Image quality improvement based on inter-frame motion compensation for photoacoustic imaging: A preliminary study

Photoacoustic imaging (PAI) is capable of providing real-time anatomical and functional information of pathological changes. In PAI, the frame averaging (FA) technique is commonly used for enhancing signal-to-noise ratio (SNR) instead of increasing the power of a pulsed laser to avoid unwanted adverse effects. However, the FA technique suffers from motion artifacts due to the limited pulse repetition frequencies (PRFs) (e.g., 10-20 Hz) of a commonly-used Nd:Yag laser. In this paper, to improve the image quality of PAI, a new FA technique combined with inter-frame motion compensation (i.e., FA-IFMC) is proposed. The RF data acquisition was conducted with a commercial ultrasound imaging system (Ultrasonix Inc., Vancouver, BC, Canada) for the 0.9-mm diameter graphite lead-injected chicken breast. For the laser excitation, a Surelite Nd:YAG OPO system (Continuum Inc., Santa Clara, CA, USA) was used at the rate of 10 Hz and at the wavelength of 700nm with a bifurcated fiber bundle. From the phantom experiment, peak signal-to-noise ratio (PSNR) and the axial resolution were improved by 15.8 dB and 1.06 mm compared to the conventional FA method, respectively. These results indicate that the suggested FA-IFMC method can improve image quality of PAI by enhancing PSNR and axial resolution due to the lowerd blurring artifacts from motions.