New MR Technologies for MR-guided Thermometry and Acoustic Radiation Force Imaging

MRI can be used to non-invasively generate temperature maps of the tissues in three dimensions. MR thermometry ensures both effectiveness and safety of thermal therapies, because it allows verifying that the necessary thermal dose is achieved in the target tissue and helps preventing the temperature increase in the healthy tissues.

In this thesis, new technologies for MR thermometry are presented. MR thermometry with high temporal resolution, which is also immune to temperature-related tissue conductivity changes, is developed and applied during patients’ hyperthermia treatments. This MR thermometry is able to monitor fast ablation procedures. Field drift correction method is investigated for thermal therapies of long duration, in which the tissue volume affected by temperature change is large. The flip angle is optimised for the MR thermometry, which uses two different methods simultaneously to combine the advantages of both of them. Optimisation of timing parameters of acoustic radiation force imaging (ARFI), which is a useful addition to high intensity focused ultrasound ablation therapy, is performed.

The new technologies for MR-guided thermometry and ARFI, which are presented in this thesis, could potentially develop this field further and make MR-guided thermal therapies more effective and safer for the patients.