2011 Joint AAPM/COMP Meeting
Michael Andre, PhD, FAIUM, University of California, San Diego and VA San Diego
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The basic imaging paradigm of medical US has remained unchanged, namely image formation
results from transmission-reception of 180 degree backscatter assuming straight-line
propagation. Our group has developed Quantitative Ultrasound CT (USCT) that creates images
of the breast from the full 3D scatter field including both transmitted and reflected signals. While
modern US provides a two-dimensional map of relative tissue “echogenicity,” USCT computes
quantitative 3D maps of tissue acoustic properties including sound speed, attenuation, scatter
density, etc., as approximations of components of the wave equation. The method corrects for
refraction, absorption, multiple scattering and more. High resolution reflection tomography is
performed in which the sound speed and attenuation maps are utilized for aberration correction
to significantly improve image quality. Clinical measurements suggest that in breast tissue,
benign lesions and cancerous lesions may be identified by these inherent acoustic. The scanner
uses a multi-frequency non-linear 3D inverse-scattering algorithm and despite the historical
computational complexity of the problem, our method is fast and practical. Conventional breast
sonography is a notoriously difficult exam to perform; the quality is dependent on the skill of the
operator as well as technical features of the scanner. In order to obtain the needed high
resolution, the field of view in sonography is very small, which greatly complicates
interpretation and localization of masses. USCT promises an automated whole-breast scan
providing a global view of the entire breast in 3D, facilitating comparison to prior exams in a
reproducible geometry. Results of our trial with over 150 subjects with confirmed breast masses
will be presented with detailed comparison to conventional sonography and MRI.
Learning Objectives:
1. Understand the principles of inverse-scatter tomography.
2. Understand the unique data acquisition and processing applied in ultrasound computed
tomography.
3. Understand the potential clinical advantages of quantitative whole breast ultrasound
imaging.
