Efficient 3-D Reconstruction in Ultrasound Elastography via a Sparse Iteration Based on Markov Random Fields

Abstract

Percutaneous needle-based liver ablation procedures are becoming increasingly common for treatment of small isolated tumors in hepatocellular carcinoma patients who are not candidates for surgery. Rapid three dimensional visualization of liver ablations has potential clinical value because it can enable interventional radiologists to plan and execute needle-based ablation procedures with real time feedback. Ensuring the right volume of tissue is ablated is desirable to avoid recurrence of tumors from residual untreated cancerous cells. Shear wave velocity measurements can be used as a surrogate for tissue stiffness to distinguish stiffer ablated regions from softer untreated tissue. This paper extends the previously reported sheaf reconstruction method to generate complete three dimensional visualizations of shear wave velocities without resorting to an approximate intermediate step of reconstructing transverse C-planes. The noisy data is modeled using a Markov random field, and a computationally tractable reconstruction algorithm that can handle grids with millions of points is developed. Results from simulated ellipsoidal inclusion data show that this algorithm outperforms standard nearest neighbor interpolation by an order of magnitude in mean squared reconstruction error. Results from phantom experiments show that it also provides a higher contrast-to-noise ratio by almost 2 dB and better SNR in the stiff inclusion by over 2 dB compared to nearest neighbor interpolation and has lower computational complexity than linear and spline interpolation.

A kernel smoothing algorithm for ablation visualization in ultrasound elastography

“…3D imaging is essential to determine if the entire tumor and surrounding margins have been successfully ablated to ensure favorable outcomes from minimally invasive procedures [20][21][22][23][24]. The algorithm described in this paper can be utilized with both current 3D ultrasound and elastographic imaging performed using a wobbler [7,16,25], two-dimensional (2D) transducer arrays [26] or other innovative approaches for 3D reconstruction [25,27,28], that are utilized in this paper.…”