Abstract: Techniques, systems and apparatus are described for magnetic resonance imaging by modifying the shape/thickness of an excitation/inversion slab. For instance, the inversion slab can be shaped as a wedge to improve temporal signal-to-noise ratio (tSNR) of arterial spin labeling (ASL) experiments by matching the temporal bolus width with the inter-pulse spacing in different feeding arteries. The shape/thickness of the excitation/inversion slab across the X-Y plane can be modified by modulating the movement of the “on-resonance” plane in space by the combination of conventional slice-selective (SS) adiabatic fast passage (AFP) and additional in-plane gradient pulses. Using this method, a computer can generate different shapes of the excitation/inversion slab.

Abstract: Techniques, systems and apparatus are described for magnetic resonance imaging by modifying the shape/thickness of an excitation/inversion slab. For instance, the inversion slab can be shaped as a wedge to improve temporal signal-to-noise ratio (tSNR) of arterial spin labeling (ASL) experiments by matching the temporal bolus width with the inter-pulse spacing in different feeding arteries. The shape/thickness of the excitation/inversion slab across the X-Y plane can be modified by modulating the movement of the “on-resonance” plane in space by the combination of conventional slice-selective (SS) adiabatic fast passage (AFP) and additional in-plane gradient pulses. Using this method, a computer can generate different shapes of the excitation/inversion slab.

Abstract: Methods, systems and apparatus for magnetic resonance imaging that facilitate applying a gradient waveform to generate a k-space trajectory in a subject, applying radio frequency (RF) pulses having a pseudorandom phase distribution, such that the RF pulses are applied to the subject at a plurality of non-uniform locations near a center of the k-space trajectory and collecting, based on the applied RF pulses and the applied gradient waveform, imaging data from the subject.

Abstract: Techniques, systems computer program products are disclosed for mapping of vascular perfusion territories by applying a train of pseudo-continuous radio frequency tagging pulses to modulate a first magnetization of one or more blood vessels that supply blood to one or more vascular perfusion territories, applying an encoding scheme using unipolar transverse gradient pulses to modulate a second magnetization of blood vessels of the vascular perfusion territories, obtaining efficiency for each blood vessel based on the applied encoding scheme and separating the vascular perfusion territories by using the obtained tagging efficiency in a decoding process.

Abstract: Techniques, systems and apparatus are described for magnetic resonance imaging. A magnetic resonance imaging (MRI) system comprises a scanner comprising a magnet, gradient coils and a radio frequency (RF) system to perform various operations. The scanner can apply a gradient field and a train of RF pulses comprising more than two phases to tag a target blood vessel, and acquire magnetic resonance signals based on the applied train of RF pulses to sample the more than two phases. The MRI system includes a data processing system in communication with the scanner to receive the acquired magnetic resonance signals and process the received magnetic resonance signal to generate images proportional to perfusion.

Abstract: Techniques, systems computer program products are disclosed increasing tagging efficiency in velocity selective arterial spin labeling using multiple velocity selective saturation modules. In one aspect, a magnetic resonance imaging method for tagging arterial blood includes using two or more velocity selective saturation (VSS) modules to tag arterial blood. The tagged arterial blood is imaged.

Abstract: Techniques and systems are disclosed for magnetic resonance imaging by applying velocity-selective excitation. In some implementations, velocity selective excitation pulses are applied to a subject, causing an observable magnetization in the subject. An image of the subject is generated based on the observable magnetization. In some implementations, additionally, velocity selective excitation is combined with arterial nulling pulses such that the contribution from the arterial portion of a subject is excluded from the observable magnetization in the subject.

Abstract: Techniques, systems computer program products are disclosed for mapping of vascular perfusion territories by applying a train of pseudo-continuous radio frequency tagging pulses to modulate a first magnetization of one or more blood vessels that supply blood to one or more vascular perfusion territories, applying an encoding scheme using unipolar transverse gradient pulses to modulate a second magnetization of blood vessels of the vascular perfusion territories, obtaining efficiency for each blood vessel based on the applied encoding scheme and separating the vascular perfusion territories by using the obtained tagging efficiency in a decoding process.

Abstract: Techniques, systems computer program products are disclosed increasing tagging efficiency in velocity selective arterial spin labeling using multiple velocity selective saturation modules. In one aspect, a magnetic resonance imaging method for tagging arterial blood includes using two or more velocity selective saturation (VSS) modules to tag arterial blood. The tagged arterial blood is imaged.

Abstract: Methods, systems and apparatus for magnetic resonance imaging that facilitate applying a gradient waveform to generate a k-space trajectory in a subject, applying radio frequency (RF) pulses having a pseudorandom phase distribution, such that the RF pulses are applied to the subject at a plurality of non-uniform locations near a center of the k-space trajectory and collecting, based on the applied RF pulses and the applied gradient waveform, imaging data from the subject.

Abstract: Techniques, systems and computer program products are disclosed for mapping of vascular perfusion territories by placing one or more blood vessels of the vascular perfusion territories in a tag condition and others in a control condition by applying a train of pseudo-continuous radio frequency tagging pulses. In addition, an encoding scheme is applied to fully invert or relax the blood vessels of the vascular perfusion territories. Also, a tagging efficiency is measured for each blood vessel based on the applied encoding scheme. Further, the vascular perfusion territories are separated by using the measured tagging efficiency in a decoding process.

Abstract: Techniques, systems and apparatus are described for magnetic resonance imaging. A magnetic resonance imaging (MRI) system comprises a scanner comprising a magnet, gradient coils and a radio frequency (RF) system to perform various operations. The scanner can apply a gradient field and a train of RF pulses comprising more than two phases to tag a target blood vessel, and acquire magnetic resonance signals based on the applied train of RF pulses to sample the more than two phases. The MRI system includes a data processing system in communication with the scanner to receive the acquired magnetic resonance signals and process the received magnetic resonance signal to generate images proportional to perfusion.

Abstract: Techniques for providing velocity-selective magnetic arterial spin labeling in magnetic resonance imaging (MRI) without spatial selectivity. In one implementation, an RF pulse train is applied to selectively tag spins according to velocities of the spins without selection based on locations of the spins. MRI images of tagged spins at an area of interest are then acquired to obtain information on perfusion at the area of interest.

Abstract: Techniques, systems computer program products are disclosed for mapping of vascular perfusion territories by placing one or more blood vessels of the vascular perfusion territories in a tag condition and others in a control condition by applying a train of pseudo-continuous radio frequency tagging pulses. In addition, an encoding scheme is applied to fully invert or relax the blood vessels of the vascular perfusion territories. Also, a tagging efficiency is measured for each blood vessel based on the applied encoding scheme. Further, the vascular perfusion territories are separated by using the measured tagging efficiency in a decoding process.

Abstract: An EPI pulse sequence is performed by an NMR system which acquires 128 images of the brain over a time interval during which the subject performs a function or is stimulated. The acquired time course NMR data is displayed in different ways for analysis. Four different methods for producing brain function images from the NMR data are described.

Abstract: A local RF and gradient coil for acquiring images of the human brain using fast NMR pulse sequences includes an end capped RF bird cage coil surrounded by a 3 axis gradient coil assembly. An RF shield is disposed between the RF coil and the gradient coils and it is divided into separate segments to reduce eddy currents induced by the changing gradient fields.

Abstract: A local RF and gradient coil for acquiring images of the human brain using fast NMR pulse sequences includes an end capped RF bird cage coil surrounded by a 3 axis gradient coil assembly. An RF shield is disposed between the RF coil and the gradient coils and it is divided into separate segments to reduce eddy currents induced by the changing gradient fields.