Comparison of chemical shift-encoded water-fat MRI and MR spectroscopy in quantification of marrow fat in postmenopausal females

Abstract

Purpose To validate a chemical shift‐encoded (CSE) water–fat imaging for quantifying marrow fat fraction (FF), using proton magnetic resonance spectroscopy (MRS) as reference. Materials and Methods Multiecho T2‐corrected MRS and CSE imaging with eight‐echo gradient‐echo acquisitions at 3T were performed to calculate marrow FF in 83 subjects, including 41 with normal bone mineral density (BMD), 26 with osteopenia, and 16 with osteoporosis (based on DXA). Eight participants were scanned three times with repositioning to assess the repeatability of CSE FF map measurements. Pearson correlation coefficient, Bland–Altman 95% limit of agreement, and Lin's concordance correlation coefficient were calculated. Results The Pearson correlation coefficient was 0.979 and Lin's concordance correlation coefficient was 0.962 between CSE‐based FF and MRS‐based FF. All data points, calculated using the Bland–Altman method, were within the limits of agreement. The intra‐ and interrater agreement for average CSE‐based FF was excellent (intrarater, intraclass correlation coefficient [ICC] = 0.993; interrater, ICC = 0.976–0.982 for different BMD groups). In the subgroups of varying BMD, inverse correlations were observed to be very similar between BMD (r = –0.560 to –0.710), T‐score (r = –0.526 to –0.747), and CSE‐based FF, and between BMD (r = –0.539 to –0.706), T‐score (r = –0.501 to –0.742), and MRS‐based FF even controlling for age, years since menopause, and body mass index. The repeatability for CSE FF map measurements expressed as absolute precision error was 1.45%. Conclusion CSE imaging is equally accurate in characterizing marrow fat content as MRS. Given its excellent correlation and concordance with MRS, the CSE sequence could be used as a potential replacement technique for marrow fat quantification. Level of Evidence: 1 J. Magn. Reson. Imaging 2017;45:66–73.

Proton density fat fraction MRI of vertebral bone marrow: Accuracy, repeatability, and reproducibility among readers, field strengths, and imaging platforms

“…So far, few validation studies have compared MRI‐based PDFF to MRS‐based estimations of bone marrow fat content in vivo. These earlier data suggested good agreement between imaging‐determined and MRS‐based PDFF, with a small reported mean bias of up to ±2.2% and coefficients of determination ( r 2 ) ranging from 0.87–0.96, demonstrating high accuracy of chemical shift‐encoding based MRI in characterizing bone marrow PDFF . In line with these findings, PDFF obtained with six‐echo multipoint Dixon sequences also showed high linearity and small bias against MRS among the three MR imagers in our study ( r 2 , 0.888–0.921).…”

“…In line with these findings, PDFF obtained with six‐echo multipoint Dixon sequences also showed high linearity and small bias against MRS among the three MR imagers in our study ( r 2 , 0.888–0.921). However, there was a slight overestimation of imaging‐based PDFF in comparison with MRS, as indicated by an intercept of –6.25 and a mean bias of –0.6% for pooled imaging data, which corroborates prior reports on vertebral bone marrow PDFF . We found that MRI‐determined PDFF measurements demonstrated higher linear correlation (ie, less variation) among the three MR imagers ( r 2 , 0.972–0.978) compared with those obtained between MRI‐determined PDFF and MRS.…”

Quantitative MRI and spectroscopy of bone marrow

“…A dual T 2 * correction can improve accuracy in fat fraction estimation, but it reduces the precision in fat quantification . Therefore, approaches with a single T 2 * correction or with a T 2 ′ correction (where T 2 ′ denotes the reversible spin dephasing relaxation constant) with a priori known water T 2 have been used. A dual T 2 * correction might be not severely affected by noise effects, when the fat quantification is performed not on a voxel‐by‐voxel basis but on a region of interest (ROI) level .…”

Quantitative imaging methods in osteoporosis

“…A study evaluating the reproducibility of signal intensity index (SII) measurements in healthy volunteers with MRI systems from different vendors and with different field strengths found intra-and inter-observer correlation coefficients ranging from 0.82 to 0.98 (102). In osteoporosis, the few studies performed until now have primarily assessed the bone marrow (103)(104)(105). Diffusionweighted imaging measures the Brownian motion of water at a microscopic level and provides information on cellularity and cellular integrity expressed in the apparent diffusion coefficient (ADC) (101).…”