A Dual-Frequency Colinear Array for Acoustic Angiography in Prostate Cancer Evaluation

Abstract

Approximately 80% of men who reach 80-years of age will have some form of prostate cancer. The challenge remains to differentiate benign and malignant lesions. Based on recent research, acoustic angiography, a novel contrast-enhanced ultrasound imaging technique, can provide high-resolution visualization of tissue microvasculature and has demonstrated the ability to differentiate vascular characteristics between healthy and tumor tissue in preclinical studies. We hypothesize that transrectal acoustic angiography may enhance the assessment of prostate cancer. In this paper, we describe the development of a dual-frequency, dual-layer co-linear array transducer for transrectal acoustic angiography. The probe consists of 64 transmitting (TX) elements with a center frequency of 3 MHz and 128 receiving (RX) elements with a center frequency of 15 MHz. The dimensions of the array are 18 mm in azimuth and 9 mm in elevation. The pitch is 280 μm for TX elements and 140 μm for RX elements. Pulse-echo tests of TX/RX elements and aperture acoustic field measurements were conducted, and the both results were compared with simulation results. Realtime contrast imaging was performed using a Verasonics system and a tissue-mimicking phantom. Non-linear acoustic responses from microbubble contrast agents at a depth of 35 mm were clearly observed. In-vivo imaging in a rodent model demonstrated the ability to detect individual vessels underneath the skin. These results indicate the potential use of the array described herein for acoustic angiography imaging of prostate tumor and identification of regions of neovascularization for the guidance of prostate biopsies.

Visualization of Microvascular Angiogenesis Using Dual-Frequency Contrast-Enhanced Acoustic Angiography: A Review

“…However, intracavity and intravascular applications of acoustic angiography have also been explored by our group and collaborators. To facilitate microvascular assessment of deep, difficult to image prostate tumors with acoustic angiography, Li et al (2018) described a colinear dual-frequency array which was tested up to 4 cm in depth in vitro and successfully detected microvasculature in vivo in a rodent model. Similarly, Lindsey et al (2017a) demonstrated the feasibility of acoustic angiography imaging with a dual-frequency endoscopic transducer for pancreatic cancer evaluation with high CTR up to 3 cm depth in vitro.…”

A Rapid Prototyping Method for Sub-MHz Single-Element Piezoelectric Transducers by Using 3D-Printed Components

“…Recent biomedical ultrasound techniques in tumor diagnosis and noninvasive therapies require complex transducer performances out of the classical categorization [ 11 , 12 , 13 , 14 ]. Thus, various customized transducers with unique specifications were developed for vascular imaging [ 15 ], drug delivery [ 16 ], immunotherapy [ 17 ], tissue ablation [ 18 ], and sonothrombolysis [ 19 ]. Although piezoelectric transducer manufacturing is already technically mature and high-end transducer customization is commercially available, long lead time (typically > 8 weeks for manufacturing) with device-packaging costs hindered prompt demonstration of new ultrasound technologies [ 20 ].…”

Ultrasound‐gated computed tomography coronary angiography: Development of ultrasound transducers with improved computed tomography compatibility

“…Because high‐density materials also have high radiopacity, this presents a challenge for developing CT‐compatible transducers. At frequencies higher than those typically used in diagnostic US imaging in humans (>15 MHz), several groups have demonstrated effective acoustic backings comprised of aluminum oxide (Al 2 O 3 ) particles in an epoxy matrix (EPO‐TEK 301) 31,34–36 . However, lower density acoustic backings such as those based on aluminum oxide have not been utilized or characterized at lower frequencies and deep penetration depth required for cardiac imaging (1–4 MHz), and the radiographic compatibility of acoustic backings has not been analyzed since the need for CT compatibility has not arisen in the past.…”

“…At frequencies higher than those typically used in diagnostic US imaging in humans (>15 MHz), several groups have demonstrated effective acoustic backings comprised of aluminum oxide (Al 2 O 3 ) particles in an epoxy matrix (EPO-TEK 301). 31,[34][35][36] However, lower density acoustic backings such as those based on aluminum oxide have not been utilized or characterized at lower frequencies and deep penetration depth required for cardiac imaging (1-4 MHz), and the radiographic compatibility of acoustic backings has not been analyzed since the need for CT compatibility has not arisen in the past. While simultaneous multimodality cardiac imaging with ultrasound and CT has not been demonstrated to our knowledge, cardiac imaging utilizing multiple modalities sequentially such as cardiac magnetic resonance imaging (CMR), echocardiography, and nuclear medicine, for example, positron emission tomography (PET) is often performed in a variety of conditions including cardiotoxicity and congenital heart disease.…”