title: A new system for in vivo assessment of the degree of nonlinear generation using the second harmonic component in echo signals.
abstract: To assess the feasibility of a new system that uses the finite amplitude method and makes possible the assessment of the degree of nonlinear generation in vivo we adopted a method for agar-gel phantoms, using varying lipid concentrations and human livers in vivo. Instead of calculating the nonlinearity parameter B/A value, we evaluated the h value, which is determined by plotting the measured values of the ratio of the amplitude of the second harmonic component to that of the fundamental component. The agar-gel phantoms of various lipid concentrations and 20 cases of normal and 21 cases of fatty liver were studied in this investigation. There was an almost linear agreement between the h value and the lipid concentration of the phantom. The h value (mean +/- SD) was 0.25 +/- 0.03 in normal liver and 0.35 +/- 0.05 in fatty liver. A statistically significant difference was found between them (p < 0.0001). This new system was considered to be usable for evaluating h in vivo as an indicator of the lipid content of the liver.
authors.affiliation: Department of Clinical Laboratory Medicine, Jichi Medical School, Tochigi 329-0498, Japan. yfujii@jichi.ac.jp
authors.forename: Yasutomo
authors.initials: Y
authors.lastname: Fujii
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Taniguchi
authors.forename: Iwaki
authors.initials: I
authors.lastname: Akiyama
authors.forename: Jing-Wen
authors.initials: JW
authors.lastname: Tsao
authors.forename: Kouichi
authors.initials: K
authors.lastname: Itoh
mesh_terms: D005234:Fatty Liver / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D006801:Humans; D008055:Lipids / Q000032:analysis*; D008099:Liver / Q000000981:diagnostic imaging*; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D014465:Ultrasonics; D014463:Ultrasonography
chemical_list: D008055:Lipids