On the performance and accuracy of 2D navigator pulses

Nehrke, Kay; Börnert, Peter; Groen, J.P.; Smink, Jouke; Böck, J. C.

doi:10.1016/s0730-725x(99)00043-0

Cited by 79 publications

(106 citation statements)

References 16 publications

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“…where y(t) ¼ [0,1] is a function of time, t, and v ¼ 2pN where N is the number of turns in the spiral (7). The shape of the pencil beam is dependent on the RF pulse shape.…”

Section: Phantom Studiesmentioning

confidence: 99%

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Cross‐sectional and In‐plane coronary vessel wall imaging using a local inversion prepulse and spiral read‐out: A comparison between 1.5 and 3 tesla

Peel

Hussain

Schaeffter

et al. 2011

Magnetic Resonance Imaging

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Purpose: To compare cross-sectional and in-plane coronary vessel wall imaging using a spiral readout at 1.5 and 3 Tesla (T). Materials and Methods:Free-breathing coronary vessel wall imaging using a local inversion technique and spiral readout was implemented. Images were acquired in ten healthy adult subjects on a 3T clinical scanner using a 32-element cardiac coil and repeated on a 1.5T clinical scanner using a 5-element coil.Results: Cross-sectional and in-plane spiral vessel wall imaging was performed at both 1.5 and 3T. In cross-sectional images, artifact scores were superior at 1.5T (P < 0.05) but no significant difference was found in image quality scores compared with 3T. Image quality (P < 0.01) and artifact scores (P < 0.01) were found to be superior for inplane images at 1.5T. Vessel wall sharpness in the in-plane orientation was also found to be higher at 1.5T (P < 0.03). Conclusion:Although excellent in-plane coronary vessel wall images can be acquired at 3T, the overall robustness may be affected by off-resonance blurring due to increased B0 inhomogeneity compared with 1.5T.

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“…where y(t) ¼ [0,1] is a function of time, t, and v ¼ 2pN where N is the number of turns in the spiral (7). The shape of the pencil beam is dependent on the RF pulse shape.…”

Section: Phantom Studiesmentioning

confidence: 99%

“…The radius of the central peak of the beam can be defined as 3.83/k max . Due to the discrete k-space covering, aliasing rings will also appear at a radius equal to multiples of 2N/k max (7). y(t) defines the position of sampled data points along the k-space trajectory and can be adjusted using the following formula:…”

Section: Phantom Studiesmentioning

confidence: 99%

Cross‐sectional and In‐plane coronary vessel wall imaging using a local inversion prepulse and spiral read‐out: A comparison between 1.5 and 3 tesla

Peel

Hussain

Schaeffter

et al. 2011

Magnetic Resonance Imaging

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“…While breathhold Bal-SSFP renal MRA is possible, most renal artery studies to date have successfully used free-breathing with a prospective respiratory navigator to handle respiratory motion (39,40,52,53).…”

Section: Balanced-steady-state Free Precession Mramentioning

confidence: 99%

Renovascular imaging in the NSF Era

Roditi

Maki

Oliveira

et al. 2009

Magnetic Resonance Imaging

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The detection of the association between nephrogenic systemic fibrosis (NSF), a rare but potentially life‐threatening disease only encountered in patients with severely impaired renal function, and the previous administration of some Gd‐chelates has cast a shadow on the administration of Gd‐chelates in patients with chronic renal failure. So far, contrast‐enhanced MR‐angiography (MRA) was considered the best diagnostic modality in patients with suspected renal disease. This review explores the most appropriate use of renal MRA with a focus on newly developed nonenhanced MRA techniques. Nonenhanced MRA techniques mainly based on SSFP with ECG‐gating allow for acceptable spatial resolution to visualize at least the proximal parts of the renal arteries. In addition functional renal imaging techniques and their current clinical role are critically appreciated. J. Magn. Reson. Imaging 2009;30:1323–1334. © 2009 Wiley‐Liss, Inc.

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“…Furthermore, the profile was convolved with a disk of radius r d = 3.83 2πk max , [12] where k max was the maximum k-space radius reached by the corresponding trajectory. The convolution was achieved by multiplying the disk's FT coefficients,…”

Section: Excitation Profilesmentioning

confidence: 99%

“…Multidimensional RF excitation (1,10,11) has many applications, such as inner volume imaging, navigator acquisition, and accounting for field inhomogeneities (10,(12)(13)(14)(15)(16)(17)(18)(19). Conversely, non-Cartesian sampling (20) has applications in fast imaging (21).…”

mentioning

confidence: 99%

Basis function cross‐correlations for Robust k‐space sample density compensation, with application to the design of radiofrequency excitations

Mitsouras

Mulkern

Afacan

et al. 2007

Magnetic Resonance in Med

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The problem of k -space sample density compensation is restated as the normalization of the independent information that can be expressed by the ensemble of Fourier basis functions corresponding to the trajectory. Specifically, multiple samples (complex exponential functions) may be contributing to each independent information element (independent basis function). Normalization can be accomplished by solving a linear system based on the cross-correlation matrix of the underlying Fourier basis functions. The solution to this system is straightforward and can be obtained without resorting to discretization since the cross-correlations of Fourier basis functions are analytically known. Furthermore, no restrictions are placed on the k -space trajectory and its point-spread function. Additionally, the linear system can be used to elucidate key trade-offs involved in k -space trajectory design. The approach can be used to compensate samples acquired for image reconstruction or designed for low flip angle radiofrequency (RF) excitation. Here it is demonstrated for the latter application, using reversed spiral trajectories. In this case the linear system approach enables one to easily incorporate additional constraints such as smoothness to the solution. For typical RF excitation durations (<20 ms) it is shown that density compensation can even be achieved without numerical iteration.Magn Reson Med 57:338-352, 2007.

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On the performance and accuracy of 2D navigator pulses

Cited by 79 publications

References 16 publications

Cross‐sectional and In‐plane coronary vessel wall imaging using a local inversion prepulse and spiral read‐out: A comparison between 1.5 and 3 tesla

Cross‐sectional and In‐plane coronary vessel wall imaging using a local inversion prepulse and spiral read‐out: A comparison between 1.5 and 3 tesla

Renovascular imaging in the NSF Era

Basis function cross‐correlations for Robust k‐space sample density compensation, with application to the design of radiofrequency excitations

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