CIBM MRI EPFL SECTION

MR Imaging Technology

Section Head: Prof. Dimitrios Karampinos (EPFL)

The activities of the CIBM MRI EPFL MR Imaging Technology Section revolve around 

RESEARCH TOPICS

RF Lab - Development of radio frequency technology for ultra-high field MRI

Description: The research focuses on the development of hardware solutions and clinical applications for ultrahigh field magnetic resonance imaging (UHF-MRI) and magnetic resonance spectroscopy (MRS). We develop new, multi-channel, single- and multi-tuned RF transmit/receive and receive-only coils, which provide more efficient RF power transmission and higher signal-to-noise ratio, and thus enabling faster MRI scans and higher spatial resolution of the acquired MR images. In this research, we use different tools to design, optimize, build and evaluate RF coils/antennas and RF components: electromagnetic field and specific absorption rate simulations, RF field optimization algorithms, RF circuit simulations, 3D mechanical design software, and everything that can be found in a well-equipped RF laboratory.

Investigator: Daniel Wenz (EPFL)

Development of multi-channel loop-dipole antenna arrays for MRI at 7.0 Tesla

Description: The aim of this project is to enhance signal-to-noise ratio (SNR) in ultrahigh field MRI at 7.0 Tesla, by developing a new generation of high channel-count, low loss, loop-dipole arrays which would enable achieving ultimate intrinsic SNR at ultrahigh field MRI and MR spectroscopy.

Investigator: Daniel Wenz (EPFL)

Collaborator: Lijing Xin (EPFL)

Development of optimal, multi-channel array combination of dielectric resonators and dipole antennas for MR spectroscopy at 7.0 Tesla

Description: Dielectric resonators are an interesting alternative to conventional loop elements, especially at ultrahigh magnetic field strengths. The properties of dielectric materials can be easily modified, what provides an extra degree of freedom for the development of new, application-oriented RF antennas. The goal of this project is to develop and optimize a multi-channel combination of dielectric resonators and dipole antennas, and explore its advantages for MRI at magnetic field strengths higher than 7.0 Tesla.

Investigator: Daniel Wenz (EPFL)

Novel hardware technologies for neuroimaging and neurostimulation

Description: 

High receive sensitivity is the holy grail of every magnetic resonance imaging (MRI) study. In our research, we aim to substantially boost receive sensitivity in different neuroimaging applications, accelerating total scan time and increasing spatial resolution.  We develop innovative hardware concepts for the next generation of MRI detectors, particularly suitable for ultra-high field (UHF) MRI (B0 ≥ 7 T), focusing on unconventional transmit and receive radio frequency (RF) coil arrays involving strategies such as dipole antennas, dielectric resonators, and flexible loop coils. In addition, we explore new solutions for advanced, MRI-based techniques that can provide unique insights into the metabolism and function of the brain, such as phosphorus (31P) MR spectroscopy and electroencephalography combined with functional MRI (EEG/fMRI). Furthermore, we are working on highly promising, non-invasive human brain stimulation strategies. In particular, we develop hybrid hardware systems enabling transcranial low-intensity focused ultrasound (LIFU) neuromodulation combined with UHF-MRI, aiming at finding new ways to treat neurological and neuropsychiatric diseases.

INVESTIGATORS: Daniel Wenz (EPFL)

COLLABORATORS: Rares Salomir (HUG), Jean-Paul Vallee (HUG), Lijing Xin (EPFL), Irena Zivkovic (TU Eindhoven, The Netherlands)

Fast metabolic imaging by magnetic resonance spectroscopic imaging

Description: Whole-brain proton magnetic resonance spectroscopic imaging (1H-MRSI) is a non-invasive technique for assessing neurochemical distribution in the brain, offering valuable insights into brain functions and neural diseases. It greatly benefits from the improved SNR at ultrahigh field strengths. However, 1H-MRSI still faces challenges, such as long acquisition time and signal contamination from water and lipids. In this project, we develop 2D and 3D short TR/TE 1H-FID-MRSI sequences using rosette trajectories with high spatial resolution for mapping brain metabolites including N-Acetyle-L-aspartic acid (NAA), Glutamate (Glu), total choline, Creatine and Phosphocreatine (tCr), and Glycine and myo-Inositol (Gly+Ins)..

