This talk will focus on new technological developments and questions in two very different applications of magnetic resonance imaging (MRI). In the past ten years advances in superconducting materials have made human sized magnets operating between 7 and 11.7 Tesla feasible. These correspond to operating frequencies of 300-500 MHz. The main RF challenges involved are enabling uniform distribution of the magnetic component of the RF field throughout the body, while maintaining the electric component to within federal safety guidelines. New RF technology includes multi-element transmit arrays and on-board amplifiers which must operate in these very strong magnetic fields. At the other end of the spectrum, much of the developing world does not have the financial resources for even low-cost commercial MRI systems. We are trying to construct a portable, budget MRI system aimed at treating children with hydrocephalus. This will consist of a Halbach permanent magnet, and multiple very low frequency modules operating at approximately 2.5 MHz. Design criteria and image reconstruction strategies will be discussed.
Andrew Webb, Leiden University Medical Center