287 results about "Rf excitation" patented technology

A method and device for inducing anaesthesia in mammals by the application of RF energy to create hyperthermia derived neural anaesthesia. An RF generator drives a plurality of electrodes placed in tissue surrounding the target nerve fiber to desiccate the desired length of nerve fiber to be desiccated in a single deployment. The device allows high-speed selection / de-selection of bipolar electrode pairs or sets under continuous RF excitation. Activation of electrode pairs is adapted in response to sensed current density and temperature (by electrodes not in the current discharge activation phase) in order to create lesions of complex and well defined shape necessary for the production of hyperthermia derived neural anaesthesia.

A method and device for inducing anaesthesia in mammals by the application of RF energy to create hyperthermia derived neural anaesthesia. An RF generator drives a plurality of electrodes placed in tissue surrounding the target nerve fibre to desiccate the desired length of nerve fibre to be desiccated in a single deployment. The device allows high-speed selection / de-selection of bipolar electrode pairs or sets under continuous RF excitation. Activation of electrode pairs is adapted in response to sensed current density and temperature (by electrodes not in the current discharge activation phase) in order to create lesions of complex and well defined shape necessary for the production of hyperthermia derived neural anaesthesia.

In a method for implementation of a magnetic resonance examination, and a magnetic resonance apparatus, and an array for acquisition of magnetic resonance signals, and a magnetic resonance signal at a magnetic resonance frequency are acquired from an examination region with an array of frequency conversion units after an RF excitation and are radiated as frequency-converted signals. The resulting signal field is acquired by a number of reception antennas of a second antenna array, which are arranged at different spatial positions and thus allow a spatial resolution of the frequency-converted signals. The acquired acquisition signals are used for image reconstruction.

A parallel magnetic resonance imaging (MRI) apparatus configurable to image a physical entity comprises:a main magnetic flux source for providing a uniform fixed magnetic field, B0;an RF array system comprising a plurality of RF coils and receivers, said RF system configured for:generating rotating RF excitation magnetic fields B1; andreceiving RF signals due to precessing nuclear magnetization on multiple spatially distinct radio frequency coils and associated receiver channels, said RF system being configured to operate in accordance with a B1 sensitivity encoding technique;a control processor for controlling imaging functionality, collecting image data and effecting data processing of the captured image data the control processor being configured with post processing capability for the B1 sensitivity encoding technique;an image display means for displaying processed image data as resultant images; andan auxiliary magnetic field means capable of producing at least one auxiliary uniform B0 step magnetic field imaging region within the main B0 magnetic field;wherein:the auxiliary magnetic field, means is configured to operate in combination with the RF coil system and the B1 sensitivity encoding technique, the imaging apparatus thereby providing faster image acquisition than that attributed to the speed up factor provided solely by the B1 sensitivity encoding technique.The invention also includes a method of imaging using this apparatus.Furthermore, the invention also includes a method and apparatus for three-dimensional MR imaging using a 1D Multiple Acquisition Micro B0 array coupled with a 2D Multiple Acquisition Micro B0 array.

A chip scale atomic clock is disclosed that provides a low power atomic time / frequency reference that employs direct RF-interrogation on an end-state transition. The atomic time / frequency reference includes an alkali vapor cell containing alkali atoms, preferably cesium atoms, flex circuits for physically supporting, heating, and thermally isolating the alkali vapor cell, a laser source for pumping alkali atoms within the alkali vapor cell into an end resonance state by applying an optical signal along a first axis, a photodetector for detecting a second optical signal emanating from the alkali vapor cell along the first axis, a pair of RF excitation coils for applying an RF-interrogation signal to the alkali atoms along a second axis perpendicular to the first axis, a pair of bias coils for applying a uniform DC magnetic field along the first axis, and a pair of Zeeman coils for applying a Zeeman interrogation signal to the alkali atoms and oriented and configured to apply a time-varying magnetic field along the second axis through the alkali vapor cell. Another flex circuit is used for physically supporting the laser source, for heating the laser source, and for providing thermal isolation of the laser source. The laser source can be a vertical cavity surface emitting laser (VSCEL). The bias coils can be Helmholtz coils.

A system composed of multiple transmit coils with corresponding RF pulse synthesizers and amplifiers is disclosed. A method of designing RF pulses specific to each transmit coil to induce spatiotemporal variations in a composite B1 field is also disclosed. The present invention supports faithful production of desired excitation profiles and accommodates the use of any coil array geometry. The present invention also supports reduction in excitation pulse length. Through effective B1 field maps for each transmit coil, mutual coupling and other inter-coil correlations are accounted for in the RF pulse design.

Embodiments of the subject invention can utilize a single coil structure for dual-mode operation. In a specific embodiment, a single coil structure can be used as a volume coil in the transmitting phase and as a phase array in the receiving phase. In an embodiment, a transmit coil array in accordance with the subject invention can be utilized for one or more of the following: 1) parallel RF excitation on an MRI scanner equipped with a multiple-channel transmitter; 2) serial RF excitation with the use of a switch system with a single channel transmitter; and 3) generation of a homogeneous B1 field for regular MRI with the use of a power splitter on a standard scanner. In a specific embodiment, the use of a concentric double loop coil with different tunings of inner and outer loops can be implemented. In an embodiment, the coil elements can be decoupled using the CRC mode of a concentric double loop coil. In an embodiment, a surface coil transmit array can provide better compatibility with a receive array. In a specific embodiment, an over-coupled technique can be used to improve the phase control of the transmitting pulse.

Magnetic resonance imaging of a body uses steady state free precession with material separation for the selective imaging of two species, such as blood or fat. The refocusing property of SSFP is used with signal phase detection to suppress either water or lipid. Phase and / or frequency of the RF excitation pulse and repetition time are selected so that resonant frequencies of water, fw, and lipid, fl, are on opposite sides of the signal null frequency.

A low-cost single-sided NMR sensor to produce depth profiles with microscopic spatial resolution is presented. The open geometry of the NMR sensor provides a non-invasive and non-destructive testing method to characterize the depth structure of objects of arbitrary size. The permanent magnet geometry generates one plane of constant magnetic field intensity parallel to the scanner surface. By combining the highly uniform static gradient with selective RF excitation, a thin flat sensitive slice can be defined. By moving the relative position between the slice and the object, one-dimensional profiles of the near surface of large samples are produced with high spatial resolution.