Employing gadolinium micro-disks as temperature probes for magnetic resonance imaging

Magnetic resonance imaging (MRI) is a critical component in many medical procedures such as treating cancer during MRI guided thermal ablations and hyperthermia. These procedures require real-time, spatially and thermally accurate temperature maps. In this paper we demonstrate the effectiveness of using uniform gadolinium micro-disks dispersed within a tissue-mimicking medium as MRI temperature sensors. Disk shaped Gd microstructures passivated with chromium were fabricated using a sputtering method and embedded in a Ringer’s solution agar gel matrix. We correlate the nuclear magnetic resonance linewidth broadening of water hydrogen nuclei in a phantom containing these Gd micro-disks with the temperature dependence of the mass magnetization of Gd. We acquired MRI images of the phantoms using the gradient echo method, which is sensitive to local magnetic field inhomogeneities. The Gd micro-disks produce a strong, predictable correlation between the brightness of T ₂* weighted MRI images and phantom temperatures, indicating that these Gd micro-disks are a good candidate for use as MRI temperature sensors.