Optimization of diagnostic and therapeutic strategies is an important element of medical science (1). For diagnostic imaging, Fryback and Thombury (2) have described a six-stage hierarchical model of efficacy in which diagnostic technology can be assessed. The initial stages of the model describe efficacy in terms of physical image quality and diagnostic accuracy (ie. sensitivity and specificity). The middle stages assess the impact of diagnostic information on the clinician's thinking and therapeutic planning. The later stages consider patient and society outcomes (ie, mortality, morbidity, and cost). These stages are interconnected such that efficacy at lower levels is necessary, although not sufficient, to ensure efficacy at higher levels. There are several implications of this model. First, it is clear that most of the research that radiologists currently do (ie, diagnostic accuracy assessment) is an intermediate outcome. Second, imaging is dimcult to assess beyond such intermediate outcomes because of confounding variables. Thus, using conventional measurements, one could be left with the impression that diagnostic information, which does not impact therapeutic planning, is not efficacious to the patient and society.
In November 1994, representatives from imaging, clinical practice, industry, government, payors. and research methodology participated in a 3-day session to discuss methods for the evaluation of diagnostic imaging. Our subgroup was charged with the assessment of methods for evaluating the '*value" of diagnostic imaging. The consensus of this subgroup was that the methods currently used in the radiological literature for assessing the value of diagnostic imaging are insuffi-Index terms: Patient outcomes -Societal outcomes Physician outcomes * Diagnostic accuracy * Decision analysis JlLRI I996 1:7-9 Abbreviations: MRI = magnetic resonance Imaging. From MR Facilities (M.F.). Waukesha. WI: Value Health Services (G.G.). Fairfax, VA, the Food and Drug Administration (R.H.], Rockville, MD: University of Groningen (M.G.M.H.). Groningen, the Netherlands; Cleveland Clinic Foundation (M.M..