Application of magnetic resonance imaging in nerve fiber tract analysis in a mouse model of stroke / 中华行为医学与脑科学杂志

ABSTRACT

Objective:To evaluate the cerebral infarct volume and the nerve fiber connectivity between cortical and neurogenesis-related regions in the mouse model of reperfusion after middle cerebral artery occlusion (MCAO) by 11.7 Tesla(11.7 T) magnetic resonance imaging (MRI).Methods:MCAO models were established in SPF grade adult male C57BL/6 mice using the suture-occluded method.MRI scans were performed at 3 days before and 1 day after modeling.Infarct volumes were calculated, and nerve fiber tracking was performed on specific brain regions to analyze the nerve fiber number and the parameters of fractional anisotropy(FA), mean diffusivity(MD), axial diffusivity (AD)and radial diffusivity(RD). SPSS 26.0 was used for statistical analysis, and paired t test was used to compare the data before and after modeling. Results:(1) After MCAO-induced ischemia, the infarct volume was up to (35.11±17.57)mm 3, and the FA value of the infarct area was significantly reduced compared with that of before modeling( t=4.73, P<0.01). (2) At the anterior-posterior(AP) + 1.2 mm section, the results of fiber tracking showed that compared with before modeling, the number of fiber bundles originating from the dorsal horn of the lateral sub-ventricle zone(SVZ)to the cortex reduced ((92 584.20±14 751.00) vs (59 815.60±6 752.46), t=4.87, P<0.01), and the number of fiber bundles projected to the infarcted area reduced ((107 671.40±10 497.57) vs (61 658.60±10 178.21), t=6.43, P<0.01). FA, AD, MD, and RD values were all decreased in different degrees( t=3.38-6.43, all P<0.05). (3) At the AP -3.8 mm section, the number of fiber bundles originating from the dorsal horn of the SVZ to the cortex decreased (after modeling(96 944.00±18 331.09), before modeling(58 767.80±16 445.25), t=2.99, P<0.05), and the values of FA, AD, MD and RD decreased after ischemia ( t=7.30, 5.05, 6.74, 4.13, all P<0.05). Conclusion:The ultra-high field strength of 11.7 T MRI can accurately detect the following results that the number of nerve fiber bundles from the SVZ to the cortex or infarct area are both significantly reduced, and diffusion tensor parameters are consistently changed in mice after 1 day of ischemia-reperfusion.