Study Of Cerebral Perfusion And Microstructural Injury In Patients With White Matter Hyperintensity Of Presumed Vascular Origin

Object:White matter hyperintensity (WMH) of presumed vascular origin on T2-Fluid Attenuated Inversion Recovery (T2-Flair) MR image is related to aging and cognitive impairment. The pathogenesis of WMH remains unclear. We investigated the cerebral blood perfusion and microstructural injury of the normal appearing white matter (NAWM) around WMH.Methods:We collected MR images of patients with WMH of presumed vascular origin. CBF map was generated from Arterial Spin Labeling (ASL) image, while FA map and MD map were generated from Diffusion Tensor Imaging (DTI), respectively. CBF, FA and MD maps were coregistered with 3D-T1 image. WMH regions and NAWM regions were segmented from T2-Flair image and 3D-T1 images. NAWM voxel bands located within 0-2mm,2-4mm,4-6mm,6-8mm,8-10mm,10-12mm and 12-14mm from the margin of WMH were generated, respectively. CBF, FA and MD were measured in areas of WMH and NAWM, and those regions stated above, respectively. Repeated measurement model was used to compare the difference of CBF, FA and MD.Results:Images of 40 patients were included in our study, of whom 24 (60%) were male. The average age was 67 years old, ranging from 49 to 82 years old. The average WMH volume was 30.7ml. From the margin of WMH to the cortex, CBF and FA of each voxel bands increased, and MD decreased. Compared with the average CBF of total NAWM, CBF was significantly decreased within WMH (21.27 vs 30.75 ml/100g*min, p＜0.001). CBF was also significantly decreased within white matter bands of 0-2mm (22.25 vs 30.75 ml/100g*min, p＜0.001),2-4mm (24.79 vs 30.75 ml/100g*min, p＜0.001),4-6mm (26.70 vs 30.75 ml/100g*min, p＜0.001), and 6-8mm (28.49 vs 30.75 ml/100g*min, p＜0.001), from the margin of WMH. No significant decrease of CBF was seen beyond 8mm from the margin of WMH. Compared with the average FA of total NAWM, FA was significantly decreased in WMH (0.2777 vs 0.4382, p＜0.001). FA was also significantly decreased within white matter bands of 0-2mm (0.4092 vs 0.4382, p＜0.001) and 2-4mm (0.4307 vs 0.4382, p = 0.032) from the margin of WMH. No decrease of FA was seen beyond 4mm from the margin of WMH. Compared with the average MD of total NAWM, MD was significantly increased within WMH, (0.00130 vs 0.00093, p＜0.001). MD was also significantly increased within white matter bands of 0-2mm (0.00099 vs 0.00093mm2/s, p＜0.001) and 2-4mm (0.00095 vs 0.00093mm2/s, p=0.032), from the margin of WMH. No increase of MD was seen beyond 4mm of the margin of WMH.Conclusion:In the area of NAWM around WMH, cerebral blood perfusion is decresed and microstructure is injured. The area of perfusion impairment is larger than microstructural injury (for 4mm in width), which may indicate that cerebral blood flow is decreased before white matter injury.