MR-angiography with non-cartesian signal acquisition

摘要

In a method and apparatus for the creation of an MR image of a vascular structure of an examination region, the spins in the examination region are saturated by the irradiation of at least one RF saturation signal, which delivers a lower signal intensity as spins in a subsequent MR signal recording for the creation of the MR angiographic image, which flow through at least one blood vessel into the examination region, and are not saturated by the RF saturation pulse. Raw data space of the MR angiographic image is read out with a non-Cartesian trajectory in the MR signal acquisition for the creation of the MR angiographic image.

主权项

1. A method for generating an angiographic image of a vascular structure in an examination region of a patient, comprising:
operating a magnetic resonance data acquisition unit comprising a radio-frequency (RF) antenna and gradient coils, in which a patient is located, by radiating, at a radiation time, at least one RF saturation pulse from said RF antenna in a volume of the patient that contains a vascular structure with blood flowing therein in a primary flow direction surrounded by surrounding tissue, said at least one RF pulse saturating nuclear spins, at said radiation time, in both said blood and said surrounding tissue, and subsequently acquiring operating said gradient coils to produce gradient fields to acquire raw magnetic resonance data from said vascular structure and said surrounding tissue from respective planar layers in said volume, each planar layer having a predetermined layer thickness and being oriented perpendicularly to said primary flow direction for generation of a magnetic resonance angiography image comprising said planar layers, and configuring said at least one RF saturation pulse to cause the nuclear spins saturated thereby to produce a lower signal intensity in said angiography image than nuclear spins, that flow in blood into the volume via at least one vessel of said vascular structure, that have not been saturated by said at least one RF pulse; operating said gradient coils to produce said gradient fields so as to enter entering said raw magnetic resonance data representing said magnetic resonance angiography image along a radial trajectory of data entry points in a k-space memory comprising a plurality of data entry points, at which said raw magnetic data are entered, organized along respective axes defined by said gradient fields, with one of said axes corresponding to said primary flow direction, and said radial trajectory being orthogonal to said one of said axes, in order to produce an undersampled raw magnetic resonance data set in said k-space memory, said radial trajectory comprising, in each of said layers, a set of spokes comprising a plurality of spokes proceeding through a center of a matrix in said k-space memory, said magnetic resonance raw data being entered along said plurality of spokes in each of said layers with the respective sets of spokes in neighboring planar layers not coinciding when said neighboring layers are superimposed with each other; and reconstructing said magnetic resonance angiographic image from the undersampled raw magnetic resonance data set entered into said k-space memory.