title: A straightforward algorithm for the quantification of power Doppler signals.
abstract: OBJECTIVE
  To document a simple algorithm that quantifies power Doppler signals by computer-based statistical image analysis.
  
  
  METHODS
  Personal computer-based software was developed. Color pixels representing power Doppler signals were separated from the background gray pixels in power Doppler images converted in BMP format. To avoid misregistration during this segmentation, a threshold value is required to adequately distinguish between gray and color pixels. Equating the intensity of each color pixel to a Power Value (PV), a histogram of Power Values in power Doppler images was obtained.
  
  
  RESULTS
  The software was designed to allow users to adjust two thresholds (Difference Threshold and Intensity Threshold) by observing the segmentation results in real time. The software calculates the following indexes within any region of interest as defined by the operator: mean PV, peak PV, standard deviation of PV, percentage power Doppler area, and integrated PV per unit area.
  
  
  CONCLUSIONS
  Power Doppler signals can be objectively quantified using this straightforward algorithm. This simple and practical method can be applied to comparative or longitudinal studies upon vascularity or blood flow.
authors.affiliation: Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, Clinical Research Institute, Seoul National University Hospital, Korea.
authors.forename: Woo Sun
authors.initials: WS
authors.lastname: Jun
authors.forename: Kyoung Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Kyobum
authors.initials: K
authors.lastname: Koo
authors.forename: Dongsung
authors.initials: D
authors.lastname: Kim
authors.forename: Jong Hyo
authors.initials: JH
authors.lastname: Kim
authors.forename: Seung Hyup
authors.initials: SH
authors.lastname: Kim
authors.forename: Byung Ihn
authors.initials: BI
authors.lastname: Choi
authors.forename: Joon Koo
authors.initials: JK
authors.lastname: Han
mesh_terms: D000465:Algorithms; D005069:Evaluation Studies as Topic; D007091:Image Processing, Computer-Assisted; D012984:Software; D018608:Ultrasonography, Doppler / Q000379:methods*