Combined T 2 ‐preparation and two‐dimensional pencil‐beam inner volume selection

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Section: Discussionmentioning

confidence: 99%

On the accuracy and precision of cardiac magnetic resonance T₂ mapping: A high‐resolution radial study using adiabatic T₂ preparation at 3 T

Bano

Feliciano

Coristine

et al. 2016

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“…In recent years, the realization arose that IVI, and in particular the signal-localization techniques that are used to facilitate this, could be used to improve PI. This is shown by several papers where an improved PI performance is described when the signal generating area was reduced in specific applications (10)(11)(12)(13)(14)(15). Most notable is the work on zoomed GRAPPA (ZOOPPA) (10), where the signal in a part of the FOV is suppressed such that high GRAPPA acceleration factors can be used to achieve high resolution fMRI (12) and DWI (11) of the remaining areas.…”

Section: Introductionmentioning

confidence: 99%

Combining a reduced field of excitation with SENSE‐based parallel imaging for maximum imaging efficiency

Mooiweer

Sbrizzi

Raaijmakers

et al. 2016

PurposeTo show that a combination of parallel imaging using sensitivity encoding (SENSE) and inner volume imaging (IVI) combines the known benefits of both techniques. SENSE with a reduced field of excitation (rFOX) is termed rSENSE.Theory and MethodsThe noise level in SENSE reconstructions is reduced by removing voxels from the unfolding process that are rendered silent by using rFOX. The silent voxels need to be identified beforehand, this is done by using rFOX in the coil sensitivity maps. In vivo experiments were performed at 7 Tesla using a 32‐channel receive coil.ResultsGood image quality could be obtained in vivo with rSENSE at acceleration factors that are higher than could be obtained using SENSE or IVI alone. With rSENSE we were also able to accelerate scans using an rFOX that was purposely designed to be imperfect or incompatible at all with IVI.ConclusionrSENSE has been demonstrated in vivo with two‐dimensionally selective radiofrequency pulses. Besides allowing additional scan acceleration, it offers a greater robustness and flexibility than IVI. The proposed method can be used with other field strengths, anatomies and other rFOX techniques. Magn Reson Med 78:88–96, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution Non Commercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

“…OVS reduces signal outside a region of interest (ROI) and has also been demonstrated to improve coronary image quality by reducing image artifacts . By creating an effectively smaller region to image, the field of view (FOV) can be reduced to shorten scan time or facilitate higher resolution imaging. Furthermore, OVS may improve motion correction by suppressing unwanted anatomy .…”

Section: Introductionmentioning

confidence: 99%

“…These pulses can be sequenced as several saturation pulses or as a single compound pulse . The second paradigm for OVS uses one spatially selective pulse and one spatially nonselective pulse for a tip‐down and tip‐up combination . Early OVS techniques used hard pulses nonselectively and sinc pulses for selectivity .…”

Section: Introductionmentioning

confidence: 99%

Combined T₂‐preparation and multidimensional outer volume suppression for coronary artery imaging with 3D cones trajectories

Zeng

Baron

Malavé

et al. 2019

Purpose To develop a modular magnetization preparation sequence for combined T2‐preparation and multidimensional outer volume suppression (OVS) for coronary artery imaging. Methods A combined T2‐prepared 1D OVS sequence with fat saturation was defined to contain a 90°−60180°60 composite nonselective tip‐down pulse, two 180°Y hard pulses for refocusing, and a −90° spectral‐spatial sinc tip‐up pulse. For 2D OVS, 2 modules were concatenated, selective in X and then Y. Bloch simulations predicted robustness of the sequence to B0 and B1 inhomogeneities. The proposed sequence was compared with a T2‐prepared 2D OVS sequence proposed by Luo et al, which uses a spatially selective 2D spiral tip‐up. The 2 sequences were compared in phantom studies and in vivo coronary artery imaging studies with a 3D cones trajectory. Results Phantom results demonstrated superior OVS for the proposed sequence compared with the Luo sequence. In studies on 15 healthy volunteers, the proposed sequence had superior image edge profile acutance values compared with the Luo sequence for the right (P < .05) and left (P < .05) coronary arteries, suggesting superior vessel sharpness. The proposed sequence also had superior signal‐to‐noise ratio (P < .05) and passband‐to‐stopband ratio (P < .05). Reader scores and reader preference indicated superior coronary image quality of the proposed sequence for both the right (P < .05) and left (P < .05) coronary arteries. Conclusion The proposed sequence with concatenated 1D spatially selective tip‐ups and integrated fat saturation has superior image quality and suppression compared with the Luo sequence with 2D spatially selective tip‐up.