Layer-Specific Manganese-Enhanced MRI of the Diabetic Rat Retina in Light and Dark Adaptation at 11.7 Tesla.
Layer-Specific Manganese-Enhanced MRI of the Diabetic Rat Retina in Light and Dark Adaptation at 11.7 Tesla.
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DOI：
10.1167/iovs.14-16128
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发表时间：
2015-06
影响因子：
4.4
通讯作者：
E. Muir;S. Chandra;Bryan H. De La Garza;Chakradhar Velagapudi;H. Abboud;T. Duong
中科院分区：
文献类型：
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作者：
E. Muir;S. Chandra;Bryan H. De La Garza;Chakradhar Velagapudi;H. Abboud;T. Duong
目的应用高分辨率锰增强磁共振成像(MEMRI)研究链脲佐菌素诱导的糖尿病大鼠视网膜不同细胞层中钙离子的异常活动，以确定MEMRI是否较以往报道的更早发现这些变化。方法SD大鼠分别于注射链脲佐菌素(STZ)后14d(n=8)和30d(n=5)注射链脲佐菌素(STZ)或赋形剂(n=7)。采用20×20×700μm的锰增强磁共振成像，以锰作为钙类似物和磁共振造影剂，对同一动物的视网膜进行明暗适应，其中一只眼被遮盖，另一只眼不遮盖。在清醒状态下获得编码明暗适应的MEMRI活动，并在麻醉下成像。结果增强扫描显示视网膜内、外、脉络膜三层结构。在正常动物中，外层视网膜在黑暗中的MEMRI活性高于光照；内视网膜在黑暗中的活性低于光照；脉络膜的活性没有差异。锰增强的MRI活性最早在高血糖后14天发生变化，并随着暗适应下视网膜外部高血糖持续时间的延长而降低。脉络膜在14天时也改变了MEMRI活动，在30天时恢复正常。视网膜内侧的MEMRI活动无明显差异。结论高血糖后14天，锰增强MRI可检测到视网膜外层钙活性进行性降低，并伴随高血糖持续时间，早于文献报道的任何其他时间点。
PURPOSE To employ high-resolution manganese-enhanced MRI (MEMRI) to study abnormal calcium activity in different cell layers in streptozotocin-induced diabetic rat retinas, and to determine whether MEMRI detects changes at earlier time points than previously reported. METHODS Sprague-Dawley rats were studied 14 days (n = 8) and 30 days (n = 5) after streptozotocin (STZ) or vehicle (n = 7) injection. Manganese-enhanced MRI at 20 × 20 × 700 μm, in which contrast is based on manganese as a calcium analogue and an MRI contrast agent, was obtained in light and dark adaptation of the retina in the same animals in which one eye was covered and the fellow eye was not. The MEMRI activity encoding of the light and dark adaptation was achieved in awake conditions and imaged under anesthesia. RESULTS Manganese-enhanced MRI showed three layers, corresponding to the inner retina, outer retina, and the choroid. In normal animals, the outer retina showed higher MEMRI activity in dark compared to light; the inner retina displayed lower activity in dark compared to light; and the choroid showed no difference in activity. Manganese-enhanced MRI activity changed as early as 14 days after hyperglycemia and decreased with duration of hyperglycemia in the outer retina in dark relative to light adaptation. The choroid also had altered MEMRI activity at 14 days, which returned to normal by 30 days. No differences in MEMRI activity were detected in the inner retina. CONCLUSIONS Manganese-enhanced MRI detects progressive reduction in calcium activity with duration of hyperglycemia in the outer retina as early as 14 days after hyperglycemia, earlier than any other time point reported in the literature.