| Selected images from seventeen TMJ radiographic film series of optimal quality were digitized, stored as Tagged Image File (TIF) format, then compressed at 4 different levels of compression (25:1, 50:1, 75:1 and 100:1) using a JPEG algorithm. A committee of experts determined truth for seven osseous characteristics for right and left sides of each TMJ (N = 34). Nine calibrated observers viewed the original film, TIFF, and compressed JPEG images and were asked to rate their confidence of, or to determine the presence or absence of a particular characteristic (faceting, sclerosis, osteophyte, erosion, shape, size and position). Areas under the ROC curve and kappa values were used as indices of observer accuracy and compared using ANOVA at a significance level of {dollar}p<0.05{dollar}.; The only statistically significant modality differences were: (1) JPEG 50 and TIFF performed better than film (position), (2) JPEG 100 performed better than film (sclerosis). |
