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Plähn NMJ, Poli S, Peper ES, Açikgöz BC, Kreis R, Ganter C, Bastiaansen JAM. Getting the phase consistent: The importance of phase description in balanced steady-state free precession MRI of multi-compartment systems. Magn Reson Med 2024; 92:215-225. [PMID: 38321594 DOI: 10.1002/mrm.30033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 01/09/2024] [Accepted: 01/12/2024] [Indexed: 02/08/2024]
Abstract
PURPOSE Determine the correct mathematical phase description for balanced steady-state free precession (bSSFP) signals in multi-compartment systems. THEORY AND METHODS Based on published bSSFP signal models, different phase descriptions can be formulated: one predicting the presence and the other predicting the absence of destructive interference effects in multi-compartment systems. Numerical simulations of bSSFP signals of water and acetone were performed to evaluate the predictions of these different phase descriptions. For experimental validation, bSSFP profiles were measured at 3T using phase-cycled bSSFP acquisitions performed in a phantom containing mixtures of water and acetone, which replicates a system with two signal components. Localized single voxel MRS was performed at 7T to determine the relative chemical shift of the acetone-water mixtures. RESULTS Based on the choice of phase description, the simulated bSSFP profiles of water-acetone mixtures varied significantly, either displaying or lacking destructive interference effects, as predicted theoretically. In phantom experiments, destructive interference was consistently observed in the measured bSSFP profiles of water-acetone mixtures, supporting the theoretical description that predicts such interference effects. The connection between the choice of phase description and predicted observation enables unambiguous experimental identification of the correct phase description for multi-compartment bSSFP profiles, which is consistent with the Bloch equations. CONCLUSION The study emphasizes that consistent phase descriptions are crucial for accurately describing multi-compartment bSSFP signals, as incorrect phase descriptions result in erroneous predictions.
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Affiliation(s)
- Nils M J Plähn
- Department of Diagnostic, Interventional and Pediatric Radiology (DIPR), Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Translation Imaging Center (TIC), Swiss Institute for Translational and Entrepreneurial Medicine, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Simone Poli
- Translation Imaging Center (TIC), Swiss Institute for Translational and Entrepreneurial Medicine, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
- MR Methodology, Department for Diagnostic and Interventional Neuroradiology, University of Bern, Bern, Switzerland
| | - Eva S Peper
- Department of Diagnostic, Interventional and Pediatric Radiology (DIPR), Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Translation Imaging Center (TIC), Swiss Institute for Translational and Entrepreneurial Medicine, Bern, Switzerland
| | - Berk C Açikgöz
- Department of Diagnostic, Interventional and Pediatric Radiology (DIPR), Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Translation Imaging Center (TIC), Swiss Institute for Translational and Entrepreneurial Medicine, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Roland Kreis
- Translation Imaging Center (TIC), Swiss Institute for Translational and Entrepreneurial Medicine, Bern, Switzerland
- MR Methodology, Department for Diagnostic and Interventional Neuroradiology, University of Bern, Bern, Switzerland
- Department for Biomedical Research, University of Bern, Bern, Switzerland
| | - Carl Ganter
- Department of Diagnostic and Interventional Radiology, TUM School of Medicine and Health, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Jessica A M Bastiaansen
- Department of Diagnostic, Interventional and Pediatric Radiology (DIPR), Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Translation Imaging Center (TIC), Swiss Institute for Translational and Entrepreneurial Medicine, Bern, Switzerland
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Sardjoe Mishre ASD, Martinez-Tellez B, Straat ME, Boon MR, Dzyubachyk O, Webb AG, Rensen PCN, Kan HE. Image registration and mutual thresholding enable low interimage variability across dynamic MRI measurements of supraclavicular brown adipose tissue during mild cold exposure. Magn Reson Med 2023. [PMID: 37183785 DOI: 10.1002/mrm.29707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 04/26/2023] [Accepted: 04/27/2023] [Indexed: 05/16/2023]
Abstract
PURPOSE Activated brown adipose tissue (BAT) enhances lipid catabolism and improves cardiometabolic health. Quantitative MRI of the fat fraction (FF) of supraclavicular BAT (scBAT) is a promising noninvasive measure to assess BAT activity but suffers from high scan variability. We aimed to test the effects of coregistration and mutual thresholding on the scan variability in a fast (1 min) time-resolution MRI protocol for assessing scBAT FF changes during cold exposure. METHODS Ten volunteers (age 24.8 ± 3.0 years; body mass index 21.2 ± 2.1 kg/m2 ) were scanned during thermoneutrality (32°C; 10 min) and mild cold exposure (18°C; 60 min) using a 12-point gradient-echo sequence (70 consecutive scans with breath-holds, 1.03 min per dynamic). Dynamics were coregistered to the first thermoneutral scan, which enabled drawing of single regions of interest in the scBAT depot. Voxel-wise FF changes were calculated at each time point and averaged across regions of interest. We applied mutual FF thresholding, in which voxels were included if their FF was greater than 30% FF in the reference scan and the registered dynamic. The efficacy of the coregistration was determined by using a moving average and comparing the mean squared error of residuals between registered and nonregistered data. Registered scBAT ΔFF was compared with single-scan thresholding using the moving average method. RESULTS Registered scBAT ΔFF had lower mean square error values than nonregistered data (0.07 ± 0.05% vs. 0.16 ± 0.14%; p < 0.05), and mutual thresholding reduced the scBAT ΔFF variability by 30%. CONCLUSION We demonstrate that coregistration and mutual thresholding improve stability of the data 2-fold, enabling assessment of small changes in FF following cold exposure.
