title: Multimaterial Decomposition Algorithm for the Quantification of Liver Fat Content by Using Fast-Kilovolt-Peak Switching Dual-Energy CT: Experimental Validation.
abstract: Purpose To assess the ability of fast-kilovolt-peak switching dual-energy computed tomography (CT) by using the multimaterial decomposition (MMD) algorithm to quantify liver fat. Materials and Methods Fifteen syringes that contained various proportions of swine liver obtained from an abattoir, lard in food products, and iron (saccharated ferric oxide) were prepared. Approval of this study by the animal care and use committee was not required. Solid cylindrical phantoms that consisted of a polyurethane epoxy resin 20 and 30 cm in diameter that held the syringes were scanned with dual- and single-energy 64-section multidetector CT. CT attenuation on single-energy CT images (in Hounsfield units) and MMD-derived fat volume fraction (FVF; dual-energy CT FVF) were obtained for each syringe, as were magnetic resonance (MR) spectroscopy measurements by using a 1.5-T imager (fat fraction [FF] of MR spectroscopy). Reference values of FVF (FVFref) were determined by using the Soxhlet method. Iron concentrations were determined by inductively coupled plasma optical emission spectroscopy and divided into three ranges (0 mg per 100 g, 48.1-55.9 mg per 100 g, and 92.6-103.0 mg per 100 g). Statistical analysis included Spearman rank correlation and analysis of covariance. Results Both dual-energy CT FVF (ρ = 0.97; P < .001) and CT attenuation on single-energy CT images (ρ = -0.97; P < .001) correlated significantly with FVFreffor phantoms without iron. Phantom size had a significant effect on dual-energy CT FVF after controlling for FVFref(P < .001). The regression slopes for CT attenuation on single-energy CT images in 20- and 30-cm-diameter phantoms differed significantly (P = .015). In sections with higher iron concentrations, the linear coefficients of dual-energy CT FVF decreased and those of MR spectroscopy FF increased (P < .001). Conclusion Dual-energy CT FVF allows for direct quantification of fat content in units of volume percent. Dual-energy CT FVF was larger in 30-cm than in 20-cm phantoms, though the effect of object size on fat estimation was less than that of CT attenuation on single-energy CT images. In the presence of iron, dual-energy CT FVF led to underestimateion of FVFrefto a lesser degree than FF of MR spectroscopy led to overestimation of FVFref.©RSNA, 2016 Online supplemental material is available for this article.
authors.affiliation: From the Department of Radiology, Kindai University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan (T.H., T. Murakami); Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan (M.H.); CT Research Group (K.S.) and MR Applications and Workflow Group (T.W.), GE Healthcare Japan, Hino, Japan; Biomedical Image Analysis Laboratory, GE Global Research, Niskayuna, NY (P.L.); Clinical Research Center, Kindai University Hospital, Osaka-Sayama, Japan (Y.C.); and Department of Diagnostic and Therapeutic Radiology, Ehime University Graduate School of Medicine, Toon, Japan (T. Mochizuki).
authors.forename: Tomoko
authors.identifier: http://orcid.org/0000-0002-1062-8403
authors.initials: T
authors.lastname: Hyodo
authors.affiliation: From the Department of Radiology, Kindai University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan (T.H., T. Murakami); Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan (M.H.); CT Research Group (K.S.) and MR Applications and Workflow Group (T.W.), GE Healthcare Japan, Hino, Japan; Biomedical Image Analysis Laboratory, GE Global Research, Niskayuna, NY (P.L.); Clinical Research Center, Kindai University Hospital, Osaka-Sayama, Japan (Y.C.); and Department of Diagnostic and Therapeutic Radiology, Ehime University Graduate School of Medicine, Toon, Japan (T. Mochizuki).
