Different pixel pitch and maximum luminance of medical grade displays may result in different evaluations of digital radiography images.

AIM: To evaluate the effects of display pixel pitch and maximum luminance on intra- and inter-observer reproducibility and observer performance when evaluating chest lesions and bone fractures. MATERIALS AND METHODS: This was a multi-institutional study for a retrospective interpretation of selected digital radiography images. Overall, 82 images were selected by senior radiologists, including 50 cases of chest lesions and 32 cases of bone fractures. These images were displayed at two pixel pitches (0.212 and 0.165 mm size pixels) and two maximum luminance values (250 and 500 cd/m2) and reviewed twice by senior and junior radiologists. All the observers had to indicate the likelihood of the presence of the lesions and to rate the relative confidence of their assessment. Cohen Kappa statistic was computed to estimate the reproducibility in correctly identifying lesions; for multi-reader-multi-case (MRMC) analysis, weighted Jackknife Alternative Free-response Receiver Operating Characteristic (wJAFROC) statistical tools was applied. RESULTS: The intra-radiologist and inter-observer reproducibility values were the highest for the 0.165 mm size pixel at 500 cd/m2 display, for both chest lesions and bone fractures evaluations. As regards chest lesions, observer performances were significantly greater with 0.165 mm size pixel display at 500 cd/m2 than with lower maximum luminance and/or larger pixel pitch displays. Concerning bone fractures, the performance obtained with 0.212 mm size pixel display at 250 cd/m2 was statistically lower than that obtained with 0.165 mm sixe pixel display at 500 cd/m2. CONCLUSION: Our results indicate that an increased maximum luminance level and a decreased pixel pitch of medical-grade display improve the accuracy of detecting both chest lesions and bone fractures.

How Does the Display Luminance Level Affect Detectability of Breast Microcalcifications and Spiculated Lesions in Digital Breast Tomosynthesis (DBT) Images?

RATIONALE AND OBJECTIVES: This study evaluates the influence of the calibrated luminance level of medical displays in the detectability of microcalcifications and spiculated lesions in digital breast tomosynthesis images. MATERIALS AND METHODS: Four models of medical displays with calibrated maximum and minimum luminance, respectively, ranging from 500 to 1000 cd/m2 and from 0.5 to 1.0 cd/m2, were investigated. Forty-eight studies were selected by a senior radiologist: 16 with microcalcifications, 16 with spiculated lesions, and 16 without lesions. All images were anonymized and blindly evaluated by one senior and two junior radiologists. For each study, lesion presence or absence and localization statements, interpretative difficulty level, and overall quality were reported. Cohen's kappa statistic was computed between monitors and within or between radiologists to estimate the reproducibility in correctly identifying lesions; for multireader-multicase analysis, the weighted jackknife alternative free-response receiver operating characteristic statistical tool was applied. RESULTS: Intraradiologist reproducibility ranged from 0.75 to 1.00. Interreader as well as reader-truth agreement values were >0.80 and higher with the two 1000 cd/m2 luminance displays than with the lower luminance displays for each radiologist. Performances in the detectability of breast lesions were significantly greater with the 1000 cd/m2 luminance displays when compared to the display with the lowest luminance value (P value <0.001). CONCLUSIONS: Our findings highlight the role of display luminance level on the accuracy of detecting breast lesions.