MRI scans can in many cases display deep or delicate tissues with difficulty. However, a new antenna can dramatically increase the quality of MRI images, while scans take less time. The antenna can be applied to existing MRI scanners.
In healthcare, MRI plays an important role in diagnosing injuries and diseases. An MRI scanner creates detailed images of the inside of your body by using a strong magnetic field and radio waves. During the scan, hydrogen atoms in your body align along the magnetic field. Radio waves then briefly disrupt these atoms, after which they return to their original position and emit weak signals.
Looking inside the body without harmful radiation
These signals are captured by the scanner and converted by a computer into cross sections of organs, tissues or bones. Thus, an MRI can be used to look inside the human body without harmful X-rays.
However, some tissues, especially if located deep inside the human body, are difficult to image. These include certain regions of the brain and tissue structures in the eye. In many cases, this limitation arises not from the MRI scanner, but from the hardware used to send and receive radio signals. For example, many conventional MRI antennas, also known as RF coils, struggle to capture enough signals to accurately image such tissues.
Higher-quality images thanks to new antenna
A new antenna developed by researchers at the Max Delbrück Centre in Berlin, Germany, could be the answer. The antenna provides higher-quality images faster, allowing even hard-to-represent tissues to be properly imaged.
This is possible by integrating metamaterials directly into the MRI antenna. Metamaterials are structures that interact with electromagnetic waves in ways not possible with natural materials. In the case of RF antennas, metamaterials allow radio signals from deep tissues to be amplified for better capture. The antenna also provides higher spatial resolution, sharper images and faster MRI scans.
The antenna was developed by a research team led by PhD student Nandita Saha in the Experimental Ultrahigh Field Magnetic Resonance lab, of professor Thoralf Niendorf. The team worked closely with researchers at the also German Rostock University Medical Center. In doing so, the researchers combined their expertise in MRI technology with expertise in clinical ophthalmology and translational imaging.
Directing radiofrequency fields more efficiently
"By using concepts from metamaterials, we were able to direct radiofrequency fields more efficiently and demonstrate how advanced physics can directly improve medical imaging," said Niendorf, lead author of the paper. "This work opens the way to faster, brighter MRI scans that could benefit patients in many clinical areas."
Using the new antenna can not only increase image quality, but also improve the comfort of patients undergoing MRI scans. For instance, the antenna allows MRI scans to be performed faster, reducing the time patients spend in the scanner. In addition, the images are of higher quality, reducing the need to repeat MRI scans.
Anatomically detailed MRI scans with high spatial resolution
"Our research shows clear relevance for ophthalmological applications, as it enables anatomically detailed MRI scans of the eye with high spatial resolution," said Professor Oliver Stachs, co-author of the paper at University Medicine Rostock. "It makes it possible to open a window into the eye and into (patho)physiological processes that were previously largely inaccessible."
"Our goal was to rethink MRI hardware from the modern perspective of antenna design," Saha adds. The technology can also be tuned to protect sensitive parts of the body during MRI, for example to reduce unwanted heating around medical implants. In addition, the technology can be used to focus RF energy more effectively for MRI-guided therapies in various cancer treatments, such as gentle heating of tumours (hyperthermia) or thermal ablation of tissue.
The results of the study have been published in the scientific journal Advanced Materials.
