Koninklijke Philips Corporation N.V.

Philips Gmbh

Gabriele Marianne Beck

Johan Samuel Van Den Brink

Paul Royston Harvey

Romhild Martijn Hoogeveen

Gerrit Hendrik Van Ijperen

Miha Fuderer

Tim Nielsen

Mariya Ivanova Doneva

Jouke Smink

Johannes Martinus Peeters

Arjan Willem Simonetti

Gwenael Henri Herigault

Patrick Gross

Gerrit Hendrik Van Yperen

Suthambhara Nagaraj

Jan Hendrik Wulbern

Chennakeshava Krishna

Alan Jerry Huang

Guruprasad Krishnamoorthy

Mathijs Visser

Christian Stehning

Peter Koken

The invention relates to a method of MR imaging of an object (). It is an object of the invention to enable MR imaging using radial acquisition with a reduced level of phase distortions and corresponding image artefacts. The method of the invention comprises the steps of: a) generating MR signals by subjecting the object to an imaging sequence comprising RF pulses and switched magnetic field gradients; b) acquiring the MR signals as radial k-space profiles, wherein pairs of spatially adjacent k-space profiles are acquired in opposite directions and wherein k-space profiles acquired in temporal proximity are close to each other in k-space; c) reconstructing an MR image from the acquired MR signals. Moreover, the invention relates to a MR device () and to a computer program for a MR device ().

Optimized k-space profile ordering for 3D radial MR imaging

The invention relates to a method of MR imaging of an object (). It is an object of the invention to enable MR imaging using a 3D radial or spiral acquisition scheme providing an enhanced image quality in the presence of motion. The method comprises the steps of: —generating MR signals by subjecting the object () to an imaging sequence comprising RF pulses and switched magnetic field gradients; —acquiring the MR signals using a 3D radial or spiral acquisition scheme with oversampling of a central portion () of k-space; —detecting motion-induced displacements (d) and/or deformations of the object () during the acquisition of the MR signals and assigning each of the acquired MR signals to a motion state; —reconstructing an MR image from the MR signals weighted in the central portion () of k-space, wherein a stronger weighting (W,) is applied to MR signals acquired in more frequent motion states, while a weaker weighting (W,) is applied to MR signals acquired in less frequent motion states. Moreover, the invention relates to a MR device () and to a computer program for a MR device ().

MR imaging using a 3D radial or spiral acquisition with soft motion gating

The invention relates to a method of MR imaging of an object () placed in an examination volume of a MR device (). It is an object of the invention to enable MR imaging using a radial (or spiral) acquisition scheme with a reduced level of motion artefacts. The method of the invention comprises the following sequence of steps: &#x2014;detecting a momentary motion&#x2014;induced displacement (&#x394;) of the object (); &#x2014;attributing the detected displacement (A) to a motion state (M-M), each motion state (M-M) corresponding to one of a plurality of contiguous ranges of displacements (&#x394;); &#x2014;determining angular coordinates of a radial or spiral k-space profile by incrementing the angular coordinates individually for each motion state (M-M) starting from initial angular coordinates; &#x2014;acquiring the k-space profile; &#x2014;repeating steps a-d a number of times; and &#x2014;reconstructing an MR image from at least the k-space profiles attributed to one of the motion states (M-M). Moreover, the invention relates to a MR device () for carrying out this method as well as to a computer program to be run on a MR device ().

MR imaging using motion-dependent radial or spiral k-space sampling

The invention relates to a method of MR imaging of an object. It is an object of the invention to enable MR imaging using the stack-of-stars acquisition scheme with an enhanced control of the contrast of the reconstructed MR image. The method of the invention comprises the steps of: a) generating MR signals by subjecting the object () to a number of shots of a multi-echo imaging sequence comprising RF pulses and switched magnetic field gradients, wherein a train of echo signals is generated by each shot; b) acquiring the echo signals according to a stack-of-stars (i.e. a hybrid radial 3D acquisition scheme wherein radial sampling is performed in each slice plane and phase encoding is performed along the slice encoding direction) or stack-of-spirals scheme, wherein the echo signals are acquired as radial or spiral k-space profiles (S-S) arranged at different positions along a slice direction in k-space, wherein echo signals from different k-space slices are acquired in each shot of the imaging sequence and wherein the echo signals are acquired from each k-space slice with different relaxation time weightings; and c) reconstructing at least one MR image of a desired contrast from the acquired echo signals using a k-space weighted image contrast (KWIC) filter. Moreover, the invention relates to a MR device () and to a computer program for a MR device ().

