Scan–rescan repeatability and impact of b0 and b1 field nonuniformity corrections in single-point whole-brain macromolecular proton fraction mapping V. L. Yarnykh, A. A. Kisel, M. Y. Khodanovich
Material type:
ArticleContent type: Текст Media type: электронный Subject(s): картирование макромолекулярной протонной фракции | метод одноточечного MPF картирования | оценка миелинизации головного мозгаGenre/Form: статьи в журналах Online resources: Click here to access online
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Journal of magnetic resonance imaging Vol. 51, № 6. P. 1789-1798Abstract: Background: Single-point macromolecular proton fraction (MPF) mapping is a recent quantitative MRI method for fast
assessment of brain myelination. Information about reproducibility and sensitivity of MPF mapping to magnetic field nonuniformity
is important for clinical applications.
Purpose: To assess scan–rescan repeatability and a value of B0 and B1 field inhomogeneity corrections in single-point
synthetic-reference MPF mapping.
Study Type: Prospective.
Population: Eight healthy adult volunteers underwent two scans with 11.5 2.3 months interval.
Field Strength/Sequence: 3T; whole-brain 3D MPF mapping protocol included three spoiled gradient-echo sequences
providing T1, proton density, and magnetization transfer contrasts with 1.25 × 1.25 × 1.25 mm3 resolution and B0 and B1
mapping sequences.
Assessment: MPF maps were reconstructed with B0 and B1 field nonuniformity correction, B0- and B1-only corrections,
and without corrections. Mean MPF values were measured in automatically segmented white matter (WM) and gray matter
(GM).
Statistical Tests: Within-subject coefficient of variation (CV), intraclass correlation coefficient (ICC), Bland–Altman plots,
and paired t-tests to assess scan–rescan repeatability. Repeated-measures analysis of variance (ANOVA) to compare field
corrections.
Results: Maximal relative local MPF errors without correction in the areas of largest field nonuniformities were about 5%
and 27% for B0 and B1, respectively. The effect of B0 correction was insignificant for whole-brain WM (P > 0.25) and GM
(P > 0.98) MPF. The absence of B1 correction caused a positive relative bias of 4–5% (P < 0.001) in both tissues. Scan–
rescan agreement was similar for all field correction options with ICCs 0.80–0.81 for WM and 0.89–0.92 for GM. CVs were
1.6–1.7% for WM and 0.7–1.0% for GM.
Data Conclusion: The single-point method enables high repeatability of MPF maps obtained with the same equipment.
Correction of B0 inhomogeneity may be disregarded to shorten the examination time. B1 nonuniformity correction
improves accuracy of MPF measurements at 3T. Reliability of whole-brain MPF measurements in WM and GM is not
affected by B0 and B1 field corrections.
Level of Evidence: 2
Technical Efficacy: Stage 1
Библиогр.: 40 назв.
Background: Single-point macromolecular proton fraction (MPF) mapping is a recent quantitative MRI method for fast
assessment of brain myelination. Information about reproducibility and sensitivity of MPF mapping to magnetic field nonuniformity
is important for clinical applications.
Purpose: To assess scan–rescan repeatability and a value of B0 and B1 field inhomogeneity corrections in single-point
synthetic-reference MPF mapping.
Study Type: Prospective.
Population: Eight healthy adult volunteers underwent two scans with 11.5 2.3 months interval.
Field Strength/Sequence: 3T; whole-brain 3D MPF mapping protocol included three spoiled gradient-echo sequences
providing T1, proton density, and magnetization transfer contrasts with 1.25 × 1.25 × 1.25 mm3 resolution and B0 and B1
mapping sequences.
Assessment: MPF maps were reconstructed with B0 and B1 field nonuniformity correction, B0- and B1-only corrections,
and without corrections. Mean MPF values were measured in automatically segmented white matter (WM) and gray matter
(GM).
Statistical Tests: Within-subject coefficient of variation (CV), intraclass correlation coefficient (ICC), Bland–Altman plots,
and paired t-tests to assess scan–rescan repeatability. Repeated-measures analysis of variance (ANOVA) to compare field
corrections.
Results: Maximal relative local MPF errors without correction in the areas of largest field nonuniformities were about 5%
and 27% for B0 and B1, respectively. The effect of B0 correction was insignificant for whole-brain WM (P > 0.25) and GM
(P > 0.98) MPF. The absence of B1 correction caused a positive relative bias of 4–5% (P < 0.001) in both tissues. Scan–
rescan agreement was similar for all field correction options with ICCs 0.80–0.81 for WM and 0.89–0.92 for GM. CVs were
1.6–1.7% for WM and 0.7–1.0% for GM.
Data Conclusion: The single-point method enables high repeatability of MPF maps obtained with the same equipment.
Correction of B0 inhomogeneity may be disregarded to shorten the examination time. B1 nonuniformity correction
improves accuracy of MPF measurements at 3T. Reliability of whole-brain MPF measurements in WM and GM is not
affected by B0 and B1 field corrections.
Level of Evidence: 2
Technical Efficacy: Stage 1
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