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首页> 外文期刊>Fluids and Barriers of the CNS >Magnetic resonance imaging indicators of blood-brain barrier and brain water changes in young rats with kaolin-induced hydrocephalus
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Magnetic resonance imaging indicators of blood-brain barrier and brain water changes in young rats with kaolin-induced hydrocephalus

机译：高岭土性脑积水幼鼠的血脑屏障和脑水变化的磁共振成像指标

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Background Hydrocephalus is associated with enlargement of cerebral ventricles. We hypothesized that magnetic resonance (MR) imaging parameters known to be influenced by tissue water content would change in parallel with ventricle size in young rats and that changes in blood-brain barrier (BBB) permeability would be detected. Methods Hydrocephalus was induced by injection of kaolin into the cisterna magna of 4-week-old rats, which were studied 1 or 3 weeks later. MR was used to measure longitudinal and transverse relaxation times (T1 and T2) and apparent diffusion coefficients in several regions. Brain tissue water content was measured by the wet-dry weight method, and tissue density was measured in Percoll gradient columns. BBB permeability was measured by quantitative imaging of changes on T1-weighted images following injection of gadolinium diethylenetriamine penta-acetate (Gd-DTPA) tracer and microscopically by detection of fluorescent dextran conjugates. Results In nonhydrocephalic rats, water content decreased progressively from age 3 to 7 weeks. T1 and T2 and apparent diffusion coefficients did not exhibit parallel changes and there was no evidence of BBB permeability to tracers. The cerebral ventricles enlarged progressively in the weeks following kaolin injection. In hydrocephalic rats, the dorsal cortex was more dense and the white matter less so, indicating that the increased water content was largely confined to white matter. Hydrocephalus was associated with transient elevation of T1 in gray and white matter and persistent elevation of T2 in white matter. Changes in the apparent diffusion coefficients were significant only in white matter. Ventricle size correlated significantly with dorsal water content, T1, T2, and apparent diffusion coefficients. MR imaging showed evidence of Gd-DTPA leakage in periventricular tissue foci but not diffusely. These correlated with microscopic leak of larger dextran tracers. Conclusions MR characteristics cannot be used as direct surrogates for water content in the immature rat model of hydrocephalus, probably because they are also influenced by other changes in tissue composition that occur during brain maturation. There is no evidence for widespread persistent opening of BBB as a consequence of hydrocephalus in young rats. However, increase in focal BBB permeability suggests that periventricular blood vessels may be disrupted.
机译：背景脑积水与脑室扩大有关。我们假设年轻大鼠的磁共振（MR）成像参数已知会受到组织含水量的影响而与心室大小平行变化，并且可以检测到血脑屏障（BBB）渗透性的变化。方法将高岭土注射入4周龄大鼠的大水罐中诱导脑积水，在1或3周后进行研究。 MR用于测量纵向和横向弛豫时间（T1和T2）以及在几个区域的表观扩散系数。脑组织含水量通过干重法测量，组织密度在Percoll梯度柱中测量。 BBB通透性通过定量成像在注射二乙g三乙酸五乙酸酯（Gd-DTPA）示踪剂后T1加权图像上的变化进行测量，并通过检测荧光葡聚糖偶联物进行显微镜观察。结果在非脑积水大鼠中，水分含量从3周龄降低至7周龄。 T1和T2以及表观扩散系数没有显示出平行变化，也没有证据表明BBB对示踪剂具有渗透性。高岭土注射后数周脑室逐渐扩大。在脑积水大鼠中，背皮质较致密，白质较弱，表明增加的水分主要限于白质。脑积水与灰质和白质中T1的短暂升高和白质中T2的持续升高有关。表观扩散系数的变化仅在白质中显着。心室大小与背水含量，T1，T2和表观扩散系数显着相关。 MR成像显示脑室周围组织灶中Gd-DTPA渗漏的证据，但不是弥漫性的。这些与较大的葡聚糖示踪剂的微观泄漏有关。结论MR特征不能用作不成熟脑积水大鼠模型中水含量的直接替代物，可能是因为它们也受到大脑成熟过程中组织组成的其他变化的影响。没有证据表明年轻大鼠脑积水导致BBB广泛持续开放。但是，局部血脑屏障通透性增加提示脑室周围血管可能受到干扰。

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