When is the right time to conduct a clinical trial of a diagnostic imaging technology?

Bruce J. Hillman, MD Constantine A. Gatsonis, PhD When is the right time to conduct a clinical trial of a diagnostic imaging technology? It is an important question. The practice of radiology has grown in both scientific and economic influence almost solely because of the dramatic technologic advancements of the past 4 decades. The continuation of the innovation-evaluation-dissemination process is essential to the future robustness of the specialty. In this continuum, evaluation—the process of technology assessment—is playing an increasingly important role as employers and payers demand more definitive evidence of the value of a technology in improving care before granting reimbursement. Without reimbursement, a technology will not be successful. Unfortunately, there is no simple answer to the question, “when is the best time?” The answer depends on a multiplicity of factors, including the nature of the technology, its intended application, the stage of development and diffusion into practice, from whose perspective the technology is being viewed, and what we will broadly refer to as nonscientific issues. This editorial will address these influences in an effort to provide readers with a better understanding of the thinking involved in clinical trial decision making. The first step is to define what is meant by a clinical trial of a diagnostic imaging technology. For purposes of this presentation, an imaging clinical trial is any research involving the use of a diagnostic imaging technology for a clinical application on living humans. Thus, we will not consider, for example, the imaging of animals or human specimens or the preclinical testing of devices for their spatial, contrast, or temporal resolution. What we will consider is the evaluation of devices, biologic agents, and pharmaceuticals for the three major applications of diagnostic imaging to clinical practice: screening and early detection of disease, diagnosis and staging of disease, and employment of imaging as a prognostic and/or predictive marker of treatment response.