Acoustic lens characterization for ultrasound and photoacoustic C-scan imaging modalities

Rao, Navalgund; Lai, Di; Bhatt, Shweta; Arnold, Stephen C.; Chinni, Bhargava; Dogra, Vikram S.

doi:10.1109/iembs.2008.4649626

Cited by 8 publications

(8 citation statements)

References 2 publications

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“…[45] The laser intensity delivered onto the ex-vivo prostate tissue was approximately 5 mJ/cm 2 , which is well below the maximum permissible energy limit (20 mJ/ cm 2 at 700 nm-79.6 mJ/cm 2 at 1000 nm) set by American National Standards Institute guidelines for safe human exposure. [6] PA imaging was performed at wavelengths of 760 nm, 850 nm, 930 nm and 970 nm that represent deoxyhemoglobin (dHb), oxyhemoglobin (HbO 2 ), lipids, and water respectively.…”

Section: Methodsmentioning

confidence: 99%

Multispectral Photoacoustic Imaging of Prostate Cancer: Preliminary Ex-vivo Results

Dogra

Chinni

Valluru

et al. 2013

Journal of Clinical Imaging Science

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Objective:The objective of this study is to validate if ex-vivo multispectral photoacoustic (PA) imaging can differentiate between malignant prostate tissue, benign prostatic hyperplasia (BPH), and normal human prostate tissue.Materials and Methods:Institutional Review Board's approval was obtained for this study. A total of 30 patients undergoing prostatectomy for biopsy-confirmed prostate cancer were included in this study with informed consent. Multispectral PA imaging was performed on surgically excised prostate tissue and chromophore images that represent optical absorption of deoxyhemoglobin (dHb), oxyhemoglobin (HbO2), lipid, and water were reconstructed. After the imaging procedure is completed, malignant prostate, BPH and normal prostate regions were marked by the genitourinary pathologist on histopathology slides and digital images of marked histopathology slides were obtained. The histopathology images were co-registered with chromophore images. Region of interest (ROI) corresponding to malignant prostate, BPH and normal prostate were defined on the chromophore images. Pixel values within each ROI were then averaged to determine mean intensities of dHb, HbO2, lipid, and water.Results:Our preliminary results show that there is statistically significant difference in mean intensity of dHb (P < 0.0001) and lipid (P = 0.0251) between malignant prostate and normal prostate tissue. There was difference in mean intensity of dHb (P < 0.0001) between malignant prostate and BPH. Sensitivity, specificity, positive predictive value, and negative predictive value of our imaging system were found to be 81.3%, 96.2%, 92.9% and 89.3% respectively.Conclusion:Our preliminary results of ex-vivo human prostate study suggest that multispectral PA imaging can differentiate between malignant prostate, BPH and normal prostate tissue.

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Section: Methodsmentioning

confidence: 99%

Multispectral Photoacoustic Imaging of Prostate Cancer: Preliminary Ex-vivo Results

Dogra

Chinni

Valluru

et al. 2013

Journal of Clinical Imaging Science

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“…Other works from the group also include the peak holding circuit for real-time PA imaging [13] and the introduction of 4 F imaging system [14] , [15] , [16] . A low-cost method using 3D printing technology to manufacture acoustic lenses and a preliminary characterization was conducted by Rao et al in 2008 [17] . Along with the use of 4 F imaging system, the group developed a scanning probe, known as PA camera [18] .…”

Section: Introductionmentioning

confidence: 99%

Characterization of lens based photoacoustic imaging system

et al. 2017

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Some of the challenges in translating photoacoustic (PA) imaging to clinical applications includes limited view of the target tissue, low signal to noise ratio and the high cost of developing real-time systems. Acoustic lens based PA imaging systems, also known as PA cameras are a potential alternative to conventional imaging systems in these scenarios. The 3D focusing action of lens enables real-time C-scan imaging with a 2D transducer array. In this paper, we model the underlying physics in a PA camera in the mathematical framework of an imaging system and derive a closed form expression for the point spread function (PSF). Experimental verification follows including the details on how to design and fabricate the lens inexpensively. The system PSF is evaluated over a 3D volume that can be imaged by this PA camera. Its utility is demonstrated by imaging phantom and an ex vivo human prostate tissue sample.

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“…Following the laser excitation of the target, PA signals are generated from all the absorbers of the target and are simultaneously focused onto an US detector by the acoustic lens [19] . The acoustic lens corrects for the loss of lateral image resolution as explained in [20]. The acoustic lens substitutes the time consuming off-line computerized and algorithm based image reconstruction, and does not produce errors in the reconstructed image.…”

Section: Pa Imaging Camera Design and Experimental Evaluationmentioning

confidence: 98%

Multi-acoustic lens design methodology for a low cost C-scan photoacoustic imaging camera

et al. 2016

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We have designed and implemented a novel acoustic lens based focusing technology into a prototype photoacoustic imaging camera. All photoacoustically generated waves from laser exposed absorbers within a small volume get focused simultaneously by the lens onto an image plane. We use a multi-element ultrasound transducer array to capture the focused photoacoustic signals. Acoustic lens eliminates the need for expensive data acquisition hardware systems, is faster compared to electronic focusing and enables real-time image reconstruction. Using this photoacoustic imaging camera, we have imaged more than 150 several centimeter size ex-vivo human prostate, kidney and thyroid specimens with a millimeter resolution for cancer detection. In this paper, we share our lens design strategy and how we evaluate the resulting quality metrics (on and off axis point spread function, depth of field and modulation transfer function) through simulation. An advanced toolbox in MATLAB was adapted and used for simulating a two-dimensional gridded model that incorporates realistic photoacoustic signal generation and acoustic wave propagation through the lens with medium properties defined on each grid point. Two dimensional point spread functions have been generated and compared with experiments to demonstrate the utility of our design strategy. Finally we present results from work in progress on the use of two lens system aimed at further improving some of the quality metrics of our system.

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Acoustic lens characterization for ultrasound and photoacoustic C-scan imaging modalities

Cited by 8 publications

References 2 publications

Multispectral Photoacoustic Imaging of Prostate Cancer: Preliminary Ex-vivo Results

Multispectral Photoacoustic Imaging of Prostate Cancer: Preliminary Ex-vivo Results

Characterization of lens based photoacoustic imaging system

Multi-acoustic lens design methodology for a low cost C-scan photoacoustic imaging camera

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