| Objective: Quantitative study of FA and T2* values was made in the SN and CS in rotenone animal model to evaluate their changed characteristics and explore the pathogenesis of PD.Methods: 18 male SD rats of the same age(2 months), weighing 300 g on average was used. Rats were divided into two groups: 2ul of dissolved rotenone in DMSO was injected(N=24) and 2u L of Saline(N=6). All the injection was conducted on the right side of the rat brain to destroy SN by means of microsyringe and stereotactic instrument. The changes of characteristics of ethological were observed on the 1, 2, 4, and 6 weeks after the injection and the MR scans were conducted at the same time point. T2-weighted sequence was acquired, and DTI and FLASH sequences were copied from the T2 WI. The FA and T2* values of the both side of the SN and CS were measured on the corresponding post-processing images of DTI and FLASH, assuming the T2 image as a reference image. The statistical analysis was performed on each data set to compare the differences of the two parameters among different groups, locations and time points.MR scan method: The coronal T2-weighted images of the rat brain were acquired through the positioning images. Then the SN of the maximum level was chosen from the coronal T2 weighted images to locate the scanning beam of the transverse T2-weighted images. The parameters were as followed: slice thickness =2 mm, slice gap=2 mm, number of slices=12. The whole CS, midbrain, pons and the most medulla oblongata were included in the transverse images. The slice thickness, slice gap and number of slices of DIT, the location and direction of the FLASH were copied from the transverse T2 images.The DTI and FLASH images were analysed on the Siemens Verio 3.0 T MR Leonardo 3682 workstation. The DTI images were corrected to avoid the image distortion caused by the head movement and inhomogeneous magnetic field. The transverse T2-weighted images, as the reference images, were fused with the DTI images in Neuro 3D window. Adjusted the window width and level to display the T2 WI clearly and selected the ROI on the slice of the maximum level of SN and CS respectively. 8mm2 ROI was selected. Drew circles in the center of SN. The CS was divided into thirds, and the circle was drawn as large as possible in every division and then the average was made. To measure the T2* value, the FLASH images were shown in the viewing window, marking the images of SN or CS of different TE values and selecting the marked images; 3/8/13/18 were the slices of the maximum level of CS, and 4/9/14/19 were the slices of SN. “T2” button was clicked under the evaluation option to acquire the T2 WI and PD T1 WI. T2 WI and FLASH images were selected, which contained the clearest anatomical details and marked the ROI(3mm2) in SN and CS respectively to obtain the T2* value.All data were measured by two radiologic doctors separately and the result was averaged. All data were analyzed using SPSS 17.0. Independent- samples T test was performed to compare the FA and T2* values in the SN and CS on the both side of the experimental and control group; Paired-sample T test was performed to compare the FA and T2* value in the SN and CS of the same individual on both side of the brain; One-way ANOVA was performed to compare the FA and T2* value of the three division(1/2/3) of the both side of the CS separately. Repeated measure design was used to compare the FA and T2* at different times(1/2/4/6 weeks). Differences were considered significant at P<0.05. The experimental procedures were performed in accordance with the Guidance Suggestions for the care and use of laboratory animals, formulated by the Ministry of Science and Technology of the People’s Republic of China.Results:1 Compared with the control group, the FA value in the right SN and CS of the experimental showed significant differences and no difference for the left side. Compared with the experiment group itself, the FA value in the right SN and CS showed significant differences for the left side, and no difference for the selected ROI(1/2/3).2 FA values of the right SN in the experiment group decreased, the degree of declined to 19.27%, and FA values of the right CS, the degree of declined to 14.53%.3 Compared with the control group or the experiment group itself, there was no difference for T2* value in both side of SN and CS.4 There was significant difference of FA value in the right SN of the same experiment rat among different time points, which was liable to ascend, gradually approaching the level of the control group. The FA value in CS didn’t change with the time. Similarly, there was also significant difference of T2* value in the right SN of the same experiment rat among different time points, namely T2* value changed with the observation time. However, there was no difference between the T2* value in the left SN and both CS area among different time.5 No correlation has been found between the T2* and FA value in the right SN(Pearson correlation coefficient=0.174, P=0.236). The ROC curve analysis found that FA value showed higher sensitivity than T2* value. The sensitivity and specificity of FA value in the right side SN were 75.0%,72.9%, respectively, and the T2*value were 50%, 70.8%.6 In the experimental group, the FA value in the right SN correlated significantly with their observation time.(Pearson correlation coefficient= 0.824**, P<0.001); No correlation has been found in the control group(Pearson correlation coefficient=0.036, P=0.810). The T2* value in the right SN correlated with their observation time(Pearson correlation coefficient=0.329*, P=0.022).Conclusions:1 In the experimental group, the FA values in the right SN and right CS were both lower than that in the opposite side, and decreased more obviously in the right SN(about for 19.27%).2 There was no significant difference of the FA value in the SN and CS. in the bilateral SN and CS between the experimental and control group. However, there was significant difference of T2* value in the right SN of the same experiment rat among different time points, namely T2* value changed with the observation time and it’s a linear correlation shown between the T2* and observation time.3 No correlation has been found between the T2* and FA values in the right SN, and FA value showed higher sensitivity than T2* value. |
PDF Full Text Request