploit the temperature dependence of the Grueneisen parameter and encode a voxel using heat generated by a focused ultrasonic transducer. The PA amplitude from the encoded voxel is increased while those from the neighboring voxels are unchanged. Consequently, the amplitude-increased PA waves propagate in all directions due to the round cross section of the encoded region and thus can be received at any viewing angle on the cross-sectional plane. We built a mathematical model for the thermally encoded PA tomography, performed a numerical simulation, and experimentally validated the ultrasonic thermal encoding efficiency. As a proof of concept, we demonstrate full-view in vivo vascular imaging and compare it to the original linear-array PA tomography system, showing dramatically enhanced imaging of arbitrarily oriented blood vessels. Since ultrasonic heating can be focused deeply, this method can be applied to deep tissue imaging and is promising for full-view imaging of other features of biomedical interest, such as tumor margins.

Additional Information

© 2015 Optical Society of America. Received 12 September 2014; revised 9 February 2015; accepted 10 February 2015 (Doc. ID 223019); published 30 March 2015. The authors appreciate Prof. James Ballard's help with editing the manuscript. This work was sponsored by National Institutes of Health (NIH) grants DP1 EB016986 (NIH Director's Pioneer Award), R01 CA186567 (NIH Director's Transformative Research Award), R01 EB016963, R01 EB010049, R01 CA159959, and S10 RR026922. L. V. W. has a financial interest in Microphotoacoustics, Inc., and Endra, Inc., which, however, did not support this work. Funding:National Institutes of Health (NIH) (DP1 EB016986, R01 CA159959, R01 CA186567, R01 EB010049, R01 EB016963, S10 RR026922).

Attached Files

Published - optica-2-4-307.pdf


Files (1.3 MB)
Name Size Download all
1.3 MB Preview Download

Additional details

August 20, 2023
October 20, 2023