title: Signal of Interest Selection Standard for Ultrasonic Backscatter in Cancellous Bone Evaluation.
abstract: The aim of this study was to examine the effect of the backscattered signal of interest (SOI) on ultrasonic cancellous bone evaluation. In vitro backscatter measurements were performed using 16 bovine cancellous bone specimens and six different transducers with central frequencies of 0.5, 1, 2.25, 3.5, 5 and 10 MHz. The SOI for signal analysis was selected by a rectangular window. The delay (T1) and duration (T2) of the time window were varied, and the apparent integrated backscatter (AIB) and its correlation to bone volume fraction (BV/TV) were calculated. The results indicate that in addition to affecting the measured value of AIB, the SOI influences the observed correlation between AIB and BV/TV. Strong positive correlations were observed for short T1 (0.5 MHz: ≤6 μs, 1 MHz: ≤3 μs, 2.25 and 3.5 MHz: ≤2 μs, 5 and 10 MHz: ≤1 μs). However, strong negative correlations were observed when T1 was long (0.5 MHz: >9 μs, 1 MHz: >7 μs, 2.25 and 3.5 MHz: >3 μs, 5 and 10 MHz: >2 μs). The T2 value, especially low values (≤3 μs), also influenced the correlation coefficients. Positive correlations were more commonly observed at lower frequencies (i.e., 0.5-1 MHz), whereas negative correlations were more common at higher frequencies (i.e., 2.25-10 MHz). An explicit standard for in vitro SOI selection and cancellous bone assessment was proposed for a broad frequency range (0.5-10 MHz). Current conflicting findings are explained, and constructive suggestions for ultrasonic backscatter cancellous bone evaluation are provided.
authors.affiliation: Department of Electronic Engineering, Fudan University, Shanghai, China.
authors.forename: Chengcheng
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Electronic Engineering, Fudan University, Shanghai, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Tang
authors.affiliation: Department of Electronic Engineering, Fudan University, Shanghai, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.affiliation: Department of Electronic Engineering, Fudan University, Shanghai, China; Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention (MICCAI) of Shanghai, Shanghai, China. Electronic address: tda@fudan.edu.cn.
authors.forename: Dean
authors.initials: D
authors.lastname: Ta
authors.affiliation: Lab of Ultrasonic Electronics, Doshisha University, Kyoto, Japan.
authors.forename: Mami
authors.initials: M
authors.lastname: Matsukawa
authors.affiliation: Department of Electronic Engineering, Fudan University, Shanghai, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Hu
authors.affiliation: Department of Electronic Engineering, Fudan University, Shanghai, China.
authors.forename: Weiqi
authors.initials: W
authors.lastname: Wang
mesh_terms: D000818:Animals; D002417:Cattle; D002681:China; D005269:Femur / Q000000981:diagnostic imaging* / Q000502:physiology*; D007090:Image Interpretation, Computer-Assisted / Q000592:standards*; D066298:In Vitro Techniques; D012016:Reference Values; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D000069453:Ultrasonic Waves; D014463:Ultrasonography / Q000379:methods / Q000592:standards*
keywords: Bone volume fraction; Cancellous bone; Osteoporosis; Signal of interest; Ultrasonic backscatter