• Title/Summary/Keyword: Photoacoustic tomography

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Photoacoustic imaging of occlusal incipient caries in the visible and near-infrared range

  • da Silva, Evair Josino;de Miranda, Erica Muniz;de Oliveira Mota, Claudia Cristina Brainer;Das, Avishek;Gomes, Anderson Stevens Leonidas
    • Imaging Science in Dentistry
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    • v.51 no.2
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    • pp.107-115
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    • 2021
  • Purpose: This study aimed to demonstrate the presence of dental caries through a photoacoustic imaging system with visible and near-infrared wavelengths, highlighting the differences between the 2 spectral regions. The depth at which carious tissue could be detected was also verified. Materials and Methods: Fifteen permanent molars were selected and classified as being sound or having incipient or advanced caries by visual inspection, radiography, and optical coherence tomography analysis prior to photoacoustic scanning. A photoacoustic imaging system operating with a nanosecond pulsed laser as the light excitation source at either 532 nm or 1064 nm and an acoustic transducer at 5 MHz was developed, characterized, and used. En-face and lateral(depth) photoacoustic signals were detected. Results: The results confirmed the potential of the photoacoustic method to detect caries. At both wavelengths, photoacoustic imaging effectively detected incipient and advanced caries. The reconstructed photoacoustic images confirmed that a higher intensity of the photoacoustic signal could be observed in regions with lesions, while sound surfaces showed much less photoacoustic signal. Photoacoustic signals at depths up to 4 mm at both 532 nm and 1064 nm were measured. Conclusion: The results presented here are promising and corroborate that photoacoustic imaging can be applied as a diagnostic tool in caries research. New studies should focus on developing a clinical model of photoacoustic imaging applications in dentistry, including soft tissues. The use of inexpensive light-emitting diodes together with a miniaturized detector will make photoacoustic imaging systems more flexible, user-friendly, and technologically viable.

Principles and Medical Applications of Biomedical Photoacoustic Tomography (의료용 광음향 단층촬영 원리와 의학적 응용)

  • Song, Chul-Gyu;Ryu, Sang-Hun;Kim, Do-Hyun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.6
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    • pp.1209-1214
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    • 2011
  • Photoacoustics has been broadly studied in biomedicine, for both human and small animal tissues. Photoacoustics uniquely combines the absorption contrast of light or radio frequency waves with ultrasound resolution. Moreover, it is non-ionizing and non-invasive, and is the fastest growing new biomedical method, with clinical applications on the way. This paper provides a brief recap of recent developments in photoacoustics in biomedicine, from basic principles to applications. The emphasized areas include the new imaging modalities as well as translational research topics. A primary PA application in biomedicine is photoacoustic tomography (PAT). The past decade has seen fast developments in both theoretical reconstruction algorithms and innovative imaging techniques, and PAT has been implemented in imaging different tissues, from centimeter-large breast tumors to several micrometer-large single red blood cels (RBC). PAT now provides structural, functional and molecular imaging. Overall, PA techniques for biomedicine are maturing. They have been widely used to study both animal and human tissues. Recently, more and more research focuses on clinical applications. Commercialized PA systems are expected to be available in the near future, and wide clinical PA applications are foreseen.

In vivo functional photoacoustic imaging (나노초 레이져를 이용한 광-초음파 이미지 결상법)

  • Oh, Jung-Taek;Li, Meng-Lin;Song, Kwang-Hyun;Xie, Xueyi;Stoica, George;Wang, Lihong V.
    • Proceedings of the Optical Society of Korea Conference
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    • 2006.02a
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    • pp.359-360
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    • 2006
  • Functional photoacoustic tomography is a new non-invasive imaging modality, and it is emerging as a very practical method for imaging biological tissue structures by means of laser-induced ultrasound. Structures with high optical absorption, such as blood vessels, can be imaged with the spatial resolution of ultrasound, which is not limited by the strong light scattering in biological tissues. By varying wavelengths of the laser light and acquiring photoacoustic images, optical absorption spectrum of each image pixel is found. Since the biochemical constituents of tissues determine the spectrum, useful functional information like oxygen saturation ($SO_2$) and total haemoglobin concentration (HbT) can be extracted. In this study, as a proof-of-principle experiment, hypoxic brain tumor vasculature and traumatic brain injury (TBI) of small animal brain are imaged with functional photoacoustic tomography. High resolution brain vasculature images of oxygen saturation and total hemoglobin concentration are provided to visualize hypoxic tumor vasculature, and hemorrhage on the cortex surface by the TBI.

