Handheld photoacoustic imaging with an articulated arm for light delivery

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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Design of optimal light delivery system for co-registered transvaginal ultrasound and photoacoustic imaging of ovarian tissue

Photoacoustics ◽

10.1016/j.pacs.2015.08.003 ◽

2015 ◽

Vol 3 (3) ◽

pp. 114-122 ◽

Cited By ~ 23

Author(s):

Hassan S. Salehi ◽

Patrick D. Kumavor ◽

Hai Li ◽

Umar Alqasemi ◽

Tianheng Wang ◽

...

Keyword(s):

Delivery System ◽

Photoacoustic Imaging ◽

Ovarian Tissue ◽

Transvaginal Ultrasound ◽

Light Delivery

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Multiangle Long-Axis Lateral Illumination Photoacoustic Imaging Using Linear Array Transducer

Sensors ◽

10.3390/s20144052 ◽

2020 ◽

Vol 20 (14) ◽

pp. 4052

Author(s):

João H. Uliana ◽

Diego R. T. Sampaio ◽

Guilherme S. P. Fernandes ◽

María S. Brassesco ◽

Marcello H. Nogueira-Barbosa ◽

...

Keyword(s):

Fiber Bundle ◽

Linear Array ◽

Photoacoustic Imaging ◽

Signal To Noise Ratio ◽

Dark Field ◽

Bright Field ◽

Light Delivery ◽

Array Transducer ◽

Dark Field Illumination ◽

Lateral Illumination

Photoacoustic imaging (PAI) combines optical contrast with ultrasound spatial resolution and can be obtained up to a depth of a few centimeters. Hand-held PAI systems using linear array usually operate in reflection mode using a dark-field illumination scheme, where the optical fiber output is attached to both sides of the elevation plane (short-axis) of the transducer. More recently, bright-field strategies where the optical illumination is coaxial with acoustic detection have been proposed to overcome some limitations of the standard dark-field approach. In this paper, a novel multiangle long-axis lateral illumination is proposed. Monte Carlo simulations were conducted to evaluate light delivery for three different illumination schemes: bright-field, standard dark-field, and long-axis lateral illumination. Long-axis lateral illumination showed remarkable improvement in light delivery for targets with a width smaller than the transducer lateral dimension. A prototype was developed to experimentally demonstrate the feasibility of the proposed approach. In this device, the fiber bundle terminal ends are attached to both sides of the transducer’s long-axis and the illumination angle of each fiber bundle can be independently controlled. The final PA image is obtained by the coherent sum of subframes acquired using different angles. The prototype was experimentally evaluated by taking images from a phantom, a mouse abdomen, forearm, and index finger of a volunteer. The system provided light delivery enhancement taking advantage of the geometry of the target, achieving sufficient signal-to-noise ratio at clinically relevant depths.

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Improvement of light penetration in biological tissue using an ultrasound-induced heating tunnel

Scientific Reports ◽

10.1038/s41598-020-73878-4 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Zong-Han Hsieh ◽

Ching-Hsiang Fan ◽

Yi-Ju Ho ◽

Meng-Lin Li ◽

Chih-Kuang Yeh

Keyword(s):

Photothermal Therapy ◽

Focused Ultrasound ◽

Photoacoustic Imaging ◽

Biological Tissues ◽

High Intensity Focused Ultrasound ◽

Light Delivery ◽

Light Fluence ◽

Strong Scattering ◽

Delivery Efficiency ◽

Phantom Experiments

Abstract The major obstacles of optical imaging and photothermal therapy in biomedical applications is the strong scattering of light within biological tissues resulting in light defocusing and limited penetration. In this study, we propose high intensity focused ultrasound (HIFU)-induced heating tunnel to reduce the photon scattering. To verify our idea, Monte Carlo simulation and intralipid-phantom experiments were conducted. The results show that the thermal effect created by HIFU could improve the light fluence at the targeted region by 3% in both simulation and phantom experiments. Owing to the fluence increase, similar results can also be found in the photoacoustic experiments. In conclusion, our proposed method shows a noninvasive way to increase the light delivery efficiency in turbid medium. It is expected that our finding has a potential for improving the focal light delivery in photoacoustic imaging and photothermal therapy.

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Optimizing light delivery in scanning photoacoustic imaging for prostate

Optoelectronics Letters ◽

10.1007/s11801-021-0077-7 ◽

2021 ◽

Vol 17 (1) ◽

pp. 53-58

Author(s):

Dong-qing Peng ◽

Zhi-gao Liu ◽

Hui-zhen Xu ◽

Li-li Zhu ◽

Hui Li

Keyword(s):

Photoacoustic Imaging ◽

Light Delivery

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Monte Carlo simulation of light transport in tissue for optimizing light delivery in photoacoustic imaging of the sentinel lymph node

Journal of Biomedical Optics ◽

10.1117/1.jbo.18.10.106008 ◽

2013 ◽

Vol 18 (10) ◽

pp. 106008 ◽

Cited By ~ 16

Author(s):

Vijitha Periyasamy ◽

Manojit Pramanik

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

Lymph Node ◽

Sentinel Lymph Node ◽

Photoacoustic Imaging ◽

Light Transport ◽

Light Delivery

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Performance Characteristics of Photoacoustic Imaging Probes with Varying Frequencies and Light-delivery Schemes

Ultrasonic Imaging ◽

10.1177/0161734619879043 ◽

2019 ◽

Vol 41 (6) ◽

pp. 319-335 ◽

Cited By ~ 1

Author(s):

Laurie J. Rich ◽

Sarah R. Chamberlain ◽

Daniela R. Falcone ◽

Robert Bruce ◽

Andrew Heinmiller ◽

...

Keyword(s):

Fiber Optics ◽

Photoacoustic Imaging ◽

Performance Characteristics ◽

Mouse Tumor ◽

Light Penetration ◽

Delivery Method ◽

Light Delivery ◽

Imaging Resolution

Photoacoustic imaging (PAI) is an emerging biomedical imaging technique that utilizes a combination of light and ultrasound to detect photoabsorbers embedded within tissues. While the clinical utility of PAI has been widely explored for several applications, limitations in light penetration and detector sensitivity have restricted these studies to mostly superficial sites. Given the importance of PA signal generation and detection on light delivery and ultrasound detector frequency, there is an ongoing effort to optimize these parameters to enhance photoabsorber detection at increased depths. With this in mind, in this study we examined performance benchmarks of a commercially available PAI/ultrasound linear array system when using different imaging frequencies and light delivery schemes. A modified light fiber jacket providing focused light delivery (FLD) at the center of the probe was compared with the built-in fiber optics lining the length of the probe. Studies were performed in vitro to compare performance characteristics such as imaging resolution, maximum imaging depth, and sensitivity to varying hematocrit concentration for each frequency and light delivery method. Monte Carlo simulations of each light delivery method revealed increased light penetration with FLD. In tissue-mimicking phantoms, vascular channels used to simulate blood vessels could be visualized at a depth of 2.4 cm when lowering imaging frequency and utilizing FLD. Imaging at lower frequencies with FLD also enabled enhanced detection of varying hematocrit concentration levels at increased depths, although lateral imaging resolution was reduced. Finally, a proof of concept in vivo probe comparison study in a mouse tumor model provided supportive evidence of our in vitro results. Collectively, our findings show that adjusting imaging frequency and applying FLD can be a straightforward approach for improving PAI performance.

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