Guidelines for using diagnostic imaging devices: an inference system.

This paper deals with optimising the use of magnetic resonance imaging (MRI) scanners through the development of a new kind of clinical guidelines called 'substrate-specific protocols'. These protocols would link the descriptive elements of lesions to the most appropriate imaging techniques on the basis of the biophysics of MRI. As many lesions have elements in common, substrate-specific protocols could have a more general character and be more firmly based on evidence than conventional guidelines. We developed an inference model to enter, structure and retrieve knowledge acquired through a literature search. This proved a practicable and attractive approach. Its exactness, however, reveals the imperfections of medical knowledge and clinical practice. We conclude that it could be hard to establish an 'evidence basis' for clinical guidelines, if 'evidence based' means rooted in natural science.