Investigator: Lijing Xin (EPFL)

Collaborators: Uzay Emir (UNC, USA),  Zhi-Pei Liang (UIUC, USA)

The neurometabolic connectome: a new window on brain disease

Description:Magnetic resonance spectroscopy is a unique non-invasive technique to measure a variety of brain metabolites (e.g., N-acetylaspartate, creatines, choline, inositol) and certain neurotransmitters (glutamate, Gamma-Aminobutyric Acid). However, so far it has remained mostly a single voxel technique with limited spatial and temporal resolution. By leveraging novel MR sequence designs (edited MRSI), spatial encoding schemes (rosette trajectory), and reconstruction methods (compressed sensing) on a state-of-the-art 7T Terra.X MR scanner the aim of this project is to improve spatial and temporal resolution to establish functional MR spectroscopic imaging (fMRSI) that enables the measurement of modulation patterns of neurotransmitter concentrations upon stimulation in the human brain, and the mapping of brain metabolic connectivity.

Investigator: Lijing Xin (EPFL), Andre Doring (EPFL)

Collaborators: Uzay Emir (UNC, USA), Zhi-Pei Liang (UIUC, USA), Dimitri Van de Ville (EPFL)

Method development for X-nuclei magnetic resonance spectroscopy

Description: X-nuclei magnetic resonance spectroscopy (MRS) allows non-invasive measurement of neurochemical, metabolic and physiological events in the living brain. The increase in sensitivity and resolution is currently driving the use of ultra-high magnetic field scanners.  However, to fully exploit these advantages of an ultra-high field human scanner necessitates the development first of advanced methodologies. Especially, the X- nuclei MRS functionality of clinical scanners is still far behind magnetic resonance imaging techniques and that on preclinical scanners, due to the need to overcome multiple technical challenges. Therefore, we focus on surmounting the technical issues, developing new X-nuclei MRS methods and advancing their capability for human MR scanner at high magnetic field. Currently our focuses are the metabolic fluxes (TCA cycle metabolism and ATP metabolism) measurement using dynamic 13C MRS, 31P MRS, MRSI and MR fingerprinting.

Investigator: Lijing Xin (EPFL)

Collaborators: Bernard Lanz (EPFL), Uzay Emir (UNC, USA), Yun Jiang (Department of Radiology, University of Michigan, USA), Xin Yu (Department of Biomedical Engineering, Case Western Reserve University, Cleveland, USA)

Functional magnetic resonance spectroscopy: targeting neurometabolic alterations underlying cognition

Description: Functional MRS (fMRS) allows us to monitor the metabolites dynamics from rest to neuronal activation. Increases in some metabolites, i.e. lactate and glutamate (one major neurotransmitter), were observed in response to neuronal activation in these tasks. These changes reflect a response to stimulated energy metabolism upon neuronal activation, offering insights into how brain neurogenetics is regulated to support these sensory tasks. Cognitive deficits have been consistently shown in aging, many psychiatric disorders, and neurodegenerative diseases such as mild cognitive impairment, Parkinson disease and Alzheimer’s disease. Therefore, the investigation of the underlying neurometabolic mechanism during a cognitive task by fMRS is of great interest.  We aim to use fMRS to investigate metabolic dynamics underlying cognition and explore the link between cognitive aspects and the functional neurochemical characteristics.

Investigator: Lijing Xin (EPFL), Antonia Kaiser (EPFL)

Collaborators: Ines Khadimallah (Center for Psychiatric Neuroscience, Department of Psychiatry, CHUV)

Promoting the modulatory capacity of intracortical inhibition in young and old: interrelation of physical exercise and sleep

The human cortical inhibitory system is known to play a crucial role for normal brain development, function and plasticity thereby acting on both, cognitive and motor processes. Furthermore, cortical inhibition is crucial for sleep induction and sleep maintenance. The principal inhibitory neurotransmitter in the central nervous system is gamma-aminobutyric acid (GABA). The general amount of GABAergic inhibition is crucial with respect to motor control and motor learning but rather the capacity to task- and phase-specifically modulate GABA release, i.e. the modulatory range. Furthermore, modulation of GABA release is also vital for sleep induction and sleep maintenance. The aim of the current study is to investigate the close reciprocal interrelation of physical activity and sleep on the mechanistic and behavioral level. This could be of great significance as there is growing recognition of the importance of sleep to improve population health due to the convincing evidence linking sleep to a range of health outcomes.

