Early experience with nuclear magnetic resonance (NMR) imaging in the investigation of ocular proptosis.

The differential diagnosis of lesions causing ocular proptosis is frequently difficult making decisions on management correspondingly difficult. Computerized axial tomography (CAT) scanning has been of great benefit in showing the location and size of such lesions. Nuclear Magnetic Resonance (NMR) imaging, a non-ionising technique, offers, in addition, the prospect of soft tissue differentiation giving an indication to the actual nature of lesions in the posterior orbit. Eleven cases of orbital proptosis have been imaged by NMR and the images of six of these are demonstrated and compared with the corresponding CAT scans. In the small area of the orbit spatial resolution is slightly less on NMR, at this early stage in its development, compared to the more fully developed CAT scans, but some degree of tissue differentiation is already possible. The safety and future potential of the technique are outlined.