title: Parametric imaging of contrast ultrasound for the evaluation of neovascularization in liver tumors.
abstract: OBJECTIVE
  To assess the efficacy of parametric imaging for the diagnosis of neovascularization in liver tumors.
  
  
  METHODS
  The subjects were 17 rabbits (five with normal liver and 12 with VX2 tumor implanted in the liver). The contrast agents used were SonoVue (Bracco, Milan, Italy). A diagnostic ultrasound system was used with a programmable replenishment sequence. The images obtained between the initial frame after the high mechanical index (MI) scan, which diminishes microbubbles in the scan volume, and the current frame were coded in color according to the arrival and peak times. After the experiment, the tumors were excised and sectioned. Sections were prepared for light microscopy with hematoxylin-eosin (HE) staining and CD31 staining to evaluate vascular density.
  
  
  RESULTS
  Arrival time imaging (ATI) delineated the fine blood vessels (100-200 mum in diameter) in all of the rabbits. Tortuous and meandering tumor vessels were visualized in the VX2 tumors. Differences of perfusion velocity between tumor tissue and tumor-free areas were shown in peak time imaging (PTI). Vascularity evaluated on the ATI and perfusion speed recognized on the ATI and PTI were related to the vascular density measured by pathological investigation.
  
  
  CONCLUSIONS
  Parametric imaging is a promising new method for the visualization of perfusion and the estimation of tumor blood vessels.
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical University, Tokyo, Japan.
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Fuminori
authors.initials: F
authors.lastname: Moriyasu
authors.forename: Naohisa
authors.initials: N
authors.lastname: Kamiyama
authors.forename: Ryo
authors.initials: R
authors.lastname: Metoki
authors.forename: Hiroko
authors.initials: H
authors.lastname: Iijima