title: Spectral normalization for ultrasonic contrast microbubble detection.
abstract: Ultrasonic contrast agents consisting of microbubbles are used to assess tissue perfusion. The microbubbles are highly reflective and nonlinear and thus produce harmonics that are stronger than those from tissues. However, the magnitude of harmonic signals resulting from a region with microbubbles also depends on the acoustic pressure of incident ultrasound and the attenuation of intervening tissues in the ultrasound path. Therefore, the harmonic magnitude, as used in traditional harmonic imaging, may not be a reliable indicator of the presence or absence of microbubbles, and hence, tissue perfusion. To compensate for these effects, we present two parameters defined as the ratio of the harmonic to the fundamental component (HFR) and the ratio of the harmonic to squared fundamental (HSFR). A simplified model is used to illustrate the usefulness of these two parameters. Experiments show that both parameters improve detection of microbubbles and that HSFR performs better than HFR.
authors.affiliation: Department of Physiology & Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
authors.forename: Shigao
authors.initials: S
authors.lastname: Chen
authors.forename: Eileen M
authors.initials: EM
authors.lastname: McMahon
authors.forename: Mostafa
authors.initials: M
authors.lastname: Fatemi
authors.forename: James F
authors.initials: JF
authors.lastname: Greenleaf
authors.forename: Marek
authors.initials: M
authors.lastname: Belohlavek
mesh_terms: D003287:Contrast Media; D004867:Equipment Design; D008863:Microspheres; D019047:Phantoms, Imaging; D014463:Ultrasonography
chemical_list: D003287:Contrast Media