title: American College of Cardiology/European Society of Cardiology International Study of Angiographic Data Compression Phase III: measurement of image quality differences at varying levels of data compression.
abstract: OBJECTIVE
  We sought to investigate up to which level of Joint Photographic Experts Group JPEG) data compression the perceived image quality and the detection of diagnostic features remain equivalent to the quality and detectability found in uncompressed coronary angiograms.
  
  
  BACKGROUND
  Digital coronary angiograms represent an enormous amount of data and therefore require costly computerized communication and archiving systems. Earlier studies on the viability of medical image compression were not fully conclusive.
  
  
  METHODS
  Twenty-one raters evaluated sets of 91 cine runs. Uncompressed and compressed versions of the images were presented side by side on one monitor, and image quality differences were assessed on a scale featuring six scores. In addition, the raters had to detect pre-defined clinical features. Compression ratios (CR) were 6:1, 10:1 and 16:1. Statistical evaluation was based on descriptive statistics and on the equivalence t-test.
  
  
  RESULTS
  At the lowest CR (CR 6:1), there was already a small (15%) increase in assigning the aesthetic quality score indicating "quality difference is barely discernible-the images are equivalent." At CR 10:1 and CR 16:1, close to 10% and 55%, respectively, of the compressed images were rated to be "clearly degraded, but still adequate for clinical use" or worse. Concerning diagnostic features, at CR 10:1 and CR 16:1 the error rate was 9.6% and 13.1%, respectively, compared with 9% for the baseline error rate in uncompressed images.
  
  
  CONCLUSIONS
  Compression at CR 6:1 provides equivalence with the original cine runs. If CR 16:1 were used, one would have to tolerate a significant increase in the diagnostic error rate over the baseline error rate. At CR 10:1, intermediate results were obtained.
authors.affiliation: II Medical Clinic, Johannes-Gutenberg-University Mainz, Germany. incis.rb@uni-mainz.de
authors.forename: R
authors.initials: R
authors.lastname: Brennecke
authors.forename: U
authors.initials: U
authors.lastname: Bürgel
authors.forename: R
authors.initials: R
authors.lastname: Simon
authors.forename: G
authors.initials: G
authors.lastname: Rippin
authors.forename: H P
authors.initials: HP
authors.lastname: Fritsch
authors.forename: T
authors.initials: T
authors.lastname: Becker
authors.forename: S E
authors.initials: SE
authors.lastname: Nissen
mesh_terms: D000328:Adult; D015982:Bias; D002309:Cardiology; D017023:Coronary Angiography / Q000379:methods* / Q000592:standards*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D004954:Esthetics; D005060:Europe; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods* / Q000592:standards*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D012955:Societies, Medical; D014481:United States