Nuclear magnetic resonance microscopic ocular imaging for the detection of early-stage cataract.

A nuclear magnetic resonance (NMR) microscopic ocular imaging was performed at 7.0 Tesla to investigate its usefulness in the detection of early-stage cataracts. For this study, galactose cataracts were generated in experimental rabbits through diet (35% galactose), and enucleated eyes were imaged at various times after initiation of the diet. In previous studies using a 0.6 Tesla conventional magnetic resonance imager (MRI), the contrast between normal and cataractous tissues in the lens was not well defined, mainly due to the partial volume effect coming from the limitation of resolution and signal-to-noise ratio (SNR). With resolution of 60 X 60 X 80 microns, early localized precataractous tissue changes were clearly observed after 5 days diet. Precataractous tissue changes were seen histologically but no visible evidence of lens change was detected by the conventional slit lamp biomicroscope at this time. Substantially elongated spin-spin relaxation times (T2) in localized cataractous tissues (72.4 +/- 8.8 msec) were consistently observed compared with those in normal lens region (16.1 +/- 3.2 msec); however, the changes of the spin-lattice relaxation time (T1) were not significant. Some ocular NMR microscopic images with corresponding histological photographs are demonstrated to show the potential of NMR microscopy.