Oxford University Innovation Ltd

Siemens Aktiengesellschaft

Isis Innovation Limited

Peter Jezzard

Thomas Okell

David Andrew Porter

Michael A Chappell

Linqing Li

Eleanor Berry

Robert Frost

Karla Miller

Systems and methods are provided to incorporate an off-resonance correction into the pulse labeling train of PCASL/VEPCASL. In one or more aspects, the systems and methods are based on a method for generating an encoding scheme for any number and arrangement of blood vessels. The off-resonance correction can be incorporated into the generation of optimized encodings to acquire arterial spin labeling (ASL) data, such as PCASL and VEPCASL data.

Off-resonance correction for pseudo-continuous arterial spin labeling

Systems and methods for motion sensitized and motion suppressed quantitative imaging of a subject are provided as a train of interlaced radio frequency (RF) and magnetic field gradient pulses. Non-selective Delay Alternating with Nutation for Tailored Excitation (DANTE) pulse trains may be used in combination with gradient pulses and short repetition times as motion-sensitive preparation modules. In one or more embodiments, the systems and methods may use a train of low flip angle radio frequency (RF) pulses in combination with a blipped field gradient pulse between each RF pulse, repeated regularly. While the longitudinal magnetization of static tissue is mostly preserved, moving spins are largely (or fully) suppressed since they fail to establish transverse steady state due to a spoiling effect caused by flow along the applied gradient. The present systems and methods can be incorporated into any existing imaging readout for applications in vessel wall imaging, angiography, high resolution structural MRI, and also functional MRI.

Motion sensitized and motion suppressed imaging using dante prepared pulse trains

Systems and methods are disclosed for quantifying absolute blood volume flow rates by fitting a kinetic model incorporating blood volume, bolus dispersion and signal attenuation to dynamic angiographic data. A self-calibration method is described for both 2D and 3D data sets to convert the relative blood volume parameter into absolute units. The parameter values are then used to simulate the signal arising from a very short bolus, in the absence of signal attenuation, which can be readily encompassed within a vessel mask of interest. The volume flow rate can then be determined by calculating the blood volume within the vessel mask and dividing by the simulated bolus duration. This method is exemplified using non-contrast magnetic resonance imaging data from a flow phantom and the cerebral arteries of healthy volunteers and a patient with Moya-Moya disease acquired using a 2D vessel-encoded pseudo-continuous arterial spin labeling pulse sequence. This allows flow quantification in downstream vessels from each brain-feeding artery separately. The systems and methods can be of use in patients with a variety of cerebrovascular diseases, such as the assessment of collateral flow in patients with steno-occlusive disease or the evaluation of arteriovenous malformations.

Quantification of blood volume flow rates from dynamic angiography data

In a magnetic resonance apparatus and operating method therefore, 3D navigator data are acquired and are used to correct spatially varying phase errors in contemporaneously acquired imaging data in each shot of a multi-shot data acquisition sequence. A mosaic sampling scheme is used to enter the diffusion-weighted magnetic resonance data and the navigator data into k-space respectively in blocks that each form a subset of the entirety of k-space. The navigator data in each shot are entered into a block that is located at the center of k-space, and, in each shot, the corresponding image data are entered into an offset block in k-space, that is offset in at least one spatial direction from the navigator data block. The offset is varied from shot-to-shot.

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Oxford, United Kingdom

Peter Jezzard