Spatially uniform sampling in 4-D EPR spectral-spatial imaging

Ahn, Kang‐Hyun; Halpern, Howard J.

doi:10.1016/j.jmr.2006.12.007

Cited by 50 publications

(49 citation statements)

References 20 publications

(25 reference statements)

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“…If the acquisition time of a projection is made proportional to 1/cosθ, the additional percentage reduction R in the acquisition time associated with ESA4 is (13) where (14) The value of R for M = 18 (with missing angle region 85°-95°) is 23% and for M = 10 (with missing angle of 81°-99°) is 26%. These savings are in addition to the 30% savings offered by ESA3 method [18]. As a result, net savings offered by ESA4 over ELA4 for M = 18 and M = 10 are 46% and 48%, respectively.…”

Section: Equal Solid Angle Sampling In 4d (Esa4)mentioning

confidence: 91%

“…The first technique presented here is an extension of the 3D ESA-based distribution [19] while the second proposed technique is an estimation of Fekete points [20] in 4D which generally results in more uniform distribution of the data. We expect about 50% reduction in the acquisition time over ELA-based distribution and about 25% reduction over the previously proposed sampling technique where ESA approximation holds only in the 3D spatial domain [18]. Since the reconstruction is carried out in a single stage without the necessity of interpolation, the spatial resolution does not degrade.…”

Section: Introductionmentioning

confidence: 87%

“…In other words, the data from the resulting sampling pattern is crowded for lower gradient strengths and sparse for higher gradient strengths. The reconstruction results for 4D EPRI using ESA3 based distributions has been reported recently [18].…”

Section: Equal Solid Angle Sampling In Spatial Domain (Esa3)mentioning

confidence: 99%

“…Since hardware limitations and SNR put a restriction on the maximum applicable gradient, the projection data corresponding to higher gradients cannot be acquired. If θ m is the missing angle (18) (19) where θ G is the spectral angle associated with the maximum applicable gradient strength G max and θ max is the spectral angle corresponding the maximum gradient reached by a sampling method.…”

Section: Missing Angle Problem and Single-stage Reconstructionmentioning

confidence: 99%

“…Although ESA-based distribution designed for 3D has been applied to 4D imaging [18], the resulting distribution has an improved uniformity only in the 3D spatial domain and the overall sampling in 4D domain is still not uniform. In addition, since the set of selected gradient orientations is identical for each applied gradient strength, there is a high redundancy in the collected data.…”

Section: Introductionmentioning

confidence: 99%

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Uniform distribution of projection data for improved reconstruction quality of 4D EPR imaging

Ahmad¹,

Vikram²,

Clymer³

et al. 2007

Journal of Magnetic Resonance

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In continuous wave (CW) electron paramagnetic resonance imaging (EPRI), high quality of reconstruction in a limited acquisition time is a high priority. It has been shown for the case of 3D EPRI, that a uniform distribution of the projection data generally enhances reconstruction quality. In this work, we have suggested two data acquisition techniques for which the gradient orientations are more evenly distributed over the 4D acquisition space as compared to the existing methods. The first sampling technique is based on equal solid angle partitioning of 4D space, while the second technique is based on Fekete points estimation in 4D to generate a more uniform distribution of data. After acquisition, filtered backprojection (FBP) is applied to carryout the reconstruction in a single stage. The single-stage reconstruction improves the spatial resolution by eliminating the necessity of data interpolation in multi-stage reconstructions. For the proposed data distributions, the simulations and experimental results indicate a higher fidelity to the true object configuration. Using the uniform distribution, we expect about 50% reduction in the acquisition time over the traditional method of equal linear angle acquisition.

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Section: Equal Solid Angle Sampling In 4d (Esa4)mentioning

confidence: 91%

Section: Introductionmentioning

confidence: 87%

Section: Equal Solid Angle Sampling In Spatial Domain (Esa3)mentioning

confidence: 99%

Section: Missing Angle Problem and Single-stage Reconstructionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Uniform distribution of projection data for improved reconstruction quality of 4D EPR imaging

Ahmad¹,

Vikram²,

Clymer³

et al. 2007

Journal of Magnetic Resonance

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Electron Paramagnetic Resonance Imaging

Eaton

2011

Encyclopedia of Analytical Chemistry

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Unpaired electrons can be measured by their absorption of electromagnetic radiation when the energy level separations established by a magnetic field match the energy of the incident electromagnetic radiation (usually microwave or radio frequency). The measurement method is called electron paramagnetic resonance (EPR). The EPR methodology can be continuous‐wave (CW), pulsed, or rapid‐scan EPR. Since the paramagnetic species are commonly not uniformly distributed in the material studied, the spatial distribution can be discerned by performing the EPR measurement in a magnetic‐field gradient, such that different parts of the sample resonate at different strengths of the applied magnetic field. Performing EPR in a gradient field and then constructing a spatial image from the acquired EPR spectra is called EPR imaging, sometimes abbreviated to EPRI. The method is analogous to MRI, but with several differences in implementation due to differences in spectral line widths, relaxation times, and unpaired spin concentrations. The goal of EPRI is to determine why the spins are where they are. Applications are as diverse as understanding physiology, measuring O 2 concentration in tumors, and determining the distribution of radiation‐induced defect centers in solid materials.

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Imaging

Epel

Halpern

2017

eMagRes

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Spatially uniform sampling in 4-D EPR spectral-spatial imaging

Cited by 50 publications

References 20 publications

Uniform distribution of projection data for improved reconstruction quality of 4D EPR imaging

Uniform distribution of projection data for improved reconstruction quality of 4D EPR imaging

Electron Paramagnetic Resonance Imaging

Imaging

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