The purpose of this study is to develop and validate rapid magnetic resonance acoustic radiation force imaging (MR-ARFI) using a single shot spiral readout for focused ultrasound (FUS) guidance and for local tissue displacement measurements. A magnetic resonance guided FUS system was used to focus a 3 MHz ultrasound beam to a predetermined position. MR-ARFI was performed with a Bruker 7 T MRI using a modified single-shot spiral readout, with additional motion encoding gradients that convert local displacement into the phase image. Post processing was then used to analyze the resulting displacement and to evaluate the method's performance for the detection of tissue changes resulting from thermal ablation. The single-shot spiral readout acquires a single MR-ARFI image in one second, which is up to two orders of magnitude faster than conventional 2D spin-warp spin echo that acquires the k-space data line by line. The ARFI displacement in tissue mimicking phantoms was detected and localized with less than 5% geometric distortion. The ARFI displacement was also measured pre and post thermal ablation in an ex vivo chicken breast. For transmitted peak negative pressure of 8.6 MPa, the maximum displacement of the tissue that was ablated to 70 °C was 78% lower than the pre-ablated tissue. Since spiral readout is not prone to geometrical distortion, it is well-suited for FUS guidance, without generating undesired temperature elevation. Additionally, local displacement measurements of tissues can be performed rapidly during thermal ablation procedures and may help to assess the success of the treatment.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6800020 | PMC |
http://dx.doi.org/10.1088/1361-6560/ab1e21 | DOI Listing |
Optical approaches have made great strides towards the goal of high-speed, energy-efficient computing necessary for modern deep learning and AI applications. Read-in and read-out of data, however, limit the overall performance of existing approaches. This study introduces a multilayer optoelectronic computing framework that alternates between optical and optoelectronic layers to implement matrix-vector multiplications and rectified linear functions, respectively.
View Article and Find Full Text PDFMagn Reson Med
November 2024
Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
Magn Reson Med
March 2025
Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK.
Magn Reson Med
February 2025
Department of Health Technology, Technical University of Denmark, Kgs. Lyngby, Denmark.
Purpose: This study aims to show the viability of conducting three-dimensional (3D) myocardial perfusion quantification covering the entire heart using both GRE and bSSFP sequences with hyperpolarized HP001.
Methods: A GRE sequence and a bSSFP sequence, both with a stack-of-spirals readout, were designed and applied to three pigs. The images were reconstructed using C coil sensitivity maps measured in a phantom experiment.
J Cardiovasc Magn Reson
December 2024
Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark.
Background: Hyperpolarized [1-C]pyruvate cardiovascular magnetic resonance imaging (HP [1-C]pyruvate CMR) visualizes key steps in myocardial metabolism. The present study aimed to examine patients with heart failure (HF) using HP [1-C]pyruvate CMR.
Methods: A cross-sectional study of patients with HF and healthy controls using HP [1-C]pyruvate CMR.
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!