Health economics in diagnostic imaging.

New technologies, such as magnetic resonance imaging, are frequently cited as major contributors to the growth of national health care expenditure. The cost-effectiveness of this modality is commonly challenged, and the lack of health economic documentation increases the level of criticism. Some common methods for evaluating imaging methods with regard to efficacy, cost, and benefits are, therefore, reviewed. Limitations in the assessment of diagnostic imaging are discussed, together with some suggestions as to which methodological approaches may be useful in this field of research.