Refraction corrected transmission ultrasound computed tomography for application in breast imaging

Abstract

Purpose:We present an iterative framework for CT reconstruction from transmission ultrasound data which accurately and efficiently models the strong refraction effects that occur in our target application: Imaging the female breast. Methods: Our refractive ray tracing framework has its foundation in the fast marching method ͑FNMM͒ and it allows an accurate as well as efficient modeling of curved rays. We also describe a novel regularization scheme that yields further significant reconstruction quality improvements. A final contribution is the development of a realistic anthropomorphic digital breast phantom based on the NIH Visible Female data set. Results: Our system is able to resolve very fine details even in the presence of significant noise, and it reconstructs both sound speed and attenuation data. Excellent correspondence with a traditional, but significantly more computationally expensive wave equation solver is achieved. Conclusions: Apart from the accurate modeling of curved rays, decisive factors have also been our regularization scheme and the high-quality interpolation filter we have used. An added benefit of our framework is that it accelerates well on GPUs where we have shown that clinical 3D reconstruction speeds on the order of minutes are possible.

Reconstruction of Microwave Absorption Properties in Heterogeneous Tissue for Microwave-Induced Thermo-Acoustic Tomography

“…It combines FMM with SART to estimate the real SV distribution of the biological tissue. FMM-SART algorithm has been done on experimental demonstrations and simulations in UCT [18]. This approach can be described in brief as follows.…”

“…(For convenience, we note the FMM based on SART as FMM-SART algorithm). FMM-SART algorithm has been applied in ultrasound computed tomography (UCT) [17][18][19][20] and has excellent performance in solving the SV distribution.…”

Acoustic attenuation imaging of tissue bulk properties with a priori information

“…There have been several attempts to address refraction effects, accounting for attenuation due to traversed pathlength 15 and using an angular spectrum method 16 that yield some improvements in reconstruction. If one could receive an estimate of all the scattered waves from small inhomogeneities within tissue of interest as well as the scatter from the tissue's boundaries, it would be possible to make an approximate image of the tissue's absorption coefficient.…”

“…[11][12][13] There are varied approaches to ultrasound attenuation tomography of the breast, encompassing different methods of processing attenuation information given the recorded RF signal. 10,[14][15][16] However, these methods produce attenuation coefficient images that are highly affected by signal losses due to diffraction at boundaries of high sound speed or acoustic impedance change. Like pulse echo imaging, which is highly sensitive to large boundaries, rather than bulk properties of the tissues, the images are highly edge enhanced.…”

High-resolution imaging without iteration: a fast and robust method for breast ultrasound tomography

“…The dominant approach in breast UST is Time-of-Flight Tomography (TFT) 9,10,12,[17][18][19][20][21][22] which applies a ray-based approach to arrival times for transmitted signals in order to produce -either directly in the case of straight rays or with iterations for bent rays -a sound-speed map. This follows the approach in X-ray CT based reconstruction systems which can rely on simple straight ray approximations 23,24 .…”