Magnetic resonance imaging method including acquiring echo signals from each k-space slice with different relaxation time weightings after echo signals from different k-space splices are acquired

A method of MR imaging of a body () of a patient reduces contrast blurring in PROPELLER imaging combined with multi-echo acquisitions. The method includes the steps of:

Propeller MR imaging with relaxation weightings varying between k-space blades and k-space data lines

An object () is placed in an examination volume of a MR device (). To enable fast MR imaging, a stack-of-stars acquisition scheme is employed with a reduced level of streaking artifacts. The acquisition scheme includes subjecting the object () to an imaging sequence of at least one RF pulse and switched magnetic field gradients and acquiring MR signals according to the stack-of-stars scheme. The MR signals are acquired as radial k-space profiles (S-S) from a number of parallel slices (-) arranged at different positions along a slice direction. The radial density of the k-space profiles (S-S) varies as a function of the slice position with the radial density being higher at more central k-space positions and lower at more peripheral k-space positions. The k-space profiles are acquired at a higher temporal density from slices at the more central positions than from slices at the more peripheral k-space positions. An MR image is reconstructed from the MR signals.

MR imaging using stack-of stars acquisition

An object to be MR imaged () is placed in an examination volume of a MR device (). For faster MR imaging a multi-echo imaging technique which is robust with respect to motion is used. The method includes

MR imaging using multi-echo k-space acquisition

At least a portion of a body () is placed in a main magnetic field Bo within the examination volume of a MR device. The portion of the body () is subject to an imaging sequence including one or more RF pulses and switched magnetic field gradients to acquire imaging signals. The portion of the body () is subject to a navigator sequence applied at least once before, during, or after the imaging sequence. The navigator sequence includes one or more RF pulses and switched magnetic field gradients controlled to acquire navigator signals with a single-point or multi-point Dixon technique. Translation and/or rotation and/or shear data reflecting motion of the body are derived from the navigator signals during the acquisition of the imaging signals. The translation and/or rotation and/or shear data are used for adapting the imaging sequence and/or for motion correction during reconstruction of an MR image.

MRI with motion correction using navigators acquired using a dixon technique

Magnetic resonance (MR) imaging of an area () of a subject of interest () includes issuing a breath-hold command to the subject of interest (), performing motion detection of the subject of interest () to detect a breath-hold condition in the area () of the subject of interest (), upon detection of the breath-hold condition in the area () of the subject of interest (), performing k-space () sampling of the area () of the subject of interest () with a given resolution, processing the k-space () samples covering the area () of the subject of interest () to obtain a MR image of the area () of the subject of interest ().

Breath-hold detection for magnetic resonance imaging

An object () is placed in an examination volume of a MR device () and imaged using a multi-echo imaging technique which is robust with respect to motion. The imaging includes subjecting the object () to a number of shots of a multi-echo imaging sequence to generate a train of echo signals by each shot and acquiring the echo signals. Each echo signal represents a k-space profile, wherein k-space () is divided into a central k-space part () and one or more peripheral k-space parts (). The central k-space part () is sampled by a single shot of the multi-echo imaging sequence, and the peripheral k-space parts () are sampled by one or more further shots () of the multi-echo sequence; and an MR image is reconstructed from the k-space profiles.

