RARE imaging: A fast imaging method for clinical MR

Hennig, Jürgen; Nauerth, Arno; Friedburg, H.

doi:10.1002/mrm.1910030602

Cited by 1,909 publications

(1,156 citation statements)

References 7 publications

Supporting

Mentioning

1,135

Contrasting

Unclassified

Order By: Relevance

“…[4][5][6] define a 2D SFA model. Note that this is a rather general discrete model of representing any discrete images, which does not rely on any assumptions (low-frequency phase, piecewise constant variation, smoothness variation, etc.)…”

Section: D Sfa Modelmentioning

confidence: 99%

“…The potentialities of MRI are, however, conditioned by imaging speed. To meet the growing need for functional imaging and moving organ imaging, fast acquisition techniques such as fast low-angle shot (FLASH) (1,2), echo planar imaging (EPI) (3), and rapid acquisition with relaxation enhancement (RARE) (4) have been developed and are used in clinics. However, the speed at which data can be measured in MRI is fundamentally limited by physical and physiological constraints.…”

mentioning

confidence: 99%

See 1 more Smart Citation

MRI reconstruction from 2D truncated k‐space

Luo¹,

Zhu²,

Li³

et al. 2011

Magnetic Resonance Imaging

View full text Add to dashboard Cite

Purpose: To shorten acquisition time by means of both partial scanning and partial echo acquisition and to reconstruct images from such 2D partial k-space acquisitions. Materials and Methods:We propose an approach to reconstructing magnetic resonance images from 2D truncated k-space in which the k-space is truncated in both phase-and frequency-encoding directions. Unlike conventional reconstruction techniques, the proposed approach is based on a newly developed 2D singularity function analysis (SFA) model and a sparse representation of an image whose parameters can be estimated from the 2D partial k-space data. Such a sparse representation leads to an accurate recovery of the missing k-space data and, hence, an accurate reconstruction of the image.Results: The proposed approach can reconstruct an image from as little as 20%-30% of the k-space data and the quality of the reconstructed image is comparable to the reference image that is reconstructed from the complete k-space data. Conclusion:Despite the high asymmetry of a 2D truncated k-space, the proposed approach allows for accurate reconstruction without the need of phase correction and, thus, overcomes the assumption of slow phase variations that is usually required by the existing reconstruction methods. It provides a new way of fast imaging for applications that require a significant reduction of the acquisition time.

show abstract

Section: D Sfa Modelmentioning

confidence: 99%

mentioning

confidence: 99%

MRI reconstruction from 2D truncated k‐space

Luo¹,

Zhu²,

Li³

et al. 2011

Magnetic Resonance Imaging

View full text Add to dashboard Cite

show abstract

“…Consequently, the overall phase resulting from the encoding gradient between adjacent 180˚RF pulses must be zero. This is achieved by applying a positive and then a negative encoding gradient lobe before and after each echo in the train (26). In our system, the use of such an imaging sequence is not practical due to the high currents required by the encoding gradients and the short time between adjacent echoes.…”

Section: Imaging Sequencementioning

confidence: 99%

Ex situ endorectal MRI probe for prostate imaging

Blank

Ish-Shalom

Shtirberg

et al. 2009

Magnetic Resonance in Med

View full text Add to dashboard Cite

A unique ex situ MRI probe, which examines samples external to its geometry, is presented. The probe is intended to be used for imaging the prostate gland via an endorectal pathway. It has a semicylindrical shape with a length of 6 cm and typical diameter of ϳ3 cm. The probe's imaging field of view spans almost along its entire length and up to a distance of 2 cm away from its surface, with an angular sector of ϳ90°. The detailed design of the probe is presented, followed by a set of representative results obtained by the current bench prototype of this system. NMR and its descendant MRI are usually pursued in a setup based on a highly homogenous static magnetic field, B 0 , with variance Ͻ1 ppm, creating nuclear spin precession at a corresponding narrow band of frequencies (1). The homogeneous static field setup has several advantages, such as the ability to obtain chemical shifts while ensuring good signal-to-noise ratio (SNR) due to the small bandwidth involved. However, this setup suffers from the need to employ large magnets that usually surround the examined sample/object. In specific cases, such as clinical MRI systems, the large magnet, and the corresponding large radiofrequency (RF) and gradient coils, are a major factor in the relative complexity and the high cost of such systems. If one is interested only in a specific small region within the body, it could be highly advantageous to obtain NMR information by using either a noninvasive handheld probe or an intracavity self-contained (magnet ϩ RF and gradient coils) NMR probe, thus avoiding the requirement for a large external magnet. Such an approach to NMR measurement or NMR imaging without a sample-surrounding magnet is termed "inside-out," or ex situ (2-6). In the "inside-out" setup it is very difficult to create highly homogeneous fields without making significant compromises regarding field magnitude. Several types of systems that operate in an "inside-out" geometry have been designed and built, demonstrating measurement capabilities of relaxation parameters (7,8), diffusion coefficients (9), spectroscopic data (10), and three-dimensional (3D) imaging (11). In the case of microscopic MRI, where very high field gradients are required to obtain a high resolution, "inside-out" systems were found to be very useful and enabled the acquisition of images with a resolution of 1 m or better, outside a superconducting magnet (4,12), or near a microscopic magnetic tip (13,14).The efforts described above were mainly directed toward materials science applications or related subjects, with appreciable achievements. In the field of medicine, recent work has demonstrated the use of a miniature intravascular ex situ NMR probe with one-dimensional imaging capability for the detection of vulnerable plaque in the coronary arteries (15-17). Larger nonimaging and/or one-dimensional imaging probes have been shown to be useful in obtaining interesting clinical results regarding the examination of tendon anisotropy, skin conditions, and breast implants (18). Despite this ...

