1
|
Hakakzadeh S, Mozaffarzadeh M, Mostafavi SM, Kavehvash Z, Rajendran P, Verweij M, de Jong N, Pramanik M. Multi-angle data acquisition to compensate transducer finite size in photoacoustic tomography. PHOTOACOUSTICS 2022; 27:100373. [PMID: 35662895 PMCID: PMC9157198 DOI: 10.1016/j.pacs.2022.100373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 05/02/2022] [Accepted: 05/13/2022] [Indexed: 05/28/2023]
Abstract
In photoacoustic tomography (PAT) systems, the tangential resolution decreases due to the finite size of the transducer as the off-center distance increases. To address this problem, we propose a multi-angle detection approach in which the transducer used for data acquisition rotates around its center (with specific angles) as well as around the scanning center. The angles are calculated based on the central frequency and diameter of the transducer and the radius of the region-of-interest (ROI). Simulations with point-like absorbers (for point-spread-function evaluation) and a vasculature phantom (for quality assessment), and experiments with ten 0.5 mm-diameter pencil leads and a leaf skeleton phantom are used for evaluation of the proposed approach. The results show that a location-independent tangential resolution is achieved with 150 spatial sampling and central rotations with angles of ±8°/±16°. With further developments, the proposed detection strategy can replace the conventional detection (rotating a transducer around ROI) in PAT.
Collapse
Affiliation(s)
- Soheil Hakakzadeh
- Department of Electrical Engineering, Sharif University of Technology, Tehran, Iran
| | - Moein Mozaffarzadeh
- Laboratory of Medical Imaging, Department of Imaging Physics, Delft University of Technology, 2628 CJ Delft, The Netherlands
| | | | - Zahra Kavehvash
- Department of Electrical Engineering, Sharif University of Technology, Tehran, Iran
| | - Praveenbalaji Rajendran
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore
| | - Martin Verweij
- Laboratory of Medical Imaging, Department of Imaging Physics, Delft University of Technology, 2628 CJ Delft, The Netherlands
- Department Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, 3015 GD Rotterdam, The Netherlands
| | - Nico de Jong
- Laboratory of Medical Imaging, Department of Imaging Physics, Delft University of Technology, 2628 CJ Delft, The Netherlands
- Department Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, 3015 GD Rotterdam, The Netherlands
| | - Manojit Pramanik
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore
| |
Collapse
|
2
|
Hui X, Malik MOA, Pramanik M. Looking deep inside tissue with photoacoustic molecular probes: a review. JOURNAL OF BIOMEDICAL OPTICS 2022; 27:070901. [PMID: 36451698 PMCID: PMC9307281 DOI: 10.1117/1.jbo.27.7.070901] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 07/01/2022] [Indexed: 05/19/2023]
Abstract
Significance Deep tissue noninvasive high-resolution imaging with light is challenging due to the high degree of light absorption and scattering in biological tissue. Photoacoustic imaging (PAI) can overcome some of the challenges of pure optical or ultrasound imaging to provide high-resolution deep tissue imaging. However, label-free PAI signals from light absorbing chromophores within the tissue are nonspecific. The use of exogeneous contrast agents (probes) not only enhances the imaging contrast (and imaging depth) but also increases the specificity of PAI by binding only to targeted molecules and often providing signals distinct from the background. Aim We aim to review the current development and future progression of photoacoustic molecular probes/contrast agents. Approach First, PAI and the need for using contrast agents are briefly introduced. Then, the recent development of contrast agents in terms of materials used to construct them is discussed. Then, various probes are discussed based on targeting mechanisms, in vivo molecular imaging applications, multimodal uses, and use in theranostic applications. Results Material combinations are being used to develop highly specific contrast agents. In addition to passive accumulation, probes utilizing activation mechanisms show promise for greater controllability. Several probes also enable concurrent multimodal use with fluorescence, ultrasound, Raman, magnetic resonance imaging, and computed tomography. Finally, targeted probes are also shown to aid localized and molecularly specific photo-induced therapy. Conclusions The development of contrast agents provides a promising prospect for increased contrast, higher imaging depth, and molecularly specific information. Of note are agents that allow for controlled activation, explore other optical windows, and enable multimodal use to overcome some of the shortcomings of label-free PAI.
