Tracking contrast agents using real-time 2D photoacoustic imaging system for cardiac applications

Ragnar Olafsson, Leonardo Montilla, Pier Ingram, Russell S. Witte

Research output: Contribution to journalConference articlepeer-review

5 Scopus citations


Photoacoustic (PA) imaging is a rapidly developing imaging modality that can detect optical contrast agents with high sensitivity. While detectors in PA imaging have traditionally been single element ultrasound transducers, use of array systems is desirable because they potentially provide high frame rates to capture dynamic events, such as injection and distribution of contrast in clinical applications. We present preliminary data consisting of 40 second sequences of co-registered pulse-echo (PE) and PA images acquired simultaneously in real time using a clinical ultrasonic machine. Using a 7 MHz linear array, the scanner allowed simultaneous acquisition of inphase-quadrature (IQ) data on 64 elements at a rate limited by the illumination source (Q-switched laser at 20 Hz) with spatial resolution determined to be 0.6 mm (axial) and 0.4 mm (lateral). PA images had a signal-to-noise ratio of approximately 35 dB without averaging. The sequences captured the injection and distribution of an infrared-absorbing contrast agent into a cadaver rat heart. From these data, a perfusion time constant of 0.23 s-1 was estimated. After further refinement, the system will be tested in live animals. Ultimately, an integrated system in the clinic could facilitate inexpensive molecular screening for coronary artery disease.

Original languageEnglish (US)
Article number71771R
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
StatePublished - 2009
EventPhotons Plus Ultrasound: Imaging and Sensing 2009 - San Jose, CA, United States
Duration: Jan 25 2009Jan 28 2009


  • Contrastagents
  • Coronary heart disease
  • Molecular imaging
  • Optoacoustic
  • Perfusion imaging
  • Photoacoustic
  • Ultrasound

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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