Array-Based Real-Time Ultrasound and Photoacoustic Ocular Imaging

남승윤,Stanislav Y. Emelianov 한국광학회 2014 Current Optics and Photonics Vol.18 No.2

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.

Review of Photoacoustic Imaging for Imaging-Guided Spinal Surgery

한승희 대한척추신경외과학회 2018 Neurospine Vol.15 No.4

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.

Contrast-enhanced dual mode imaging: photoacoustic imaging plus more

박성조,정운상,이승현,이동현,김철홍 대한의용생체공학회 2017 Biomedical Engineering Letters (BMEL) Vol.7 No.2

Conventional biomedical imaging modalities inwide clinical use, such as ultrasound imaging, X-raycomputed tomography, magnetic resonance imaging, andpositron emission tomography, can provide morphological,anatomical, and functional information about biologicaltissues. However, single mode imaging in conventionalmedicine provides only limited information for definitivediagnoses. Thus, combinational diagnosis using multipleimaging modalities has become increasingly important. Recently, photoacoustic imaging (PAI) has gained significantattention, and several PAI prototypes have been usedin clinical trials. At the same time, PAI has been tested incombination with conventional imaging modalities. For allthese imaging modalities, various contrast-enhancingagents have been developed for various purposes. In thisreview article, we will focus on recent progress in developingdual mode contrast agents for PAI in combinationwith other conventional imaging modalities.

바이오 응용을 위한 초음파 및 광학 기반 다중 모달 영상 기술

이문환,박희연,이경수,김세웅,김지훈,황재윤 한국음향학회 2023 韓國音響學會誌 Vol.42 No.5

이 연구는 초음파 광학 영상 기반의 다중 모달 영상 기술에 대한 최신 연구 동향과 응용 가능성에 대해 조사하였다. 초음파 영상은 실시간 영상 기능을 가지고 있으며 인체에 상대적으로 안전한 특성으로 인해 의료 분야에서 다양한질병의 진단에 사용되고 있다. 그러나 초음파 영상은 해상도가 낮은 한계가 있어 진단 정확도를 향상시키기 위해 다른광학 영상과의 결합을 통한 다중 모달 영상 기술 개발 연구가 진행되고 있다. 특히 초음파 광학 영상 기반의 다중 모달영상 기술은 각각의 영상 기법의 장점을 극대화하고 단점을 보완함으로써 질병 진단 정확도를 향상시킬 수 있는 수단으로 사용되고 있다. 이러한 기술은 초음파의 실시간 영상 기능과 광간섭 단층 영상 융합 기술, 초음파 광음향 다중 모달영상 기술, 초음파 형광 다중 모달 영상 기술, 초음파 형광 시정수 다중 모달 영상 기술 및 초음파 분광 다중 모달 영상기술 등 다양한 형태로 제안되고 있다. 본 연구에서는 이러한 초음파 광학 영상 기반의 다중 모달 영상 기술의 최신 연구동향을 소개하고, 의학 및 바이오 분야에서의 응용 가능성을 조사하였다. 이를 통해 초음파와 광학 기술의 융합이 어떻게 진행되고 있는지에 대한 통찰력을 제공하고, 의료 분야에서의 진단 정확도 향상을 위한 새로운 접근 방식에 대한기반을 마련하였다. 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.

Photoacoustic Monitoring of the Viability of Mesenchymal Stem Cells Labeled with Indocyanine Green

Yoo, J.M.,Yun, C.,Bui, N.Q.,Oh, J.,Nam, S.Y. Elsevier 2019 IRBM Vol.40 No.1

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>Stem cell therapy has a huge potential to enhance the recovery of damaged tissues and organs. However, it has been reported that majority of implanted stem cells cannot survive after implantation. Therefore, noninvasive monitoring of stem cell viability is essential to estimate the efficacy of stem cell therapy. However, current imaging methods have disadvantages for monitoring of stem cell viability such as cost, penetration depth, and safety. To overcome the limitations, photoacoustic imaging well known for sufficient penetration depth, relatively low cost, and non-ionizing radiation can be a novel alternative assessment method of stem cell viability.</P> <P><B>Methods</B></P> <P>In this study, indocyanine green was used as exogenous photoacoustic contrast agents to label mesenchymal stem cells. The photoacoustic signals were acquired before and after the cell death and quantified to monitor photoacoustic signal changes related to the cell viability.</P> <P><B>Results</B></P> <P>The fluorescence intensity changes of ICG labeled MSCs corresponded to decrease of PA intensity after cell death. Furthermore, the PA imaging of MSCs showed similarity between the PA intensity and the cell viability.</P> <P><B>Conclusion</B></P> <P>The experimental results imply the feasibility of noninvasive detection of stem cell viability during therapeutic procedures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ICG can be used as an MSC labeling probe for PA imaging. </LI> <LI> PA imaging of MSCs showed similarity between the PA intensity and the cell viability. </LI> <LI> PA imaging with ICG labeling is an alternative to detect MSCs viability non-invasively. </LI> </UL> </P>

