The double-stage delay-multiply-and-sum image reconstruction method improves imaging quality in a LED-based photoacoustic array scanner

Mozaffarzadeh, Moein; Hariri, Ali; Moore, Colman; Jokerst, Jesse V.

doi:10.1016/j.pacs.2018.09.001

Cited by 47 publications

(38 citation statements)

References 53 publications

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“…The application of DAS and DMAS for AR‐PAM systems has been reported before . As evaluated in References for PAI and for US imaging, DS_DMAS even outperforms DMAS, mainly in terms of noise level (and hence contrast). In this paper, we propose to combine DS_DMAS algorithm with SAFT for AR‐PAM systems.…”

Section: Methodsmentioning

confidence: 83%

“…In this work, due to the importance of vasculature, DS_DMAS algorithm has been used in an AR‐PAM system to have a higher image quality and vasculature distinguishability. Since DS_DMAS outperforms DAS and DMAS in macroscopic‐scale PAI scenarios, as demonstrated in , we expect to obtain a higher image quality with DS_DMAS in microscopic‐scale PAI systems as well. DS_DMAS is utilized as the beamformer used in SAFT to synthesize the new A‐lines.…”

Section: Introductionmentioning

confidence: 79%

“…In this paper, we propose to combine DS_DMAS algorithm with SAFT for AR‐PAM systems. The DS_DMAS beamformer is generated from the expansion of the DMAS Equation , and its formula combined with SAFT is as follows:

y_{SAFT + DS_DMAS} ((), i, t) = \frac{2}{{(2 N_{D})}^{2} - 2 N_{D}} \sum_{j = - N_{D}}^{N_{D} - 2} \sum_{k = j + 1}^{N_{D} - 1} {\overset{true˜}{italicrf}}_{jk} ((), i, t),

where

\begin{matrix} lefttrue \\ {\overset{rf}{true}}_{italicjk} (i, t) = S . \sqrt{(||,, {rf}_{j} ((), i, t) . {rf}_{k} ((), i, t))} \\ S = sign ({italicrf}_{j} (i, t) . {italicrf}_{k} (i, t)), \\ for - N_{D} \leq j < k \leq N_{D} - 1, \end{matrix}

and

{rf}_{f} ((), i, t) = \frac{1}{N_{D} - f} \sum_{k = f + 1}^{N_{D}} {\overset{true^}{RF}}_{fk} ((), i, t) .

…”

Section: Methodsmentioning

confidence: 99%

“…This algorithm was recently used in an AR‐PAM system to improve the image quality . We have previously reported an algorithm called double‐stage delay‐multiply‐and‐sum (DS_DMAS) , which outperforms DMAS in the terms of resolution and contrast.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced contrast acoustic‐resolution photoacoustic microscopy using double‐stage delay‐multiply‐and‐sum beamformer for vasculature imaging

Mozaffarzadeh

Varnosfaderani

Sharma

et al. 2019

Journal of Biophotonics

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In acoustic-resolution photoacoustic microscopy (AR-PAM) systems, the lateral resolution in the focal zone of the ultrasound (US) transducer is determined by the numerical aperture (NA) of the transducer. To have a high lateral resolution, a large NA is used. However, the larger the NA, the smaller the depth of focus [DOF]. As a result, the lateral resolution is deteriorated at depths out of the focal region. The synthetic aperture focusing technique (SAFT) along with a beamformer can be used to improve the resolution outside the focal region. In this work, for image formation in AR-PAM, we propose the double-stage delay-multiply-and-sum (DS_DMAS) algorithm to be combined with SAFT. The proposed method is evaluated experimentally using hair targets and in vivo vasculature imaging. It is shown that DS_DMAS provides a higher resolution and contrast compared to other methods. For the B-mode images obtained using the hair phantom, the proposed method reduces the average noise level for all the depths by about 134%, 57% and 23%, compared to the original low-resolution, SAFT+DAS and SAFT+DMAS methods, respectively. All the results indicate that the proposed method can be an appropriate algorithm for image formation in AR-PAM systems. K E Y W O R D S acoustic-resolution photoacoustic microscopy, contrast enhancement, synthetic aperture focusing technique, vasculature imaging, virtual source Moein Mozaffarzadeh, Mehdi H. H. Varnosfaderan and Arunima Sharma contributed equally to this study.