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hori
authors.affiliation: From the Department of Radiology, Kindai University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan (T.H., T. Murakami); Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan (M.H.); CT Research Group (K.S.) and MR Applications and Workflow Group (T.W.), GE Healthcare Japan, Hino, Japan; Biomedical Image Analysis Laboratory, GE Global Research, Niskayuna, NY (P.L.); Clinical Research Center, Kindai University Hospital, Osaka-Sayama, Japan (Y.C.); and Department of Diagnostic and Therapeutic Radiology, Ehime University Graduate School of Medicine, Toon, Japan (T. Mochizuki).
authors.forename: Peter
authors.initials: P
authors.lastname: Lamb
authors.affiliation: From the Department of Radiology, Kindai University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan (T.H., T. Murakami); Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan (M.H.); CT Research Group (K.S.) and MR Applications and Workflow Group (T.W.), GE Healthcare Japan, Hino, Japan; Biomedical Image Analysis Laboratory, GE Global Research, Niskayuna, NY (P.L.); Clinical Research Center, Kindai University Hospital, Osaka-Sayama, Japan (Y.C.); and Department of Diagnostic and Therapeutic Radiology, Ehime University Graduate School of Medicine, Toon, Japan (T. Mochizuki).
authors.forename: Kosuke
authors.initials: K
authors.lastname: Sasaki
authors.affiliation: From the Department of Radiology, Kindai University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan (T.H., T. Murakami); Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan (M.H.); CT Research Group (K.S.) and MR Applications and Workflow Group (T.W.), GE Healthcare Japan, Hino, Japan; Biomedical Image Analysis Laboratory, GE Global Research, Niskayuna, NY (P.L.); Clinical Research Center, Kindai University Hospital, Osaka-Sayama, Japan (Y.C.); and Department of Diagnostic and Therapeutic Radiology, Ehime University Graduate School of Medicine, Toon, Japan (T. Mochizuki).
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Wakayama
authors.affiliation: From the Department of Radiology, Kindai University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan (T.H., T. Murakami); Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan (M.H.); CT Research Group (K.S.) and MR Applications and Workflow Group (T.W.), GE Healthcare Japan, Hino, Japan; Biomedical Image Analysis Laboratory, GE Global Research, Niskayuna, NY (P.L.); Clinical Research Center, Kindai University Hospital, Osaka-Sayama, Japan (Y.C.); and Department of Diagnostic and Therapeutic Radiology, Ehime University Graduate School of Medicine, Toon, Japan (T. Mochizuki).
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Chiba
authors.affiliation: From the Department of Radiology, Kindai University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan (T.H., T. Murakami); Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan (M.H.); CT Research Group (K.S.) and MR Applications and Workflow Group (T.W.), GE Healthcare Japan, Hino, Japan; Biomedical Image Analysis Laboratory, GE Global Research, Niskayuna, NY (P.L.); Clinical Research Center, Kindai University Hospital, Osaka-Sayama, Japan (Y.C.); and Department of Diagnostic and Therapeutic Radiology, Ehime University Graduate School of Medicine, Toon, Japan (T. Mochizuki).
authors.forename: Teruhito
authors.initials: T
authors.lastname: Mochizuki
authors.affiliation: From the Department of Radiology, Kindai University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan (T.H., T. Murakami); Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan (M.H.); CT Research Group (K.S.) and MR Applications and Workflow Group (T.W.), GE Healthcare Japan, Hino, Japan; Biomedical Image Analysis Laboratory, GE Global Research, Niskayuna, NY (P.L.); Clinical Research Center, Kindai University Hospital, Osaka-Sayama, Japan (Y.C.); and Department of Diagnostic and Therapeutic Radiology, Ehime University Graduate School of Medicine, Toon, Japan (T. Mochizuki).
authors.forename: Takamichi
authors.initials: T
authors.lastname: Murakami
mesh_terms: D000465:Algorithms; D000818:Animals; D005234:Fatty Liver / Q000000981:diagnostic imaging* / Q000473:pathology*; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D019047:Phantoms, Imaging; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*