Ultra-High Field MR

The overall focus of the group is to advance the technology and thereby unleash the full potential of ultra-high field MR. Ultra-high field MR offers unique opportunities for revealing new insight into the relationship between structure and function of the human body as part of our clinical research studies.

7T log final

 

OBJECTIVES

The Ultra-High Field MR group strives at providing state-of-the-art sequences and protocols, which take full advantage of the 7T system available at DRCMR. MR systems operating at fields of 7 tesla or above pose a series of technical challenges for reaching the full potential of the systems:

  • The improved signal-to-noise at 7 tesla allows submillimeter structural and functional image resolution which offers new insights into the understanding of the organization and processes of the body in health and disease. However, a good compensation of subject motion is required to avoid image degradation, which would defeat the purpose of ultra-high resolution imaging. We work on fast image readout approaches and navigator-based correction methods to reduce the effects from motion and the increased physiological noise we unfortunately experience at higher field strength.
  • The higher radiofrequency (RF) at 7 tesla causes strong interactions between the electromagnetic fields and the human body, which makes optimal RF control challenging within the allowed specific absorption rate (SAR) levels using traditional transmit approaches. Our solution is to develop more advanced excitation approaches and to use novel multi-transmit RF technologies available on our state-of-the-art equipment. These new transmit concepts will allow highly improved RF distributions in the human body, and thereby deliver superior image quality at safe SAR levels.
  • Controlling motion and RF requires confinement of inhomogeneities and fluctuations in the main B0 field. We therefore work on advanced shim and dephasing techniques to not only achieve an ideal homogeneous field, but also to take advantage of being able to control the field temporally during the sequences. We exploit this to make novel zoom imaging methods, to exclude unwanted tissue such as fat as well as in advanced RF pulse designs.

RESEARCH PROJECTS

The technical innovations, made by the group, are available and applied to all clinical studies performed on the system. The group’s clinical interest ranges from high-resolution structural, functional and quantitative imaging to advanced spectroscopy editing and imaging. We apply these techniques to aging studies, studies of neurodegenerative diseases, in particular Parkinsonism, neuropsychiatric research and research on various other diseases. Examples of ongoing or upcoming projects typically conducted in synergy with other groups within or outside DRCMR are listed below:

  • Diffusion weighted magnetic resonance spectroscopy at ultra-high field: Unravelling microstructural changes in cerebral white matter in patients with multiple sclerosis Henrik Lundell is currently pursuing the first clinical ultra-high field (7T) MR study in Denmark. In his project, he combines magnetic resonance spectroscopy with diffusion MRI to shed new light into the microstructural alterations in major motor white-matter tract caused by multiple sclerosis. 
  • Brain metabolite changes across the lifespan: a 7T MR study Anouk Marsman and Anna Lind Hansen exploit the high sensitivity of MRS at 7T to look into which role glutamate, GABA, GSH and lactate plays in neurochemical mechanisms that are important in brain development, function and plasticity as well as neuropsychiatric and neurodegenerative diseases.
  • A generalized prospective motion correction framework for improved spectroscopy, structural and angiographic imaging Mads Andersen and Vincent Boer are developing techniques to update the position of the imaging/spectroscopy volume in real-time, as small head motion occur during scanning. Motion is monitored using extra sequence modules (navigators) that acquire dynamic MR data in pauses of the target imaging/spectroscopy sequence.

7tscan27tscan

Figur 1: T2-weighted images acquired at 3T in a subject who moved half way through the scan. Top image was acquired without motion correction; bottom image was acquired with motion correction. The motion was similar in timing and magnitude for the two acquisitions.

Group Members

saschag
Esben Thade Petersen

Group Leader

saschag
Vincent O. Boer

Postdoc

saschag
Anouk Marsman

Postdoc

saschag
Anna Lind Handsen

PhD Student

Show all associated staff

External Collaborators

Jeroen Hendrikse

Department of Radiology, University Medical Center Utrecht, The Netherlands


Dennis Klomp

Department of Radiology, University Medical Center Utrecht, The Netherlands


Andrew Webb

Department of Radiology, Leiden University Medical Center, The Netherlands


Matthias van Osch

Department of Radiology, Leiden University Medical Center, The Netherlands


Itamar Rohnen

Department of Radiology, Leiden University Medical Center, The Netherlands


Karin Markenroth Bloch

Swedish National 7T facility, Lund, Sweden


Gunther Helms

Swedish National 7T MRI Facility, Medical Radiation Physics, Lund, Sweden


Freddy Ståhlberg

Swedish National 7T MRI Facility, Medical Radiation Physics, Lund, Sweden


Lene Juel Rasmussen

Center for Healthy Aging, University of Copenhagen, Denmark


Erik Lykke Mortensen

Department of Public Health, University of Copenhagen, Denmark


Birte Yding Glenthøj

Center for Neuropsychiatric Schizophrenia Research, Mental Health Services, Capital Region of Denmark, Denmark


Brian Villumsen Broberg

Center for Neuropsychiatric Schizophrenia Research, Mental Health Services, Capital Region of Denmark, Denmark


Kirsten Borup Bojesen

Center for Neuropsychiatric Schizophrenia Research, Mental Health Services, Capital Region of Denmark, Denmark


Egill Rostrup

Functional Imaging Unit, Rigshospitalet Glostrup, Denmark