show abstract

“…Before acquiring a second echo, a phaseencoding gradient is applied again. This gradient has either the same strength as for the first echo for apparent T 2 measurement of Lac or has a different strength (like the rapid acquisition with relaxation enhancement [RARE] readout (24)) to further accelerate the experiment. This part of the sequence can be repeated to acquire multiple echoes.…”

Section: Signal Detection Portionmentioning

confidence: 99%

Sensitive J‐coupled metabolite mapping using Sel‐MQC with selective multi‐spin‐echo readout

Melkus

Mörchel

Behr

et al. 2009

Magnetic Resonance in Med

View full text Add to dashboard Cite

The selective multiple quantum coherence technique is combined with a read gradient to accelerate the measurement of a specific scalar-coupled metabolite. The sensitivities of the localization using pure phase encoding and localization with the read gradient are compared in experiments at high magnetic field strength (17.6 T). Multiple spin-echoes of the selective multiple quantum coherence edited metabolite are acquired using frequency-selective refocusing of the specified molecule group. The frequency-selective refocusing does not affect the J-modulation of a coupled spin system, and the echo time is not limited to a multiple of 1/J to acquire pure in-phase or antiphase signal. The multiple echoes can be used to accelerate the metabolite imaging experiment or to measure the apparent transverse relaxation T 2 . A simple phase-shifting scheme is presented, which enables the suppression of editing artifacts resulting from the multiple spin-echoes of the water resonance. In 1 H NMR spectroscopy, the spectral overlap of resonances is a common problem when information about a specific metabolite (e.g., lactate [Lac]) is desired in vivo. In the last decades, several types of spectral editing schemes were developed to filter the metabolite of interest from coresonant or overlapping signals (1-4). The class of multiple quantum coherence (MQC) filters using magnetic field gradients for editing provides robust single-shot editing techniques. One of the single-shot editing filters is the frequency selective multiple quantum coherence editing scheme (Sel-MQC) proposed by He et al. (5). This selective MQC filter enables editing of a single scalar-coupled spin system with simultaneous suppression of water and other resonances in one scan.Successful applications of the Sel-MQC editing sequence have been shown in several studies in which the metabolite of interest is overlapped by other spins with a similar chemical shift. For instance, in extracranial tumor tissues, the Lac CH 3 resonance (at 1.33 parts per million [ppm]) has been filtered from overlapping methylene groups of mobile lipids (5,6). A recent preliminary study on healthy and cancerous human breast tissue has shown a robust application of the Sel-MQC editing sequence to detect polyunsaturated fatty acids (PUFA) (7). The olefinic methylene protons of PUFA at 5.3 ppm that are coupled with the allylic methylene protons of unsaturated acyl chains at 2.8 ppm were detected in breast tissue, and the PUFA pattern is sensitive to breast tissue changes, including cancerous alterations. An adiabatic version of the Sel-MQC scheme was used by de Graaf et al. (8) to detect the ␤H1-glucose resonance at 4.63 ppm in rat brain in vivo. Executing the Sel-MQC sequence with adiabatic radiofrequency pulses allows optimal sensitivity when surface coils are used. In recent years, several extensions of the Sel-MQC editing scheme have been developed, such as Hadamard encoding for localization (9,10), multislice selection using spatial-spectral selective pulses (11), T 1 and T 2 relaxation ...

show abstract

RARE imaging: A fast imaging method for clinical MR

Cited by 1,909 publications

References 7 publications

MRI reconstruction from 2D truncated k‐space

MRI reconstruction from 2D truncated k‐space

Ex situ endorectal MRI probe for prostate imaging

Sensitive J‐coupled metabolite mapping using Sel‐MQC with selective multi‐spin‐echo readout

Contact Info

Product

Resources

About