A5054222841- Advanced MRI Techniques and Applications
- Advanced NMR Techniques and Applications
- Electron Spin Resonance Studies
- Atomic and Subatomic Physics Research
- Ultrasound and Hyperthermia Applications
- VLSI and Analog Circuit Testing
- Integrated Circuits and Semiconductor Failure Analysis
- Lanthanide and Transition Metal Complexes
- Ultrasound Imaging and Elastography
Technical University of Denmark
2020-2025
<title>Abstract</title> Hyperpolarized Magnetic Resonance Imaging (HypMRI) offers valuable insights into dynamic physiological processes <italic>in vivo</italic>. We introduce hyperpolarized <sup>15</sup>N,d<sub>9</sub>-Betaine (trimethyl-<sup>2</sup>H<sub>9</sub>-<sup>15</sup>N-glycine) as an endogenous MRI contrast agent with a long-lived signal suited for comprehensive molecular tracking. With detectable vivo</italic> lasting more than 14 minutes and high polarization efficiency, supports...
Acute ischemic stroke patients benefit from reperfusion in a short time-window after debut. Later treatment may be indicated if viable brain tissue is demonstrated and this outweighs the inherent risks of late reperfusion. Magnetic resonance imaging (MRI) with hyperpolarized [1-13C]pyruvate an emerging technology that directly images metabolism. Here, we investigated its potential to detect stroke. Stroke was induced pigs by intracerebral injection endothelin 1. During ischemia, rate...
Purpose To develop a coil‐based method to obtain accurate sensitivity profiles in 13 C MRI at 3T from the endogenous 23 Na. An eight‐channel array is designed for MR acquisitions. As application examples, used two‐fold accelerated acquisitions of both hyperpolarized metabolic imaging pig kidneys and human brain. Methods A flexible coil was tuned optimally (32.1 MHz), with coupling coefficients matched be nearly identical resonance frequency Na (33.8 MHz). This done by enforcing high...
A quality assurance protocol for RF coils is proposed, which can be used volume (Tx/Rx) and surface (Rx) coils. Following this protocol, a benchmarking of seven (from three different MR sites) dedicated to 13C MRI at 3T reported. Coil performance particularly important the frequency, since coil-to-sample noise ratio typically high. The are evaluated experimentally using proposed based on spectroscopic imaging performed with two phantoms: one head-shaped, cylindrical shape nearly twice first...
Purpose: Water freely diffuses across cell membranes, making it suitable for measuring absolute tissue perfusion. In this study, we introduce an imaging method conducting coronary artery angiography and quantifying myocardial perfusion the entire heart using hyperpolarized water. Methods: 1H was dissolution dynamic nuclear polarization (dDNP) with UV-generated radicals. Submillimeter resolution images were acquired as 2D projections a spoiled GRE (SPGRE) sequence gated on diastole. Dynamic...
Purpose To test a new parallel imaging strategy for acceleration of hyperpolarized 13 C MR acquisitions based on 3D blipped stack‐of‐spirals trajectory and conjugate‐gradient SENSE reconstruction with precalibrated sensitivities. Methods The was developed an factor 4, undersampled gradient blips during spiral readout. volumetric coverage large FOV high spatial resolution. High temporal resolution attained through spectral‐spatial excitation 4 excitations per volume. evaluated in simulations...
Purpose This article presents a novel 14‐channel receive‐only array for 13 C human head imaging at 3 T that explores the SNR gain by operating cryogenic temperature cooled liquid nitrogen. Methods Cryostats are developed to evaluate single‐coil bench performance and cool with nitrogen while having enough thermal insulation between coils sample. The distribution coil is measured. Circuits adapted −189°C environment implemented in array. images acquired room 3T scanner. Results Compared...
We propose a 3D gradient echo sequence with hyperpolarized HP001 as contrast agent for whole heart myocardial perfusion quantification. The estimated values are correlated the from dynamic enhanced (DCE)-MRI.
As an alternative to Gadolinium, metabolically inert hyperpolarized contrast agents have been used in perfusion studies. For myocardial measurements, it is challenging reliably obtain perfusion-related signals due partial volume effects. We propose a constrained decomposition approach, enforcing prior knowledge of the residue function being temporally decreasing. The method capable separating arterial and components quantified map not visibly affected by
Abstract Purpose This study aims to show the viability of conducting three‐dimensional (3D) myocardial perfusion quantification covering entire heart using both GRE and bSSFP sequences with hyperpolarized HP001. Methods A sequence a sequence, stack‐of‐spirals readout, were designed applied three pigs. The images reconstructed C coil sensitivity maps measured in phantom experiment. Perfusion was quantified constrained decomposition method, estimated rest/stress values from GRE/bSSFP Dynamic...
Motivation: Conventional cardiac MRI plays an essential role in diagnosing coronary artery disease (CAD). However, the image quality is limited by low SNR. Goal(s): Hyperpolarized water can address this problem and be alternative to Gd-based MR contrast agents for angiography (MRA) myocardial perfusion with minimal safety concerns. Approach: In work, we demonstrate a procedure achieve high-resolution motion-free MRA 3D whole heart quantification using hyperpolarized water. Results: The work...
Flexible coil arrays are increasingly popular in magnetic resonance imaging (MRI), due to their superior anatomical fitting and patient comfort. Several concepts have been proposed, using self-resonant structures for the implementation of detecting coils. In this work, we show that flexible can be implemented a simpler way, standard copper wire, as long decoupling between elements is kept high. The design approach proposed here extended any frequency, an example 7-channel array <sup...
The Seiffert spirals trajectory has favorable properties for hyperpolarized 13 C MRI. It allows high degrees of undersampling and combined conjugate gradient compressed sensing SENSE reconstruction when multi-channel arrays are used. was evaluated in simulations, phantom, vivo C-urea MRI pig kidneys with retrospective temporal resolution. For single-frequency imaging, flexible acceleration is achieved through based on any number combination spiral arms. Simulations demonstrated noise-like...
Parallel imaging can aid hyperpolarized 13 C MRI in extracting more information the limited time window of signal. Using a dedicated, flexible receive coil design with coupling coefficients matched for both and 23 Na, sensitivity profiles reconstruction be acquired at Na frequency. We demonstrate this method two vivo experiments involving pig kidneys human brain using two-times accelerated 3D blipped stack-of-spirals sequence dual-resolution. The results show good SNR, coverage, resolution....