Explanipedia

Erratum to: MRI‐Based Transfer Function Determination through the Transfer Matrix by Jointly Fitting the Incident and Scattered B1+ Field (Magn Reson Med. 2020; 83:1081–1095) Open

Janot P. Tokaya, Alexander Raaijmakers, Michael A. Eijbersen, Peter R. Luijten, Alessandro Sbrizzi , et al. · 2023

This erratum aims to correct a couple of small errors in some of the equations in our original paper 'MRI-based transfer function determination through the transfer matrix by jointly fitting the incident and scattered B1+ field' by Tokaya …

Tier‐based formalism for safety assessment of custom‐built radio‐frequency transmit coils Open

Bart R. Steensma, Alireza Sadeghi‐Tarakameh, Ettore Flavio Meliadò, Cornelis A. T. van den Berg, Dennis W. J. Klomp , et al. · 2022

The purpose of this work is to propose a tier‐based formalism for safety assessment of custom‐built radio‐frequency (RF) coils that balances validation effort with the effort put in determinating the safety factor. The formalism has three …

Blood Flow Velocity Pulsatility and Arterial Diameter Pulsatility Measurements of the Intracranial Arteries Using 4D PC-MRI Open

Kees M. van Hespen, Hugo J. Kuijf, Jeroen Hendrikse, Peter R. Luijten, Jaco J.M. Zwanenburg · 2021

SAR and temperature distributions in a database of realistic human models for 7 T cardiac imaging Open

Bart R. Steensma, Ettore Flavio Meliadò, Peter R. Luijten, Dennis W. J. Klomp, Cornelis A. T. van den Berg , et al. · 2021

Purpose To investigate inter‐subject variability of B 1 + , SAR and temperature rise in a database of human models using a local transmit array for 7 T cardiac imaging. Methods Dixon images were acquired of 14 subjects and segmented in die…

Real‐time assessment of potential peak local specific absorption rate value without phase monitoring: Trigonometric maximization method for worst‐case local specific absorption rate determination Open

Ettore Flavio Meliadò, Alessandro Sbrizzi, Cornelis A. T. van den Berg, Peter R. Luijten, Alexander Raaijmakers · 2020

Purpose Multi‐transmit MRI systems are typically equipped with dedicated hardware to sample the reflected/lost power in the transmit channels. After extensive calibration, the amplitude and phase of the signal at the feed of each array ele…

Introduction of Ultra-High-Field MR Imaging in Infants: Preparations and Feasibility Open

Kim V. Annink, Niek E. van der Aa, Jeroen Dudink, Thomas Alderliesten, Floris Groenendaal , et al. · 2020

7T MR imaging is feasible in infants, and good-quality scans could be obtained.

The YOUth cohort study: MRI protocol and test-retest reliability in adults Open

Elizabeth E.L. Buimer, Pascal Pas, Rachel M. Brouwer, Martijn Froeling, Hans Hoogduin , et al. · 2020

Metabolite cycled liver 1H MRS on a 7 T parallel transmit system Open

Aline Xavier, C.S. Arteaga de Castro, Marcelo E. Andía, Peter R. Luijten, Dennis W. J. Klomp , et al. · 2020

Introduction Single‐voxel 1 H MRS in body applications often suffers from respiratory and other motion induced phase and frequency shifts, which lead to incoherent averaging and hence to suboptimal results. Methods Here we show the applica…

Conditional safety margins for less conservative peak local SAR assessment: A probabilistic approach Open

Ettore Flavio Meliadò, Alessandro Sbrizzi, Cornelis A. T. van den Berg, Bart R. Steensma, Peter R. Luijten , et al. · 2020

Purpose The introduction of a linear safety factor to address peak local specific absorption rate (pSAR 10g ) uncertainties (eg, intersubject variation, modeling inaccuracies) bears one considerable drawback: It often results in over‐conse…

Explaining RF induced current patterns on implantable medical devices during MRI using the transfer matrix Open

Janot P. Tokaya, Cornelis A. T. van den Berg, Peter R. Luijten, Alexander Raaijmakers · 2020

Purpose In this work a simulation study is performed to gain insights in the patterns of induced radiofrequency (RF) currents for various implant‐like structures at 1.5 T. The previously introduced transfer matrix (TM) is used to determine…

