Abstract: A system for magnetic resonance (MR) spectroscopy includes a plurality of gradient coils positioned about a bore of a magnet and an RF coil assembly coupled to a pulse generator to emit RF pulse sequences and arranged to receive resulting MR signals from a subject of interest. A system control is also included in the MR spectroscopy system and is coupled to the plurality of gradient coils and the RF coil assembly. The system control is programmed to cause the RF coil assembly to emit a first RF pulse and a second RF pulse, wherein at least one of the first and second RF pulses is spectrally selective and at least one of the first and second RF pulses is spatially selective. The system control is also programmed to cause the RF coil assembly to emit a third RF pulse after a pre-defined time delay to generate a stimulated echo and detect MR signals resulting from the stimulated echo.

Abstract: A system and method for improving available signal-to-noise ratio (SNR) and speed of MR imaging of hyperpolarized substances is disclosed. The system and method include decoupling spin effects of hydrogen nuclei from non-hydrogen nuclei of interest during sampling of MR signals therefrom. Though the hydrogen nuclei of the hyperpolarized substance may not be directly bonded to the non-hydrogen nuclei of interest, resonance splitting may still impact SNR. Long range decoupling improves T2* time, and thus preserves signal strength and available SNR.

Abstract: A system and method for improving available signal-to-noise ratio (SNR) and speed of MR imaging of hyperpolarized substances is disclosed. The system and method include decoupling spin effects of hydrogen nuclei from non-hydrogen nuclei of interest during sampling of MR signals therefrom. Though the hydrogen nuclei of the hyperpolarized substance may not be directly bonded to the non-hydrogen nuclei of interest, resonance splitting may still impact SNR. Long range decoupling improves T2* time, and thus preserves signal strength and available SNR.

Abstract: A system for magnetic resonance (MR) spectroscopy includes a plurality of gradient coils positioned about a bore of a magnet and an RF coil assembly coupled to a pulse generator to emit RF pulse sequences and arranged to receive resulting MR signals from a subject of interest. A system control is also included in the MR spectroscopy system and is coupled to the plurality of gradient coils and the RF coil assembly. The system control is programmed to cause the RF coil assembly to emit a first RF pulse and a second RF pulse, wherein at least one of the first and second RF pulses is spectrally selective and at least one of the first and second RF pulses is spatially selective. The system control is also programmed to cause the RF coil assembly to emit a third RF pulse after a pre-defined time delay to generate a stimulated echo and detect MR signals resulting from the stimulated echo.

Abstract: A system for magnetic resonance (MR) spectroscopy includes a plurality of gradient coils positioned about a bore of a magnet and an RF coil assembly coupled to a pulse generator to emit RF pulse sequences and arranged to receive resulting MR signals from a subject of interest. A system control is also included in the MR spectroscopy system and is coupled to the plurality of gradient coils and the RF coil assembly. The system control is programmed to cause the RF coil assembly to emit a first RF pulse and a second RF pulse, wherein at least one of the first and second RF pulses is spectrally selective and at least one of the first and second RF pulses is spatially selective. The system control is also programmed to cause the RF coil assembly to emit a third RF pulse after a pre-defined time delay to generate a stimulated echo and detect MR signals resulting from the stimulated echo.

Abstract: A system for magnetic resonance (MR) spectroscopy includes a plurality of gradient coils positioned about a bore of a magnet and an RF coil assembly coupled to a pulse generator to emit RF pulse sequences and arranged to receive resulting MR signals from a subject of interest. A system control is also included in the MR spectroscopy system and is coupled to the plurality of gradient coils and the RF coil assembly. The system control is programmed to cause the RF coil assembly to emit a first RF pulse and a second RF pulse, wherein at least one of the first and second RF pulses is spectrally selective and at least one of the first and second RF pulses is spatially selective. The system control is also programmed to cause the RF coil assembly to emit a third RF pulse after a pre-defined time delay to generate a stimulated echo and detect MR signals resulting from the stimulated echo.

Abstract: A system and method for MR imaging includes a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet, and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images. The apparatus further includes a controller programmed to determine a variable flip angle (VFA) sequence to excite a hyperpolarized material in a subject and to determine a delay period during which application of the VFA sequence is delayed after injection of a hyperpolarized contrast agent. The delay period is based on dynamic data of the hyperpolarized material acquired from the subject. The controller is also programmed to cause application of the VFA sequence to excite the hyperpolarized material in the subject and to acquire MR data from the hyperpolarized material using an isotropic centric phase encoding (iCPE) technique.

Abstract: A system and method for improving available signal-to-noise ratio (SNR) and speed of MR imaging of hyperpolarized substances is disclosed. The system and method include decoupling spin effects of hydrogen nuclei from non-hydrogen nuclei of interest during sampling of MR signals therefrom. Though the hydrogen nuclei of the hyperpolarized substance may not be directly bonded to the non-hydrogen nuclei of interest, resonance splitting may still impact SNR. Long range decoupling improves T2* time, and thus preserves signal strength and available SNR.

Abstract: A technique is set forth for MR spectroscopy that is capable of reducing signal overlap between metabolite signals for improved clinical analysis of metabolite content. The technique includes varying an echo time across a scanning dimension. Once a span of echo time for an acquisition dimension is determined, and the number of acquisition data points is known, a variance between echo times can be determined. A pulse sequence with differing echo times is then applied for each frame, and after data is acquired, an image is reconstructed that significantly improves metabolite signal separation.

