Automated liver sampling using a gradient dual‐echo Dixon‐based technique

Abstract

Magnetic resonance spectroscopy of the liver requires input from a physicist or physician at the time of acquisition to insure proper voxel selection, while in multiecho chemical shift imaging, numerous regions of interest must be manually selected in order to ensure analysis of a representative portion of the liver parenchyma. A fully automated technique could improve workflow by selecting representative portions of the liver prior to human analysis. Complete volumes from three-dimensional gradient dual-echo acquisitions with twopoint Dixon reconstruction acquired at 1.5 and 3 T were analyzed in 100 subjects, using an automated liver sampling algorithm, based on ratio pairs calculated from signal intensity image data as fat-only/water-only and log(in-phase/opposedphase) on a voxel-by-voxel basis. Using different gridding variations of the algorithm, the average correct liver volume samples ranged from 527 to 733 mL. The average percentage of sample located within the liver ranged from 95.4 to 97.1%, whereas the average incorrect volume selected was 16.5-35.4 mL (2.9-4.6%). Average run time was 19.7-79.0 s. The algorithm consistently selected large samples of the hepatic parenchyma with small amounts of erroneous extrahepatic sampling, and run times were feasible for execution on an MRI system console during exam acquisition.

Quantification of Hepatic Steatosis With a Multistep Adaptive Fitting MRI Approach: Prospective Validation Against MR Spectroscopy

“…Simple workflow and reliable functionality of the technique are important for such methods to gain wide acceptance in fast-paced clinical settings, and such implementations have been shown by other groups [2,21,22,24,25]. In theory, further automation could be achieved by combining these techniques with liver sampling or segmentation methods, further simplifying workflow and providing user-independent measures of proton density fat fraction [47][48][49][50][51].…”

Detection of Liver Steatosis With a Novel Ultrasound-Based Technique: A Pilot Study Using MRI-Derived Proton Density Fat Fraction as the Gold Standard

“…For each examination, a noncontrast, complex-based gradient-echo 3D sequence, which provides whole-liver coverage, was obtained (4,14). It includes several features that compensate for confounding effects: low flip angle for reducing T1 effects, a multifat peak model for robust lipid estimation and multiple echo acquisitions for R2*/T2* estimation and correction (5,15–18). The single breath-hold sequence with 6 echoes was performed and provided volumetric PDFF.…”

Accuracy of Automated Liver Contouring, Fat Fraction, and R2* Measurement on Gradient Multiecho Magnetic Resonance Images

“…13 In this workflow, the liver is screened for fat and iron deposition with a T1-weighted dual-gradient-echo MR sequence with 2-point Dixon technique, which is part of routine liver MRI protocols. 14 This technique includes an algorithm for inline segmentation of the liver in water-only 3D image volumes from the T1-weighted dual-gradient-echo MR sequence. If the screening result is positive for fat and/or iron deposition, the additional multigradientecho sequence for quantification is acquired and multiple ROIs need to be placed manually in the liver.…”