This educational talk is designed to provide a broad overview of the functions and interactions of the subsystems of a modern clinical MRI scanner and explain various design constraints originating from engineering and physiological limitations.
MRI is an imaging modality with its versatility and non-invasive nature unparalleled by any other modalities. Its soft tissue contrast fundamentally comes from the inside of the body, and the electromagnetic energy employed for imaging is very much transparent to biological tissue and functions. The systems engineering for an MRI scanner is well developed and arguably mature, with over 30,000 scanners worldwide producing more than 10,000 patient scans every hour. At the same time, steady progress is being made to MRI engineering in terms of fast imaging, ultra-high-field imaging, and compact scanners, with many breakthrough technologies first announced in meetings like the present one.
Most technical and clinical users of MRI use the host computer interface, RF receive coils, and pulse sequence development environment without much exposure to various hardware subsystems behind the cover of the scanner. These include the main magnet, the gradient coils, and the RF transmit coil(s) along with their control electronics. Understanding the inner workings and interactions of these subsystems helps understand the limits of everyday imaging parameters and identify and appreciate potential areas of future innovation.
This presentation will cover the basic operational principles of field-generating and signal detection units of an MRI scanner, their interconnections, and important design limitations that come from engineering and physiological constraints. This course thus provides a ground work and introduction for the following lectures in the session on more details of individual subsystem engineering.