Abstract: A technique is set forth for MR spectroscopy that is capable of reducing signal overlap between metabolite signals for improved clinical analysis of metabolite content. The technique includes varying an echo time across a scanning dimension. Once a span of echo time for an acquisition dimension is determined, and the number of acquisition data points is known, a variance between echo times can be determined. A pulse sequence with differing echo times is then applied for each frame, and after data is acquired, an image is reconstructed that significantly improves metabolite signal separation.

Abstract: A system and method for imaging is presented that includes exciting water-exchangeable spins in oxygen-bearable molecules in a ROI having a change in oxygen status. A proton transfer within the ROI from exchangeable protons within water is detected such that changes in oxygen levels across the ROI are distinguishable.

Abstract: A field-frequency lock system for an MRI system includes a microcoil and resonant sample located to sense changes in the polarizing magnetic field. Changes are detected as a shift in frequency of the NMR signal produced by the resonant sample, and the frequency shift is used to compensate the MRI system. Compensation is achieved by adjusting the RF reference signal employed in the MRI system transceiver.

Abstract: Chemical shift error in proton magnetic resonance spectroscopy is reduced by applying a volume excitation pulse sequence such as PRESS and very selective out-of-volume saturation pulses to limit that volume to a volume-of-interest free of the misregistration errors associated with the excitation sequence. The resulting volume is then only limited by the very small chemical shift misregistration of the very selective saturation pulses.

Abstract: Disclosed is improved quantitative in vivo spectroscopy by means of F1-oversampled J-Resolved 2D spectroscopy. Reconstruction makes full use of internal signals for 2D water lineshape, T.sub.2 and partial volume correction, and analysis uses 2D complex model spectra fitting. The preferred embodiment of the new method integrates these features into PRESS localized brain spectroscopy and is carried out without the need for water suppression.

Abstract: A pure water subtraction method for eliminating interfering sidebands of residual water including spurious signals from extraneous sources such as eddy current effects, Bo magnetic field drift, patient motion and the like. Unsuppressed and partially water suppressed magnetic signal data are obtained, and a low frequency water-phase-correction is applied thereto. The water phase corrected partially suppressed data is subtracted from the water phase corrected unsuppressed data to get a pure water reference (i.e. metabolite signals cancel). A scaled version of the pure water reference is subtracted from the partially suppressed data to eliminate spurious water signals.

Abstract: Susceptibility artifacts in slice selective volume magnetic resonance spectroscopy are reduced by applying phase encoding at a nominal resolution equal to or larger than the slice selection dimensions. In a preferred embodiment of the method, phase encoding is applied along the axes of the first and last RF slice selections. The volume of interest is contained completely within a single pixel defined by the 2D phase encoding. Unsuppressed water reference signal from the volume of interest is relatively unaffected by these artifacts and is collected without phase encoding.

Abstract: A signal function S(t.sub.1, t.sub.2) is obtained from a plurality of coherence transfer pathways in a single acquisition by preparing a molecular system in a coherent non-equilibrium state, and alternately and sequentially detecting signals at individual sampling points, in t.sub.2, from the plurality of coherence transfer pathways by using gradient refocusing of a new pathway after signal detection at a sampling point in another pathway. A frequency domain spectrum S(.omega..sub.1,.omega..sub.2) is constructed by first Fourier transforming the time domain signals S(t.sub.1, t.sub.2) in the t.sub.2 dimension and producing real and imaginary components which modulate as sine and cosine signals in t.sub.1. The real (.omega..sub.2) cosine (t.sub.1) components are combined with the imaginary (.omega..sub.2) sine (t.sub.1) components to form a complex data set S(t.sub.1, .omega..sub.2) that is amplitude modulated in t.sub.1. The complex data set is then Fourier transformed in the t.sub.

Abstract: A signal function S(t.sub.1, t.sub.2) is obtained from a plurality of coherence transfer pathways in a single acquisition by preparing a molecular system in a coherent non-equilibrium state, and alternately and sequentially detecting signals at individual sampling points, in t.sub.2, from the plurality of coherence transfer pathways by using gradient refocusing of a new pathway after siganl detection at a sampling point in another pathway. The gradient encoding and refocusing of coherence pathways can use inhomogeneous rf-pulses (B.sub.1 gradients) or B.sub.0 field gradients. The coherence transfer pathways can be sequentially selected in an arbitrary order.

Abstract: A multiple quantum excitation pulse sequence for producing NMR signals is optimized for reconstructing images of the distribution and levels of metabolites in vivo using magnetic field gradients. Unwanted signals from water are reduced by application of composite magnetic field gradients, unwanted signals from lipids are reduced by use of a frequency selective pulse optimized to null the lipid signals, and the signal-to-noise ratio of the signals produced by lactate are enhanced by the addition of two 180.degree. excitation pulses to the sequence.

Abstract: A method for obtaining high resolution NMR spectra without the need for phase cycling includes the application of magnetic field gradient pulses to select specific coherences. By using actively shielded gradients, a gradient pulse is applied during the evolution period of the selected coherence to dephase the transverse magnetization and another gradient pulse refocuses the desired coherences remaining during the acquisition period.