CT density decrease in water intoxication rat model of brain oedema.

OBJECTIVES: The aim of this study was to determine whether water intoxication affects the radiodensity of brain tissue in CT scan examination in the rat model of brain oedema.

METHODS: A standard CT scan of the brain was obtained in a group of rats, first at control conditions (controls - CG) and then after hyperhydration (oedema model-EG) in the region of interest (ROI) corresponding to the area of coronary sections with pixel size 0.125 mm in position A (bregma +2.43 mm), position B (bregma -2.92 mm), position C (bregma -12.73 mm). Densitometrically determined mean values (MV), expressed in Hounsfield units (HU) were processed by standard statistical methods.

RESULTS: The average MV density was 120.49±6.79 HU for the control measurement and 88.01±4.72 HU after the hyperhydration, which represents decrease in the density by 32.48 HU (p<0.001). In the control measurement the average value of HU for the position A was 121.98, for position B 112.4 and for position C 127.08. In conditions of hyperhydration, the average MV density in position A was 89.95 HU in position B 84.67 HU and in position C 89.43 HU. The differences between the CG and EG were in all positions A, B, C statistically significant (p<0.001). In the control measurement, the differences between position A×B (p<0.05) and B×C (p<0.001) were statistically significant. After hyperhydration no significant difference between the position A, B, C was found.

CONCLUSION: water intoxication caused by hyperhydration in rats can induce diffuse brain oedema, which is reflected in the CT examination by the decrease of brain tissue density, expressed in HU. The value of the measured density depends on the location and size of the measured brain area.