Thermally Reversible Nanoparticle Aggregation: Modeling T2 Variation with Temperature

Bashar Issa¹, ², Ihab M. Obaidat¹, Shahnaz M. Qadri², Yousef Haik, ²³

Magnetic nanoparticles have been previously used as both MRI contrast and hyperthermia agents. The overall aim is to develop a MRI-based thermal mapping technique for the heated tissue. The first step is the modeling of relaxation times at different temperatures. Echo Limited Regime is used to fit the T2 data using a modified particle size that takes into account the clustering of particles. It is believed that thermally enhanced surface layer spins plays pivotal role in the thermally reversible agglomeration of particles up to a temperature around Curie temperature 43^oC. Thermally induced agglomeration can be used as temperature sensor.