This invention relates to a device for retrieving information about one or more states of a mammalian body comprising: (a) a magnetic resonance imaging device comprising a first set of one or more radio-frequency coils for measuring the body temperature Ti at a selected location of a mammalian body, (b) a local heating means including a second set of one or more radio-frequency coils, said second set comprising at least two channels for delivering focused radio frequency energy to said selected location of said mammalian body and raising the temperature Ti thereof, and (c) means for modulating said radio-frequency energy delivered by said second set of coils as a function of said temperature Ti in order to reach and maintain a predefined temperature Tp above the normal mammalian body temperature Tb.