Urinary calculi on computed radiography: comparison of observer performance with hard-copy versus soft-copy images on different viewer systems.

Abstract

The purpose of this study was to compare observer performance for detecting urinary calculi using abdominal computed radiography with hard-copy versus soft-copy images and with a high-resolution video monitor versus a liquid-crystal-display (LCD) monitor. We compared observer performance for detecting urinary calculi using three sets of radiographs-hard-copy images, soft-copy images displayed on a LCD monitor (1280 x 1024 bits), and soft-copy images displayed on a high-resolution video monitor using receiver operating characteristic curve analysis with a continuous rating scale. Computed radiography was archived with a 2140 x 1760 pixel resolution and a 10-bit depth. The selected data set included 62 images: 27 images showing proven urinary calculi smaller than 6 mm and three in number, and 35 images containing no proven abnormalities. Eleven radiologists (three genitourinary radiologists and eight general radiologists) participated in the study. Interpretations of three sets of randomly distributed radiographs were performed individually in three separate sessions at 1-week intervals. No statistically significant differences were found in the area under the receiver operating characteristic curve for detecting urinary calculi or in the interpreting times between soft-copy and hard-copy images; the mean areas under the receiver operating characteristic curve of hard-copy images, soft-copy images displayed on an LCD monitor, and soft-copy images displayed on a high-resolution video monitor were 0.579, 0.610, and 0.732, respectively. However, soft-copy images showed relatively improved diagnostic accuracy among less experienced radiologists (p < 0.05). For detecting urinary calculi, soft-copy images offered a diagnostic accuracy similar to or slightly more accurate than that of hard-copy images obtained in a laser-printed film-based environment. The diagnostic performance with soft-copy images viewed on an LCD monitor was comparable to that of soft-copy images viewed on a high-resolution video monitor.