MRIs and the Perception of Risk

Article excerpt

I. INTRODUCTION

The most important safety decision concerning MRIs was to change the name of the procedure. In the late 1970s, the procedure known as nuclear magnetic resonance (NMR) became magnetic resonance imaging (MRI) because of the negative connotations the word "nuclear" invited.1 Since then, the use of MRIs has flourished. The procedure is now routinely conducted to make medical diagnoses and to study the brain functioning of healthy volunteers participating in research studies devised by, among others, neuroscientists and economists.

There is nothing intrinsically wrong with changing a procedure's name to respond to a public perception of risk, especially when experts do not share that perception. Yet, while MRIs rarely injure patients or test subjects,2 there is reason to believe that they have important health and safety consequences not captured in standard informed consent forms. These concerns ironically involve perception of risk. On the one hand, unexpected incidental findings of clinically significant conditions in volunteer research subjects raise a host of ethical concerns. On the other hand, clinically irrelevant MRI findings sometimes lead to needless and dangerous interventions. In both cases, risk perception plays a role in understanding and dealing with the problem. The name change from NMR to MRI, however, will not exempt this procedure from difficult choices in the years ahead.

The following takes a closer look at the role risk perception plays in the use of MRIs to study brain functioning. Part II begins by describing the history of nuclear magnetic resonance, a history that illustrates the way basic research led to unimagined practical applications decades later. Part III turns to the history of the name change, which includes a formal vote by the American College of Radiology to remove the word "nuclear" from the procedure to allay public fears.3 Part IV discusses the recent literature on the difficult problem of what to do when an MRI administered to a presumably healthy volunteer in a research setting reveals the possibility of a medical problem that may or may not be clinically relevant, but which will cause fear in either case. This problem-which has medical, legal and ethical dimensions-deserves the full attention of the research community. Finally, this article concludes with abrief summary of the legal implications of the risk perceptions of research subjects.

II. HISTORICAL EMERGENCE OF NUCLEAR MAGNETIC RESONANCE

The development of MRIs began with early twentieth century research on the quantum mechanical nature of the atomic nucleus.4 The story, in highly simplified terms, goes like this. In the 1930s, the physicist 1.1. Rabi, working at Columbia University, began to study the magnetic properties of atoms.5 He bathed lithium chloride molecules with magnetic fields and radio waves in a successful effort to induce and measure the resonance frequency that occurs when the nucleus absorbs energy from the radio signal that is equal to a particular change in its energy state.6 This technique enabled Rabi to learn a tremendous amount about how atoms are bound together and how their nuclei are affected by nearby atoms.7

In the 1940s, Edward Purcell at Harvard and Felix Bloch at Stanford, working independently, each developed ways to observe the magnetic resonance of the proton-the nucleus of the hydrogen atom-in liquids and solids.8 Rabi worked with isolated molecules. By working with solids and liquids, Purcell, Bloch, and researchers who followed, were able to probe the internal structure of a variety of materials, making it possible for chemists, biologists, and physicists to analyze the structure of molecules.9 The technique pioneered by Purcell and Bloch came to be called nuclear magnetic resonance (NMR).

It was not until 1969 that Raymond Damadian, a physician at the Downstate Medical Center in Brooklyn, New York, began to do experiments designed to show that NMR could be used to probe living tissue for signs of disease. …