Disclosed herein is an RF probe for use with a medical imaging apparatus, the probe comprising an intracorporeal self-tuned resonator coil for receiving a signal indicative of an image of an interior portion of a body. The resonator coil is preferably coupled to a transmission medium having a characteristic impedance such that the resonator coil is substantially self-matching with the transmission medium's characteristic impedance. Preferably the resonator coil comprises an open wound conductor having a plurality of turns. The length of the resonator coil can be used to tune the resonator coil to a desired frequency, such as the Larmour frequency. Further, a return lead of the transmission medium is preferably coupled to an end of the conductor, and a signal lead of the transmission medium is preferably coupled to a point on the winding, thereby defining a turns ratio for the resonator coil. The turns ratio of the resonator coil can be used to match the resonator coil to the characteristic impedance of the transmission medium. Because the resonator coil of the present invention is self-tuning and self-matching, it avoids the use of bulky and relatively expensive tuning and matching circuits.