Nuclear magnetic resonance imaging. Review of early clinical experience

Nuclear magnetic resonance tomography is a powerful new imaging modality which produces cross-sectional images similar to those obtained by computerized tomography. However, unlike computerized tomography, nuclear magnetic resonance imaging does not use ionizing radiation but rather utilizes an apparently safe interaction between magnetic fields, radio waves, and atomic nuclei. Basic principles of nuclear magnetic resonance imaging are discussed briefly and promising early clinical applications are reviewed. The two magnetic relaxation times, T1 and T2, provide discrimination between tissues based on differences in fat and water content. Tumors are readily differentiated from normal tissue on the basis of the increased water content, primarily due to edema and hypervascularity. Although nuclear magnetic resonance imaging is very sensitive in the detection of these abnormalities, it is not yet able to provide a specific diagnosis.