Yuan Weihong, McAllister James P, Lindquist Diana M, Gill Nicholas, Holland Scott K, Henkel David, Rajagopal Akila, Mangano Francesco T
Department of Radiology, Pediatric Neuroimaging Research Consortium, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 44529, USA.
Childs Nerv Syst. 2012 Jan;28(1):47-54. doi: 10.1007/s00381-011-1590-y. Epub 2011 Oct 13.
Diffusion tensor imaging (DTI) is a non-invasive MRI technique that has been used to quantify white matter (WM) abnormality in both clinical and experimental hydrocephalus (HCP). However, no DTI study has been conducted to characterize anisotropic diffusion properties in an animal model of infantile HCP. This DTI study was designed to investigate a rat model of HCP induced at postnatal day 21, a time developmentally equivalent to the human infancy.
DTI data were acquired at approximately 4 weeks after the induction of HCP with kaolin injection. Using a 7 Tesla small animal MRI scanner we performed high-resolution DTI on 12 rats with HCP and 6 saline controls. Regions of interest (ROI) examined with quantitative comparisons include the genu, body, and splenium of the corpus callosum (gCC, bCC, and sCC, respectively), anterior, middle, and posterior external capsule (aEC, mEC, and pEC, respectively), internal capsule (IC), and fornix (FX). For each ROI, DTI metrics including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (Dax), and radial diffusivity (Drad) were calculated.
We found that the anisotropic diffusion properties were abnormal across multiple WM regions in the brains of the HCP rats. Statistically significant differences included: (1) decreased FA and increased MD and Drad values in the gCC and bCC; (2) increased Dax in the sCC; (3) increased FA and Dax in the aEC; (4) increased FA in the mEC; (5) increased MD and Drad in the pEC; (6) increased FA and Dax in IC; (7) increased FA in FX.
These preliminary results provide the first evidence of WM injury quantified by DTI in a rat model of infantile HCP. Our data showed that DTI is a sensitive tool to characterize patterns of WM abnormalities and support the notion that WM impairment is region specific in response to HCP.
扩散张量成像（DTI）是一种非侵入性磁共振成像技术，已用于量化临床和实验性脑积水（HCP）中的白质（WM）异常。然而，尚未有DTI研究对婴儿期HCP动物模型的各向异性扩散特性进行表征。本DTI研究旨在调查出生后第21天诱导的HCP大鼠模型，该时间在发育上等同于人类婴儿期。
在注射高岭土诱导HCP后约4周采集DTI数据。使用7特斯拉小动物磁共振成像扫描仪，对12只HCP大鼠和6只生理盐水对照大鼠进行高分辨率DTI。通过定量比较检查的感兴趣区域（ROI）包括胼胝体的膝部、体部和压部（分别为gCC、bCC和sCC）、前、中、后外囊（分别为aEC、mEC和pEC）、内囊（IC）和穹窿（FX）。对于每个ROI，计算包括分数各向异性（FA）、平均扩散率（MD）、轴向扩散率（Dax）和径向扩散率（Drad）在内的DTI指标。
我们发现HCP大鼠大脑中多个WM区域的各向异性扩散特性异常。统计学上的显著差异包括：（1）gCC和bCC中FA降低，MD和Drad值增加；（2）sCC中Dax增加；（3）aEC中FA和Dax增加；（4）mEC中FA增加；（5）pEC中MD和Drad增加；（6）IC中FA和Dax增加；（7）FX中FA增加。
这些初步结果提供了DTI在婴儿期HCP大鼠模型中量化WM损伤的首个证据。我们的数据表明，DTI是表征WM异常模式的敏感工具，并支持WM损伤在HCP反应中具有区域特异性的观点。
