The assessment of medical technologist. Examples from Switzerland.

The need for assessment of new medical technologies has recently become evident in many countries, especially for the people responsible for health care policy. There are multiple reasons for making evaluation: rising costs in health care, medical efficacy, safety, as well as social and political issues. Each stage of life of a diagnostic, therapeutic or preventive technology, from its emergence to obsolescence, can be assessed by an appropriate procedure. In Switzerland, a country with decentralized health care as well as political systems, the assessment is made by various institutions. Evaluative aspects are included in some National Research Foundation programs. Most work, however, is done by the division of medical techniques at the Swiss Hospital Institute. The panel of experts has recently prepared a report on magnetic resonance imaging (MRI). As a result of the initial evaluation, the need for this new technology in this country, and the number and sites of MRI systems for the next few years were established. The capital, running and unitary costs of this diagnostic procedure were estimated. The report will be of aid to the people planning investments and dealing with questions of reimbursement and other issues of health care policy. The methods of epidemiology, biostatistics, sociology and health economics used by the institutes of social and preventive medicine are very helpful in the procedures of technology assessment.

Magnetic resonance imaging: present and future applications.

Magnetic resonance (MR) imaging has created considerable excitement in the medical community, largely because of its great potential to diagnose and characterize many different disease processes. However, it is becoming increasingly evident that, because MR imaging is similar to computed tomography (CT) scanning in identifying structural disorders and because it is more costly and difficult to use, this highly useful technique must be judged against CT before it can become an accepted investigative tool. At present MR imaging has demonstrated diagnostic superiority over CT in a limited number of important, mostly neurologic, disorders and is complementary to CT in the diagnosis of certain other disorders. For most of the remaining organ systems its usefulness is not clear, but the lack of ionizing radiation and MR's ability to produce images in any tomographic plane may eventually prove to be advantageous. The potential of MR imaging to display in-vivo spectra, multinuclear images and blood-flow data makes it an exciting investigative technique. At present, however, MR imaging units should be installed only in medical centres equipped with the clinical and basic research facilities that are essential to evaluate the ultimate role of this technique in the care of patients.

NMR in medicine.

Nuclear magnetic resonance (NMR) offers a powerful new probe of the body's internal anatomy and function. The technique utilizes a combination of static and radio frequency (RF) magnetic fields to excite a weak resonant magnetic field emission from various selected naturally abundant nuclei in the body such as hydrogen (1H), phosphorus (31P) and carbon (13C). The emissions can be spatially encoded by application of magnetic field gradients, to enable the generation of high resolution anatomical images which reflect the nuclear density distribution, and/or spatial variations in the molecular level and chemical environments of the nuclei as measured by the NMR relaxation times and chemical shifts. 1H NMR relaxation time images are proving useful for the detection of a wide spectrum of disorders, whilst spatially localized 31P and 13C NMR chemical shift spectra measure directly the metabolic status of living tissue. A qualitative explanation of NMR, NMR imaging, relaxation times, and chemical shifts is presented, and the historical development, future of the technology, and its range of applications explored.