[Magnetic resonance imaging (MRI)-directed focussed ultrasound. Methods and applications in oncological treatment].

Focussed ultrasound is the only known technology that allows non-invasive local hyperthermia. Since MRI may be employed to obtain real-time temperature maps non-invasively, the combination of these two technologies offers great advantages, specifically aimed towards oncological studies. Real-time identification of the target region and accurate control of the temperature evolution during the treatment are now possible. Thermal ablation of pathological tissue, local drug delivery using thermosensitive microcarriers and controlled transgene expression using thermosensitive promoters have recently been demonstrated with this unique technology, and based on these experiments the combination of focussed ultrasound and MRI thermometry holds promise for future oncological diagnostics and treatment. In this paper we review some of the recent methodological developments as well as experimental and first clinical studies using this approach.