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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
Categories In Publication

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
Categories In Publication

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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