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Section: Methodsmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 79%

y_{SAFT + DS_DMAS} ((), i, t) = \frac{2}{{(2 N_{D})}^{2} - 2 N_{D}} \sum_{j = - N_{D}}^{N_{D} - 2} \sum_{k = j + 1}^{N_{D} - 1} {\overset{true˜}{italicrf}}_{jk} ((), i, t),

where

\begin{matrix} lefttrue \\ {\overset{rf}{true}}_{italicjk} (i, t) = S . \sqrt{(||,, {rf}_{j} ((), i, t) . {rf}_{k} ((), i, t))} \\ S = sign ({italicrf}_{j} (i, t) . {italicrf}_{k} (i, t)), \\ for - N_{D} \leq j < k \leq N_{D} - 1, \end{matrix}

and

{rf}_{f} ((), i, t) = \frac{1}{N_{D} - f} \sum_{k = f + 1}^{N_{D}} {\overset{true^}{RF}}_{fk} ((), i, t) .

…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhanced contrast acoustic‐resolution photoacoustic microscopy using double‐stage delay‐multiply‐and‐sum beamformer for vasculature imaging

Mozaffarzadeh

Varnosfaderani

Sharma

et al. 2019

Journal of Biophotonics

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“…The photons absorbed by the tissue lead to a spatially confined temperature increases in turn leading to rapid volume expansion and photoacoustic pressure waves. The generated photoacoustic signals are detected by wideband ultrasound transducers . Photoacoustic signals are received and stored after each laser pulse.…”

Section: Introductionmentioning

confidence: 99%

Noninvasive staging of pressure ulcers using photoacoustic imaging

Hariri

Chen

Moore

et al. 2019

Wound Repair Regeneration

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Ulcers including pressure ulcers and diabetic foot ulcers damage the skin and underlying tissue in people with compromised blood circulation. They are classified into four stages of severity and span from mild reddening of the skin to tissue damage and muscle/bone infections. Here, we used photoacoustic imaging as a noninvasive method for detecting early tissue damage that cannot be visually observed while also staging the disease using quantitative image analysis. We used a mouse model of pressure ulcers by implanting subdermal magnets in the dorsal flank and periodically applying an external magnet to the healed implant site. The magnet-induced pressure was applied in cycles, and the extent of ulceration was dictated by the number of cycles. We used both laser-and lightemitting diode (LED)-based photoacoustic imaging tools with 690 nm excitation to evaluate the change in photoacoustic signal and depth of injury. Using laser-based photoacoustic imaging system, we found a 4.4-fold increase in the photoacoustic intensity in stage I vs. baseline (no pressure). We also evaluated the depth of injury using photoacoustics. We measured a photoacoustic ulcer depth of 0.38 AE 0.09 mm, 0.74 AE 0.11 mm, 1.63 AE 0.4 mm, and 2.7 AE 0.31 mm (n = 4) for stages I-IV, respectively. The photoacoustic depth differences between each stage were significant (p < 0.05). We also used an LED-based photoacoustic imaging system to detect early stage (stage I) pressure ulcers and observed a 2.5-fold increase in photoacoustic signal. Importantly, we confirmed the capacity of this technique to detect dysregulated skin even before stage I ulcers have erupted. We also observed significant changes in photoacoustic intensity during healing suggesting that this approach can monitor therapy. These findings were confirmed with histology. These results suggest that this photoacoustic-based approach might have clinical value for monitoring skin diseases including pressure ulcers.

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Validation of delay‐multiply‐and‐standard‐deviation weighting factor for improved photoacoustic imaging of sentinel lymph node

Paridar

Mozaffarzadeh

Periyasamy

et al. 2019

Journal of Biophotonics

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Delay‐and‐sum (DAS) is one of the most common algorithms used to construct the photoacoustic images due to its low complexity. However, it results in images with high sidelobes and low resolution. Delay‐and‐standard‐deviation (DASD) weighting factor can improve the contrast of the images compared to DAS. However, it still suffers from high sidelobes. In this work, a new weighting factor, named delay‐multiply‐and‐standard‐deviation (DMASD) is introduced to enhance the contrast of the reconstructed images compared to other mentioned methods. In the proposed method, the SD of the mutual multiplied delayed signals are calculated, normalized and multiplied to DAS beamformed data. The results show that DMASD improves the signal‐to‐noise‐ratio about 19.29 and 7.3 dB compared to DAS and DASD, respectively, for in vivo imaging of the sentinel lymph node. Moreover, the contrast ratio is improved by the DMASD about 23.61 and 10.81 dB compared to DAS and DASD, respectively.

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The double-stage delay-multiply-and-sum image reconstruction method improves imaging quality in a LED-based photoacoustic array scanner

Cited by 47 publications

References 53 publications

Enhanced contrast acoustic‐resolution photoacoustic microscopy using double‐stage delay‐multiply‐and‐sum beamformer for vasculature imaging

Enhanced contrast acoustic‐resolution photoacoustic microscopy using double‐stage delay‐multiply‐and‐sum beamformer for vasculature imaging

Noninvasive staging of pressure ulcers using photoacoustic imaging

Validation of delay‐multiply‐and‐standard‐deviation weighting factor for improved photoacoustic imaging of sentinel lymph node

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