Measurement of breast lesion display luminance and overall image display luminance relative to optimum luminance for contrast perception

Introduction: To minimize fatigue due to eye adaptation and maximize contrast perception, it has been suggested that lesion luminance be matched to overall image luminance to perceive the greatest number of grey level differences. This work examines whether lesion display luminance matches the overall image and breast tissue display luminance and whether these factors are positioned within the optimum luminance for maximal contrast sensitivity. Methods: A set of 42 mammograms, collected from 21 patients and containing 15 malignant and 6 benign lesions, was used to assess overall image luminance. Each image displayed on the monitor was divided into 16 equal regions. The luminance at the midpoint of each region was measured using a calibrated photometer and the overall image luminance was calculated. Average breast tissue display luminance was calculated from the subset of regions containing of only breast tissue. Lesion display luminance was compared with both overall image display luminance and average breast tissue display luminance. Results: Statistically significant differences (p<0.0001) were noted between overall image display luminance (4.3±0.7 cd/m2) and lesion display luminance (15.0±6.8 cd/m2); and between average breast tissue display luminance (6.8±1.3 cd/m2) and lesion display luminance (p<0.002). Conclusions: Lesion luminance was significantly higher than the overall image and breast tissue luminance. Luminance of lesions and general breast tissue fell below the optimum luminance range for contrast perception. Breast lesion detection sensitivity and specificity may be enhanced by use of brighter monitor displays.