Magnetic Appeal: MRI and the Myth of Transparency

2. Painting by Numbers: The Development of Magnetic Resonance Imaging and the Visual Turn in Medicine

M agnetic resonance imaging (MRI) occupies an important symbolic space in contemporary science and popular culture. In 2003, Drs. Paul Lauterbur and Peter Mansfield were awarded the Nobel Prize in Physiology and Medicine for developing MRI technology, an event symbolizing the importance of this imaging technique to the broader scientific community. Yet while MRI is viewed as the gold standard in imaging diagnostics by policy makers and medical practitioners , it has assumed celebrity status in mass media. It is nearly impossible to read newspapers and magazines or watch television dramas such as Law and Order and ER without coming across a passage, scene, or dialogue that invokes the technology. Even the Dalai Lama (2005) singled MRI out as representative of the highest technological achievement in modern times. Today, MRI scans and technology are central to medical practice, identities of health and illness, and social life more generally. Yet there is nothing inevitable about how MRI is presently designed or interpreted. The name of the technology, the design of the machine, and the representation of MRI data were debated and transformed during its initial development in the 1970s and immediately after its introduction into clinical medical practice in the 1980s. During these periods, research scientists , in response to culturally embedded interactions with other scientists , radiologists, and prospective patients, creatively appropriated and 2 Painting by Numbers The Development of Magnetic Resonance Imaging and the Visual Turn in Medicine adapted machine design, the appearance of data output, and terminology to collectively produce what today is known as MRI. The development of MRI technology occurred within two cultural contexts : (1) the sociotechnical turn toward visuality and (2) an emphasis on nuclear technologies and knowledge. Drawing on sociological analyses of technological innovation, this chapter addresses several critical questions. How did research scientists choose to represent the data in changing ways— from numbers to pictures of specific kinds? How did these decisions, as well as issues of professional control, relate to the broader cultural context of visualization ? And, finally, how did the development of MRI relate to both scientific work in and shifting public perceptions of atomic research? This chapter shows that scientists selected from a range of possibilities to settle on and ultimately create a new technology. Their choices can only be understood through sustained discussions of larger cultural priorities and conventions. An “Imaging” Machine?: Nuclear Physics and the Development of MRI The ideas that provide the foundation for MRI technology are rooted in early twentieth century investigations of the internal structure of the atom and the rise of physics in scientific practice (Kevles 1987). An understanding of the centrality of nuclear physics to MRI development gives insight into how the technology produces anatomical images, and, in doing so, complicates common perceptions of it as an imaging apparatus. MRI, despite its current construction as a visualizing technique, does not produce anatomical images in a straightforward fashion. It has no photographic lens, nor does it use x-ray techniques to create pictures of the internal body. Instead, MRI is used to numerically measure how hydrogen nuclei absorb and release energy in response to particular frequencies. The understanding of nuclei as a site of energy absorption and emission builds on nuclear magnetic resonance (NMR) research, a scientific area of inquiry developed in the early twentieth century. The term “nuclear magnetic resonance,” coined by physicist Isidor Rabi in the 1930s, describes how nuclei of atoms absorb and release energy in response to specific frequencies when placed in a magnetic field (Wehrli 1992, 34). This process is similar to that of a tuning fork. If a person strikes a tuning fork tuned to a particular frequency, other tuning forks in the vicinity tuned to the same frequency will pick up the energy from the humming tuning fork, start to vibrate, and emit a sound. The nucleus of an atom does the same. In response to a particular frequency, the nucleus of an atom will absorb energy and then relax by emitting energy. Since different atoms (or the same atom PAINTING BY NUMBERS 25 in different environments) have different relaxation rates, this information can be used to identify the composition of a molecule; in the case of MRI, the machine measures how hydrogen nuclei absorb and release energy, which in turn provides knowledge about the placement of hydrogen atoms in the body and therefore knowledge about anatomy in the body. The...