Abstract: A magnetic resonance imaging system includes a bore, a table configured to support a patient being imaged and movable to move the patient in and out of the bore, a motion sensor, a controller configured to detect patient motion based on changes in an RF signal from the motion sensor. The motion sensor includes a self-resonant spiral (SRS) coil excited by a drive signal to radiate a magnetic field having a predefined resonant frequency and a driver-receiver coupled to the SRS coil and configured to generate the drive signal to excite the SRS coil and to receive the RF signal from the SRS coil. The motion sensor is located such that a portion of the patient is within the magnetic field while the patient is being imaged in the bore.

Abstract: A table for an MRI system includes a top surface for supporting a patient being imaged and a motion sensor for sensing motion of the patient. The motion sensor is located below the top surface and includes a self-resonant spiral (SRS) coil and a coupling loop. The coupling loop generates a drive RF signal to excite the SRS coil to radiate a magnetic field having a predefined resonant frequency. The coupling loop also receives a reflection RF signal from the SRS coil. The motion sensor is located such that at least a portion of a torso of the patient being imaged is within the magnetic field. A controller is configured to detect patient motion based on the reflection RF signal.

Abstract: A table for an MRI system includes a top surface for supporting a patient being imaged and a motion sensor for sensing motion of the patient. The motion sensor is located below the top surface and includes a self-resonant spiral (SRS) coil and a coupling loop. The coupling loop generates a drive RF signal to excite the SRS coil to radiate a magnetic field having a predefined resonant frequency. The coupling loop also receives a reflection RF signal from the SRS coil. The motion sensor is located such that at least a portion of a torso of the patient being imaged is within the magnetic field. A controller is configured to detect patient motion based on the reflection RF signal.

Abstract: An RF receiver apparatus for translating multiple channels of MR data across a single readout cable is disclosed. The RF receiver apparatus is designed to separately translate In-phase and Quadrature components of an MR signal to a data acquisition system for signal processing. Moreover, multiple channels of In-phase and Quadrature signals may be transmitted as composite signals to the data acquisition system across a single coaxial cable. The composite signals may then be filtered to recover the multiple channels of data. The RF receiver apparatus is particularly applicable with a phased-array coil architecture.

Abstract: A magnetic resonance imaging system has a electromagnet coil assembly for exciting nuclei of an animal placed within the assembly and a mechanism to receive magnetic resonance signals from the nuclei and reconstruct an image of the animal from those signals. A plethysmograph is provided to sense the peripheral arterial pulse of the animal and gate the MRI system. A sensor for the plethysmograph includes a fiber optic cable having a pair of optical fibers which extend into the magnet assembly. A probe is connected to one end of the cable and is adapted to be attached to a digit of the animal so that ends of the optical fibers are adjacent the animal's skin. The other end of the cable couples to a circuit which sends light through one of the optical fibers to the probe, and which receives light returned from the probe through the other optical fiber. The circuit produces an electrical signal corresponding to the intensity of light received from the other optical fiber.

Abstract: An electrode assembly, particularly useful in nuclear magnetic resonance apparatus, for sensing a physical characteristic of a live study subject includes an electrode positioned in electrical contact with the subject for sensing the physical characteristic. The electrode assembly further includes a lead wire connected at one of its ends to the electrode and having an impedance selected to protect the study subject from heating. The impedance is also selected to have a low voltage coefficient of resistivity in order to prevent conversion of radio-frequency energy to ECG in-band energy.

Abstract: As CRT display is housed in a magnetic shield to reduce the image distortions caused by the external magnetic field produced by an NMR scanner. To further improve image quality, three sets of compensating coils are positioned around the CRT display and inside the shield to produce magnetic fields which offset the effects of the residual external magnetic field components that penetrate the shield or enter through the window in the shield used to view the CRT screen.

Abstract: There is provided a power source for continuously energizing electrically isolated devices used to monitor the physiological state of a subject undergoing an examination in an NMR scanner having a magnet, RF and gradient coils. The power source is made up of a first element for generating energy of one type and a second element for receiving this energy and converting it to a second energy type used to energize the electrically isolated devices. The first and second elements are operatively coupled to one another through an electrically isolated medium to permit continuous transfer of energy from the first to the second element and to reject interference due to the NMR apparatus subsystems. In one embodiment the first element may be an array of light-emitting diodes, while the second element may be an array of photovoltaic cells. In another embodiment, the first and second elements may be ultrasonic transducers coupled through air or a ceramic substrate.