Research Papers on Anders E. Vrålstad Portfolio

Coherence-Based Sound Speed Aberration Correction — With Clinical Validation in Fetal Ultrasound

Fri, 08 May 2026 00:00:00 +0000

Anders Emil Vrålstad, Peter Fosodeder, Karin Ulrike Deibele, Siri Ann Nyrnes, Ole-Marius Hoel Rindal, Vibeke Skoura-Torvik, Martin Mienkina and Svein-Erik Måsøy.

The preprint is published on arXiv. The full peer-reviewed paper is published in IEEE Transactions on Medical Imaging, found here. The abstract and supplementary GIF images are found below.

Abstract

The purpose of this work is to demonstrate a robust and clinically validated method for correcting sound speed aberrations in medical ultrasound. We propose a correction method that calculates the focus delays directly from the observed two-way distributed average sound speed. The method beamforms multiple coherence images and selects the sound speed that maximizes the coherence for each image pixel. The main contribution of this work is the direct estimation of aberration, without the ill-conditioned inversion of a local sound speed map, and the proposed processing of coherence images, which adapts to in vivo situations where low coherent regions and off-axis scattering represent a challenge. The method is validated in vitro and in silico showing a high correlation with the ground truth speed of sound maps. Further, the method is clinically validated by being applied to channel data recorded from 172 fetal Bmode images, and 12 case examples are presented and discussed in detail. The data is recorded with a GE HealthCare Voluson Expert 22 system with an eM6c matrix array probe. The images are evaluated by three expert clinicians, and the results show that the corrected images are preferred or gave a quality equivalent to that without correction (1540 m/s) for 72.5% of the 172 images. In addition, a sharpness metric from digital photography is used to quantify image quality improvement. The increase in sharpness and the change in average sound speed are shown to be linearly correlated with a Pearson Correlation Coefficient of 0.67.

Retrospective Transmit Correction of Blocked Arrays Applied to Cardiac Ultrasound Imaging

Mon, 27 Apr 2026 00:00:00 +0000

A new paper I worked on after my PhD is now publised in IEEE Transactions on Ultrasonics. The title of the paper is “Retrospective Transmit Correction of Blocked Arrays Applied to Cardiac Ultrasound Imaging”. Read the paper here.

The code for creating the simulations are found at the USTB website by following this link.

Sound Speed and Virtual Source Correction in Synthetic Transmit Focusing

Mon, 10 Jun 2024 00:00:00 +0000

My first paper for my PhD is called “Sound Speed and Virtual Source Correction in Synthetic Transmit Focusing” and is published in IEEE Open Journal of Ultrasonics, Ferroelectrics, and Frequency Control (Volume 4).

Read the open-access article here.

Universal REFoCUS Beamforming With Spatial Weighting

Wed, 08 May 2024 00:00:00 +0000

My second paper for my PhD is called “Universal REFoCUS Beamforming With Spatial Weighting” and is published in IEEE Open Journal of Ultrasonics, Ferroelectrics, and Frequency Control (Volume 4).

Read the open-access article here.