Collapse
Affiliation(s)
- Xie Hui
- Nanyang Technological University, School of Chemical and Biomedical Engineering, Singapore
| | - Mohammad O. A. Malik
- Nanyang Technological University, School of Chemical and Biomedical Engineering, Singapore
| | - Manojit Pramanik
- Nanyang Technological University, School of Chemical and Biomedical Engineering, Singapore
| |
Collapse
|
3
|
Rajendran P, Pramanik M. High frame rate (∼3 Hz) circular photoacoustic tomography using single-element ultrasound transducer aided with deep learning. JOURNAL OF BIOMEDICAL OPTICS 2022; 27:066005. [PMID: 36452448 PMCID: PMC9209813 DOI: 10.1117/1.jbo.27.6.066005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 06/01/2022] [Indexed: 05/29/2023]
Abstract
Significance In circular scanning photoacoustic tomography (PAT), it takes several minutes to generate an image of acceptable quality, especially with a single-element ultrasound transducer (UST). The imaging speed can be enhanced by faster scanning (with high repetition rate light sources) and using multiple-USTs. However, artifacts arising from the sparse signal acquisition and low signal-to-noise ratio at higher scanning speeds limit the imaging speed. Thus, there is a need to improve the imaging speed of the PAT systems without hampering the quality of the PAT image. Aim To improve the frame rate (or imaging speed) of the PAT system by using deep learning (DL). Approach For improving the frame rate (or imaging speed) of the PAT system, we propose a novel U-Net-based DL framework to reconstruct PAT images from fast scanning data. Results The efficiency of the network was evaluated on both single- and multiple-UST-based PAT systems. Both phantom and in vivo imaging demonstrate that the network can improve the imaging frame rate by approximately sixfold in single-UST-based PAT systems and by approximately twofold in multi-UST-based PAT systems. Conclusions We proposed an innovative method to improve the frame rate (or imaging speed) by using DL and with this method, the fastest frame rate of ∼ 3 Hz imaging is achieved without hampering the quality of the reconstructed image.
Collapse
Affiliation(s)
| | - Manojit Pramanik
- Nanyang Technological University, School of Chemical and Biomedical Engineering, Singapore
| |
Collapse
|
4
|
Kang J, Koehler RC, Graham EM, Boctor EM. Photoacoustic assessment of the fetal brain and placenta as a method of non-invasive antepartum and intrapartum monitoring. Exp Neurol 2022; 347:113898. [PMID: 34662542 PMCID: PMC8756814 DOI: 10.1016/j.expneurol.2021.113898] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 10/06/2021] [Accepted: 10/12/2021] [Indexed: 11/21/2022]
Abstract
A noninvasive monitor for concurrent evaluation of placental and fetal sagittal sinus sO 2 for both antepartum surveillance at the late 2nd and 3rd trimesters and intrapartum monitoring would be a great advantage over current methods. A PA fetal brain and placental monitor has potential value to rapidly identify the fetus at risk for developing hypoxia and ischemia of a sufficient degree that brain injury or death may develop, which may be prevented by intervention with delivery and other follow-up treatments.
Collapse
Affiliation(s)
- Jeeun Kang
- Laboratory for Computational Sensing and Robotics, Whiting School of Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America; Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Raymond C Koehler
- Department of Anesthesia and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Ernest M Graham
- Department of Gyn-Ob, Division of Maternal-Fetal Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America; Neuroscience Intensive Care Nursery Program, Johns Hopkins University School of Medicine; Baltimore, MD, United States of America.
| | - Emad M Boctor
- Laboratory for Computational Sensing and Robotics, Whiting School of Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America; Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| |
Collapse
|
5
|
Jana D, Wang D, Rajendran P, Bindra AK, Guo Y, Liu J, Pramanik M, Zhao Y. Hybrid Carbon Dot Assembly as a Reactive Oxygen Species Nanogenerator for Ultrasound-Assisted Tumor Ablation. JACS AU 2021; 1:2328-2338. [PMID: 34977901 PMCID: PMC8715545 DOI: 10.1021/jacsau.1c00422] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Indexed: 06/01/2023]
Abstract
The efficacy of reactive oxygen species (ROS)-based therapy is substantially constrained by the limited ROS generation, stern activation conditions, and lack of a straightforward reaction paradigm. Carbon dots (CDs) have been highly sought after for therapeutic applications for their biocompatibility and intrinsic fluorescence imaging capabilities, making them suitable for ROS generation. Herein, we synthesized a CD-based ultrasmall hybrid nanostructure possessing active sites of Mo, Cu, and IR-780 dye. After cooperative self-assembly with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol), the obtained assembly (CMIR-CDa) exhibits near-infrared fluorescence imaging and photoacoustic tomography. Interestingly, CMIR-CDa can generate singlet oxygen (1O2), hydroxyl radical (·OH), and superoxide radical anion (O2 • -) upon ultrasound stimulus owing to its sonosensitizing and enzyme-mimicking properties, showing an enhanced efficacy for tumor ablation in vivo. The collective in vitro and in vivo results indicate that CMIR-CDa has a high potency as an ROS nanogenerator under US irradiation, even at a low concentration. The present study offers an approach for engineering hybrid CDs in a bioinspired way for intratumoral ROS augmentation in response to deep tissue penetrable external stimuli.
