1987 年 22 巻 3 号 p. 157-165
In early 1980th magnetic resonance imaging (MRI) became utilized practically as a medical diagnostic instrument. MRI has several advantages over computed tomography (CT) in the evaluation of anatomy and pathology of human body. First, contrast resolution obtained by MRI surpasses that of CT, because, with MRI, several parameters such as T1 and T2 relaxation times, mobile proton density, and blood flow affect signal intensity and manipulation of tissue cotrast is achieved by highlighting differences in these parameters, and differences in density on CT is obtained only by attenuation differences of the X-ray beam. Other advantages of MRI include the ability to depict cross-sectional anatomy in any planes without patient manipulation, the lack of artifacts from bony structures and air, and the absence of ionizing-irradiation.
Because of these capabilities, MRI has quickly evolved into the premier imaging tool for central nervous system including brain and spinal cord. In addition, usefulness of MRI has been recognized in the spine, heart and great vessels, pelvis and extremities and it will become one of the important diagnostic imaging methods in various organs and parts.