Information content and quality of MR thumb images.

This study investigates the relation between objective and subjective parameters which relate to the quality of magnetic-resonance images, with a view to developing procedures for minimizing imaging time. The investigation uses high-resolution images of the thumb as example. Detection thresholds for an artificial lesion and ratings of image quality were obtained for a variety of images, with several experienced observers. In addition, the information content was calculated for each image, using the method developed by Fuderer (1988 IEEE Tralns. Med. Imaging 7 368-80). Results suggest that information content can be used as a predictor of either detection threshold or quality rating, with a critical information content beyond which there is no significant improvement in either of these aspects of image quality. Since it is possible to estimate the effect of imaging variables on information content, it is possible to predict the effect of time-saving imaging strategies on image quality. A procedure is suggested for determining the combination of imaging variables which gives the shortest possible imaging time whilst retaining image quality.