scholarly journals Fabrication of Coaxial and Confocal Transducer Based on Sol-Gel Composite Material for Optical Resolution Photoacoustic Microscopy

Diagnostics ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Masayuki Tanabe ◽  
Tai Chieh Wu ◽  
Makiko Kobayashi ◽  
Che Hua Yang
Keyword(s):  
Ex Vivo ◽  
Photoacoustic Imaging ◽  
Sol Gel ◽  
Optical Resolution ◽  
Maximum Amplitude ◽  
Photoacoustic Signal ◽  
Center Frequency ◽  
Photoacoustic Microscopy ◽  
3 Dimensional ◽  
Pulse Echo

We have newly developed coaxial and confocal optical-resolution photoacoustic microscopy based on sol-gel composite materials. This transducer contains a concave-shaped piezoelectric layer with a focus depth of 5 mm and a hole with a diameter of 3 mm at the center to pass a laser beam into a phantom. Therefore, this system can directly detect an excited photoacoustic signal without prisms or acoustic lenses. We demonstrate the capability of the system through pulse-echo and photoacoustic imaging experiments. The center frequency of the fabricated transducer is approximately 7 MHz, and its relative bandwidth is 86%. An ex-vivo experiment is conducted, and photoacoustic signals are clearly obtained. As a result, 2- and 3-dimensional maximum amplitude projection images are reconstructed.

scholarly journals Photoacoustic imaging of 3D-printed vascular networks

2022 ◽  
Author(s):  
Chenshuo Ma ◽  
Wanlu Li ◽  
Daiwei Li ◽  
Maomao Chen ◽  
Mian Wang ◽  
...  
Keyword(s):  
3D Printing ◽  
Photoacoustic Imaging ◽  
Optical Resolution ◽  
Blood Oxygenation ◽  
Circulation System ◽  
Photoacoustic Microscopy ◽  
Label Free ◽  
Digital Light Processing ◽  
3D Printed

Abstract Thrombosis in the circulation system can lead to major myocardial infarction and cardiovascular deaths. Understanding thrombosis formation is necessary for developing safe and effective treatments. In this work, using digital light processing (DLP)-based 3D printing, we fabricated sophisticated in vitro models of blood vessels with internal microchannels that can be used for thrombosis studies. In this regard, photoacoustic microscopy (PAM) offers a unique advantage for label-free visualization of the 3D-printed vessel models, with large penetration depth and functional sensitivity. We compared the imaging performances of two PAM implementations: optical-resolution PAM and acoustic-resolution PAM, and investigated 3D printed- vessel structures with different patterns of microchannels. Our results show that PAM can provide clear microchannel structures at depths up to 3.6 mm. We further quantified the blood oxygenation in the 3D-printed vascular models, showing that thrombi had lower oxygenation than the normal blood. We expect that PAM can find broad applications in 3D printing and bioprinting for in vitro studies of various vascular and other diseases.

scholarly journals Method for the biomechanical analysis of aqueous veins and perilimbal sclera by three-dimensional photoacoustic imaging and strain field calculation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Linyu Ni ◽  
John Riesterer ◽  
Huaizhou Wang ◽  
Layla Berry ◽  
Kara Blackburn ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Photoacoustic Imaging ◽  
Three Dimensional ◽  
Optical Resolution ◽  
Element Model ◽  
Biological Tissues ◽  
Biomechanical Analysis ◽  
Field Calculation ◽  
Photoacoustic Microscopy ◽  
Strain Calculation

AbstractA method motivated by the eye’s aqueous veins is described for the imaging and strain calculation within soft biological tissues. A challenge to the investigation of the biomechanics of the aqueous vein—perilimbal sclera tissue complex is resolution of tissue deformations as a function of intraocular pressure and the subsequent calculation of strain (a normalized measure of deformation). The method involves perfusion of the eye with a contrast agent during conduction of non-invasive, optical resolution photoacoustic microscopy. This imaging technique permits three-dimensional displacement measurements of tracked points on the inner walls of the veins which are used in a finite element model to determine the corresponding strains. The methods are validated against two standard strain measurement methods. Representative porcine globe perfusion experiments are presented that demonstrate the power of the method to determine complex strain fields in the veins dependent on intraocular pressure as well as vein anatomy. In these cases, veins are observed to move radially outward during increases in intraocular pressure and to possess significant spatial strain variation, possibly influenced by their branching patterns. To the authors’ knowledge, these are the only such quantitative, data driven, calculations of the aqueous vein strains available in the open literature.