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Review of Photoacoustic Imaging for Imaging-Guided Spinal Surgery

  • Han, Seung Hee
    • Neurospine
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    • v.15 no.4
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    • pp.306-322
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    • 2018
  • This review introduces the current technique of photoacoustic imaging as it is applied in imaging-guided surgery (IGS), which provides the surgeon with image visualization and analysis capabilities during surgery. Numerous imaging techniques have been developed to help surgeons perform complex operations more safely and quickly. Although surgeons typically use these kinds of images to visualize targets hidden by bone and other tissues, it is nonetheless more difficult to perform surgery with static reference images (e.g., computed tomography scans and magnetic resonance images) of internal structures. Photoacoustic imaging could enable real-time visualization of regions of interest during surgery. Several researchers have shown that photoacoustic imaging has potential for the noninvasive diagnosis of various types of tissues, including bone. Previous studies of the surgical application of photoacoustic imaging have focused on cancer surgery, but photoacoustic imaging has also recently attracted interest for spinal surgery, because it could be useful for avoiding pedicle breaches and for choosing an appropriate starting point before drilling or pedicle probe insertion. This review describes the current instruments and clinical applications of photoacoustic imaging. Its primary objective is to provide a comprehensive overview of photoacoustic IGS in spinal surgery.

Phantom Evaluation and Development of Photoacoustic Tomography Imaging System using Unfocused Ultrasound Transducer and Back-Projection Algorithm (역투사 알고리듬과 비촛점 트랜스듀서를 적용한 광음향 단층영상 장치개발과 팬텀실험)

  • Ryu, Sang-Hun;Kim, Do-Hyun;Song, Chul-Gyu
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.12
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    • pp.2349-2351
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    • 2010
  • Photo Acoustic Tomography (PAT) is a hybrid imaging modality which combines high contrast of optical imaging and spatial resolution of ultrasound imaging, thus it is suitable to image biological tissue noninvasively. Laser-induced photoacoustic signals were measured from a sample by means of an unfocused ultrasound transducer, then PAT image was reconstructed based on a universal back-projection algorithm. To evaluate the feasibility of our system, phantom test was performed, consequently, the PAT images obtained using our system showed highly analogous shape and volume with those of the phantom. This result demonstrated that our system can provide a powerful tool for imaging the substructure of biological tissue in non-invasive manner.

Development of Laser Induced Real Time Photoacoustic Tomography Imaging System and Phantom Evaluation (레이저 유도방식의 실시간 광음향 단층영상 기술 개발과 팬텀이미지 평가)

  • Ryu, Sang-Hun;Shin, Dong-Ho;Song, Chul-Gyu
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.6
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    • pp.879-884
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    • 2012
  • Photoacoustic Tomography (PAT) is a promising medical imaging modality by reason of its particularity. It combines optical imaging contrast of optical imaging with the spatial resolution of ultrasound imaging and can demonstrate change of biological feature in an image. For that reason, many studies are in progress to apply this technic for diagnosis. But, real-time PAT system is necessary to confirm a biological reaction induced by external stimulation immediately. Thus, we developed a real-time PAT system using linear array transducer and self-developed Data acquisition board (DAQ) resources, To evaluate the feasibility and performance of our proposed system, two type of phantom test were also performed. As a result of those experiments, the proposed system shows enough performance and confirm its usefulness.

