Recent Posts

Y-NET: HYBRID DEEP LEARNING IMAGE RECONSTRUCTION FOR PHOTOACOUSTIC TOMOGRAPHY IN VIVO

Post author By PhotoSound
Post date September 21, 2023
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Author(s): Hengrong Lan, Daohuai Jiang, Changchun Yang, Feng Gao, Fei Gao

ABSTRACT

Conventional reconstruction algorithms (e.g., delay-and-sum) used in photoacoustic imaging (PAI) provide a fast solution while many artifacts remain, especially for limited-view with ill-posed problem. In this paper, we propose a new convolutional neural network (CNN) framework Y-Net: a CNN architecture to reconstruct the initial PA pressure distribution by optimizing both raw data and beamformed images once. The network combines two encoders with one decoder path, which optimally utilizes more information from raw data and beamformed image. We compared our result with some ablation studies, and the results of the test set show better performance compared with conventional reconstruction algorithms and other deep learning method (U-Net). Both in-vitro and in-vivo experiments are used to validated our method, which still performs better than other existing methods. The proposed Y-Net architecture also has high potential in medical image reconstruction for other imaging modalities beyond PAI.

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RADIATION-INDUCED ACOUSTIC SIGNAL DENOISING USING A SUPERVISED DEEP LEARNING FRAMEWORK FOR IMAGING AND THERAPY MONITORING

Post author By PhotoSound
Post date September 21, 2023
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Author(s): Zhuoran Jiang, Siqi Wang, Yifei Xu, Leshan Sun, Gilberto Gonzalez, Yong Chen, Q. Jackie Wu, Liangzhong Xiang, Lei Ren

ABSTRACT

Radiation-induced acoustic (RA) imaging is a promising technique for visualizing radiation energy deposition in tissues, enabling new imaging modalities and real-time therapy monitoring. However, it requires measuring hundreds or even thousands of averages to achieve satisfactory signal-to-noise ratios (SNRs). This repetitive measurement increases ionizing radiation dose and degrades the temporal resolution of RA imaging, limiting its clinical utility. In this study, we developed a general deep inception convolutional neural network (GDI-CNN) to denoise RA signals to substantially reduce the number of averages. The multi-dilation convolutions in the network allow for encoding and decoding signal features with varying temporal characteristics, making the network generalizable to signals from different radiation sources. The proposed method was evaluated using experimental data of X-ray-induced acoustic, protoacoustic, and electroacoustic signals, qualitatively and quantitatively. Results demonstrated the effectiveness and generalizability of GDI-CNN: for all the enrolled RA modalities, GDI-CNN achieved comparable SNRs to the fully-averaged signals using less than 2% of the averages, significantly reducing imaging dose and improving temporal resolution. The proposed deep learning framework is a general method for few-frame-averaged acoustic signal denoising, which significantly improves RA imaging’s clinical utilities for low-dose imaging and real-time therapy monitoring.

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AUTOMATIC FORCE-CONTROLLED 3D PHOTOACOUSTIC SYSTEM FOR HUMAN PERIPHERAL VASCULAR IMAGING

Post author By PhotoSound
Post date September 21, 2023
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Author(s): David C. Garrett, Jinhua Xu, Geng Ku, and Lihong V. Wang

ABSTRACT

We developed a system for whole-body human ultrasound tomography in reflection and transmission modes. A custom 512-element ultrasound receiver array with a rotating single-element ultrasound transmitter are used to generate 2D isotropically resolved images across the entire human cross-section. We demonstrate this technique in regions such as the abdomen and legs in healthy volunteers. Compared to handheld-probe-based ultrasonography, this approach provides a substantially larger field of view, depends less on operator training, and obtains quantitative tissue parameter profiles in addition to reflectivity images. Whole-body ultrasound tomography could be valuable in applications such as organ disease screening, image-guided needle biopsy, and treatment monitoring.