scholarly journals Detection of Melanoma Metastases in Resected Human Lymph Nodes by Noninvasive Multispectral Photoacoustic Imaging

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Gerrit Cornelis Langhout ◽  
Diederik Johannes Grootendorst ◽  
Omgo Edo Nieweg ◽  
Michel Wilhelmus Jacobus Maria Wouters ◽  
Jos Alexander van der Hage ◽  
...  
Keyword(s):  
Lymph Nodes ◽  
Sentinel Node ◽  
Near Infrared ◽  
Ex Vivo ◽  
Photoacoustic Imaging ◽  
Frozen Section ◽  
Photoacoustic Signal ◽  
Melanoma Metastasis ◽  
Prognostic Information ◽  
Melanoma Metastases

Objective. Sentinel node biopsy in patients with cutaneous melanoma improves staging, provides prognostic information, and leads to an increased survival in node-positive patients. However, frozen section analysis of the sentinel node is not reliable and definitive histopathology evaluation requires days, preventing intraoperative decision-making and immediate therapy. Photoacoustic imaging can evaluate intact lymph nodes, but specificity can be hampered by other absorbers such as hemoglobin. Near infrared multispectral photoacoustic imaging is a new approach that has the potential to selectively detect melanin. The purpose of the present study is to examine the potential of multispectral photoacoustic imaging to identify melanoma metastasis in human lymph nodes.Methods. Three metastatic and nine benign lymph nodes from eight melanoma patients were scannedex vivousing a Vevo LAZR©multispectral photoacoustic imager and were spectrally analyzed per pixel. The results were compared to histopathology as gold standard.Results. The nodal volume could be scanned within 20 minutes. An unmixing procedure was proposed to identify melanoma metastases with multispectral photoacoustic imaging. Ultrasound overlay enabled anatomical correlation. The penetration depth of the photoacoustic signal was up to 2 cm.Conclusion. Multispectral three-dimensional photoacoustic imaging allowed for selective identification of melanoma metastases in human lymph nodes.

scholarly journals Feasibility Study of Precise Balloon Catheter Tracking and Visualization with Fast Photoacoustic Microscopy

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5585
Author(s):  
Jahae Kim ◽  
Thi Thao Mai ◽  
Jin Young Kim ◽  
Jung-Joon Min ◽  
Chulhong Kim ◽  
...  
Keyword(s):  
Feasibility Study ◽  
Ex Vivo ◽  
Balloon Catheter ◽  
Maximum Amplitude ◽  
Arterial Stenosis ◽  
Imaging Method ◽  
Photoacoustic Microscopy ◽  
Depth Of Penetration ◽  
Cross Sectional ◽  
Catheter Tracking

Correct guiding of the catheter is a critical issue in almost all balloon catheter applications, including arterial stenosis expansion, coronary arterial diseases, and gastrointestinal tracking. To achieve safe and precise guiding of the balloon catheter, a novel imaging method with high-resolution, sufficient depth of penetration, and real-time display is required. Here, we present a new balloon catheter guiding method using fast photoacoustic microscopy (PAM) technique for precise balloon catheter tracking and visualization as a feasibility study. We implemented ex vivo and in vivo experiments with three different medium conditions of balloon catheter: no air, air, and water. Acquired cross-sectional, maximum amplitude projection (MAP), and volumetric 3D PAM images demonstrated its capability as a new imaging guiding tool for balloon catheter tracking and visualization.

scholarly journals 3-Dimensional ventricular electrical activation pattern assessed from a novel high-frequency electrocardiographic imaging technique: principles and clinical importance

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pavel Jurak ◽  
Laura R. Bear ◽  
Uyên Châu Nguyên ◽  
Ivo Viscor ◽  
Petr Andrla ◽  
...  
Keyword(s):  
High Frequency ◽  
Ex Vivo ◽  
Clinical Importance ◽  
Electrical Activation ◽  
Bundle Branch Block ◽  
Electrocardiographic Imaging ◽  
3 Dimensional ◽  
Intraventricular Conduction ◽  
Clinical Measurements ◽  
Activation Times

