A higher dimensional homodyne filter for phase sensitive partial Fourier reconstruction of magnetic resonance imaging

Paul, Joseph Suresh; Pillai, Uma Krishna Swamy

doi:10.1016/j.mri.2015.06.005

Cited by 3 publications

(2 citation statements)

References 9 publications

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“…Instead of adopting a brain anatomical template, we used a brain structure image (denoted by χ 0 [ r ]) for fmap visualization by selecting a 3D χ source volume from χ[ r ,t]. We performed image enhancement (e.g., a homodyne filtering [ 42 ]) on χ 0 [ r ] to enhance the cortex structure (gyri and sulci patterns). The montage displays of 3D image χ 0 [ r ] are presented in S8 Fig .…”

Section: Resultsmentioning

confidence: 99%

Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping

2018

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PurposeTo computationally separate dynamic brain functional BOLD responses from static background in a brain functional activity for forward fMRI signal analysis and inverse mapping.MethodsA brain functional activity is represented in terms of magnetic source by a perturbation model: χ = χ0 +δχ, with δχ for BOLD magnetic perturbations and χ0 for background. A brain fMRI experiment produces a timeseries of complex-valued images (T2* images), whereby we extract the BOLD phase signals (denoted by δP) by a complex division. By solving an inverse problem, we reconstruct the BOLD δχ dataset from the δP dataset, and the brain χ distribution from a (unwrapped) T2* phase image. Given a 4D dataset of task BOLD fMRI, we implement brain functional mapping by temporal correlation analysis.ResultsThrough a high-field (7T) and high-resolution (0.5mm in plane) task fMRI experiment, we demonstrated in detail the BOLD perturbation model for fMRI phase signal separation (P + δP) and reconstructing intrinsic brain magnetic source (χ and δχ). We also provided to a low-field (3T) and low-resolution (2mm) task fMRI experiment in support of single-subject fMRI study. Our experiments show that the δχ-depicted functional map reveals bidirectional BOLD χ perturbations during the task performance.ConclusionsThe BOLD perturbation model allows us to separate fMRI phase signal (by complex division) and to perform inverse mapping for pure BOLD δχ reconstruction for intrinsic functional χ mapping. The full brain χ reconstruction (from unwrapped fMRI phase) provides a new brain tissue image that allows to scrutinize the brain tissue idiosyncrasy for the pure BOLD δχ response through an automatic function/structure co-localization.

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Section: Resultsmentioning

confidence: 99%

Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping

2018

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“…The combination of this bi-directional homodyne reconstruction with phase preservation also enabled successful fat and water separation with Dixon. Although other reconstruction methods such as projection onto convex sets (POCS) 26,27 can also be used to reduce the zero-filling artifacts, the bi-directional homodyne reconstruction minimizes these artifacts without iterative reconstructions, such that successful reconstructions can be performed even with high B 0 inhomogeneities. SShTSE-mDixon used a higher receiver bandwidth (870 Hz/pixel) compared to standard SShTSE and SShTSE-SPAIR acquisitions (440 Hz/pixel).…”

Section: Discussionmentioning

confidence: 99%

Single‐shot RARE with Dixon: Application to robust abdominal imaging with uniform fat and water separation at 3T

Wang

Udayakumar

et al. 2021

Magnetic Resonance in Med

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Purpose To develop a true single shot turbo spin echo (SShTSE) acquisition with Dixon for robust T2‐weighted abdominal imaging with uniform fat and water separation at 3T. Methods The in‐phase (IP) and out‐of‐phase (OP) echoes for Dixon processing were acquired in the same repetition time of a SShTSE using partial echoes. A phase‐preserved bi‐directional homodyne reconstruction was developed to compensate the partial echo and the partial phase encoding of SShTSE. With IRB approval, the SShTSE‐Dixon was compared against standard SShTSE, without and with fat suppression using spectral adiabatic inversion recovery (SPAIR) in 5 healthy volunteers and 5 patients. The SNR and contrast ratio (CR) of spleen to liver were compared among different acquisitions. Results The bi‐directional homodyne reconstruction successfully minimized ringing artifacts because of partial acquisitions. SShTSE‐Dixon achieved uniform fat suppression compared to SShTSE‐SPAIR with fat suppression failures of 1/10 versus 10/10 in the axial plane and 0/5 versus 5/5 in the coronal plane, respectively. The SNRs of the liver (12.2 ± 4.9 vs. 11.7 ± 5.2; P = .76) and spleen (25.9 ± 11.6 vs. 23.7 ± 9.7; P = .14) were equivalent between fat‐suppressed images (SShTSE‐Dixon water‐only and SShTSE‐SPAIR). The SNRs of liver (14.4 ± 5.7 vs. 13.4 ± 5.0; P = .60) and spleen (26.5 ± 10.1 vs. 25.7 ± 8.5; P = .56) were equivalent between non‐fat‐suppressed images (SShTSE‐Dixon IP and SShTSE). The CRs of spleen to liver were also similar between fat‐suppressed images (2.6 ± 0.4 vs. 2.5 ± 0.5; P =.92) and non‐fat‐suppressed images (2.3 ± 0.6 vs. 2.2 ± 0.4; P =.84). Conclusion SShTSE‐Dixon generates robust abdominal T2‐weighted images at 3T with and without uniform fat suppression, along with perfectly co‐registered fat‐only images in a single acquisition.

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Computed inverse MRI (CIMRI) for intrinsic brain magnetic susceptibility mapping

Chen

2021

Computers in Biology and Medicine

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A higher dimensional homodyne filter for phase sensitive partial Fourier reconstruction of magnetic resonance imaging

Cited by 3 publications

References 9 publications

Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping

Brain functional BOLD perturbation modelling for forward fMRI and inverse mapping

Single‐shot RARE with Dixon: Application to robust abdominal imaging with uniform fat and water separation at 3T

Computed inverse MRI (CIMRI) for intrinsic brain magnetic susceptibility mapping

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