Development and clinical translation of photoacoustic mammography

Tsuyoshi Shiina,Masakazu Toi,Takayuki Yagi 대한의용생체공학회 2018 Biomedical Engineering Letters (BMEL) Vol.8 No.2

To practically apply photoacoustic (PA) imaging technology in medicine, we have developed prototypes of a photoacousticmammography (PAM) device to acquire images for diagnosing breast cancer in the Kyoto University/Canon joint researchproject (CK project supported by MEXT, Japan). First, the basic ability of the PAM system to visualize the network ofblood vessels and the Hb saturation index was evaluated using a prototype of PAM that has a flat scanning detector and iscapable of simultaneously acquiring photoacoustic (PA) and ultrasound images. Next, another prototype of a PAM devicewith hemispherical sensors was developed to improve the visibility of the 3D structure of vessels by reducing the limitedview effect. In clinical examination of breast cancer cases, the PAM system allowed 3D visualization of fine vesselnetworks with a spatial resolution of a half-millimeter and enabled us to determine the features of tumor-related vascularstructures in human breast cancer. In addition, the oxygen saturation status of Hb was visualized using two differentwavelengths, enabling more precise characterization of the tumor microenvironment. Results of clinical evaluation usingour developed prototype of a PAM device confirmed that PA imaging technology has the potential to promote earlydetection of breast cancer, and realization of its practical use is expected in the near future.

의료용 광음향 단층촬영 원리와 의학적 응용

송철규(Chul Gyu Song),유상훈(Sang Hun Ryu),김도훈(Do Hyun Kim) 대한전기학회 2011 전기학회논문지 Vol.60 No.6

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.

Preparation of dual-modal nanoprobe for photoacoustic imaging and detection of surface-enhanced raman scattering (SERS) signal

정철환,강호만,이윤식 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

Photoacoustic (PA) imaging is very promising technique, based on the generation of ultrasonic wave after irradiation of a light to a material. PA signal has high resolution and great penetration depth, because the degree of ultrasonic scattering is lower than that of fluorescence. Therefore, it is known to be very powerful tool for in vivo imaging. On the other hand, SERS nanoprobe is continuously receiving high attention as an outstanding nanomaterial for multiplexed detection of target bio molecule. SERS signals do not have photobleaching problem, and have much narrower peak width than fluorescence. Herein, we have synthesized near-IR nanoprobe which can generate both PA and SERS signals. The nanoprobe is biocompatible due to the hydrophilic surface modification, and is expected to be an effective tool for in vivo imaging and multiplexed detection.

All-optical optoacoustic micro-tomography in refl ection mode

Tamar Harary,Yoav Hazan,Amir Rosenthal 대한의용생체공학회 2023 Biomedical Engineering Letters (BMEL) Vol.13 No.3

High-resolution optoacoustic imaging at depths beyond the optical diffusion limit is conventionally performed using amicroscopy setup where a strongly focused ultrasound transducer samples the image object point-by-point. Althoughrecent advancements in miniaturized ultrasound detectors enables one to achieve microscopic resolution with an unfocuseddetector in a tomographic configuration, such an approach requires illuminating the entire object, leading to an inefficientuse of the optical power, and imposing a trans-illumination configuration that is limited to thin objects. We developed anoptoacoustic micro-tomography system in an epi-illumination configuration, in which the illumination is scanned withthe detector. The system is demonstrated in phantoms for imaging depths of up to 5 mm and in vivo for imaging thevasculature of a mouse ear. Although image-formation in optoacoustic tomography generally requires static illumination,our numerical simulations and experimental measurements show that this requirement is relaxed in practice due to lightdiffusion, which homogenizes the fluence in deep tissue layers.

주파수 필터링 함수에 따른 시간 및 주파수 영역 광음향 측정에 대한 노이즈-대비-신호 분석

강동열 한국광학회 2019 한국광학회지 Vol.30 No.2

We investigate the signal-to-noise ratios (SNRs) of time-domain (i.e. pulsed illumination) and frequency-domain (i.e. chirped illumination) photoacoustic signals measured by a spherically focused ultrasound transducer for spherical absorbers. The simulation results show that the time-domain photoacoustic SNR is higher than that of frequency-domain photoacoustic signals, as reported in the previous literature. We understand the reason for this SNR gap between the two measurement modes by analyzing photoacoustic-signal spectra, considering the incident beam energy controlled by the maximum permissible exposure. As the result of this approach, we find that filtering off the DC term in the chirped signal’s spectrum improves frequency-domain photoacoustic SNRs by up to approximately 5 dB. In particular, it is observed that photoacoustic SNRs are highly sensitive to an upper-frequency value of frequency filtering functions, and the optimal upper-frequency values maximizing the SNR are different in time- and frequency-domain photoacoustic measurements.