To evaluate the feasibility, stability and process on diffusion weighted imaging (DWI) in acute phase of a middle cerebral artery (MCA) embolic occlusion stroke model in beagle dogs, and to discuss the potential mechanisms of lacunar infarction.

Six adult beagle dogs were involved in this study. After the catheterization was manipulated into the left internal carotid artery, an autologous clot about 1.7 mm in diameter and 5 mm long was injected through the catheter in each dog. The DWI was performed to evaluate the progression of ischemic lesions at 30 min interval within 6 h after embolization. The MR examinations with the same parameters and neurobehavioral scoring were performed at 24 h and 7 days after procedure. These animals were sacrificed for pathological examination at 7 days after embolization.

The left proximal MCA ware successfully occluded in all dogs using single-thrombus method. The solitary or multiple ischemic lesions shown as high signal intensity on DWI were observed with the mean detecting time of (1.22±0.51)h in the deep brain area, and the mean diameter of induced infarctions was (6.90±2.08)mm on 6 h-DWI after embolization. The mean volume of these lesions was (168.39±138.11)mm3, (186.88±161.54)mm3 and (165.89±135.30)mm3 at 6 h on DWI, 24 h and 7 days on T2 image, respectively. The statistical analysis didn’t show significant difference in the volume among the three time points (P=0.0531). The neuro-behavioral scores were 4.50±1.38 at 24 h and 2.33±0.82 at 7 days after procedure (P=0.0009). The ischemic infarctions located in the basilar ganglion area were most frequent in pathological examination.

The DWI abnormalities resembling lacunar infarcts can be detected in early phase after reliable proximal MCA occlusion using thrombi in beagle dogs, which exist abundant collateral anastomosis between the ECA and ICA. Our results provide further support for the concept that emboli may be a potential cause of lacunar infarcts.