MR temperature monitoring for MR-RF hyperthermia — A systems-level approach

Non-invasive high-resolution 3D MR temperature maps can significantly improve dosimetry during thermal dose delivery in hyperthermic oncology. However, with long treatment times, system- and patient-induced drift in the B₀ main magnetic field of the MR scanner may adversely impact the accuracy of temperature measurements. In addition, the insertion of conventional RF hyperthermia apparatus into an MR scanner obstructs the use of commercial MR receive coil arrays in the scanner bore. If they had been available for use, such receive arrays could potentially increase imaging signal-to-noise ratio (SNR) and/or temporal resolution of MR thermometry. Here, we describe a systems-level perspective of improving temperature monitoring in MR-RF hyperthermia. This approach includes a previously developed fat-referenced MR thermometry technique, and a dual-function coil array design that addresses the limitations in imaging SNR and temporal resolution that are inherent in conventional MR-guided RF hyperthermia systems. We will also discuss system-level considerations that can adversely impact MRT measurements when integrating a RF hyperthermia sub-system with a MRI system.