MR imaging using multi-echo segmented k-space acquisition

The invention relates to a magnetic resonance imaging system () for acquiring at least one set of k-space blade data from an imaging zone of a subject (), wherein the magnetic resonance imaging system () comprises a memory () for storing machine executable instructions and a processor () for controlling the magnetic resonance imaging system (), wherein execution of the machine executable instructions causes the processor () to perform for each blade of the at least one set of k-space blade data: control the MRI system () to acquire at least one k-space blade data using at least one echo time for purposes of performing a Dixon technique, wherein k-space blade data are acquired in accordance with a blade shape; reconstruct at least one blade image data using the at least one k-space blade data; generate water blade image data and fat blade image data using the at least one blade image data; and transform the water and fat blade image data to water and fat k-space blade data respectively and perform PROPELLER reconstruction of the water and fat k-space blade data.

Propeller with Dixon water fat separation

The invention relates to a method of magnetic resonance (MR) imaging of at least a portion of a body () placed in a stationary and substantially homogeneous main magnetic field. The method comprises the following steps; &#x2014;exciting nuclear magnetization selectively within a spatially restricted volume of interest () by subjecting the portion to an imaging sequence (IMG) comprising at least one RF pulse (&#x3b1;) and switched magnetic field gradients (GX/GY); &#x2014;acquiring at least one MR imaging signal from the volume of interest (); &#x2014;exciting nuclear magnetization within a spatially restricted navigator volume () by subjecting said portion to a navigator sequence (NAV) comprising at least one RF pulse and switched magnetic field gradients, wherein the navigator volume () at least partially overlaps with the volume of interest (); &#x2014;acquiring at least one MR navigator signal from said navigator volume (); &#x2014;reconstructing a MR image from the acquired MR imaging signals. It is an object of the invention to enable MR imaging with reliable motion detection and high image quality. For this purpose, the invention proposes that the nuclear magnetization within the volume of interest () is transformed back into longitudinal magnetization prior to application of the navigator sequence (NAV) by subjecting said portion to an unlabeling sequence (UNLBL) comprising at least one RF pulse (&#x2212;&#x3b1;).

MR imaging using navigators

The invention relates to a method for cardiac magnetic resonance imaging. The method comprises the steps of monitoring the ECG of a patient and detecting the occurrence of R-waves (R, R, R) in the ECG, acquiring a plurality of phase encoded MR signals (a, b, c, d, e) per cardiac cycle by subjecting the patient to a sequence of RF pulses and magnetic field gradient pulses, and reconstructing an MR image from at least a part of the MR signals (a, b, C, d, e). For providing an improved cardiac MRI method which enables the acquisition and reconstruction of high quality MR images of the heart in cases in which the heart cycle of the examined patient changes over time or is irregular because of arrythmia, the invention proposes that the ECG of the patient is monitored continuously during acquisition of MR signals, wherein MR signals (dto c, bto a, cto b) used for image reconstruction are retrospectively selected depending on the time interval between successive R-waves (R, R, R).

Method for cardiac magnetic resonance imaging

A magnetic resonance imaging scanner () includes a main magnet (), magnetic field gradient coils (), and one or more radio frequency coils (). A sequence generator () generates an anti-ghosting imaging sequence by dividing k-space into a plurality of profile sub-sets. The sequence generator () includes a profile sub-sets ordering processor () that orders profiles within each profile sub-set such that the order of profiles within each sub-set is generally different from the orders of the other profile sub-sets, and a profile sub-sets acquisition ordering processor () that orders the profile sub-sets in accordance with a selected long-term profiles ordering. The magnetic resonance imaging scanner () executes the anti-ghosting imaging sequence to generate imaging data. A reconstruction processor () reconstructs the generated imaging data into a reconstructed image substantially free of ghosting.

Randomized ordered k-space sub-sets for shared pre-pulses in MRI

A magnetic resonance imaging method is provided in which the magnetic resonance signals are acquired by sampling a selected region in the k-space. The selected region in the k-space is chosen in dependence on the object or structure to be imaged. In particular an anisotropic central sector in the k-space is chosen, its axis being dependent on the spatial orientation of the object or structure to be imaged. The magnetic resonance imaging method in accordance with the invention is particularly suitable for imaging arteries separately from veins in magnetic resonance angiography.

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Eindhoven, Netherlands

Gabriele Marianne Beck