Array-Based Real-Time Ultrasound and Photoacoustic Ocular Imaging

  • Nam, Seung Yun;Emelianov, Stanislav Y.
    • Journal of the Optical Society of Korea
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    • v.18 no.2
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    • pp.151-155
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    • 2014
  • Although various ophthalmic imaging methods, including fundus photography and optical coherence tomography, have been applied for effective diagnosis of ocular diseases with high spatial resolution, most of them are limited by shallow imaging penetration depth and a narrow field of view. Also, many of those imaging modalities are optimized to provide microscopic anatomical information, while functional or cellular information is lacking. Compared to other ocular imaging modalities, photoacoustic imaging can achieve relatively deep penetration depth and provide more detailed functional and cellular data based on photoacoustic signal generation from endogenous contrast agents such as hemoglobin and melanin. In this paper, array-based ultrasound and photoacoustic imaging was demonstrated to visualize pigmentation in the eye as well as overall ocular structure. Fresh porcine eyes were visualized using a real-time ultrasound micro-imaging system and an imaging probe supporting laser pulse delivery. In addition, limited photoacoustic imaging field of view was improved by an imaging probe tilting method, enabling visualization of most regions of the retina covered in the ultrasound imaging.

Simultaneous Imaging Using Combined Optical Coherence Tomography (OCT) and Photoacoustic Microscopy (PAM) (광간섭 단층 촬영 장치와 광음향 현미경의 결합을 통한 동시 이미지 획득 연구)

  • Kim, Sehui;Lee, Changho;Han, Seonghoon;Kang, Hyun Wook;Oh, Junghwan;Kim, Jeehyun;Kim, Chulhong
    • Journal of Biomedical Engineering Research
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    • v.34 no.2
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    • pp.91-96
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    • 2013
  • In this study, we developed an integrated optical coherence tomography - photoacoustic microscopy (OCT-PAM) system to simultaneously provide optical absorption and scattering information. Two different laser sources, such as a pulsed laser for PAM and a superluminescent diode for OCT, were employed to implement the integrated OCT-PAM system. The performance of the OCT-PAM system was measured by imaging carbon fibers. We then imaged black and white hairs to demonstrate the simultaneous OCT-PAM imaging capabilities. As a result, OCT can produce 3-D images of both black and white hairs, whereas PAM is only able to image the black hair due to strong optical absorption of black hair.

Development of Photoacoustic System for Breast Cancer Detection (유방암 진단용 광음향 영상 시스템 개발)

  • Lee, Soonhyouk;Ji, Yun-Seo;Lee, Rena
    • Progress in Medical Physics
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    • v.24 no.3
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    • pp.183-190
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    • 2013
  • Recently, the photoacoustic imaging system has been widely and intensively developed, and has been shown the possibility of diagnosis for early stage cancer. In this study, we developed a photoacoustic tomography imaging system with a commercial ultra sound device and a linear array probe. A tube phantom and a chicken breast phantom was made for the possibility of a system as a breast cancer detection. A moving average filter and a band pass filter with 3~6 MHz bandwidth were developed for background noise elimination before delay-and-sum beamforming algorithm was used for image reconstruction. As a result, we showed that some signal processing procedure before beamforming was effective for the photoacoustic image reconstruction.

Ultrasound-optical imaging-based multimodal imaging technology for biomedical applications (바이오 응용을 위한 초음파 및 광학 기반 다중 모달 영상 기술)

  • Moon Hwan Lee;HeeYeon Park;Kyungsu Lee;Sewoong Kim;Jihun Kim;Jae Youn Hwang
    • The Journal of the Acoustical Society of Korea
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    • v.42 no.5
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    • pp.429-440
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    • 2023
  • This study explores recent research trends and potential applications of ultrasound optical imaging-based multimodal technology. Ultrasound imaging has been widely utilized in medical diagnostics due to its real-time capability and relative safety. However, the drawback of low resolution in ultrasound imaging has prompted active research on multimodal imaging techniques that combine ultrasound with other imaging modalities to enhance diagnostic accuracy. In particular, ultrasound optical imaging-based multimodal technology enables the utilization of each modality's advantages while compensating for their limitations, offering a means to improve the accuracy of the diagnosis. Various forms of multimodal imaging techniques have been proposed, including the fusion of optical coherence tomography, photoacoustic, fluorescence, fluorescence lifetime, and spectral technology with ultrasound. This study investigates recent research trends in ultrasound optical imaging-based multimodal technology, and its potential applications are demonstrated in the biomedical field. The ultrasound optical imaging-based multimodal technology provides insights into the progress of integrating ultrasound and optical technologies, laying the foundation for novel approaches to enhance diagnostic accuracy in the biomedical domain.