Collapse
Affiliation(s)
- Deblin Jana
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Dongdong Wang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Praveenbalaji Rajendran
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore
| | - Anivind Kaur Bindra
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Yi Guo
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Jiawei Liu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Manojit Pramanik
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore
| | - Yanli Zhao
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore
| |
Collapse
|
6
|
Photoacoustic imaging aided with deep learning: a review. Biomed Eng Lett 2021; 12:155-173. [DOI: 10.1007/s13534-021-00210-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/19/2021] [Accepted: 11/07/2021] [Indexed: 12/21/2022] Open
|
7
|
Recent Technical Progression in Photoacoustic Imaging—Towards Using Contrast Agents and Multimodal Techniques. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11219804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
For combining optical and ultrasonic imaging methodologies, photoacoustic imaging (PAI) is the most important and successful hybrid technique, which has greatly contributed to biomedical research and applications. Its theoretical background is based on the photoacoustic effect, whereby a modulated or pulsed light is emitted into tissue, which selectively absorbs the optical energy of the light at optical wavelengths. This energy produces a fast thermal expansion in the illuminated tissue, generating pressure waves (or photoacoustic waves) that can be detected by ultrasonic transducers. Research has shown that optical absorption spectroscopy offers high optical sensitivity and contrast for ingredient determination, for example, while ultrasound has demonstrated good spatial resolution in biomedical imaging. Photoacoustic imaging combines these advantages, i.e., high contrast through optical absorption and high spatial resolution due to the low scattering of ultrasound in tissue. In this review, we focus on advances made in PAI in the last five years and present categories and key devices used in PAI techniques. In particular, we highlight the continuously increasing imaging depth achieved by PAI, particularly when using exogenous reagents. Finally, we discuss the potential of combining PAI with other imaging techniques.
Collapse
|
8
|
Rajendran P, Pramanik M. Deep-learning-based multi-transducer photoacoustic tomography imaging without radius calibration. OPTICS LETTERS 2021; 46:4510-4513. [PMID: 34525034 DOI: 10.1364/ol.434513] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Pulsed laser diodes are used in photoacoustic tomography (PAT) as excitation sources because of their low cost, compact size, and high pulse repetition rate. In combination with multiple single-element ultrasound transducers (SUTs) the imaging speed of PAT can be improved. However, during PAT image reconstruction, the exact radius of each SUT is required for accurate reconstruction. Here we developed a novel deep learning approach to alleviate the need for radius calibration. We used a convolutional neural network (fully dense U-Net) aided with a convolutional long short-term memory block to reconstruct the PAT images. Our analysis on the test set demonstrates that the proposed network eliminates the need for radius calibration and improves the peak signal-to-noise ratio by ∼73% without compromising the image quality. In vivo imaging was used to verify the performance of the network.
Collapse
|
9
|
Yang X, Chen YH, Xia F, Sawan M. Photoacoustic imaging for monitoring of stroke diseases: A review. PHOTOACOUSTICS 2021; 23:100287. [PMID: 34401324 PMCID: PMC8353507 DOI: 10.1016/j.pacs.2021.100287] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 07/02/2021] [Accepted: 07/16/2021] [Indexed: 05/14/2023]
Abstract
Stroke is the leading cause of death and disability after ischemic heart disease. However, there is lacking a non-invasive long-time monitoring technique for stroke diagnosis and therapy. The photoacoustic imaging approach reconstructs images of an object based on the energy excitation by optical absorption and its conversion to acoustic waves, due to corresponding thermoelastic expansion, which has optical resolution and acoustic propagation. This emerging functional imaging method is a non-invasive technique. Due to its precision, this method is particularly attractive for stroke monitoring purpose. In this paper, we review the achievements of this technology and its applications on stroke, as well as the development status in both animal and human applications. Also, various photoacoustic systems and multi-modality photoacoustic imaging are introduced as for potential clinical applications. Finally, the challenges of photoacoustic imaging for monitoring stroke are discussed.