Introduction of the snake antenna array: Geometry optimization of a sinusoidal dipole antenna for 10.5T body imaging with lower peak SAR Open

Bart R. Steensma, Pierre‐François Van de Moortele, M. Arcan Ertürk, Andrea Grant, Gregor Adriany , et al. · 2020

Purpose To improve imaging performance for body MRI with a local transmit array at 10.5T, the geometry of a dipole antenna was optimized to achieve lower peak specific absorption rate (SAR) levels and a more uniform transmit profile. Metho…

Pushing functional MRI spatial and temporal resolution further: High‐density receive arrays combined with shot‐selective 2D CAIPIRINHA for 3D echo‐planar imaging at 7 T Open

Arjan D. Hendriks, Federico D’Agata, Luisa Raimondo, Tim Schakel, Liesbeth Geerts , et al. · 2020

To be able to examine dynamic and detailed brain functions, the spatial and temporal resolution of 7 T MRI needs to improve. In this study, it was investigated whether submillimeter multishot 3D EPI fMRI scans, acquired with high‐density r…

Effect of Fixed-Density Thresholding on Structural Brain Networks: A Demonstration in Cerebral Small Vessel Disease Open

Bruno Miguel de Brito Robalo, Naomi Vlegels, J. Meier, Alexander Leemans, Geert Jan Biessels , et al. · 2020

A popular solution to control for edge density variability in structural brain network analysis is to threshold the networks to a fixed density across all subjects. However, it remains unclear how this type of thresholding affects the basi…

High‐resolution in vivo MR‐STAT using a matrix‐free and parallelized reconstruction algorithm Open

Oscar van der Heide, Alessandro Sbrizzi, Peter R. Luijten, Cornelis A. T. van den Berg · 2020

MR‐STAT is a recently proposed framework that allows the reconstruction of multiple quantitative parameter maps from a single short scan by performing spatial localisation and parameter estimation on the time‐domain data simultaneously, wi…

Issue Information Open

Sebastian Martin, Andreas Endt, Tristan Wetscherek, A. K. Kuder, Michael Uder , et al. · 2020

Rest of World), €3741 (Europe), £2958 (UK

Correcting time‐intensity curves in dynamic contrast‐enhanced breast MRI for inhomogeneous excitation fields at 7T Open

Michael J. van Rijssel, Josien P. W. Pluim, H M Chan, Lieke van den Wildenberg, Alexander Schmitz , et al. · 2019

Purpose Inhomogeneous excitation at ultrahigh field strengths (7T and above) compromises the reliability of quantified dynamic contrast‐enhanced breast MRI. This can hamper the introduction of ultrahigh field MRI into the clinic. Compensat…

Validating faster DENSE measurements of cardiac-induced brain tissue expansion as a potential tool for investigating cerebral microvascular pulsations Open

Ayodeji L. Adams, Max A. Viergever, Peter R. Luijten, Jaco J.M. Zwanenburg · 2019

MRI‐based transfer function determination through the transfer matrix by jointly fitting the incident and scattered field Open

Janot P. Tokaya, Alexander Raaijmakers, Peter R. Luijten, Alessandro Sbrizzi, Cornelis A. T. van den Berg · 2019

Purpose A purely experimental method for MRI‐based transfer function (TF) determination is presented. A TF characterizes the potential for radiofrequency heating of a linear implant by relating the incident tangential electric field to a s…

Accelerating implant RF safety assessment using a low‐rank inverse update method Open

Peter R. S. Stijnman, Janot P. Tokaya, Jeroen van Gemert, Peter R. Luijten, Josien P. W. Pluim , et al. · 2019

Purpose Patients who have medical metallic implants, e.g. orthopaedic implants and pacemakers, often cannot undergo an MRI exam. One of the largest risks is tissue heating due to the radio frequency (RF) fields. The RF safety assessment of…

A deep learning method for image‐based subject‐specific local SAR assessment Open

Ettore Flavio Meliadò, Alexander Raaijmakers, Alessandro Sbrizzi, Bart R. Steensma, Matteo Maspero , et al. · 2019

Purpose Local specific absorption rate (SAR) cannot be measured and is usually evaluated by offline numerical simulations using generic body models that of course will differ from the patient's anatomy. An additional safety margin is neede…

