Super-Resolution Photoacoustic Microscopy via Modified Phase Compounding

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)3411-3420
Journal / PublicationIEEE Transactions on Medical Imaging
Issue number11
Online published21 Jun 2022
Publication statusPublished - Nov 2022


Acoustic-resolution photoacoustic microscopy (AR-PAM) system can provide 3-D images of facial tissues. The lateral resolution of AR-PAM depends on the numerical aperture (NA) of the acoustic lens and the central frequency of the ultrasonic transducer. There is a trade-off between resolution enhancement and imaging depth. The acoustic beam is tight in the acoustic focal plane but expands in the out-of-focus regions, deteriorating the resolution. High-NA AR-PAM has depth-variant resolution. Synthetic aperture focusing technique (SAFT) based on a virtual detector (VD) concept can compensate for the beam shape and improve the lateral resolution via beamforming. Although, beamforming can enhance the resolution but the lateral resolution in the focal plane is still limited by acoustic diffraction. Structured-illumination can shift the spatial spectrum of an image to low frequencies hence high-frequency contents can be reserved to overcome the diffraction limit. Conventional structured-illumination via using a three-phase-shifting method can improve the resolution by two folds. Here, a modified phase-shifting method is used to generate the second harmonic of the fringes and double the spectral shift. In this idea, higher frequency information compared to the three-phase shifting method can fall into the band-limited system response. The modified phase-shifting method expands the spatial bandwidth and increases the lateral resolution by five folds. The mathematical relations and the theory are discussed in the context. Tungsten filament result shows resolution improvement from 44.6 μm to 11.3 μm by the modified structured illumination. In vivo and ex vivo experimental results validate the system performance.

Research Area(s)

  • Acoustic beams, Diffraction, Fourier-domain reconstruction, Image resolution, Imaging, modified phase compounding method, Optical diffraction, second harmonic, Signal resolution, Spatial resolution, structured-illumination, super-resolution, synthetic aperture focusing technique, virtual detector, volumetric photoacoustic microscopy

Citation Format(s)

Super-Resolution Photoacoustic Microscopy via Modified Phase Compounding. / Amjadian, Mohammadreza; Mostafavi, Seyed Masood; Chen, Jiangbo et al.
In: IEEE Transactions on Medical Imaging, Vol. 41, No. 11, 11.2022, p. 3411-3420.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review