Magnetic resonance imaging in 166Ho liver radioembolization

Abstract

To assure safety and to increase efficacy of intra-arterial radioembolization, it is essential to assess the biodistribution of the radioactive microspheres after treatment. In this respect, holmium microspheres (Ho-MS) and magnetic resonance imaging (MRI) form a promising combination. While Ho-MS possess attractive radioembolization characteristics, MRI is a non-invasive imaging modality that offers soft tissue contrast and enables microsphere biodistribution measurements. In this thesis the utility of MRI in holmium liver radioembolization was explored. The feasibility of MRI-based assessment of the intrahepatic Ho-MS biodistribution was investigated in 15 patients. R2* maps, constructed from multi gradient echo images, were found to visualize the deposition of Ho-MS with great detail. The total amount of Ho-MS, calculated based on the linear relationship between R2* and Ho-MS concentration, was comparable to the delivered amount (89±19% on average).Single photon emission computed tomography (SPECT) images showed good visual resemblance to MRI-based maps. A good correlation was found for the whole liver mean absorbed radiation dose as assessed by MRI and SPECT (correlation coefficient: 0.93; P