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7 Tesla oropharynx imaging

Introduction

Magnetic Resonance Imaging (MRI) allows “looking” inside the human body by a permanent magnetic field and radiofrequency (rf) waves. Many imaging modalities such as X-ray and CT apply small doses of ionizing radiation. Because MRI relies on fundamentally different physical principles, such radiation is not needed. Another benefit is the excellent soft tissue contrast (see Figure 1 for a comparison between CT and MR).

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Figure 1: CT and MR image of the neck with a tumor (Verduijn 2009).

At the UMC Utrecht several MRI scanners are used in clinical practice, their field strengths range from 1 to 3 Tesla (more than 50 000 times larger than the earth magnetic field). The UMC Utrecht is also one of the two medical centers in the Netherlands that host an ultra-high field scanner (7 Tesla). Brain imaging at 7 Tesla shows very good high-resolution results. The regions located lower in the head and neck region, such as the mouth and the throat, are more challenging, because of the air cavities that cause distortions. Moreover, no commercial coils are available to generate the rf waves for these regions. For advancing the research in these areas, we are looking for a motivated master student to help developing coils dedicated for these lower regions.

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Figure 2: MR image of the head and neck region, with the arrow indicating the oropharynx.


Project goal

The research goal is the development and application of transmit coils for imaging tumors in the oropharyngeal region. Several constraints should be considered, such as safety aspects, amount of energy deposited into the patient and the possibility to use the coil in combination with an immobilization mask used in radiotherapy.

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Figure 3. Left: simulation model for the neck coil. Right: top view of the magnetic field.

Work plan

In the first part of the project several antenna designs combined with dielectric substrates are simulated with EM simulation software to study the electric and magnetic fields and the specific absorption rate (SAR, the amount of energy deposited into the body). After choosing the most optimal design, the coil is manufactured. In the final stage the coil is tested and characterized on the 7 Tesla MRI scanner and oropharynx images are obtained.

Research environment

The student will work in the MRI research group of radiotherapy and interact with the high-field MR group of radiology. During the project the student will acquire knowledge of electromagnetic fields and MR imaging. For this project we are looking for a student with a nearly finished master in electrical engineering, biomedical engineering or (applied) physics, who has affinity with radiofrequency (rf) techniques.

For more information please contact:

Dr. Ir. Hanneke Bluemink (j.j.bluemink[at]umcutrecht.nl, 088-7550285) 
Dr. Ir. Nico van den Berg (c.a.t.vandenberg[at]umcutrecht.nl)