Intracranial Vessel Wall Magnetic Resonance Imaging Does Not Allow for Accurate and Precise Wall Thickness Measurements Open

Kees M. van Hespen, Jaco J.M. Zwanenburg, Anita A. Harteveld, Peter R. Luijten, Jeroen Hendrikse , et al. · 2019

SNR optimized 31P functional MRS to detect mitochondrial and extracellular pH change during visual stimulation Open

Arjan D. Hendriks, Wybe J. M. van der Kemp, Peter R. Luijten, Natalia Petridou, Dennis W. J. Klomp · 2019

Summary Energy metabolism of the human visual cortex was investigated by performing 31 P functional MRS. Introduction The human brain is known to be the main glucose demanding organ of the human body and neuronal activity can increase this…

Contradiction between amide‐CEST signal and pH in breast cancer explained with metabolic MRI Open

Erwin Krikken, Wybe J. M. van der Kemp, Vitaliy Khlebnikov, Thijs van Dalen, Maartje Los , et al. · 2019

Purpose Metabolic MRI is a noninvasive technique that can give new insights into understanding cancer metabolism and finding biomarkers to evaluate or monitor treatment plans. Using this technique, a previous study has shown an increase in…

Issue Information Open

Lidi Wan, Wei Zhao, Yajun Ma, Saeed Jerban, Adam C. Searleman , et al. · 2019

Rest of World), €3562 (Europe), £2817 (UK

Early detection of changes in phospholipid metabolism during neoadjuvant chemotherapy in breast cancer patients using phosphorus magnetic resonance spectroscopy at 7T Open

Erwin Krikken, Wybe J. M. van der Kemp, P. J. van Diest, Thijs van Dalen, Hanneke W.M. van Laarhoven , et al. · 2019

The purpose of this work was to investigate whether noninvasive early detection (after the first cycle) of response to neoadjuvant chemotherapy (NAC) in breast cancer patients was possible. 31 P‐MRSI at 7 T was used to determine different …

Methodological consensus on clinical proton MRS of the brain: Review and recommendations Open

Martin Wilson, Ovidiu C. Andronesi, Peter B. Barker, Robert Bartha, Alberto Bizzi , et al. · 2019

Proton MRS ( 1 H MRS) provides noninvasive, quantitative metabolite profiles of tissue and has been shown to aid the clinical management of several brain diseases. Although most modern clinical MR scanners support MRS capabilities, routine…

Microbleeds colocalize with enlarged juxtacortical perivascular spaces in amnestic mild cognitive impairment and early Alzheimer’s disease: A 7 Tesla MRI study Open

Willem H. Bouvy, Susanne J. van Veluw, Hugo J. Kuijf, Jaco J.M. Zwanenburg, Jaap Kappelle , et al. · 2019

MRI-visible perivascular spaces (PVS) in the semioval centre are associated with cerebral amyloid angiopathy (CAA), but it is unknown if PVS co-localize with MRI markers of CAA. To examine this, we assessed the topographical association be…

Volume increase in the dentate gyrus after electroconvulsive therapy in depressed patients as measured with 7T Open

Jasper O. Nuninga, René C.W. Mandl, Marco P. Boks, Steven C. Bakker, Metten Somers , et al. · 2019

Reducing distortions in echo‐planar breast imaging at ultrahigh field with high‐resolution off‐resonance maps Open

Michael J. van Rijssel, Frank Zijlstra, Peter R. Seevinck, Peter R. Luijten, Kenneth G. A. Gilhuijs , et al. · 2019

Purpose DWI is a promising modality in breast MRI, but its clinical acceptance is slow. Analysis of DWI is hampered by geometric distortion artifacts, which are caused by off‐resonant spins in combination with the low phase‐encoding bandwi…

Model-based reconstruction of non-rigid 3D motion-fields from minimal $k$-space data: MR-MOTUS Open

Niek R. F. Huttinga, Cornelis A. T. van den Berg, Peter R. Luijten, Alessandro Sbrizzi · 2019

Estimation of internal body motion with high spatio-temporal resolution can greatly benefit MR-guided radiotherapy/interventions and cardiac imaging, but remains a challenge to date. In image-based methods, where motion is indirectly estim…

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