Lars G. Hanson
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View article: Optimal Variable Flip Angle Schemes for Hyperpolarized MR Kinetic Modeling Robust to RF Field Variations
Optimal Variable Flip Angle Schemes for Hyperpolarized MR Kinetic Modeling Robust to RF Field Variations Open
Hyperpolarized carbon‐13 magnetic resonance has enabled the real‐time observation of biochemical pathways in living cellular systems. Pharmacokinetic modeling of such experiments provides estimates of conversion rates between metabolites, …
View article: Increasing the measurable frequency range of magnetic field oscillations with off‐resonance spin‐lock preparation pulses
Increasing the measurable frequency range of magnetic field oscillations with off‐resonance spin‐lock preparation pulses Open
Purpose Oscillatory magnetic fields—arising from, e.g., neuronal currents or induced currents during brain stimulation—can be measured with spin‐lock preparation pulses, where the frequency of the measured field matches the amplitude of th…
View article: Increased brain coverage and efficiency when measuring current-induced magnetic fields by use of simultaneous multi-slice echo-planar MRI
Increased brain coverage and efficiency when measuring current-induced magnetic fields by use of simultaneous multi-slice echo-planar MRI Open
Purpose Magnetic resonance current density imaging (MRCDI) can non-invasively validate electric field simulations in volume conductor head models. Weak electric currents are injected using scalp electrodes while measuring the MR phase pert…
View article: United States PRRSV 1-4-4 L1C.5 isolate demonstrates similar pathogenicity to a historic Chinese highly pathogenic PRRSV
United States PRRSV 1-4-4 L1C.5 isolate demonstrates similar pathogenicity to a historic Chinese highly pathogenic PRRSV Open
Porcine reproductive and respiratory syndrome virus (PRRSV) is a major economic and animal health burden on the United States swine industry due to morbidity- and mortality-associated losses affecting all stages of pig production. Currentl…
View article: 3D quantitative myocardial perfusion imaging with hyperpolarized HP001(bis‐1,1‐(hydroxymethyl)‐[1‐<sup>13</sup>C]cyclopropane‐d8): Application of gradient echo and balanced SSFP sequences
3D quantitative myocardial perfusion imaging with hyperpolarized HP001(bis‐1,1‐(hydroxymethyl)‐[1‐<sup>13</sup>C]cyclopropane‐d8): Application of gradient echo and balanced SSFP sequences Open
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 bSS…
View article: Hyperpolarized Water for Coronary Artery Angiography and Whole-Heart Myocardial Perfusion Quantification
Hyperpolarized Water for Coronary Artery Angiography and Whole-Heart Myocardial Perfusion Quantification Open
Purpose: Water freely diffuses across cell membranes, making it suitable for measuring absolute tissue perfusion. In this study, we introduce an imaging method for conducting coronary artery angiography and quantifying myocardial perfusion…
View article: MR imaging of the magnetic fields induced by injected currents can guide improvements of individualized head volume conductor models
MR imaging of the magnetic fields induced by injected currents can guide improvements of individualized head volume conductor models Open
Volume conductor models of the human head are routinely used to estimate the induced electric fields in transcranial brain stimulation (TBS) and for source localization in electro- and magnetoencephalography (EEG and MEG). Magnetic resonan…
View article: Volumetric measurements of weak current–induced magnetic fields in the human brain at high resolution
Volumetric measurements of weak current–induced magnetic fields in the human brain at high resolution Open
Purpose Clinical use of transcranial electrical stimulation (TES) requires accurate knowledge of the injected current distribution in the brain. MR current density imaging (MRCDI) uses measurements of the TES‐induced magnetic fields to pro…
View article: A head template for computational dose modelling for transcranial focused ultrasound stimulation
A head template for computational dose modelling for transcranial focused ultrasound stimulation Open
Transcranial focused Ultrasound Stimulation (TUS) at low intensities is emerging as a novel non-invasive brain stimulation method with higher spatial resolution than established transcranial stimulation methods and the ability to selective…
View article: Decomposition-based framework for tumor classification and prediction of treatment response from longitudinal MRI
Decomposition-based framework for tumor classification and prediction of treatment response from longitudinal MRI Open
Objective. In the field of radiation oncology, the benefit of MRI goes beyond that of providing high soft-tissue contrast images for staging and treatment planning. With the recent clinical introduction of hybrid MRI linear accelerators it…
View article: Optimized flip angle schemes for the split acquisition of fast spin‐echo signals (SPLICE) sequence and application to diffusion‐weighted imaging
Optimized flip angle schemes for the split acquisition of fast spin‐echo signals (SPLICE) sequence and application to diffusion‐weighted imaging Open
Purpose The diffusion‐weighted SPLICE (split acquisition of fast spin‐echo signals) sequence employs split‐echo rapid acquisition with relaxation enhancement (RARE) readout to provide images almost free of geometric distortions. However, d…
View article: Tracking of rigid head motion during<scp>MRI</scp>using an <scp>EEG</scp>system
Tracking of rigid head motion during<span>MRI</span>using an <span>EEG</span>system Open
Purpose To demonstrate a novel method for tracking of head movements during MRI using electroencephalography (EEG) hardware for recording signals induced by native imaging gradients. Theory and Methods Gradient switching during simultaneou…
View article: Data-driven separation of MRI signal components for tissue characterization
Data-driven separation of MRI signal components for tissue characterization Open
The msNMF can robustly separate MR signals into components with relation to the underlying tissue composition, and may potentially be useful for e.g. tumor tissue characterization.
