Brain Susceptibility Weighted Imaging Signal Changes in Acute Hemorrhagic Anemia: An Experimental Study Using a Rabbit Model

BACKGROUND: The aim of this study was to investigate susceptibility-weighted imaging (SWI) signal changes in different brain regions in a rabbit model of acute hemorrhagic anemia. MATERIAL/METHODS: Ten New Zealand white rabbits were used for construction of the model of acute hemorrhagic anemia. Signal intensities of SWI images of the bilateral frontal cortex, frontal white matter, temporal lobe, and thalamic nuclei were measured. In addition, the cerebral gray-white contrast and venous structures of the SWI images were evaluated by an experienced physician. RESULTS: Repeated bloodletting was associated with significant reductions in red blood cell count, hemoglobin concentration, hematocrit, pH, and PaCO(2), and elevations of blood lactate and PaO(2). In normal status, the SWI signal intensity was significantly higher in the frontal cortex than in the frontal white matter (63.10±22.82 vs. 52.50±20.29; P<0.05). Repeated bloodletting (5 occasions) caused significant (P<0.05) decreases in the SWI signals of the frontal cortex (from 63.10±22.82 to 37.70±4.32), temporal lobe (from 52.50±20.29 to 42.60±5.54), and thalamus (from 60.40±20.29 to 39.40±3.47), but was without effect in the frontal white matter. The cerebral white-gray contrast and venous structures were clearer after bloodletting than before bloodletting. CONCLUSIONS: The effect of hemorrhage on the brain is reflected by SWI signal changes in the cerebral cortex and gray matter nuclei.