title: Visualization of uveal perfusion by contrast-enhanced harmonic ultrasonography at a low mechanical index: a pilot animal study.
abstract: OBJECTIVE
  To evaluate contrast-enhanced harmonic ultrasonography at a low mechanical index for its usefulness in visualizing uveal perfusion.
  
  
  METHODS
  The study was performed with 9 rabbits, 6 intact and 3 with focal impaired blood flow in the uvea. Ultrasonography was performed by harmonic imaging (transmit, 5 MHz; receive, 10 MHz) with a contrast agent. The agent was administered at a dose of 50 microL/kg. Transmission power was at a mechanical index of 0.2, which is below the US Food and Drug Administration guideline. The images were compared between the impaired and intact eyes. For uveal measurements, video signal intensity-versus-time plots were generated in all cases. The plots were analyzed to obtain the rate of signal intensity increase and peak signal intensity.
  
  
  RESULTS
  A clear increase of signal intensity was observed after contrast agent administration. The signal intensity of the uvea was lower in the impaired eye than in the intact eye. In the impaired eye, the intensity was lower on the side with impaired flow than on the other side. The differences were significant.
  
  
  CONCLUSIONS
  Our findings suggest that uveal perfusion can be visualized by contrast-enhanced harmonic ultrasonography in the harmonic imaging mode at a low mechanical index.
authors.affiliation: Department of Ophthalmology, School of Medicine, The University of Tokushima, Japan.
authors.forename: Tomihiko
authors.initials: T
authors.lastname: Hirokawa
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nishikage
authors.forename: Takehiro
authors.initials: T
authors.lastname: Moroe
authors.forename: Makoto
authors.initials: M
authors.lastname: Kajima
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hayashi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Naito
authors.forename: Shinta
authors.initials: S
authors.lastname: Yamane
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shiota
mesh_terms: D000818:Animals; D003287:Contrast Media; D005260:Female; D005466:Fluorocarbons; D008297:Male; D010865:Pilot Projects; D011817:Rabbits; D014463:Ultrasonography / Q000379:methods; D014602:Uvea / Q000098:blood supply* / Q000000981:diagnostic imaging
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons; C042852:perflutren