Quantitative transmission ultrasound tomography: Imaging and performance characteristics.

Bilal Malik,Mark Lenox,Robin Terry,James Wiskin

doi:10.1002/mp.12957

Abstract

PurposeQuantitative Transmission (QT) ultrasound has shown promise as a breast imaging modality. This study characterizes the performance of the latest generation of QT ultrasound scanners: QT Scanner 2000.MethodsThe scanner consists of a 2048‐element ultrasound receiver array for transmission imaging and three transceivers for reflection imaging. Custom fabricated phantoms were used to quantify the imaging performance parameters. The specific performance parameters that have been characterized are spatial resolution (as point spread function), linear measurement accuracy, contrast to noise ratio, and image uniformity, in both transmission and reflection imaging modalities.ResultsThe intrinsic in‐plane resolution was measured to be better than 1.5 mm and 1.0 mm for transmission and reflection modalities respectively. The linear measurement accuracy was measured to be, on average, approximately 1% for both the modalities. Speed of sound image uniformity and measurement accuracy were calculated to be 99.5% and <0.2% respectively. Contrast to noise ratio (CNR) measurements vary as a function of object size.ConclusionsThe results show an improvement in the imaging performance of the system in comparison to earlier ultrasound tomography systems, which are applicable to clinical applications of the system, such as breast imaging.

Highlights

The idea of ultrasound tomography has been an object of research since the paper of Wild and Reid.[1]
Other early work included that at General Electric and the University of Colorado.[4,5]. This was followed by research at the University of Utah resulting in several papers and dissertations from the Johnson Advanced Imaging Methods (AIM) Lab in the Department of Bioengineering at University of Utah.[6,7]
These images of tissue characteristics were low resolution and crude by today’s standards, they showed that quantitative information could be a valuable adjunct to standard hand-held ultrasound (HHUS) — i.e. B-mode images

Summary

INTRODUCTION

The idea of ultrasound tomography has been an object of research since the paper of Wild and Reid.[1]. Linear approximations to the forward scattering problem in the Lippmann-Schwinger equation lead to the Born or Rytov approximations These have been investigated by Lavarello et al in 2D and 3D, and others.[16,17] these methods fail for the contrast and size of the human breast.[18,19] Attempts to carry these ideas to higher order, the so-called “distorted wave Born inversions”, have not been as successful as required for clinical use. A previous paper made an initial attempt to reconcile these issues.[22] That initial work combined with recent interaction with the FDA performed for the purposes of 510(k) approval has resulted in the development of a series of performance tests that are comprehensive and can form the basis for future regulatory guidance as well as industry standards In this new series of tests, we evaluate both accuracy and precision of the system to measure quantitative values as well as spatial information. More typical tomographic measurements like uniformity, contrast-to-noise, and spatial resolution/point-spread-function (PSF) are measured for both transmission and reflection modalities

MATERIALS AND METHODS

AND DISCUSSION

CONCLUSION