Clinical trials in the fields of ophthalmology, ENT and neurosurgery with an NMR tomograph showing high spatial resolution

The report describes the results of a clinical trial using a Niederfeld NMR tomograph that was carried out during 1985/86 and completed in 1987. The relaxation parameters for ocular and orbital tissues clearly point to the fact that optimum contrast enhancement is most likely to be seen for T2 sequences. A suitable phantom was prepared from paramagnetically doped gels that ensured adequate simulation of all relaxation parameters of tissues found in the eye. Optimum surface coils for the orbital region, which were another subject studied in this context, were especially developed for tomographic uses. The most remarkable finding of the clinical studies was the method's enormous discriminating power in the differential diagnosis of ocular malignant melanoma. It perimits the melanin content of any such tumor to be determined quantitatively. A relaxation time of T2 in the range between 85 and 120 msec was seen to be characteristic of tissue containing melanin. Foreign bodies and implantations of solid consistency and a size of less than 0.5 x 0.5 mm2 escaped detection by this method. The silicone oil used to simulate the hyaline body ensured sharply outlined displays. In inflammatory changes of the optic nerve it was for the first time possible to detect the precise focus of inflammation and demyelinisation. The subarachnoidal oedema was newly introduced as a diagnostic criterion and the accuracy of visualisation and measurement achieved here deserves to be described as unique. If the relaxation time of the subretinal liquid is measured in retinal detachment, it is possible to estimate the time of its onset and, thus, the probable outcome of surgery. (orig./MG)