  Magnetic Resonance Imaging (MRI) has become a popular modality in guiding
minimally invasive thermal therapies, due to its advanced, non-ionizing,
imaging capabilities and its ability to record changes in temperature. A
variety of MR thermometry techniques have been developed over the years, and
Proton Resonance Frequency (PRF) Shift Thermometry is the current clinical gold
standard to treat a variety of cancers. It is used extensively to guide
hyperthermic thermal ablation techniques such as high-intensity focused
ultrasound (HIFU) and laser-induced thermal therapy (LITT). Essential
attributes of PRF Shift Thermometry include excellent linearity with
temperature, good sensitivity, and independence from tissue type. This
non-invasive temperature mapping method gives accurate quantitative measures of
the temperature evolution inside biological tissues. In this review, the
current status and new developments in the fields of MR-guided HIFU and LITT
are presented with an emphasis on breast, prostate, bone, uterine and brain
treatments.
