Magnetization transfer and frequency distribution effects in the SSFP ellipse

Wood, Tobias C.; Teixeira, Rui Pedro A. G.; Malik, Shaihan J.

doi:10.1002/mrm.28149

Cited by 7 publications

(14 citation statements)

References 30 publications

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“…At the same time, in vivo estimates of relaxation parameters with CELF show biases compared to conventional spin-echo methods, due to microstructural sensitivity of bSSFP imaging. Further development of CELF is warranted to resolve these estimation errors, which might eventually provide useful opportunities for CELF in quantitative MRI applications including relaxometry, magnetization transfer (MT) mapping [43] and conductivity mapping [44].…”

Section: Discussionmentioning

confidence: 99%

Constrained Ellipse Fitting for Efficient Parameter Mapping With Phase-Cycled bSSFP MRI

Keskin

Yılmaz²,

Çukur³

2022

IEEE Trans. Med. Imaging

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Balanced steady-state free precession (bSSFP) imaging enables high scan efficiency in MRI, but differs from conventional sequences in terms of elevated sensitivity to main field inhomogeneity and nonstandard T 2 /T 1 -weighted tissue contrast. To address these limitations, multiple bSSFP images of the same anatomy are commonly acquired with a set of different RF phase-cycling increments. Joint processing of phasecycled acquisitions serves to mitigate sensitivity to field inhomogeneity. Recently phase-cycled bSSFP acquisitions were also leveraged to estimate relaxation parameters based on explicit signal models. While effective, these model-based methods often involve a large number of acquisitions (N ≈ 10-16), degrading scan efficiency. Here, we propose a new constrained ellipse fitting method (CELF) for parameter estimation with improved efficiency and accuracy in phase-cycled bSSFP MRI. CELF is based on the elliptical signal model framework for complex bSSFP signals; and it introduces geometrical constraints on ellipse properties to improve estimation efficiency, and dictionarybased identification to improve estimation accuracy. CELF generates maps of T 1 , T 2 , off-resonance and on-resonant bSSFP signal by employing a separate B 1 map to mitigate sensitivity to flip angle variations. Our results indicate that CELF can produce accurate off-resonance and bandingfree bSSFP maps with as few as N = 4 acquisitions, while estimation accuracy for relaxation parameters is notably limited by biases from microstructural sensitivity of bSSFP imaging.

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Section: Discussionmentioning

confidence: 99%

Constrained Ellipse Fitting for Efficient Parameter Mapping With Phase-Cycled bSSFP MRI

Keskin

Yılmaz²,

Çukur³

2022

IEEE Trans. Med. Imaging

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show abstract

Section: Discussionmentioning

confidence: 99%

“…Recent work by Wood et al 22 has demonstrated that the PLANET method 23 , 24 , 25 for phase‐cycled bSSFP can be applied to qMT at higher field strengths to derive qMT parameter estimates free from banding artefacts. However, Wood et al 22 utilized the signal model from Gloor et al, 1 which translated into increased errors in their parameter estimation, particularly in white matter. We hypothesize that combining the method from Wood et al 22 with our methods here would provide increased accuracy, leading to a method which can produce qMT parameter estimates quickly over all clinical field strengths.…”

Section: Discussionmentioning

confidence: 99%

Unbiased signal equation for quantitative magnetization transfer mapping in balanced steady‐state free precession MRI

Bayer

Bock

Jezzard

et al. 2021

Magnetic Resonance in Med

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“…CELF shows improved estimation accuracy compared to PLANET, and it offers higher scan efficiency by reducing the number of required. This scan efficiency can provide useful opportunities in other quantitative applications such as magnetization transfer (MT) parameter mapping [43], and conductivity mapping [44].…”

Section: Discussionmentioning

confidence: 99%

Constrained Ellipse Fitting for Efficient Parameter Mapping with Phase-cycled bSSFP MRI

Keskin,

Yılmaz,

Çukur

2021

Preprint

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Balanced steady-state free precession (bSSFP) imaging enables high scan efficiency in MRI, but differs from conventional sequences in terms of elevated sensitivity to main field inhomogeneity and nonstandard T 2 /T 1 -weighted tissue contrast. To address these limitations, multiple bSSFP images of the same anatomy are commonly acquired with a set of different RF phase-cycling increments. Joint processing of phase-cycled acquisitions serves to mitigate sensitivity to field inhomogeneity. Recently phase-cycled bSSFP acquisitions were also leveraged to estimate relaxation parameters based on explicit signal models. While effective, these model-based methods often involve a large number of acquisitions (N≈10-16), degrading scan efficiency. Here, we propose a new constrained ellipse fitting method (CELF) for parameter estimation with improved efficiency and accuracy in phasecycled bSSFP MRI. CELF is based on the elliptical signal model framework for complex bSSFP signals; and it introduces geometrical constraints on ellipse properties to improve estimation efficiency, and dictionary-based identification to improve estimation accuracy. Simulated, phantom and in vivo experiments demonstrate that the proposed method enables enhanced parameter estimation with as few as N=4 acquisitions, thus it holds great potential for improving utility of bSSFP-based parametric mapping.

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Magnetization transfer and frequency distribution effects in the SSFP ellipse

Cited by 7 publications

References 30 publications

Constrained Ellipse Fitting for Efficient Parameter Mapping With Phase-Cycled bSSFP MRI

Constrained Ellipse Fitting for Efficient Parameter Mapping With Phase-Cycled bSSFP MRI

Unbiased signal equation for quantitative magnetization transfer mapping in balanced steady‐state free precession MRI

Constrained Ellipse Fitting for Efficient Parameter Mapping with Phase-cycled bSSFP MRI

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