American College of Cardiology European Society of Cardiology international study of angiographic data compression phase I - The effects of lossy data compression on recognition of diagnostic features in digital coronary angiography

Objectives This study intended to determine the effect of varying degrees o f lossy Joint Photographic Experts Group (JPEG) compression on detection of coronary angiographic Features. Background Compression of digital coronary angiograms facilitates playback of images and decreases cost. There are little data on the effect of compre ssion on the accuracy of coronary angiography. Methods At six centers, 71 angiographers each reviewed a set of 100 angiogr aphic sequences. The 100 sequences were divided into four, 25-sequence subs ets. Each subset of 25 was displayed either as original images or at one of three compression ratios (CRs) (6.1, 10:1 or 16:1). The effect of lossy co mpression on the sensitivity and specificity for detection of diagnostic fe atures was determined. The effect of compression on subjective measures of image quality graded by the angiographers was also examined. Results Lossy compression at a ratio of 16:1 decreased the sensitivity for the detection of diagnostic features (76% vs. 80% P=0.004). The largest eff ect was in the detection of calcification (52% vs. 63% at 16:1 compression vs, original images, P<0.001). Subjective indicators of image quality indic ated a reduction in confidence in interpretation at CRs of 10:1 and 16:1. Conclusions With increased ratios of lossy compression, a degradation of di gital coronary angiograms occurs that results in decreased diagnostic accur acy. The sensitivity for detection of common diagnostic features was decrea sed, and subjective assessment of image quality was impaired. Caution is wa rranted in the interpretation of coronary angiograms that have been subject ed to lossy JPEG compression beyond a ratio of 6:1. (Eur Heart J 2000; 21: 668-678) (C) 2000 The European Society of Cardiology.