Acute cerebral infarction: effect of JPEG compression on detection at CT.
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.
Ohgiya
Yoshimitsu
Y
Department of Radiology, Showa University School of Medicine, Tokyo, Japan. yogiya@gd5.so-net.ne.jp
Gokan
Takehiko
T
Nobusawa
Hiroshi
H
Hirose
Masanori
M
Seino
Noritaka
N
Fujisawa
Hidefumi
H
Baba
Maiko
M
Nagai
Kyoko
K
Tanno
Keisuke
K
Takeyama
Nobuyuki
N
Munechika
Hirotsugu
H
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