T(1) and T(2) measurements of the fine structures of the in vivo and enucleated human eye.

ABSTRACT

PURPOSE: To measure T(1) and T(2) of the fine structures of the in vivo eye. MATERIALS AND METHODS: Involuntary saccades make it difficult to obtain artifact-free images. Using a method recently reported (Bert et al, Acad Radiol 2006;12368-378), near artifact-free spin-echo images were obtained. Both an isolated enucleated eye and eight human subjects were studied at 1.5 T. Spin-echo variable TR/TE data was acquired for T(1)/T(2) determination. Average relaxation times were calculated two ways. First, an arithmetic average over different subjects was computed. Second, all data was normalized using the fitted amplitudes of each data set and pooled to obtain a single least squares fit. RESULTS: In vivo T(1)/T(2) (msec) are arithmetic average T(1), T(2), normalized data T(1), T(2). Anterior chamber 6233 +/- 979, 468 +/- 149, 5053 +/- 1052, 450 +/- 49. Ciliary body 1916 +/- 184, 80 +/- 7, 2038 +/- 114, 76 +/- 3. Chorioretina 1717 +/- 500, 72 +/- 25, 1511 +/- 230, 78 +/- 3. Extraocular muscle 1581 +/- 646, 41 +/- 7, 1470 +/- 231, 41 +/- 1. Iris 3334 +/- 989, 163 +/- 63, 3376 +/- 338, 153 +/- 10. Lens cortex 1712 +/- 466, 93 +/- 36, 1413 +/- 177, 100 +/- 5. Lens nucleus 1133 +/- 40, 26 +/- 3, 1138 +/- 47, 25 +/- 0.4. Optic nerve 1906 +/- 301, 68 +/- 16, 1805 +/- 244, 71 +/- 2. Posterior chamber 7915 +/- 4897, 241 +/- 14, 3323 +/- 2154, 251 +/- 38. Vitreous humor 5768 +/- 1190, 756 +/- 804, 4855 +/- 1846, 390 +/- 8. CONCLUSION: In vivo T(1) and T(2) for many of the fine structures of the human eye have been measured.