Photoacoustic and high-frequency power Doppler ultrasound biomicroscopy: a comparative study.
Both photoacoustic imaging and power Doppler ultrasound are capable of producing images of the vasculature of living subjects, however, the contrast mechanisms of the two modalities are very different. We present a quantitative and objective comparison of the two methods using phantom data, highlighting relative merits and shortcomings. An imaging system for combined photoacoustic and high-frequency power Doppler ultrasound microscopy is presented. This system uses a swept-scan 25-MHz ultrasound transducer with confocal dark-field laser illumination optics. A pulse-sequencer enables ultrasonic and laser pulses to be interlaced so that photoacoustic and power Doppler ultrasound images can be coregistered. Experiments are performed on flow phantoms with various combinations of vessel size, flow velocity, and optical wavelength. For the task of blood volume detection, power Doppler is seen to be advantageous for large vessels and high flow speeds. For small vessels with low flow speeds, photoacoustic imaging is seen to be more effective than power Doppler at the detection of blood as quantified by receiver operating characteristic analysis. A combination of the two modes could provide improved estimates of fractional blood volume in comparison with either mode used alone.
University of Alberta, Department of Electrical and Computer Engineering, Edmonton, Alberta T6G 2V4, Canada. yjiang5@ualberta.ca
Yan
Y
Jiang
Tyler
T
Harrison
Janaka
J
Ranasinghesagara
Roger J
RJ
Zemp
D001783:Blood Flow Velocity; D001808:Blood Vessels / Q000000981:diagnostic imaging; D018056:Hemorheology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D017078:Laser-Doppler Flowmetry / Q000379:methods / Q000706:statistics & numerical data; D033401:Microscopy, Acoustic / Q000379:methods* / Q000706:statistics & numerical data; D055620:Optical Phenomena; D019047:Phantoms, Imaging; D012372:ROC Curve; D012815:Signal Processing, Computer-Assisted