MRI of Diabetic Retinopathy

糖尿病视网膜病变(DR)是导致工作年龄成年人失明的主要原因，大约发生在 45%的糖尿病患者。糖尿病视网膜病变通常由疾病的晚期表现来诊断，例如视力模糊。 眼底形态异常。在做出临床诊断时，视力丧失或失明 这往往是不可避免的结果。临床试验的结果证明，严格的血糖控制在 糖尿病的早期阶段在降低DR风险方面是有效的，因此，及早识别糖尿病个体 那些有DR风险的人将能够及时进行干预，将视力丧失的风险降至最低。 视网膜由三个主要细胞层(光感受器、双极细胞和神经节)和两个血管组成。 (视网膜和脉络膜)包围视网膜的层，每一层都受到我们实验室博士的不同影响 开创了基于回波平面的创新型特定层级血流和功能磁共振技术 在~80x80x1000微米处成像。眼睛的回声平面成像存在易感性伪影和图像 模糊，这排除了最早和最可靠的DR检测。此外，尽管荧光素 血管造影术被广泛应用于血管可视化和糖尿病视网膜病变的诊断，但它不具有层分辨率 而荧光素(一种光学造影剂)会引起严重的负面反应，特别是在糖尿病患者中 通常有肾功能受损。可提供血管层分辨率的替代方法 不需要造影剂也将具有重要的临床意义。 我们最近探索了非回声平面成像方法来研究视网膜。我们的初步数据 显示平衡稳态自由进动(BSSFP)MRI可显著改善图像质量和 血流和功能磁共振的空间分辨率，以及磁共振血管成像(MRA)提供的层特异性 不使用造影剂的大鼠视网膜中的视网膜和脉络膜血管。在这项建议中，我们的目标是：i)进一步 建立bSSFP和MRA方法研究大鼠视网膜板层特异性 试剂，II)评价这些检测链脲佐菌素诱导的视网膜最早变化的方法 糖尿病，以及iii)测试严格的血糖控制可以逆转这些非常早期的视力损失的假设 糖尿病患者视网膜改变的表现。我们的中心假设是异常的视网膜和脉络膜 糖尿病视网膜病变早期的血流和神经血管偶联 这些新的MRI方法可在解剖改变之前检测到，并可通过严格的血糖控制逆转。

Diabetic retinopathy (DR) is the leading cause of blindness in working-age adults and occurs in about 45% of diabetic patients. DR is often diagnosed by late manifestations of the disease, such as blurred vision and abnormal appearance of the fundus. By the time a clinical diagnosis is made, vision loss or blindness is often the inevitable outcome. Results from clinical trials have documented that strict glycemic control in the early stages of diabetes is effective in reducing the risk of DR. Thus, early identification of diabetic individuals who are at risk of DR will enable timely intervention to minimize the risk of vision loss. The retina consists of three major cell layers (photoreceptor, bipolar, and ganglion) and two vascular (retinal and choroidal) layers bounding the retina, each of which is affected differently by DR. Our laboratory has pioneered innovative layer-specific blood-flow and functional MRI techniques based on echo-planar imaging at ~80x80x1000 µm. Echo-planar imaging of the eye suffers from susceptibility artifacts and image blurring, which precludes the earliest and most reliable DR detection. Moreover, although fluorescein angiography is widely used for visualization of vessels and diagnosis of DR, it does not have layer resolution and fluorescein (an optical contrast agent) can cause severe negative reactions, especially in diabetics who often have compromised renal function. Alternative approaches that can provide vascular layer resolution without needing a contrast agent will also have important clinical significance. We have recently explored non-echo-planar imaging approaches to study the retina. Our preliminary data show that balanced steady-state free precession (bSSFP) MRI provides markedly improved image quality and spatial resolution for blood-flow and functional MRI, and that MR angiography (MRA) provides layer-specific retinal and choroid vessels in the rat retina without using a contrast agent. In this proposal, we aim: i) to further develop bSSFP and MRA methods to study the rat retina with laminar specificity without using a contrast agent, ii) to evaluate these approaches to detect the earliest changes in retina of streptozotocin-induced diabetes, and iii) to test the hypothesis that strict glycemic control reverses these very early pre-vision loss manifestations of retinal changes in diabetes. Our central hypothesis is that abnormal retinal and choroidal blood flow and neurovascular coupling in the early pre-clinical stage of retinal changes in diabetes are detectable by these novel MRI methods prior to anatomic changes, and are reversed by strict glycemic control.