Collapse
Affiliation(s)
- Xi Yang
- Zhejiang University, Hangzhou, 310024, Zhejiang, China
- CenBRAIN Lab., School of Engineering, Westlake University, Hangzhou, 310024, Zhejiang, China
- Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou, 310024, Zhejiang, China
| | - Yun-Hsuan Chen
- CenBRAIN Lab., School of Engineering, Westlake University, Hangzhou, 310024, Zhejiang, China
- Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou, 310024, Zhejiang, China
| | - Fen Xia
- Zhejiang University, Hangzhou, 310024, Zhejiang, China
- CenBRAIN Lab., School of Engineering, Westlake University, Hangzhou, 310024, Zhejiang, China
- Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou, 310024, Zhejiang, China
| | - Mohamad Sawan
- CenBRAIN Lab., School of Engineering, Westlake University, Hangzhou, 310024, Zhejiang, China
- Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou, 310024, Zhejiang, China
- Corresponding author at: CenBRAIN Lab., School of Engineering, Westlake University, Hangzhou, 310024, Zhejiang, China.
| |
Collapse
|
10
|
Prakash J, Kalva SK, Pramanik M, Yalavarthy PK. Binary photoacoustic tomography for improved vasculature imaging. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210135R. [PMID: 34405599 PMCID: PMC8370884 DOI: 10.1117/1.jbo.26.8.086004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/29/2021] [Indexed: 05/09/2023]
Abstract
SIGNIFICANCE The proposed binary tomography approach was able to recover the vasculature structures accurately, which could potentially enable the utilization of binary tomography algorithm in scenarios such as therapy monitoring and hemorrhage detection in different organs. AIM Photoacoustic tomography (PAT) involves reconstruction of vascular networks having direct implications in cancer research, cardiovascular studies, and neuroimaging. Various methods have been proposed for recovering vascular networks in photoacoustic imaging; however, most methods are two-step (image reconstruction and image segmentation) in nature. We propose a binary PAT approach wherein direct reconstruction of vascular network from the acquired photoacoustic sinogram data is plausible. APPROACH Binary tomography approach relies on solving a dual-optimization problem to reconstruct images with every pixel resulting in a binary outcome (i.e., either background or the absorber). Further, the binary tomography approach was compared against backprojection, Tikhonov regularization, and sparse recovery-based schemes. RESULTS Numerical simulations, physical phantom experiment, and in-vivo rat brain vasculature data were used to compare the performance of different algorithms. The results indicate that the binary tomography approach improved the vasculature recovery by 10% using in-silico data with respect to the Dice similarity coefficient against the other reconstruction methods. CONCLUSION The proposed algorithm demonstrates superior vasculature recovery with limited data both visually and based on quantitative image metrics.
Collapse
Affiliation(s)
- Jaya Prakash
- Indian Institute of Science, Department of Instrumentation and Applied Physics, Bangalore, Karnataka, India
- Address all correspondence to Jaya Prakash,
| | - Sandeep Kumar Kalva
- Nanyang Technological University, School of Chemical and Biomedical Engineering, Singapore, Singapore
| | - Manojit Pramanik
- Nanyang Technological University, School of Chemical and Biomedical Engineering, Singapore, Singapore
| | - Phaneendra K. Yalavarthy
- Indian Institute of Science, Department of Computational and Data Sciences, Bangalore, Karnataka, India
| |
Collapse
|
11
|
Das D, Sivasubramanian K, Rajendran P, Pramanik M. Label-free high frame rate imaging of circulating blood clots using a dual modal ultrasound and photoacoustic system. JOURNAL OF BIOPHOTONICS 2021; 14:e202000371. [PMID: 33231356 DOI: 10.1002/jbio.202000371] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/01/2020] [Accepted: 11/23/2020] [Indexed: 05/06/2023]
Abstract
Deep vein thrombosis (DVT) is a disorder when a blood clot (thrombus) is formed in one of the deep veins. These clots detach from the original sites and circulate in the blood stream at high velocities. Diagnosing these blood clots at an early stage is necessary to decide the treatment strategy. For label-free, in vivo, and real-time detection, high framerate photoacoustic imaging can be used. In this work, a dual modal clinical ultrasound and photoacoustic (PA) system is used for the high framerate PA imaging of circulating blood clots in blood at linear velocities up to 107 cm/sec. Blood clot had 1.4 times higher signal-to-noise ratio (SNR) in the static mode and 1.3 times higher SNR compared to blood PA signal in the flow experiments. This work demonstrates that fast-moving circulating blood clots are easy to recognize against the background PA signal and may aid in early diagnosis.
