Abstract: A spread-spectrum transmission system wherein a plurality of spread-spectrum signals are frequency division multiplexed by offsetting the center or carrier frequencies of the spread-spectrum signals by a fraction of the spectral-line spacing of the signals. The signals are generated by modulating a carrier with a pseudo-noise (PN) code signal. At a receiver, demultiplexing is carried out by mixing (42) the received multiplexed signal with a plurality of local oscillator frequencies (43) which are offset from each other in the same manner as the centre or carrier frequencies of the multiplexed spread-spectrum signals. The mixed signals are then further mixed (45) with generated PN code signals (47) corresponding to those used to generate the multiplexed spread-spectrum signals. The epoch of each generated PN code signal is then advanced or retarded in response to a respective epoch control signal (48) generated by a respective controller (46).

Abstract: A resonance exciting coil (C) excites magnetic resonance in nuclei disposed in an image region in which a main magnetic field and transverse gradients have been produced. A flexible receiving coil (D) includes a flexible plastic sheet (40) on which one or more loops (20) are adhered to receive signals from the resonating nuclei. Velcro straps (46) strap the flexible sheet and the attached coil into close conformity with the surface of the portion of the patient to be imaged. An impedance matching or coil resonant frequency adjusting network (50) is mounted on the flexible sheet for selectively adjusting at least one of an impedance match and the peak sensitivity resonant frequency of the receiving coil. A preamplifier (52) amplifies the received signals prior to transmission on a cable (24). A selectively variable voltage source (70) applies a selectively adjustable DC bias voltage to the cable for selectively adjusting at least one of the impedance match and the LC resonant frequency of the receiving coil.

Abstract: A resonance exciting coil (C) excites magnetic resonance in nuclei disposed in an image region in which a main magnetic field and transverse gradients have been produced. A flexible receiving coil (D) includes a flexible plastic sheet (40) on which one or more loops (20) are adhered to receive signals from the resonating nuclei. Velcro straps (46) strap the flexible sheet and the attached coil into close conformity with the surface of the portion of the patient to be imaged. An impedance matching or coil resonant frequency adjusting network (50) is mounted on the flexible sheet for selectively adjusting at least one of an impedance match and the peak sensitivity resonant frequency of the receiving coil. A preamplifier (52) amplifies the received signals prior to transmission on a cable (24). A selectively variable voltage source (70) applies a selectively adjustable DC bias voltage to the cable for selectively adjusting at least one of the impedance match and the LC resonant frequency of the receiving coil.

Abstract: A binomial pulse generator (32) selectively generates binomial radio frequency excitation pulses (60) which induce magnetic resonance only in selected hydrogen dipoles and suppresses resonance in others. An inversion pulse generator (34) generates a first inversion pulse (70) in the presence of a first magnetic field gradient (72) generated by a gradient control (22). The inversion pulse only inverts the magnetization of resonating nuclei in a first plane defined by the first magnetic field gradient. A second inversion pulse (74) applied in the presence of a second magnetic field gradient (76) inverts the magnetization of resonating nuclei in a second planar region defined by the second magnetic field gradient. A third inversion pulse (78) applied concurrently with a third magnetic field gradient (80) inverts the magnetization of resonating nuclei in a third planar region defined by the third magnetic field gradient.

Abstract: The magnetic resonance signals in a magnetic resonance imaging apparatus are detected by a surface or localized coil assembly (D). To improve the field homogeneity and increase the signal-to-noise ratio when examining a region of interest deep within a subject, the surface coil assembly is configured with a first coil portion (22) and a second coil portion (24). The first coil portion is disposed along an exterior surface of the subject. The second coil portion is disposed parallel to the first coil portion and displaced outward a distance (44) from the first coil portion and the subject exterior surface. The first and second coil portions are electrically interconnected with an opposite current phase in a dipole pair such that the second current portion reduces the sensitivity of the first coil portion to magnetic resonance signals originating close to the surface of the subject.