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DUAL-SCAN PHOTOACOUSTIC TOMOGRAPHY FOR THE IMAGING OF VASCULAR STRUCTURE ON FOOT

Post author By PhotoSound
Post date September 20, 2023
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Author(s): Chuqin Huang, Yanda Cheng, Wenhan Zheng, Robert W Bing, Huijuan Zhang, Isabel Komornicki, Linda M Harris, Praveen R Arany, Saptarshi Chakraborty, Qifa Zhou, Wenyao Xu, Jun Xia

ABSTRACT

Chronic leg ulcers are affecting approximately 6.5 million Americans, and they are associated with significant mortality, reduced quality of life, and high treatment costs. Since many chronic ulcers have underlying vascular insufficiency, accurate assessment of tissue perfusion is critical to treatment planning and monitoring. This study introduces a dual-scan photoacoustic tomography system that can simultaneously image the dorsal and plantar sides of the foot to reduce imaging time. To account for the unique shape of the foot, the system employs height-adjustable and articulating base ball stages that can scan along the foot’s contour. In vivo results from healthy volunteers demonstrate the system’s ability to acquire clear images of foot vasculature, and results from patients indicate that the system can image patients with various ulcer conditions. We also investigated various photoacoustic features and examined their correlation with the foot condition. Our preliminary results indicate that vessel sharpness, occupancy, intensity, and density could all be used to assess tissue perfusion. This research demonstrated the potential of photoacoustic tomography for routine clinical tissue perfusion assessment.

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EVALUATION OF ULTRASOUND SENSORS FOR TRANSCRANIAL PHOTOACOUSTIC SENSING AND IMAGING

Post author By PhotoSound
Post date September 20, 2023
Categories In Publication

Author(s): Thomas Kirchner, Claus Villringer, and Jan Laufer

ABSTRACT

Significance: Biomedical photoacoustic (PA) imaging is typically used to exploit absorption-based contrast in soft tissue at depths of several centimeters. When it is applied to measuring PA waves generated in the brain, the acoustic properties of the skull bone cause not only strong attenuation but also a distortion of the wavefront, which diminishes image resolution and contrast. This effect is directly proportional to bone thickness. As a result, transcranial PA imaging in humans has been challenging to demonstrate.
Aim: We measured the acoustic constraints imposed by the human skull to design an ultrasound sensor suitable for transcranial PA imaging and sensing.
Approach: We calculated the frequency dependent losses of human cranial bones in silico and performed measurements ex vivo using broadband ultrasound sources based on PA excitation, such as a single vessel phantom with tissue-mimicking optical absorption. We imaged the phantoms using a planar Fabry-Perot sensor and employed a range of piezoelectric and optical ultrasound sensors to measure the frequency dependent acoustic transmission through human cranial bone.
Results: Transcranial PA images show typical frequency and thickness-dependent attenuation and aberration effects associated with acoustic propagation through bone. The skull insertion loss measurements showed significant transmission at low frequencies. In comparison to conventional piezoelectric sensors, the performance of plano-concave optical resonator (PCOR) ultrasound sensors was found to be highly suitable for transcranial PA measurements. They possess high acoustic sensitivity at a low acoustic frequency range that coincides with the transmission window of
human skull bone. PCOR sensors showed low noise equivalent pressures and flat frequency response which enabled them to outperform conventional piezoelectric transducers in transcranial PA sensing experiments.
Conclusions: Transcranial PA sensing and imaging requires ultrasound sensors with high sensitivity at low acoustic frequencies, and a broad and ideally uniform frequency response. We designed and fabricated PCOR sensors and demonstrated their suitability for transcranial PA sensing.

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HIGH-SPEED THREE-DIMENSIONAL PHOTOACOUSTIC COMPUTED TOMOGRAPHY FOR PRECLINICAL RESEARCH AND CLINICAL TRANSLATION

Post author By PhotoSound
Post date September 19, 2023
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Authors: Li Lin, Peng Hu, Xin Tong, Rui Cao, Xiaoyun Yuan, David C. Garrett, Junhui Shi, Konstantin Maslov & Lihong V. Wang

ABSTRACT

Photoacoustic computed tomography (PACT) has generated increasing interest for uses in preclinical research and clinical translation. However, the imaging depth, speed, and quality of existing PACT systems have previously limited the potential applications of this technology.
To overcome these issues, we developed a three-dimensional photoacoustic computed tomography (3D-PACT) system that features large imaging depth, scalable field of view with isotropic spatial resolution, high imaging speed, and superior image quality. 3D-PACT allows for multipurpose imaging to reveal detailed angiographic information in biological tissues ranging from the rodent brain to the human breast. In the rat brain, we visualize whole brain vasculatures and hemodynamics. In the human breast, an in vivo imaging depth of 4 cm is achieved by scanning the breast within a single breath hold of 10 s. Here, we introduce the 3D-PACT system to provide a unique tool for preclinical research and an appealing prototype for clinical translation.

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