DIAGNOSIS OF THE CANCERS BY NMR-CT.

NMR-CT is undergoing clinical evaluation with encouraging results in humans, especially in CNS diseases. NMR images reflect signals from hydrogen nuclei, and contrast in NMR images is produced by four tissue factors (i. e. , proton density. T//1 and T//2 relaxation times, and velocity distribution of the blood flow). Among them T//1 and T//2 relaxation times are most important factors to delineate malignant tumors from host tissues or organs. However, it is often difficult to make precise diagnoses, because there are considerable overlaps in relaxation parameters between malignant tumors and other benign lesions. NMR-CT is more sensitive to pathological changes than X-CT, but NMR-CT diagnoses of cancers at their early stages are now difficult because of its poor spatial resolution, particularly in the images of chest and abdomen. The author describes the clinical utility and limitations of NMR-CT in reference to several images he obtained on a 0. 12-0. 15 Tesla and 0. 35 Tesla device.