title: Acute cerebral infarction: effect of JPEG compression on detection at CT.
abstract: OBJECTIVE
  To evaluate the effect of Joint Photographic Experts Group (JPEG) compression ratios of 10:1 and 20:1 on detection of acute cerebral infarction at computed tomography (CT).
  
  
  METHODS
  CT images obtained in 25 patients with acute cerebral infarction and 25 patients with no lesions were compressed by means of a JPEG algorithm at ratios of 10:1 and 20:1. Normal and abnormal sections (on original and compressed images) were reviewed by using a color soft-copy computed monochrome cathode ray tube monitor. Five observers rated the presence or absence of a lesion with a 50-point scale (0, definitely absent; 25, equivocal; and 50, definitely present). Diagnostic accuracy was evaluated with receiver operating characteristic (ROC) curve analysis. Significant difference was defined as a P value less than.05 for the area tested with a two-tailed paired Student t test.
  
  
  RESULTS
  At ROC analysis, no statistically significant difference was detected for all cases considered together (Az [area under the ROC curve] = 0.887 +/- 0.038 [mean +/- SD] on noncompressed images, Az = 0.897 +/- 0.038 on 10:1 compressed images, and Az = 0.842 +/- 0.073 on 20:1 compressed images; P >.05).
  
  
  CONCLUSIONS
  JPEG compression at ratios of 10:1 and 20:1 was tolerated in the detection of acute cerebral infarction at CT.
authors.affiliation: Department of Radiology, Showa University School of Medicine, Tokyo, Japan. yogiya@gd5.so-net.ne.jp
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Ohgiya
authors.forename: Takehiko
authors.initials: T
authors.lastname: Gokan
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nobusawa
authors.forename: Masanori
authors.initials: M
authors.lastname: Hirose
authors.forename: Noritaka
authors.initials: N
authors.lastname: Seino
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Fujisawa
authors.forename: Maiko
authors.initials: M
authors.lastname: Baba
authors.forename: Kyoko
authors.initials: K
authors.lastname: Nagai
authors.forename: Keisuke
authors.initials: K
authors.lastname: Tanno
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Takeyama
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Munechika
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002544:Cerebral Infarction / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed