Low field, high performance: Making MRI more accessible and versatile with low-field scanners

Magnetic resonance imaging (MRT) has become indispensable for diagnostics and therapy monitoring in practically all areas of medicine. However, due to the high cost, only a small portion of the world's population has access to this technology. MRI scanners are characterized by the strength of their magnetic field, and traditionally, high field strength devices are considered superior in terms of image quality. Most devices in clinical use today work with 1.5 Tesla or 3 Tesla. However, low-field scanners are much cheaper, and recently there has been renewed scientific interest in low-field MRI (field strength < 1 Tesla). The aim of this project is to investigate the potential of low-field MRI for diagnostic imaging. For this purpose, two devices are being tested that work at low field strengths (0.55 Tesla and 0.06 Tesla) but are equipped with modern hardware components and software for image reconstruction. The work program is divided into the following three goals: Goal 1 is to perform routine radiological examinations on low-field scanners with diagnostic image quality. For this purpose, technical parameters of MRI imaging are adapted to the physical properties of the low-field environment. In addition, acceleration techniques are used that have already been developed but are not yet used across the board in clinical practice (e.g. compressed sensing and AI-based image post-processing). The brain and abdomen were selected as exemplary body regions. The motivation is to make MRI accessible to those patients who have so far been denied it (mainly because of high costs or metal implants). Goal 2 deals with lung imaging, which is technically difficult on high-field scanners. In the case of low field strength, on the other hand, the physical framework conditions are more advantageous due to favorable relaxation times and lower susceptibility effects. These advantages are exploited in combination with the new "pilot tone" technique for tracking respiratory movement to allow better imaging of lung structure and quantification of lung function. Under Objective 3, low-field MRI will be used to identify the cause of dyspnea in Long -Investigate Covid, building on the previously developed methodology. For this purpose, the structure and function of the lungs in patients with post-acute COVID-19 disease are examined in low-field MRI and compared with control groups who have recovered after hospital discharge or who have never been hospitalized for COVID-19. The MRI findings are correlated with clinical data and with previous CT images from the acute phase of the disease. The processing of Objective 3 is expected to extend beyond the two-year period of this project.