Recent advances in NMR imaging

Proton NMR signals may be obtained from the human body in such a way as to produce two-dimensional images of anatomical slices. The NMR signal is mapped in the selected slice by application of field gradients which provide spatial encoding. Over the past twelve years the method has been developed to provide excellent NMR image which are useful in clinical practice. Its introduction into major hospitals is proceeding rapidly with a dozen commercial companies supplying the market, and over two hundred whole-body systems currently installed worldwide. As a method of medical imaging NMR has the advantages that it uses no ionizing radiation, that it gives sections in transverse, coronal and sagittal planes with equal ease, and that good tissue and pathological contrast are provided through relaxation time differences, using T/sub 1/-weighted and T/sub 2/-weighted images. Paramagnetic agents are being used to improve contrast of lesions in images. Special receiver coils and surface coils have been developed for improved imaging of selected parts of the body. Efficient use of time is achieved by the multi-echo/multi-slice procedure enabling images to be obtained in an average of a few seconds. Using special techniques real-time imaging is possible. Magnetic field strengths in use range from 0.02 to 2 Tesla. In vivo NMR spectroscopy using H/sup 1/, C/sup 13/ and P/sup 31/ provides an additional source of clinical information. Current trends suggest that before very long whole-body NMR systems will be found in all major hospitals