Student Spotlight

Magnetic Resonance Imaging Group: Filiz Yetisir

Filiz Yetisir

Hometown, Country:

Academic history prior to coming to MIT:
B.Sc. in Electrical and Electronics Engineering at Bilkent University, Turkey

What brought you to MIT?
During my last year in undergrad, I did a senior project with Prof. Ergin Atalar on imaging shear waves created by a mechanical actuator inside an agar phantom using Magnetic Resonance Imaging (MRI). I was amazed by the fact that MRI makes it possible to see inside things and I knew I wanted to witness this superpower more often. Prof. Atalar is friends with my current advisor Prof. Elfar Adalsteinsson and highly recommended him. After meeting with Elfar, it was obvious to me what a great mentor he would be.

What problem are you trying to solve with your current research and what are some possible applications?
The focus of my work is improving high resolution and contrast MRI by optimizing the trade-off between uniform imaging of the brain and low energy deposition into the body. High resolution and contrast brain imaging is critical in early and/or accurate diagnosis of many diseases such as Multiple Sclerosis (MS). For instance, high resolution and contrast, which is achievable in high magnetic field systems, enables the detection of small MS lesions at the early stages of the disease. At high fields, the RF (radiofrequency) transmit field distribution over the brain is no longer uniform, which may lead to an erroneous diagnosis.

One solution is to transmit the RF energy used to ‘see inside’ the brain from multiple independent channels rather than from only one channel as in the traditional systems. This so-called parallel transmission (pTx) configuration gives us the freedom to cancel out the non-uniformity of the transmit field by using a smart combination of the sensitivity profiles of each channel. With multiple RF energy sources, managing the temperature rise in the body due to electric fields becomes much more challenging and if not done optimally, it may negate the benefit of higher resolution imaging. I work on optimizing the RF energy deposition from multiple transmit channels to mitigate the non-uniformities in the RF transmit field while keeping the temperature rise in the human body under safety limits, even for infants.

What interests you most about your research?
It is highly motivating to me that my research pushes the limits of high resolution imaging, a technology which will enable clinicians to discover many unknown facts about the human brain. More generally, MRI is a very interdisciplinary research area. It is fascinating to constantly learn about various different fields such as functional MRI, cancer studies, fetal imaging and at the same time think about different RF pulse design approaches for each of them.

What are your future plans?
My next project is on fetal imaging, an extremely challenging and understudied area due to the unpredictable motion of the fetus. Detecting abnormalities in fetal brain as early as possible is crucial in the effectiveness of the treatments and using RF pulse design, I am planning to reduce the motion artifacts to have higher quality images.

I have not yet decided what I will do after my PhD but I may shift my focus entirely on fetal imaging and pursue an academic career or stay as an expert in parallel transmission high field MRI and work in industry to help bring high resolution imaging into every day clinical use.