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  • Nickel, Marcel D.  (2)
  • Wu, Holden H.  (2)
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  • 1
    In: Magnetic Resonance in Medicine, Wiley, Vol. 83, No. 6 ( 2020-06), p. 1964-1978
    Abstract: To develop an accurate free‐breathing 3D liver mapping approach and to evaluate it in vivo. Methods A free‐breathing multi‐echo stack‐of‐radial sequence was applied in 5 normal subjects and 6 patients at 3 Tesla. Respiratory motion compensation was implemented using the inherent self‐gating signal. A breath‐hold Cartesian acquisition was the reference standard. Proton density fat fraction and were measured and compared between radial and Cartesian methods using Bland‐Altman plots. The normal subject results were fitted to a linear mixed model ( P 〈 .05 considered significant). Results Free‐breathing stack‐of‐radial without self‐gating exhibited signal attenuation in echo images and artifactually elevated apparent values. In the Bland‐Altman plots of normal subjects, compared to breath‐hold Cartesian, free‐breathing stack‐of‐radial acquisitions of 22, 30, 36, and 44 slices, had mean differences of 27.4, 19.4, 10.9, and 14.7 s −1 with 800 radial views, and they had 18.4, 11.9, 9.7, and 27.7 s −1 with 404 views, which were reduced to 0.4, 0.9, −0.2, and −0.7 s −1 and to −1.7, −1.9, −2.1, and 0.5 s −1 with self‐gating, respectively. No substantial proton density fat fraction differences were found. The linear mixed model showed free‐breathing radial results without self‐gating were significantly biased by 17.2 s −1 averagely ( P = .002), which was eliminated with self‐gating ( P = .930). Proton density fat fraction results were not different ( P 〉 .234). For patients, Bland‐Altman plots exhibited mean differences of 14.4 and 0.1 s −1 for free‐breathing stack‐of‐radial without self‐gating and with self‐gating, respectively, but no substantial proton density fat fraction differences. Conclusion The proposed self‐gating method corrects the respiratory motion bias and enables accurate free‐breathing stack‐of‐radial quantification of liver .
    Type of Medium: Online Resource
    ISSN: 0740-3194 , 1522-2594
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 1493786-4
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  • 2
    In: Journal of Magnetic Resonance Imaging, Wiley, Vol. 53, No. 1 ( 2021-01), p. 118-129
    Abstract: Stack‐of‐radial multiecho gradient‐echo MRI is promising for free‐breathing liver quantification and may benefit children. Purpose To validate stack‐of‐radial MRI with self‐gating motion compensation in phantoms, and to evaluate it in children. Study Type Prospective. Phantoms Four vials with different driven by a motion stage. Subjects Sixteen pediatric patients with suspected nonalcoholic fatty liver disease or steatohepatitis (five females, 13 ± 4 years, body mass index 29.2 ± 8.6 kg/m 2 ). Field Strength/Sequences Stack‐of‐radial, and 2D and 3D Cartesian multiecho gradient‐echo sequences at 3T. Assessment Ungated and gated stack‐of‐radial proton density fat fraction (PDFF) and maps were reconstructed without and with self‐gating motion compensation. Stack‐of‐radial measurements of phantoms without and with motion were validated against reference 2D Cartesian results of phantoms without motion. In subjects, free‐breathing stack‐of‐radial and reference breath‐hold 3D Cartesian were acquired. Subject inclusion for statistical analysis and region of interest placement were determined independently by two observers. Statistical Tests Phantom results were fitted with a weighted linear model. Demographic differences between excluded and included subjects were tested by multivariate analysis of variance. PDFF and measurements were compared using Bland–Altman analysis. Interobserver agreement was assessed by the intraclass correlation coefficient (ICC). Results Ungated stack‐of‐radial inside moving phantom vials showed a significant positive bias of 64.3 s −1 ( P   〈  0.00001), unlike gated results ( P 〉  0.31). Subject inclusion decisions for statistical analysis from two observers were consistent. No significant differences were found between four excluded and 12 included subjects ( P = 0.14). Compared to breath‐hold Cartesian, ungated and gated free‐breathing stack‐of‐radial exhibited mean differences of 18.5 s −1 and 3.6 s −1 . Mean PDFF differences were 1.1% and 1.0% for ungated and gated measurements, respectively. Interobserver agreement was excellent (ICC for PDFF = 0.99, ICC for = 0.90; P   〈  0.0003). Data Conclusion Stack‐of‐radial MRI with self‐gating motion compensation seems to allow free‐breathing liver and PDFF quantification in children. Level of Evidence 2 Technical Efficacy Stage 2
    Type of Medium: Online Resource
    ISSN: 1053-1807 , 1522-2586
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 1497154-9
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