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Affiliation(s)
- Aashley S D Sardjoe Mishre
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, the Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
- Department of Radiology, C.J. Gorter MRI Center, Leiden University Medical Center, Leiden, the Netherlands
| | - Borja Martinez-Tellez
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, the Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Maaike E Straat
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, the Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Mariëtte R Boon
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, the Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Oleh Dzyubachyk
- Department of Radiology, Division of Image Processing, Leiden University Medical Center, Leiden, the Netherlands
- Department of Cell and Chemical Biology, Electron Microscopy Section, Leiden University Medical Center, Leiden, the Netherlands
| | - Andrew G Webb
- Department of Radiology, C.J. Gorter MRI Center, Leiden University Medical Center, Leiden, the Netherlands
| | - Patrick C N Rensen
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, the Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Hermien E Kan
- Department of Radiology, C.J. Gorter MRI Center, Leiden University Medical Center, Leiden, the Netherlands
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Keskin K, Yilmaz U, Cukur T. Constrained Ellipse Fitting for Efficient Parameter Mapping With Phase-Cycled bSSFP MRI. IEEE TRANSACTIONS ON MEDICAL IMAGING 2022; 41:14-26. [PMID: 34351856 DOI: 10.1109/tmi.2021.3102852] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
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 [Formula: see text]-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 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 dictionary-based identification to improve estimation accuracy. CELF generates maps of [Formula: see text], [Formula: see text], off-resonance and on-resonant bSSFP signal by employing a separate [Formula: see text] map to mitigate sensitivity to flip angle variations. Our results indicate that CELF can produce accurate off-resonance and banding-free 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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Wood TC, Teixeira RPAG, Malik SJ. Magnetization transfer and frequency distribution effects in the SSFP ellipse. Magn Reson Med 2019; 84:857-865. [PMID: 31872921 PMCID: PMC7216875 DOI: 10.1002/mrm.28149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/15/2019] [Accepted: 12/06/2019] [Indexed: 01/08/2023]
Abstract
Purpose To demonstrate that quantitative magnetization transfer (qMT) parameters can be extracted from steady‐state free‐precession (SSFP) data with no external T1 map or banding artifacts. Methods SSFP images with multiple MT weightings were acquired and qMT parameters fitted with a two‐stage elliptical signal model. Results Monte Carlo simulations and data from a 3T scanner indicated that most qMT parameters could be recovered with reasonable accuracy. Systematic deviations from theory were observed in white matter, consistent with previous literature on frequency distribution effects. Conclusions qMT parameters can be extracted from SSFP data alone, in a manner robust to banding artifacts, despite several confounds.
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Affiliation(s)
- Tobias C Wood
- Department of Neuroimaging, King's College London, London, UK
| | - Rui P A G Teixeira
- School of Imaging Sciences and Biomedical Engineering, King's College London, London, UK
| | - Shaihan J Malik
- School of Imaging Sciences and Biomedical Engineering, King's College London, London, UK
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Shcherbakova Y, van den Berg CAT, Moonen CTW, Bartels LW. Investigation of the influence of B 0 drift on the performance of the PLANET method and an algorithm for drift correction. Magn Reson Med 2019; 82:1725-1740. [PMID: 31317584 PMCID: PMC6772029 DOI: 10.1002/mrm.27860] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 04/26/2019] [Accepted: 05/23/2019] [Indexed: 01/03/2023]
Abstract
Purpose The PLANET method was designed to simultaneously reconstruct maps of T1 and T2, the off‐resonance, the RF phase, and the banding free signal magnitude. The method requires a stationary B0 field over the course of a phase‐cycled balanced SSFP acquisition. In this work we investigated the influence of B0 drift on the performance of the PLANET method for single‐component and two‐component signal models, and we propose a strategy for drift correction. Methods The complex phase‐cycled balanced SSFP signal was modeled with and without frequency drift. The behavior of the signal influenced by drift was mathematically interpreted as a sum of drift‐dependent displacement of the data points along an ellipse and drift‐dependent rotation around the origin. The influence of drift on parameter estimates was investigated experimentally on a phantom and on the brain of healthy volunteers and was verified by numerical simulations. A drift correction algorithm was proposed and tested on a phantom and in vivo. Results Drift can be assumed to be linear over the typical duration of a PLANET acquisition. In a phantom (a single‐component signal model), drift induced errors of 4% and 8% in the estimated T1 and T2 values. In the brain, where multiple components are present, drift only had a minor effect. For both single‐component and two‐component signal models, drift‐induced errors were successfully corrected by applying the proposed drift correction algorithm. Conclusion We have demonstrated theoretically and experimentally the sensitivity of the PLANET method to B0 drift and have proposed a drift correction method.
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Affiliation(s)
- Yulia Shcherbakova
- Center for Image Sciences, Imaging Division, University Medical Center Utrecht, Utrecht, Netherlands
| | - Cornelis A T van den Berg
- Department of Radiotherapy, Imaging Division, University Medical Center Utrecht, Utrecht, Netherlands
| | - Chrit T W Moonen
- Center for Image Sciences, Imaging Division, University Medical Center Utrecht, Utrecht, Netherlands
| | - Lambertus W Bartels
- Center for Image Sciences, Imaging Division, University Medical Center Utrecht, Utrecht, Netherlands
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