Acceptable compression ratio of full-field digital mammography using JPEG 2000.

ABSTRACT

AIM: To estimate the acceptable compression ratio of full-field digital mammography (FFDM) using the Joint Photographic Experts Group (JPEG) 2000 compression algorithm. MATERIALS AND METHODS: Eighty cases that included images of 40 masses (20 benign, 20 malignant) and 40 microcalcifications (20 benign, 20 malignant) were collected. The images were compressed to five different lossy ratios 201, 401, 601, 801, and 1001, and four radiologists independently determined whether the compressed group was distinguishable from the control group. The ratio of the compressed group that was rated indistinguishable from the control group was compared for each reviewer, and the results were analysed for agreements of three or more reviewers. RESULTS: The ability to distinguish the compressed image from the control group is given as a range across the four reviewers 0-1.3% (0/80 to 1/80) of the 201, 0-2.5% (0/80 to 2/80) of the 401, 5-7.5% (4/80 to 6/80) of the 601, 10-37.5% (8/80 to 30/80) of the 801, and 30-87.5% (24/80 to 70/80) of the 1001. For three compression groups (201, 401, and 601), three or more reviewers agreed that there was a distinguishable difference for 0/80, 0/80, and 3/80 images, respectively. Thus, the compressed images do not differ significantly from the control group (p>0.05). However, the 801 and 1001 compressed images were different for 9/80 and 29/80 images, respectively, which is significantly different from the control group (p<0.05). CONCLUSION: The lossy 601 compression ratio for FFDM is visually identical to the control image and, therefore, potentially acceptable for primary interpretation.