AbstractThe study introduces and validates a novel high-frequency (100–400 Hz bandwidth, 2 kHz sampling frequency) electrocardiographic imaging (HFECGI) technique that measures intramural ventricular electrical activation. Ex-vivo experiments and clinical measurements were employed. Ex-vivo, two pig hearts were suspended in a human-torso shaped tank using surface tank electrodes, epicardial electrode sock, and plunge electrodes. We compared conventional epicardial electrocardiographic imaging (ECGI) with intramural activation by HFECGI and verified with sock and plunge electrodes. Clinical importance of HFECGI measurements was performed on 14 patients with variable conduction abnormalities. From 3 × 4 needle and 108 sock electrodes, 256 torso or 184 body surface electrodes records, transmural activation times, sock epicardial activation times, ECGI-derived activation times, and high-frequency activation times were computed. The ex-vivo transmural measurements showed that HFECGI measures intramural electrical activation, and ECGI-HFECGI activation times differences indicate endo-to-epi or epi-to-endo conduction direction. HFECGI-derived volumetric dyssynchrony was significantly lower than epicardial ECGI dyssynchrony. HFECGI dyssynchrony was able to distinguish between intraventricular conduction disturbance and bundle branch block patients.

scholarly journals Ex-Vivo Measurement of the pH in Aqueous Humor Samples by a Tapered Fiber-Optic Sensor

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5075
Author(s):  
Ondřej Podrazký ◽  
Jan Mrázek ◽  
Jana Proboštová ◽  
Soňa Vytykáčová ◽  
Ivan Kašík ◽  
...  
Keyword(s):  
Cataract Surgery ◽  
Aqueous Humor ◽  
Fiber Optic ◽  
Ex Vivo ◽  
Sol Gel ◽  
Ph Sensor ◽  
Fiber Optic Sensor ◽  
Optic Sensor ◽  
Tapered Optical Fiber ◽  
Practical Demonstration

A practical demonstration of pH measurement in real biological samples with an in-house developed fiber-optic pH sensor system is presented. The sensor uses 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) fluorescent dye as the opto-chemical transducer. The dye is immobilized in a hybrid sol-gel matrix at the tip of a tapered optical fiber. We used 405 nm and 450 nm laser diodes for the dye excitation and a photomultiplier tube as a detector. The sensor was used for the measurement of pH in human aqueous humor samples during cataract surgery. Two groups of patients were tested, one underwent conventional phacoemulsification removal of the lens while the other was subjected to femtosecond laser assisted cataract surgery (FLACS). The precision of the measurement was ±0.04 pH units. The average pH of the aqueous humor of patients subjected to FLACS and those subjected to phacoemulsification were 7.24 ± 0.17 and 7.31 ± 0.20 respectively.

scholarly journals Towards Transabdominal Functional Photoacoustic Imaging of the Placenta: Improvement in Imaging Depth Through Optimization of Light Delivery

2021 ◽  
Author(s):  
Kristie Huda ◽  
Kenneth F. Swan ◽  
Cecilia T. Gambala ◽  
Gabriella C. Pridjian ◽  
Carolyn L. Bayer
Keyword(s):  
Delivery System ◽  
Light Propagation ◽  
Ex Vivo ◽  
Photoacoustic Imaging ◽  
Incidence Angle ◽  
Incident Angle ◽  
Placental Tissue ◽  
Light Delivery ◽  
Imaging Depth ◽  
The Impact

AbstractFunctional photoacoustic imaging of the placenta could provide an innovative tool to diagnose preeclampsia, monitor fetal growth restriction, and determine the developmental impacts of gestational diabetes. However, transabdominal photoacoustic imaging is limited in imaging depth due to the tissue’s scattering and absorption of light. The aim of this paper was to investigate the impact of geometry and wavelength on transabdominal light delivery. Our methods included the development of a multilayer model of the abdominal tissue and simulation of the light propagation using Monte Carlo methods. A bifurcated light source with varying incident angle of light, distance between light beams, and beam area was simulated to analyze the effect of light delivery geometry on the fluence distribution at depth. The impact of wavelength and the effects of variable thicknesses of adipose tissue and muscle were also studied. Our results showed that the beam area plays a major role in improving the delivery of light to deep tissue, in comparison to light incidence angle or distance between the bifurcated fibers. Longer wavelengths, with incident fluence at the maximum permissible exposure limit, also increases fluence within deeper tissue. We validated our simulations using a commercially available light delivery system and ex vivo human placental tissue. Additionally, we compared our optimized light delivery to a commercially available light delivery system, and conclude that our optimized geometry could improve imaging depth more than 1.6×, bringing the imaging depth to within the needed range for transabdominal imaging of the human placenta.

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