CT scan and histological findings in experimental cerebral infarctions in cats

Experimental cerebral infarctions were made in sixty-five cats by the transorbital approach. CT scanning was done at various periods after right-middle cerebral artery occlusion, and all cases were studied histopathologically. Cerebral microcirculation was studied by the carbon perfusion method, and blood-brain barrier (BBB) dysfunction was studied by intravenous fluorescein administration. The iodine content of brain tissue was measured and this value was compared with the findings on CT scan. Experimental cerebral infarction was divided into four stages according to CT scan findings. These are the pre-edema stage, edema stage, edema diminishing stage, and cavity stage. The low density area (LDA) in the edema stage has a mass effect and a spongy appearance is seen histopathologically. LDA in the edema diminishing stage is localized to the extent of the macroscopic infarcted region, and macrophage (so called ''gitter cells'') and capillaries are seen. Fluorescein stain indicating the area of BBB dysfunction shows almost the same extent as the area of disturbed microcirculation indicated by impaired carbon filling. In the edema diminishing stage, there is good carbon filling in the infarcted region, and enlarged capillaries with carbon black inside are seen. The study of iodine content showed that the iodine level is very high in the infarcted region, and the level has good correlation with the number of capillaries. The mechanism of contrast enhancement in the cerebral infarction seems to be well linked to the capillaries with BBB dysfunction. This study indicates that the contrast medium leaks through the capillary wall. (author)