| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1985: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1984: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
The purpose of this study is to analyse the MR images of various experimental animal models, surving the data to clinical diagnostic aids as well.
The NMR system used is CXP 20tb (registive magnet, 0.477tesla, Bruker ), and the pulse sequences used are inversion recovery as T1 weighted image and CPMG as proton density and weighted images. We used small white rabbits with no abnormalities in the orbital region.
1. The MR images of orbit in normal rabbit.
Images of the eye show the lens, aqueous, vitreous and sclera. The lens is clearly seen in many images, as a dark structure surrounded by the aqueous and vitreous, because of its relatively long T1 and short T2. Aqueous and vitreous have essentially identical NMR characteristics, showing extreme changes in relative intensity with variations in imaging parameters. On CPMG images with a short echo delay, signal is almost absent, increasing the signal with the longer echo delays. On IR images, they are seen as dark images, except with very short echo delay. Both T1 and T2 of them are long. The sclera is seen as a fine rim of relatively low signal on T2 weighted and T1 image with short echo delay. It has a very long T1 and a short T2. In the retrobulbar region, the optic nerve, extraocular muscles and orbital fat are distinguishable. The optic nerve and extraocular muscles are seen as relatively dark images because of their long T1 ( nerve>muscle ) and short T2. The orbital fat is seen as high intensity with all imaging techniques. This is to be the result of very short T1 and short T2. These results in rabbit are consistent well to the human data.
2. Enhanced MRI with Gd-DTPA
The MR images after intra-venous administration of 0.2mmol/Kg of Gd-DTPA were analysed. Even in the case of normal rabbit, the shortening of T1 was demonstrated within one hour of the administration, but this effect diminished after two hours.
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