Improving the quality of photoacoustic images using the short-lag spatial coherence imaging technique

Pourebrahimi, Behnaz; Yoon, Sangpil; Dopsa, Dustin; Kolios, Michael C.

doi:10.1117/12.2005061

Cited by 35 publications

(24 citation statements)

References 9 publications

(10 reference statements)

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“…In addition, this beamformer was applied to in vivo ultrasound data to reduce clutter noise artifacts in cardiac [16][17][18], liver [19], thyroid [14], and vascular [15] images. Similar clutter reduction benefits were achieved when the SLSC beamformer was applied to photoacoustic data [20].…”

Section: Introductionsupporting

confidence: 52%

Short-lag spatial coherence beamforming of photoacoustic images for enhanced visualization of prostate brachytherapy seeds

Bell

Kuo

Song

et al. 2013

Biomed. Opt. Express

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Abstract:Prostate brachytherapy, administered by implanting tiny radioactive seeds to treat prostate cancer, currently relies on transrectal ultrasound imaging for intraoperative visualization of the metallic seeds. Photoacoustic (PA) imaging has been suggested as a feasible alternative to ultrasound imaging due to its superior sensitivity to metal surrounded by tissue. However, PA images suffer from poor contrast when seeds are distant from the light source. We propose a transperineal light delivery method and investigate the application of a short-lag spatial coherence (SLSC) beamformer to enhance low-contrast photoacoustic signals that are distant from this type of light source. Performance is compared to a conventional delay-and-sum beamformer. A pure gelatin phantom was implanted with black ink-coated brachytherapy seeds and the mean contrast was improved by 3-25 dB with the SLSC beamformer for fiber-seed distances ranging 0.6-6.3 cm, when approximately 10% of the receive aperture elements were included in the short-lag sum. For fiber-seed distances greater than 3-4 cm, the mean contrast-to-noise ratio (CNR) was approximately doubled with the SLSC beamformer, while mean signal-to-noise ratios (SNR) were mostly similar with both beamformers. Lateral resolution was decreased by 2 mm, but improved with larger short-lag values at the expense of poorer CNR and SNR. Similar contrast and CNR improvements were achieved with an uncoated brachytherapy seed implanted in ex vivo tissue. Results indicate that the SLSC beamformer has potential to enhance the visualization of prostate brachytherapy seeds that are distant from the light source.

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Section: Introductionsupporting

confidence: 52%

Short-lag spatial coherence beamforming of photoacoustic images for enhanced visualization of prostate brachytherapy seeds

Bell

Kuo

Song

et al. 2013

Biomed. Opt. Express

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“…16,17 The SLSC beamformer was previously applied to photoacoustic images to improve the contrast of various targets. 16,18 The DAS and SLSC beamformers were applied to the acquired data by first delaying the signals received by the transducer to account for differences in arrival time, where s i (n) represents the time-delayed signal received by the ith transducer element at sample number (or depth), n. One pixel in a DAS image was obtained by summation of all s i at a particular depth n. To apply the SLSC beamformer, the normalized spatial coherence across the receive aperture,R, and the resulting short-lag spatial coherence, R sl , was calculated as follows: 17,19 …”

Section: Beamforming Of Photoacoustic Datamentioning

confidence: 98%

Feasibility of transcranial photoacoustic imaging for interventional guidance of endonasal surgeries

et al. 2014

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Endonasal surgeries to remove pituitary tumors incur the deadly risk of carotid artery injury due to limitations with real-time visualization of blood vessels surrounded by bone. We propose to use photoacoustic imaging to overcome current limitations. Blood vessels and surrounding bone would be illuminated by an optical fiber attached to the endonasal drill, while a transducer placed on the pterional region outside of the skull acquires images. To investigate feasibility, a plastisol phantom embedded with a spherical metal target was submerged in a water tank. The target was aligned with a 1-mm optical fiber coupled to a 1064nm Nd:YAG laser. An Ultrasonix L14-5W/60 linear transducer, placed approximately 1 cm above the phantom, acquired photoacoustic and ultrasound images of the target in the presence and absence of 2-and 4-mm-thick human adult cadaveric skull specimens. Though visualized at 18 mm depth when no bone was present, the target was not detectable in ultrasound images when the 4-mm thick skull specimen was placed between the transducer and phantom. In contrast, the target was visible in photoacoustic images at depths of 17-18 mm with and without the skull specimen. To mimic a clinical scenario where cranial bone in the nasal cavity reduces optical transmission prior to drill penetration, the 2-mm-thick specimen was placed between the phantom and optical fiber, while the 4-mm specimen remained between the phantom and transducer. In this case, the target was present at depths of 15-17 mm for energies ranging 9-18 mJ. With conventional delay-and-sum beamforming, the photoacoustic signal-tonoise ratios measured 15-18 dB and the contrast measured 5-13 dB. A short-lag spatial coherence beamformer was applied to increase signal contrast by 11-27 dB with similar values for SNR at most laser energies. Results are generally promising for photoacoustic-guided endonasal surgeries.

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“…As with wavelet denoising [15, 20], SVD could also be used to reduce residual noise, for instance by performing a second truncation of the singular value matrix in which diagonal elements of the singular value matrix that are below a certain threshold are zeroed [15–17]. Examples of artifact reduction methods that have recently shown promise include localised vibration tagging [11], short-lag spatial coherence weighting [12, 21,22], and synthetic aperture PA-guided focused US [13]. …”

Section: Resultsmentioning

confidence: 99%

Identification and removal of laser-induced noise in photoacoustic imaging using singular value decomposition

Hill¹,

Xia²,

Clarkson³

et al. 2016

Biomed. Opt. Express

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Singular value decomposition (SVD) was used to identify and remove laser-induced noise in photoacoustic images acquired with a clinical ultrasound scanner. This noise, which was prominent in the radiofrequency data acquired in parallel from multiple transducer elements, was induced by the excitation light source. It was modelled by truncating the SVD matrices so that only the first few largest singular value components were retained, and subtracted prior to image reconstruction. The dependency of the signal amplitude and the number of the largest singular value components used for noise modeling was investigated for different photoacoustic source geometries. Validation was performed with simulated data and measured noise, and with photoacoustic images acquired from the human forearm and finger in vivo using L14-5/38 and L40-8/12 linear array clinical imaging probes. The use of only one singular value component was found to be sufficient to achieve near-complete removal of laser-induced noise from reconstructed images. This method has strong potential to increase image quality for a wide range of photoacoustic imaging systems with parallel data acquisition.

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Improving the quality of photoacoustic images using the short-lag spatial coherence imaging technique

Cited by 35 publications

References 9 publications

Short-lag spatial coherence beamforming of photoacoustic images for enhanced visualization of prostate brachytherapy seeds

Short-lag spatial coherence beamforming of photoacoustic images for enhanced visualization of prostate brachytherapy seeds

Feasibility of transcranial photoacoustic imaging for interventional guidance of endonasal surgeries

Identification and removal of laser-induced noise in photoacoustic imaging using singular value decomposition

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