View article: Sensitivity and resolution improvement for in vivo magnetic resonance current‐density imaging of the human brain
Sensitivity and resolution improvement for in vivo magnetic resonance current‐density imaging of the human brain Open
Purpose Magnetic resonance current‐density imaging (MRCDI) combines MRI with low‐intensity transcranial electrical stimulation (TES; 1‐2 mA) to map current flow in the brain. However, usage of MRCDI is still hampered by low measurement sen…
View article: Elevated body weight modulates subcortical volume change and associated clinical response following electroconvulsive therapy
Elevated body weight modulates subcortical volume change and associated clinical response following electroconvulsive therapy Open
Background: Obesity is a frequent somatic comorbidity of major depression, and it has been associated with worse clinical outcomes and brain structural abnormalities. Converging evidence suggests that electroconvulsive therapy (ECT) induce…
View article: On the Reconstruction of Magnetic Resonance Current Density Images of the Human Brain: Pitfalls and Perspectives
On the Reconstruction of Magnetic Resonance Current Density Images of the Human Brain: Pitfalls and Perspectives Open
Magnetic resonance current density imaging (MRCDI) of the human brain aims to reconstruct the current density distribution caused by transcranial electric stimulation from MR-based measurements of the current-induced magnetic fields. The r…
View article: Sensitivity and resolution improvement for in-vivo magnetic resonance current density imaging (MRCDI) of the human brain
Sensitivity and resolution improvement for in-vivo magnetic resonance current density imaging (MRCDI) of the human brain Open
Purpose Magnetic resonance current density imaging (MRCDI) combines MR brain imaging with the injection of time-varying weak currents (1-2 mA) to assess the current flow pattern in the brain. However, the utility of MRCDI is still hampered…
View article: Safety evaluation of a new setup for transcranial electric stimulation during magnetic resonance imaging
Safety evaluation of a new setup for transcranial electric stimulation during magnetic resonance imaging Open
Coupling to the RF field can be reliably prevented by low-conductivity leads, enabling cable paths optimal for MRCDI. Compared to commercial copper leads with safety resistors, the low-conductivity leads had lower total impedance, enabling…
View article: Multi-site benchmarking of clinical 13C RF coils at 3T
Multi-site benchmarking of clinical 13C RF coils at 3T Open
A quality assurance protocol for RF coils is proposed, which can be used for volume (Tx/Rx) and surface (Rx) coils. Following this protocol, a benchmarking of seven coils (from three different MR sites) dedicated to 13C MRI at 3T is report…
View article: Three‐dimensional accelerated acquisition for hyperpolarized <sup>13</sup>C MR with blipped stack‐of‐spirals and conjugate‐gradient SENSE
Three‐dimensional accelerated acquisition for hyperpolarized <sup>13</sup>C MR with blipped stack‐of‐spirals and conjugate‐gradient SENSE Open
Purpose To test a new parallel imaging strategy for acceleration of hyperpolarized 13 C MR acquisitions based on a 3D blipped stack‐of‐spirals trajectory and conjugate‐gradient SENSE reconstruction with precalibrated sensitivities. Methods…
View article: Data-Based Parametric Biomechanical Models for Cyclic Motions
Data-Based Parametric Biomechanical Models for Cyclic Motions Open
We present a method to convert motion capture data and anthropometric statistics into parametric biomechanical models of cyclic motions, such as walking, cycling and running. The motivation is ease of modelling and the desire to make model…
View article: Coil profile estimation strategies for parallel imaging with hyperpolarized <sup>13</sup>C MRI
Coil profile estimation strategies for parallel imaging with hyperpolarized <sup>13</sup>C MRI Open
Purpose To investigate auto‐ and pre‐calibration coil profile estimation for parallel imaging reconstruction of hyperpolarized 13 C MRI volumetric data. Methods Parallel imaging reconstruction was studied with 3 different approaches for co…
View article: Correction of stray magnetic fields caused by cable currents is essential for human in-vivo brain magnetic resonance current density imaging (MRCDI)
Correction of stray magnetic fields caused by cable currents is essential for human in-vivo brain magnetic resonance current density imaging (MRCDI) Open
Accurate mapping of current flows in the human brain is important for many neuroscientific applications. MRCDI is an emerging method, which combines MRI with externally applied alternating currents to derive current flow distributions base…