Image quality, diagnostic certainty, and accuracy: comparison of conventional and digital urograms.

Our previous research showed that radiologists could interpret digital urograms with sensitivity, specificity, and receiver operating characteristic (ROC) curve performance similar to their interpretations of conventional urograms. To evaluate further the suitability of digital radiology for performing excretory urography, we investigated relationships among image quality, radiologists' certainty of diagnostic decisions, and diagnostic accuracy for digital and conventional urograms. We examined data from a study of 100 excretory urograms performed using matched film-screen and digital exposures. Three radiologists rated the quality of digital urographic images compared to film-screen images. Image quality did not correlate well with diagnostic accuracy for either modality, perhaps because of the overall high level of quality of the exposures. Radiologists' level of certainty in their diagnostic decisions decreased with poorer image quality for both modalities. The similarities of the tested relationships provides further evidence that digital technology is suitable for use in urography.