Semi-anthropomorphic photoacoustic breast phantom.

Maura Dantuma,Srirang Manohar,Rianne van Dommelen

doi:10.1364/boe.10.005921

Abstract

Imaging parameters of photoacoustic breast imaging systems such as the spatial resolution and imaging depth are often characterized with phantoms. These objects usually contain simple structures in homogeneous media such as absorbing wires or spherical objects in scattering gels. While these kinds of basic phantoms are uncluttered and useful, they do not challenge the system as much as a breast does, and can thereby overestimate the system's performance. The female breast is a complex collection of tissue types, and the acoustic and optical attenuation of these tissues limit the imaging depth, the resolution and the ability to extract quantitative information. For testing and challenging photoacoustic breast imaging systems to the full extent before moving to in vivo studies, a complex breast phantom which simulates the breast's most prevalent tissues is required. In this work we present the first three dimensional multi-layered semi-anthropomorphic photoacoustic breast phantom. The phantom aims to simulate skin, fat, fibroglandular tissue and blood vessels. The latter three are made from custom polyvinyl chloride plastisol (PVCP) formulations and are appropriately doped with additives to obtain tissue realistic acoustic and optical properties. Two tumors are embedded, which are modeled as clusters of small blood vessels. The PVCP materials are surrounded by a silicon layer mimicking the skin. The tissue mimicking materials were cast into the shapes and sizes expected in the breast using 3D-printed moulds developed from a magnetic resonance imaging segmented numerical breast model. The various structures and layers were assembled to obtain a realistic breast morphology. We demonstrate the phantom's appearance in both ultrasound imaging as photoacoustic tomography and make a comparison with a photoacoustic image of a real breast. A good correspondence is observed, which confirms the phantom's usefulness.

Highlights

A combination of imaging techniques is nowadays used for breast cancer diagnosis
Multiple studies have shown that US does have a good performance in dense breasts and that the addition of this technique to MMG decreases the false positive (FP) and false negative (FN) rates
The diagnostic work-up is extended with contrast enhanced magnetic resonance imaging (CE-MRI) when MMG and US do not lead to a decisive conclusion

Summary

Introduction

A combination of imaging techniques is nowadays used for breast cancer diagnosis. X-ray mammography (MMG) and/or ultrasound (US) imaging are almost always used and have been shown to decrease the breast cancer mortality [1]. The sensitivity is even lower in women with dense breasts (30-48%) due to the low radiographic contrast [1,3]. Multiple studies have shown that US does have a good performance in dense breasts and that the addition of this technique to MMG decreases the false positive (FP) and false negative (FN) rates. CE-MRI has a higher sensitivity than MMG and is not affected by breast density, but has a limited specificity [4]. MRI is relatively expensive, has a limited accessibility and requires the injection of contrast agents [1]. As a result of these demerits, the search for non-invasive imaging techniques that may complement or substitute the current techniques is ongoing

Methods

Results

Conclusion