Noquist: Reduced field‐of‐view imaging by direct Fourier inversion

Moratal-Perez, D.; Hong, Chung-Yi; Pettigrew, Roderic I.; Millet, José; Dixon, William J.

doi:10.1002/mrm.10694

Cited by 37 publications

(48 citation statements)

References 24 publications

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“…Matrix inversion methods have extensively been used in MR image reconstruction. These examples include parallel imaging (5)(6)(7)(8), singular value decomposition (SVD) encoding (19,20), k-space gridding (21)(22)(23), model based dynamic imaging (24,25), and Noquist (26). In Noquist, direct Fourier inversion is performed on sparsely sampled data to reconstruct an image for a partial FOV.…”

Section: Theorymentioning

confidence: 99%

Bunched phase encoding (BPE): A new fast data acquisition method in MRI

Moriguchi

Duerk

2006

Magnetic Resonance in Med

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A new fast data acquisition method, "Bunched Phase Encoding" (BPE), is presented. In conventional rectilinear data acquisition, only a readout gradient (and no phase encoding gradient) is applied when k-space data are acquired. Reduction of the number of phase encoding lines by increasing the phase encoding step size often leads to aliasing artifacts. Papoulis's generalized sampling theory asserts that in some cases aliasing artifact-free signals can be reconstructed even if the Nyquist criterion is violated in some regions of the Fourier domain. In this study, Papoulis's theoretical construct is exploited to reduce the number of acquired phase encoding lines. To achieve this, k-space data are sampled along a "zigzag" trajectory during each readout; samples are acquired at a sampling frequency higher than that of the normal rectilinear acquisition. The total number of TR cycles and, hence, the total scan time can be reduced. Data acquisition speed is often critical in practical MR imaging (MRI) applications. Conventional rectilinear MRI data acquisition time is equal to TR * N pe , where N pe is equal to the number of phase encoding (PE) lines in the rectilinear data acquisition. Reduction of the number of PE lines often leads to undesirable artifacts (e.g., aliasing) in the reconstructed image. To date, various kinds of reconstruction techniques have been developed to reduce MRI scan time. These methods include partial Fourier imaging (1-4) and parallel imaging (5-8). In partial Fourier imaging, data are acquired in only a limited part of the target k-space. The missing k-space data are "estimated" using special reconstruction techniques. However, image quality often depends on the original k-space coverage and a priori estimated information, e.g., an image phase map, used in the reconstruction process.In parallel imaging, parts of k-space data are collected using multiple receiver channels. Image reconstruction can be performed based on knowledge of the receiver coils' sensitivities. Although parallel imaging is a promising fast data acquisition method, it requires more than one receiver channel. Furthermore, an appropriate coil arrangement and accurate sensitivity maps are essential for image reconstruction with sufficient reduction of aliasing artifacts.A generalized sampling theory was proposed by Papoulis in 1977 (9). This theory asserts that in certain cases (e.g., under the condition that f(t) is zero outside a finite interval, i.e., time-limited) the original function f(t) can be reconstructed without aliasing artifacts even if the Nyquist criterion is violated in portions of the Fourier domain (9). For example, if m bunched samples are acquired at 1/m-th the Nyquist rate in the Fourier domain, it is possible to reconstruct the original time-limited function f(t) without aliasing artifacts.In this study we take advantage of this theoretical construct to reduce the number of TR cycles in rectilinear MRI data acquisitions. In the newly proposed method, the PE step size is set larger than that of the conve...

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Section: Theorymentioning

confidence: 99%

Bunched phase encoding (BPE): A new fast data acquisition method in MRI

Moriguchi

Duerk

2006

Magnetic Resonance in Med

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“…Rather, extra knowledge may be incorporated to ensure that the process of balancing Eqs. [4] and [5] produces optimal results. In this case, static voxels are preidentified and are given signal estimates lower than ⌿ so that the reconstruction selects in favor of dynamic spectra over static ones even in regions where both have SNR ϳ 1.…”

Section: Discussionmentioning

confidence: 99%

“…For each point in x-f space use the model to reduce C to find the optimum problem size as defined by the trade-off between Eqs. [4] and [5]. Solve the reduced problem and fill the excluded aliases with zeros.…”

Section: Overview Of Methodsmentioning

confidence: 99%

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x‐f choice: Reconstruction of undersampled dynamic MRI by data‐driven alias rejection applied to contrast‐enhanced angiography

Malik

Schmitz

O’Regan

et al. 2006

Magnetic Resonance in Med

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A technique for reconstructing dynamic undersampled MRI data, termed "x-f choice," was developed and applied to dynamic contrast-enhanced MR angiography (DCE-MRA). Regular undersampling in k-t space (a hybrid of k-space and time) creates aliasing in the conjugate x-f space that must be resolved. When regions in the object containing fast dynamic change are sparse, as in DCE-MRA, signal overlap caused by aliasing is often much less than the undersample factor would imply. x-f Choice reconstruction identifies overlapping signals using a model of the full non-aliased x-f space that is automatically generated from the undersampled data, and applies parallel imaging (PI) to separate them. No extra reference scans are required to generate either the model or the coil sensitivity maps. At each location in the reconstructed images, g-factor noise amplification is compared with predicted reconstruction errors to obtain an optimized solution. Acceleration factors greater than the number of receiver coils are possible, but are limited by the sparseness of the dynamic content and the signal-to-noise ratio (SNR) (in DCE-MRA the latter is dominant). Temporal fidelity was validated for up to a factor 10 speed-up using retrospectively undersampled data from a six-coil array. The method was tested on volunteers using fivefold prospective undersampling. Magn Reson Med 56:811-823, 2006.

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“…Reduced field of view (rFOV) techniques [3][4][5][6] represent another class of fast MR imaging techniques that make use of redundancy in the MR image series. The idea is to use the fact that in typical image series -e.g., for imaging motion or perfusion -only a part of the field of view is changing, that is the dynamic part.…”

Section: Introductionmentioning

confidence: 99%

Fast Motion Imaging Using Reduced Field of View Partial Fourier Mri

Agarwal

Abd‐Elmoniem

Prince

2007

2007 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro

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Fast MR imaging techniques often exploit the redundancy present in an underlying MR image time series to compensate for k-space undersampling. When imaging motion using techniques like HARP, DENSE, and phase contrast (PC), it is the phase in static regions that is constant and therefore redundant. In this paper, we present a technique that first estimates the phase in the static portion of an undersampled MR image time series and then uses a partial Fourier reconstruction technique to combine phase in the static portion and undersampled data to reconstruct the full image time series. The technique is illustrated using a computational phantom undergoing simulated cardiac motion and imaged using the HARP protocol. Results demonstrate a gradual degradation of accuracy with loss of data due to undersampling, indicating that a 25% speedup in imaging time is possible for an image time series in which 50% of the pixels correspond to the object that do not move over time.

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Noquist: Reduced field‐of‐view imaging by direct Fourier inversion

Cited by 37 publications

References 24 publications

Bunched phase encoding (BPE): A new fast data acquisition method in MRI

Bunched phase encoding (BPE): A new fast data acquisition method in MRI

x‐f choice: Reconstruction of undersampled dynamic MRI by data‐driven alias rejection applied to contrast‐enhanced angiography

Fast Motion Imaging Using Reduced Field of View Partial Fourier Mri

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