Estimation of Hepatic Proton-Density Fat Fraction by Using MR Imaging at 3.0 T

Abstract

Purpose:To compare the accuracy of several magnetic resonance (MR) imaging-based methods for hepatic proton-density fat fraction (FF) estimation at 3.0 T, with spectroscopy as the reference technique. Materials and Methods:This prospective study was institutional review board approved and HIPAA compliant. Informed consent was obtained. One hundred sixty-three subjects (39 with known hepatic steatosis, 110 with steatosis risk factors, 14 without risk factors) underwent proton MR spectroscopy and non-T1-weighted gradient-echo MR imaging of the liver. At spectroscopy, the reference FF was determined from frequency-selective measurements of fat and water proton densities. At imaging, FF was calculated by using two-, three-, or six-echo methods, with single-frequency and multifrequency fat signal modeling. The three-and sixecho methods corrected for T2 * ; the two-echo methods did not. For each imaging method, the fat estimation accuracy was assessed by using linear regression between the imaging FF and spectroscopic FF. Binary classifi cation accuracy of imaging was assessed at four reference spectroscopic thresholds (0.04, 0.06, 0.08, and 0.10 FF). Results:Regression intercept of two-, three-, and six-echo methods were 2 0.0211, 0.0087, and 2 0.0062 ( P , .001 for all three) without multifrequency modeling and 2 0.0237 ( P , .001), 0.0022, and 2 0.0007 with multifrequency modeling, respectively. Regression slope of two-, three-, and six-echo methods were 0.8522, 0.8528, and 0.7544 ( P , .001 for all three) without multifrequency modeling and 0.9994, 0.9775, and 0.9821 with multifrequency modeling, respectively. Signifi cant deviation of intercept and slope from 0 and 1, respectively, indicated systematic error. Classification accuracy was 82.2%-90.1%, 93.9%-96.3%, and 83.4%-89.6% for two-, three-, and six-echo methods without multifrequency modeling and 88.3%-92.0%, 95.1%-96.3%, and 94.5%-96.3% with multifrequency modeling, respectively, depending on the FF threshold. T2 * -corrected (three-and six-echo) multifrequency imaging methods had the overall highest FF estimation and classifi cation accuracy. Among methods without multifrequency modeling, the T2 * -corrected threeecho method had the highest accuracy.

Effects of Insulin Glargine and Liraglutide Therapy on Liver Fat as Measured by Magnetic Resonance in Patients With Type 2 Diabetes: A Randomized Trial

“…The sequence parameters were flip angle, 108; field of view, 400 mm; section thickness, 9 mm; 1 mm gap; receiver bandwidth, 1,215 Hz/pixel; sensitivity encoding acceleration factor, 2.6; acquired voxel size, 2.5 3 2.5 3 9 mm; number of averages, 1; TR, 235 ms; the first TE was 1.15 ms, with a ΔTE of 1.15 ms (therefore, the 7 TEs were 1.15, 2.30, 3.45, 4.60, 5.75, 6.90, and 8.05 ms) (23).…”

“…MRI-PDFF maps were calculated pixelby-pixel with MatLab 8.1 R2013a software (MathWorks, Natick, MA) according to a method described by Yokoo et al (23). The algorithm simultaneously estimated T2* and PDFF in each pixel on the image by using nonlinear least squares fitting from all seven echoes.…”

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

“…If deposition disease is suspected in that volume according to predefined criteria, the technologist can be alerted and a multiecho or spectroscopic acquisition performed immediately; these techniques provide a more accurate quantitative assessment of the severity of disease than dual-echo imaging (2)(3)(4)6,7,9). This would allow for tailoring of an MRI examination to a patient's individual needs, reducing the need to perform spectroscopy or multiecho acquisitions routinely, as well as obviating the need for the patient to return for a second examination for quantification of previously unsuspected disease.…”

“…Magnetic resonance (MR) is an accurate, noninvasive tool for the assessment of diffuse hepatic deposition disease, namely hepatic steatosis and iron overload (1)(2)(3). A variety of MR-based techniques are available for detection and characterization of hepatic deposition disease, including dual-echo technique, multiecho acquisition, and breath-hold single voxel or volumetric spectroscopy (1,(4)(5)(6)(7)(8)(9).…”

“…A variety of MR-based techniques are available for detection and characterization of hepatic deposition disease, including dual-echo technique, multiecho acquisition, and breath-hold single voxel or volumetric spectroscopy (1,(4)(5)(6)(7)(8)(9). Non-invasive techniques have several advantages over percutaneous liver biopsy (the reference standard for diagnosis of deposition disease), including a much larger sample volume, lower cost, and avoidance of the periprocedural complications associated with biopsy (3,(10)(11)(12)(13)(14).…”