[en] The purpose of this experimental study was to evaluate early CT and MRI findings of cerebral sparganosis, to correlate the imaging findings with histopathologic findings, and to determine capability of CT and MRI to differentiate live worm from the dead. After scolices of three to four spargana, which were obtained from naturally infected snakes, were introduced into cerebral hemispheres of 21 mongrel cats, sequential brain CT and MRI were performed at the 2nd, 4th, 8th and 12th week, and the imaging findings were analyzed and compared with the histopathologic findings. Spargana were found in 16 sites of 10 cat brains (48%); they were located in basal ganglia (5 cases), periventricular white matter and centrum semiovale (4 cases), subdural (2 cases) or subarachnoid spaces (1 case), and lateral ventricle (2 cases). The larvae were also observed in the contralateral hemisphere (3 cases). The lesions without larvae (presumably tracts) were found in 22 sites of 14 cat brains (67%); they were located in periventricular white matter and centrum semiovale (11 cases), basal ganglia (5 cases), midbrain (3 cases) and frontal lobe (2 cases). The lesions without larvae were also found in the contralateral hemi-sphere (7 cases). On CT, the lesions with larvae showed high density in 75% (9/12) and were enhanced in 38% (3/8) as a nodular pattern. On MRI they showed iso-(7/11) or low signal intensity (4/11) on T1-weighted images, mainly isosignal intensity on proton density-weighted images, and variable signal intensity on T2-weighted images. Contrast enhancement of variable shapes was seen in 50% (4/8). The lesions without larvae showed iso-(14/22) or low density (6/22) on CT and were rarely enhanced (2/17). On MRI they mostly showed isosignal intensity on both T1-weighted and proton density-weighted images, and variable signal intensity on T2-weighted images. They were enhanced in 29% (5/17) on contrast-enhanced MRI. Dilatation of ipsilateral ventricle was found in 43% (9/12); it was seen as early as the second week in 5 cats. On histopathologic examinations, there was only mild degree of inflammation and edema around both the larvae and the lesions without larvae in most cases. Granulation tissues, small calcifications, and small hemorrhages were observed nearby the larvae in six, one and two cases, respectively. At the lesions without larvae, small calcifications and hemorrhages were found in three and nine cases, respectively. It was not possible to determine the viability of the larvae by using CT or MRI findings and even by histopathologic findings. The results indicate that the spargana actively move within brain tissue in early stage, and cause mild degree of inflammation and edema around the larvae and the tracts, but presumably produce early degeneration of cerebral white matter, resulting in dilatation of ipsilateral ventricle. Additionally, CT may differentiate the lesions with worms from tracts (the lesions without worms), but viability of the larvae can not be determined by either CT or MRI