MRI with optical wireless transmission in the analog regime

Magnetic resonance imaging, or MRI for short, can be used to capture images of the inside of the human body. Especially for soft tissues, such as the brain, ligaments and tendons, or the internal organs, the level of detail achieved in the images and the amount of anatomical and functional information are unsurpassed - and all without harmful X-ray radiation. MRI is constantly being developed further. Among the key achievements of recent decades are detectors, so-called radiofrequency coils, with multiple receive channels and associated methods for shortening the duration of examinations. In terms of detectors, intensive research is also being conducted on flexible materials, which allow the coils to be better adapted to the patient`s anatomy, increasing comfort and the achievable data quality. However, the development of flexible multichannel detectors is increasingly hitting its limits in terms of scalability, handling and safety when using conventional coaxial cables for data transmission. The complexity of the cabling increases dramatically with the number of detector channels and the flexibility of the coils is severely limited by large cable strands. This is exactly where the OPTIMAL project comes in. The goal of the project is the wireless transmission of the MRI signal. OPTIMAL differs from other work on wireless MRI detectors in two main points: Data transmission is not realized with conventional WLAN or Bluetooth, but with light, and the signal is not transmitted digitally, but in analog form. Data transmission by means of light, also called optical free-space communication, has characteristic advantages such as a high data rate, low energy requirements and no interaction with electromagnetic fields that occur during an MRI examination. By transmitting the analog signal, the power requirements for electronic components on the MRI detectors can be further reduced. It also allows a wireless transmission system to be designed that is compatible with existing MRI scanners and their image processing system. The first-time use of optical free-space communication in MRI represents a major challenge. In an MRI scanner, very high electromagnetic fields occur about 60,000 times as strong as the earth`s magnetic field for which commercially available components are not designed. In addition, losses in analog signal transmission must be avoided at all costs, otherwise the quality of the MRI images will be reduced. With the approach described above, the OPTIMAL project aims at realizing the world`s first completely wireless MRI coil. In addition to the wireless transmission of the MRI signal, this also includes wireless solutions for the control of the detectors and for the power supply. To reach the challenging goals of this project interdisciplinary collaboration is crucial. Roberta Frass (PI) from MedUni Wien has extensive MRI expertise, while Michael Hofbauer (Co-PI) from TU Wien provides experience in integrated opto-electronics and lasers.