Abstract
ObjectivesTo prospectively evaluate a 3D-multiecho-Dixon sequence with inline calculation of proton density fat fraction (PDFF) and R2* (qDixon), and an improved version of it (qDixon-WIP), for the MR-quantification of hepatic iron in a clinical setting.MethodsPatients with increased serum ferritin underwent 1.5-T MRI of the liver for the evaluation of hepatic iron overload. The imaging protocol for R2* quantification included as follows: (1) a validated, 2D multigradient-echo sequence (initial TE 0.99 ms, R2*-ME-GRE), (2) a 3D-multiecho-Dixon sequence with inline calculation of PDFF and R2* (initial TE 2.38 ms, R2*-qDixon), and optionally (3) a prototype (works-in-progress, WIP) version of the latter (initial TE 1.04 ms, R2*-qDixon-WIP) with improved water/fat separation and noise-corrected parameter fitting. For all sequences, three manually co-registered regions of interest (ROIs) were placed in the liver. R2* values were compared and linear regression analysis and Bland-Altman plots calculated.ResultsForty-six out of 415 patients showed fat-water (F/W) swap with qDixon and were excluded. A total of 369 patients (mean age 52 years) were included; in 203/369, the optional qDixon-WIP was acquired, which showed no F/W swaps. A strong correlation was found between R2*-ME-GRE and R2*-qDixon (r2 = 0.92, p < 0.001) with Bland-Altman revealing a mean difference of − 3.82 1/s (SD = 21.26 1/s). Correlation between R2*-GRE-ME and R2*-qDixon-WIP was r2 = 0.95 (p < 0.001) with Bland-Altman showing a mean difference of − 0.125 1/s (SD = 30.667 1/s).ConclusionsThe 3D-multiecho-Dixon sequence is a reliable tool to quantify hepatic iron. Results are comparable with established relaxometry methods. Improvements to the original implementation eliminate occasional F/W swaps and limitations regarding maximum R2* values.Key Points• The 3D-multiecho-Dixon sequence for 1.5 T is a reliable tool to quantify hepatic iron.• Results of the 3D-multiecho-Dixon sequence are comparable with established relaxometry methods.• An improved version of the 3D-multiecho-Dixon sequence eliminates minor drawbacks.
Highlights
In recent years, magnetic resonance imaging (MRI) has been established for the evaluation of hepatic iron overload [1, 2]
Results of the 3D-multiecho-Dixon sequence are comparable with established relaxometry methods
Results of the liver iron concentration (LIC)-based analysis for qDixon are provided in Tables 2, 3, 4, and 5
Summary
Magnetic resonance imaging (MRI) has been established for the evaluation of hepatic iron overload [1, 2]. The benefits of MRI are at hand: non-invasive, nowadays widely available, no relevant risk factors, additional information on iron overload of the spleen and pancreas, reduction of sampling errors to a minimum [3,4,5]. One problem is the wide range of different techniques, as e.g. R2 or R2* relaxometry or the signal-intensity-ratio method [6,7,8,9]. Most of these approaches do not have regulatory approval for iron quantification, which limits their use in larger multicenter studies or clinical trials. Consensus is still missing, which makes it even more difficult for each institution to find the best approach
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