Abstract: A method of reducing artifacts in steady-state free precession (SSFP) signals for use in magnetic resonance imaging is provided. A plurality of SSFP imaging sequences is applied to an object. An imaging data for each of the SSFP imaging sequences is acquired. The imaging data is combined using a weighted combination where weights depend on a control parameter that adjusts a trade-off between banding artifact reduction and signal to noise ratio (SNR).

Abstract: Imaging time using PILS is reduced by using multiple coils with localized sensitivities with each coil having a separate demodulation channel thereby permitting parallel signal processing and image reconstruction. Images from the multiple coils are then combined to form an image with a larger field of view (FOV).

Abstract: Artifact reduction in steady state free precession magnetic resonance imaging uses weighting of acquired image data to emphasize higher signals and then establishing an image signal based on the combined weighted signals. In one embodiment, a SSFP imaging sequence uses phase cycling and acquired image data is squared with the squared data then combined. The final image signal is based on the square root of the squared data.

Abstract: Magnetic resonance signals for imaging species having short spin-spin relaxation times (T.sub.2) are obtained without the need for a refocusing lobe. A series of RF excitation pulses are applied to the species with magnetic resonance signals being detected after each RF excitation pulse is applied. The magnetic resonance signals are then combined to provide the imaging signals. In one embodiment, each RF excitation pulse is half of a conventional slice-selective pulse with each pulse being slewed to zero.

Abstract: A method of collecting image data with selective spectral suppression for at least two species is provided. A sequence of RF excitation pulses is repeatedly applied, whereby a repeated sequence of at least two substantially different spectrally selective steady-state magnetizations is established. Magnetic gradients are applied between said RF pulses. A plurality of magnetic resonance image (MRI) signals is acquired. The plurality of MRI signals is combined using a weighted combination where the weights depend on a control parameter that adjusts a trade-off between selective spectral suppression and signal-to-noise ratio (SNR).

Abstract: Multiple inversion recovery flow imaging employs at least four spin inversion pulses following saturation of static nuclei spins to null nuclei in static material having different spin-lattice relaxation times (T.sub.1) with the inversion pulses being spaced in time to substantially reduce the longitudinal magnetization of the T.sub.1 species present. The saturation of static nuclei spins includes applying a sequence of saturation pulses with adjacent pulses being separated by a diphasing gradient to avoid refocusing coherence. The detection of signals includes applying at least one RF read-out pulse near the nulling point.

Abstract: A new technique for imaging a material with a high T2/T1 ratio such as articular cartilage uses driven equilibrium Fourier transform (DEFT), a method of enhancing signal strength without waiting for full T1 recovery. Compared to other methods, DEFT imaging provides a good combination of bright cartilage and high contrast between cartilage and surrounding tissue. Both theoretical predictions and images show that DEFT is a valuable method for imaging articular cartilage when compared to spoiled gradient recalled acquisition in the steady-state (SPGR) or fast spin echo (FSE). T2-decay, T1 recovery, echo time, magnetization density, proton density, and equilibrium density per proton are related by a derived equation.

Abstract: A fast, spectrally-selective steady-state free precession (SSFP) imaging method is presented. Combining k-space data from SSFP sequences with certain phase schedules of radiofrequency excitation pulses permits manipulation of the spectral selectivity of the image. For example, lipid and water can be rapidly resolved. The contrast of each image depends on both T1 and T2, and the relative contribution of the two relaxation mechanisms to image contrast can be controlled by adjusting the flip angle. Several applications of the technique are presented, including fast musculoskeletal imaging, brain imaging, and angiography. The technique is referred to herein as linear combination steady-state free precession (LCSSFP) and fluctuating equilibrium magnetic resonance (FEMR).

Abstract: An RF coil assembly includes a plurality of RF source coils and an RF target coil separate from the plurality of RF source coils. A computer is programmed to acquire MR data of an imaging object from each of the plurality of RF source coils and to acquire MR data of the imaging object from the RF target coil. The computer is further programmed to calculate a set of weights based on a relationship between MR data acquired from each RF source coil and MR data acquired from the RF target coil and to reconstruct an image based on an application of the set of weights to at least a portion of the MR data acquired from each of the plurality of RF source coils.

