Patient-specific biases in fat fraction estimates of malignant bone marrow due to relaxation times measured with STEAM at 3T
Author(s)
Type
Journal Article
Abstract
Semi-quantitative fat fraction estimation using 2-point Dixon sequences is widely used in whole body (WB) MR imaging for malignant bone disease but is biased by relaxation times. Understanding this bias requires water- and fat-specific relaxometry data in normal-appearing marrow and lesions. This study measured bone marrow relaxation times in healthy volunteers and WB-MRI patients using MRS at 3T. Five healthy female volunteers (mean age 38.0 ± 2.5 years) and 24 patients with
malignant bone disease undergoing clinical WB-MRI (13 male; mean age 67.7 ± 9.7 years; primary cancers: breast = 5, melanoma = 1, multiple myeloma = 8, prostate = 10) underwent variable inversion/echo time STEAM and 3D gradient echo fat-water imaging. MRS water and fat peaks were fitted to determine T1, T2, R2* (from linewidths), and proton density fat fraction (PDFF). Scan-rescan repeatability of MRS parameters was assessed in volunteers. Lesions were classified by disease state according to clinical reports and segmented in Dixon
imaging data for comparison of fat fraction estimates with MRS. Repeatability was evaluated using coefficients of variation. Summary statistics (mean, standard deviation and range) were reported; exploratory inferential statistics were also determined with normality (Shapiro-Wilk) and variance (Levene’s) tests before one-way ANOVA and Tukey’s comparisons (p < 0.05). Monte Carlo simulations assessed relaxation bias on PDFF.
All quantitative MRS parameters were repeatable (coefficient of variation < 10%). Water T1 and T2 were most sensitive to disease state in patients, ranging from 1121–2206 ms and 15–71 ms respectively, and were demonstrated to substantially affect 2-point Dixon fat fraction estimates with Monte Carlo simulation. Imaging PDFF achieves closer agreement with MRS PDFF than 2-point Dixon methods. These findings remain preliminary due to the small sample size, but they suggest value in future studies with larger cohorts evaluating water relaxation times or PDFF in malignant bone disease.
malignant bone disease undergoing clinical WB-MRI (13 male; mean age 67.7 ± 9.7 years; primary cancers: breast = 5, melanoma = 1, multiple myeloma = 8, prostate = 10) underwent variable inversion/echo time STEAM and 3D gradient echo fat-water imaging. MRS water and fat peaks were fitted to determine T1, T2, R2* (from linewidths), and proton density fat fraction (PDFF). Scan-rescan repeatability of MRS parameters was assessed in volunteers. Lesions were classified by disease state according to clinical reports and segmented in Dixon
imaging data for comparison of fat fraction estimates with MRS. Repeatability was evaluated using coefficients of variation. Summary statistics (mean, standard deviation and range) were reported; exploratory inferential statistics were also determined with normality (Shapiro-Wilk) and variance (Levene’s) tests before one-way ANOVA and Tukey’s comparisons (p < 0.05). Monte Carlo simulations assessed relaxation bias on PDFF.
All quantitative MRS parameters were repeatable (coefficient of variation < 10%). Water T1 and T2 were most sensitive to disease state in patients, ranging from 1121–2206 ms and 15–71 ms respectively, and were demonstrated to substantially affect 2-point Dixon fat fraction estimates with Monte Carlo simulation. Imaging PDFF achieves closer agreement with MRS PDFF than 2-point Dixon methods. These findings remain preliminary due to the small sample size, but they suggest value in future studies with larger cohorts evaluating water relaxation times or PDFF in malignant bone disease.
Date Issued
2026-04-01
Date Acceptance
2026-01-27
Citation
NMR in Biomedicine, 2026, 39 (4)
ISSN
0952-3480
Publisher
Wiley
Journal / Book Title
NMR in Biomedicine
Volume
39
Issue
4
Copyright Statement
© 2026 The Author(s). NMR in Biomedicine published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,provided the original work is properly cited.
License URL
Identifier
10.1002/nbm.70242
Subjects
bone marrow | fat quantification | metastasis | relaxometry | spectroscopy | whole-body ADC, apparent diffusion coefficient
FF, signal-weighted fat fraction
PD, proton density
PDFF, proton density fat fraction
R2*, transverse relaxation rate
STEAM, stimulated echo acquisition mode
WB-MRI, whole-body MRI
Publication Status
Published
Article Number
70242
Date Publish Online
2026-02-24