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Master Thesis

"Getting rid of the fat"

"Suppressing subcutaneous fat in 7T MR Spectroscopy by inner volume excitation"

 

Introduction

The first results coming from the recently installed 7 Tesla (7T) MR system in Utrecht are spectacular revealing new aspects of brain structure, vasculature and function. To push the application span of our 7T MR scanner even further, the department of Radiology and Radiotherapy is very active in the development of new technology and hardware. One of the new promising techniques is the so-called inner volume excitation. In this technique an array of antennas is positioned around the body. Each antenna is driven with a specially designed radiofrequency (RF) pulse, which allows a selective excitation of an organ or any arbitrary region in the body. This can be applied to suppress unwanted signals from neighbouring regions or to study physiologic processes by selectively exciting parts of organs or individual blood vessels.

Goal of the master assignment

This master thesis focuses on the use of inner volume excitation in 7T MR spectroscopy of the brain. MR spectroscopy is applied to study metabolic processes in centre of the brain. The small signals originating from these processes are now overwhelmed by the signal coming from subcutaneous fat around the skull. The use of inner volume excitation would suppress the fat signal and solve this issue very efficiently.

Work plan

The design of the special RF pulses needed for inner volume selection will be the first task in the project. The challenge of the RF pulse design is to balance between the desired excitation pattern and staying within safe margins of RF induced tissue heating. In the second part of the project the designed RF pulses have to be implemented on the 7T MR scanner and MR spectroscopy experiments have to be performed on phantoms. To guarantee a safe operation, the amount of RF heating will be quantified with MR thermometry and compared with the electromagnetic simulations. In the last phase of the project the technique will be tested on human volunteers.

Research environment

The candidate will be integrated in the MRI groups of the departments of Radiotherapy and Radiology which have a strong international research focus. The candidate will acquire in the project a broad general knowledge about MR physics.

master01

Typical MR spectrum of a region in the brain (left). Currently limited to distant regions from the skull as lipid signals will contaminate the spectra (right). With an array of antennas or coils located close to the skull (center), the selectivity of the MR spectroscopy method can be improved using multi channel RF excitation.


Contact Persons

Dr. Nico van den Berg
Department of Radiotherapy,
University Medical Centre Utrecht
e-mail: c.a.t.vandenberg[at]umcutrecht.nl
tel. +31 88 7556037

Dr. Dennis Klomp
Department of Radiology
University Medical Centre Utrecht
email: D.W.J.Klomp-2[at]umcutrecht.nl
tel:+31 88 7551391