Characterisation of holmium-165 micro-spheres in low-field MRI

Holmium (Ho) micro-spheres can be imaged in trans-arterial radio-embolisation (TARE) us- ing magnetic resonance imaging (MRI). MRI offers many benefits compared to conventional imaging techniques used in TARE. In previous studies this has been extensively researched using high-field MRI systems of 1.5T and 3T. However, low-field MRI can offer certain advantages over high-field MRI for TARE. To investigate the possibility of using low-field MRI in TARE, holmium micro-spheres are tested in low-field MRI using a 0.5T MRI scanner. Using phantoms containing a range of holmium micro-sphere concentrations, relaxivity r∗2 has been determined at 0.5T 1.5T and 3T. The results at 0.5T show that holmium-microspheres have a significant contrast effect, opening up possibilities for further research into the use of low-field MRI in Ho-TARE.