Abstract: A technique is provided for passively detecting the presence and location of an underground object. A plurality of individual antennas positioned in a linear array are directed to receive fields of view which are mutually parallel in azimuth. The linear array is then focused at a plurality of different angles in azimuth for passively acquiring low level random noise signals in the RF spectrum which are emitted by the underground object and by the intervening media.

Abstract: A variable geometry coil system includes a single fixed horizontal coil and a vertically oriented pair of movable coils interconnected through an electronic matrix to allow for a multi-mode system which enables either the vertical pair or the horizontal coil to function alone or to enable a quadrature combination of the coils for optimum signal performance. The vertical coil pair includes two matched coils which are loaded to reduce their tuning sharpness so as to eliminate the need for clinical tuning prior to utilization. Signal losses incurred by the Q reduction are compensated for by including an integrated preamplifier at the signal output.

Abstract: A hyperthermia treatment apparatus includes an annular radio frequency (RF) antenna array with bolus that is compatible with a magnetic resonance imaging (MRI) machine. Antenna elements polarized parallel to the axis of the cylinder are used for forming a Specific Absorption Ratio (SAR) map as well as for directing the energy to accomplish hyperthermia. The array may be dynamically controlled to focus energy at any specified region within the cylinder. The array is positioned inside an MRI machine and is tuned to the machine's hydrogen resonant frequency. For treatment planning, the array is employed to form an SAR map via RF current density imaging. Using this map, array phase, amplitude, and temporal weighting are optimized until the SAR maxima is congruent with the treatment volume. For treatment, RF radiation is applied to the subject to induce heating of the treatment volume using these optimal array parameters. Temperature is periodically determined via noninvasive MRI methods (i.e.

Abstract: An MRI machine RF body coil is arranged so that it can also function as a hyperthermia treatment apparatus by arranging the RF body coil as an array of individual antenna element connected to each other by individually controllable switches and feedthrough elements.

Abstract: A reflectometer tuning unit for a magnetic resonance imaging (MRI) system, provided for the standing wave voltage adjustment of various MRI receive coil units, and which is also capable of detection of various open/short fault conditions in the MRI receive coil unit or the coaxial cable connected to the MRI receive coil unit. The reflectometer tuning unit comprises an oscillator, a directional coupler, and a measuring system. The oscillator produces an output signal having its frequency tuned to the Larmor frequency of the magnetic resonance imaging system. The directional coupler has OUT, IN and CPL ports. The output of the oscillator is connected to the OUT port, and selected impedances, and later the receive coil unit, are connected to the IN port. The directional coupler produces an output signal at the CPL port which is proportional to the port of energy reflected back from the IN port to the OUT port, which is also proportional to the impedance mismatch presented by the impedance at the IN port.

Abstract: A magnetic resonance imaging receiver system for producing high resolution images of the foot and ankle regions of a human subject. The magnetic resonance imaging receiver comprises an antenna for receiving resonance signals produced by a magnetic resonance imaging, radio frequency excitation magnetic apparatus, a free standing foot cradle assembly for supporting and rigidly holding the foot and ankle of the subject, and a tuning/impedance matching circuit for providing for the maximum transfer of radio frequency energy from the antenna to the receiver unit in the magnetic resonance imaging, radio frequency excitation magnet apparatus. The system utilizes fixed local coils which operate in the receive only mode for receiving electromagnetic signals from resonating nuclei produced by a whole body MRI scanner system or the like to produce high quality images.