Collapse
Affiliation(s)
- Dhiman Das
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore
| | | | | | - Manojit Pramanik
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore
| |
Collapse
|
12
|
Das D, Sharma A, Rajendran P, Pramanik M. Another decade of photoacoustic imaging. Phys Med Biol 2020; 66. [PMID: 33361580 DOI: 10.1088/1361-6560/abd669] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 12/23/2020] [Indexed: 01/09/2023]
Abstract
Photoacoustic imaging - a hybrid biomedical imaging modality finding its way to clinical practices. Although the photoacoustic phenomenon was known more than a century back, only in the last two decades it has been widely researched and used for biomedical imaging applications. In this review we focus on the development and progress of the technology in the last decade (2010-2020). From becoming more and more user friendly, cheaper in cost, portable in size, photoacoustic imaging promises a wide range of applications, if translated to clinic. The growth of photoacoustic community is steady, and with several new directions researchers are exploring, it is inevitable that photoacoustic imaging will one day establish itself as a regular imaging system in the clinical practices.
Collapse
Affiliation(s)
- Dhiman Das
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, SINGAPORE
| | - Arunima Sharma
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, SINGAPORE
| | - Praveenbalaji Rajendran
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, SINGAPORE
| | - Manojit Pramanik
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive, N1.3-B2-11, Singapore, 637457, SINGAPORE
| |
Collapse
|
13
|
Rajendran P, Pramanik M. Deep learning approach to improve tangential resolution in photoacoustic tomography. BIOMEDICAL OPTICS EXPRESS 2020; 11:7311-7323. [PMID: 33408998 PMCID: PMC7747891 DOI: 10.1364/boe.410145] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/29/2020] [Accepted: 11/15/2020] [Indexed: 05/09/2023]
Abstract
In circular scan photoacoustic tomography (PAT), the axial resolution is spatially invariant and is limited by the bandwidth of the detector. However, the tangential resolution is spatially variant and is dependent on the aperture size of the detector. In particular, the tangential resolution improves with the decreasing aperture size. However, using a detector with a smaller aperture reduces the sensitivity of the transducer. Thus, large aperture size detectors are widely preferred in circular scan PAT imaging systems. Although several techniques have been proposed to improve the tangential resolution, they have inherent limitations such as high cost and the need for customized detectors. Herein, we propose a novel deep learning architecture to counter the spatially variant tangential resolution in circular scanning PAT imaging systems. We used a fully dense U-Net based convolutional neural network architecture along with 9 residual blocks to improve the tangential resolution of the PAT images. The network was trained on the simulated datasets and its performance was verified by experimental in vivo imaging. Results show that the proposed deep learning network improves the tangential resolution by eight folds, without compromising the structural similarity and quality of image.
Collapse
Affiliation(s)
- Praveenbalaji Rajendran
- Nanyang Technological University, School of Chemical and Biomedical Engineering, 62 Nanyang Drive, Singapore 637459, Singapore
| | - Manojit Pramanik
- Nanyang Technological University, School of Chemical and Biomedical Engineering, 62 Nanyang Drive, Singapore 637459, Singapore
| |
Collapse
|
14
|
Kuniyil Ajith Singh M, Xia W. Portable and Affordable Light Source-Based Photoacoustic Tomography. SENSORS (BASEL, SWITZERLAND) 2020; 20:E6173. [PMID: 33138296 PMCID: PMC7663770 DOI: 10.3390/s20216173] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 12/27/2022]
Abstract
Photoacoustic imaging is a hybrid imaging modality that offers the advantages of optical (spectroscopic contrast) and ultrasound imaging (scalable spatial resolution and imaging depth). This promising modality has shown excellent potential in a wide range of preclinical and clinical imaging and sensing applications. Even though photoacoustic imaging technology has matured in research settings, its clinical translation is not happening at the expected pace. One of the main reasons for this is the requirement of bulky and expensive pulsed lasers for excitation. To accelerate the clinical translation of photoacoustic imaging and explore its potential in resource-limited settings, it is of paramount importance to develop portable and affordable light sources that can be used as the excitation light source. In this review, we focus on the following aspects: (1) the basic theory of photoacoustic imaging; (2) inexpensive light sources and different implementations; and (3) important preclinical and clinical applications, demonstrated using affordable light source-based photoacoustics. The main focus will be on laser diodes and light-emitting diodes as they have demonstrated promise in photoacoustic tomography-the key technological developments in these areas will be thoroughly reviewed. We believe that this review will be a useful opus for both the beginners and experts in the field of biomedical photoacoustic imaging.
Collapse
Affiliation(s)
- Mithun Kuniyil Ajith Singh
- Research and Business Development Division, CYBERDYNE INC., Stationsplein 45, A4.004, 3013 AK Rotterdam, The Netherlands;
| | - Wenfeng Xia
- School of Biomedical Engineering& Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, UK
| |
Collapse
|