About this Research Topic
Magnetic Resonance Imaging and Spectroscopy, MRI-MRS, have become indispensable diagnostic tools in numerous medical applications, providing anatomical, functional, and chemical information non-invasively with ever-increasing sensitivity and specificity. However, many challenges remain regarding the performance of MR instrumentation to improve the sensitivity, safety, and accessibility of these modalities. In this context, a traditional strategy is to develop Ultra High Field scanners, but this gives rise to many technical challenges and safety issues. More recently, the opposite trend has been followed by developing Very Low Field MR systems, avoiding safety issues, and wave propagation-related image distortions. However, their inherently low MR signal amplitude comes along with poor sensitivity.
Both, the Ultra High and Ultra-Low Field domain, consequently, call for creativity to open the way for the next generation of MR systems.
Today’s challenges in the development of MR instrumentation arise from the different requirements and limitations faced at different magnetic fields strengths, and all target the improvement of image quality, safety, and diagnostic value of MR.
At Ultra High Field, the strongest need concerns the improvement of RF transmission systems regarding RF excitation homogeneity, efficiency, patient safety, and associated Specific Absorption Rate (SAR) limitations. Today’s most-followed strategy is the use of high-density, adaptable transmit coil arrays allowing for specific excitation profiles. The use of different RF elements, such as dipoles, is also an actively investigated domain.
At Ultra-Low Field, but also for MR of X-nuclei, the most challenging task is to increase the sensitivity of the RF detection system, driven by the need to overcome the sensitivity-based limitation of image quality and spatio-temporal resolution set by the various noise sources present in the MR experiment. To this end, several strategies employing new coil geometries, new materials, or cryogenic devices have been investigated. The need for more capable electronics in terms of noise and speed, such as low-noise amplification systems, is also crucial.
In addition, the trend toward portability and ease of use of MR instrumentation calls for other features that increase usability but impose novel technological challenges, such as flexibility, lightweight or wireless devices.
The scope of this Research Topic covers all innovative developments in MR hardware over the whole range of static field strengths. A non-exhaustive list of potential target hardware systems is given below:
● RF coils for detection and/or transmission
● MR signal transmission systems
● Electronics and devices for RF coil controlling
● Gradients, magnets and associated circuitry
● Field cycling
● Devices for image correction (e.g. motion, physiological sensors, E/H-field probes, etc.)
● Electronics circuitry
All types of manuscripts are welcome, ranging from Original Research papers describing recent developments of new hardware to Review papers analyzing the state of the art of a given hardware system. As a general trend, papers should present innovative research rather than incremental development of existing systems.
Topic Editor Elmar Laistler is co-founder and shareholder of ALSIX GmbH, a spin-off company from the Medical University of Vienna, dedicated to RF coil development. Topic Editor Mathieu Sarracanie is a co-founder and shareholder of Hyperfine Research, a company developing low-field mobile MRI scanners. Topic Editor Lionel Broche holds two patents related to low-field MRI systems (US20180031667 and 102019000007647). All other Topic Editors declare no competing interests with regards to the Research Topic subject.
Keywords: MRI, MRS, hardware, ultra-high field, ultra-low field
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