Investigator: Lijing Xin (EPFL), Wolfgang Taube (University of Fribourg)

Collaborators: Benedikt Lauber (University of Fribourg)

Method development for multinuclear (1H, 13C and 31P) magnetic resonance spectroscopy

Description: Multinuclear magnetic resonance spectroscopy (MRS) using 1H, 13C and 31P nuclei allows non-invasive measurement of neurochemical, metabolic and physiological events in the living brain. The increase in sensitivity and resolution is currently driving the use of ultra-high magnetic field scanners.  However, to fully exploit these advantages of an ultra-high field human scanner necessitates the development first of advanced methodologies. Especially, the multinuclear MRS functionality of clinical scanners is still far behind magnetic resonance imaging techniques and that on preclinical scanners, due to the need to overcome multiple technical challenges. Therefore, we focus on surmounting the technical issues, developing new multinuclear MRS methods and advancing the multinuclear MRS capability for human MR scanner at high magnetic field.

Investigator: Lijing Xin (EPFL)

Collaborators: Yun Jiang (Department of Radiology, University of Michigan, USA), Xin Yu (Department of Biomedical Engineering, Case Western Reserve University, Cleveland, USA)

Biomarkers in psychiatric disorders

Psychiatric disorders are complex neurodevelopmental disorders involving interplay between genetic, developmental and environmental factors. Using advanced 1H, 13C and 31P MRS techniques, we carry on a translational approach in patients with psychosis, for the exploration of potential biomarkers and the identification of molecular mechanisms affecting brain development and regulation that are relevant for the pathophysiology of schizophrenia. The discovery of biomarkers will help us to achieve early diagnose of the disease and ultimately early intervention or even prevention.

Investigator: Lijing Xin (EPFL)

Collaborators: Kim Q Do (UNIL), Prof. Philippe Conus (Service of General Psychiatry, Department of Psychiatry, CHUV),  Ines Khadimallah (Center for Psychiatric Neuroscience, Department of Psychiatry, CHUV), Patric Hagmann (Department of Radiology, CHUV), Paul Klauser (Center for Psychiatric Neuroscience, Department of Psychiatry, CHUV)

Central blood pressure regulation by the brainstem and influence by renal sympathetic afference: a functional magnetic resonance imaging (fMRI) study in hypertensive and normotensive participant

Description: Essential hypertension is a highly prevalent disorder and a major contributor to cardiovascular morbidity and mortality. In hypertension, the overactivity of sympathetic nervous system (SNS) has been found to be implicated in its initiation, maintenance and adverse consequences. The SNS is composed of an afferent and an efferent arm, which respectively bring sensory input information to the brain and then transmits sympathetic outflow from the brain to peripheral organs. It has been shown in animals that selective removal of the afferent renal component of the SNS can modulate central sympathetic outflow to these peripheral organs. In humans, the effect of the afferent component of the SNS on the brain has been difficult to assess so far. In a pilot study in healthy volunteers at 7T, we have shown that a cold pressor test applied to the leg induces a change in BOLD signal intensity in the brainstem. Whether these responses differ in hypertensive patients or whether they can be modulated with renal denervation is unknown. The scope of this project is to evaluate if the brainstem BOLD response to stress is higher in hypertensive patients than in normotensive controls, and that in patients responsive to renal denervation, the BOLD response to stress is decreased compared to non-responders or to non-denervated resistant patients.

Investigator:  (EPFL)

Collaborators:  Grégoire Wuerzener and Murielle Hendriks-Balk (Nephrology, CHUV)