Abstract: Real time spatially localized velocity distribution is measured using magnetic resonance techniques by first exciting a column-shaped region using a 2D RF excitation pulse. A cyclical readout gradient is then played along the excited column's axis while the magnetic resonance signal is continuously sampled to create a 2D sample set of velocity frequency vs. spatial frequencies in the same direction. If the cyclical readout gradient, for example a sawtooth-shaped gradient, has lobes of increasing area, the spacing between samples in the velocity-frequency direction is increased to emphasize sampling at low velocity-frequency and to more coarsely sample high velocity-frequencies. The sequence can be repeated to collect a time series of velocity-position images, which can then be sampled to create a velocity-time image at a single location.

Abstract: A steady-state condition for tipped nuclear spins is accelerated or catalyzed by first determining magnetization magnitude of the steady state and the scaling magnetization along one axis (Mz) to at least approximate the determined magnetization magnitude. Then the scaled magnetization is rotated to coincide with a real-valued eigenvector extension of the tipped steady-state magnetization. Any error vector will then decay to the steady-state condition without oscillation. In one embodiment, the magnetic resonance imaging utilizes steady-state free precession (SSFP). The scaling and rotating steps are followed by the steps of applying read-out magnetic gradients and detecting magnetic resonance signals from the tipped nuclear spins. The magnetization magnitude is determined by eigenvector analysis, and the eigenvector extension is a real-valued eigenvector determined in the analysis.

Abstract: A method of providing selective spectral suppression in balanced SSFP magnetic resonance imaging for a first and second species is provided. A plurality of balanced SSFP images are acquired. Each acquisition includes applying RF excitations in a sequence of TR intervals with each being applied in an associated TR interval. The sequence of TR intervals includes at least one data acquisition TR interval and at least two secondary TR intervals each having a duration that is shorter than the data acquisition TR interval. A first secondary TR interval precedes the data acquisition TR interval and a second secondary TR interval follows the data acquisition TR interval. The duration of the second secondary TR interval is substantially equal to the first secondary TR interval such that the sequence of TR intervals is substantially symmetric with respect to duration about a center point of the sequence of TR intervals.

Abstract: The selective imaging of an object having two materials with different relaxation times (T1 or T2) is provided by using a driven equilibrium sequence (T2 weighted preparation sequence) followed by an inversion recovery sequence. In the driven equilibrium sequence the object is placed in a static magnetic field along a longitudinal axis, an excitation pulse is applied to tip nuclei spins into a transverse plane, and at least one refocusing pulse is applied to produce a spin echo having a magnetization component as a function of relaxation time. At least one pulse is then applied to the object to drive the spin echo to an inverted position along the longitudinal axis. A readout excitation is then applied at a later time when the longitudinal magnetization of one material is substantially reduced. In one embodiment, an inversion pulse is applied prior to the T2 weighted preparation sequence.

Abstract: Magnetic resonance signals for imaging species having short spin-spin relaxation times (T.sub.2) are obtained without the need for a refocusing lobe. A series of RF excitation pulses are applied to the species with magnetic resonance signals being detected after each RF excitation pulse is applied. The magnetic resonance signals are then combined to provide the imaging signals. In one embodiment, each RF excitation pulse is half of a conventional slice-selective pulse with each pulse being slewed to zero. Contrast between the imaged short T.sub.2 species and longer T.sub.2 species can be enhanced by first applying an RF signal having sufficient amplitude to excite the longer T.sub.2 species but insufficient amplitude to excite the short T.sub.2 species whereby the longer T.sub.2 species are tipped by the RF signal. A magnetic gradient can then be applied to dephase the tipped nuclei of the longer T.sub.2 species. The imaging signals are then obtained from magnetic resonance signals from the short T.sub.