Human brain hemorrhage: Quantification of perihematoma edema by use of diffusion-weighted MR imaging

BACKGROUND AND PURPOSE: Animal models have clearly shown a critical role for extravascular blood in the initiation of the vasogenic edema associated with intracerebral hemorrhage (ICH). Nevertheless, the relevance of these observations to the human disease process has not been evaluated. With a prospectively collected cohort of nine patients, we report the relation between intraparenchymal blood clot volume and elevation of perihematoma brain tissue (and homologous contralateral brain tissue) apparent diffusion coefficient (ADC). METHODS: Patients with acute and subacute supratentorial ICH were prospectively evaluated by using diffusion-weighted imaging. ADC was measured in perihematoma tissue and in homologous contralateral regions. The relationship between ADC and volume of hematoma was determined by using linear regression analysis. RESULTS: Nine patients were enrolled in the study. The mean hematoma volume was 30.8 cc (range, 2.6-74 cc). The ADC in the perihematoma regions was 172.5 × 10^-5 mm²/s (range, 120.1-302.5 × 10^-5 mm²/s) and in the contralateral corresponding regions of interest was 87.6 × 10-5 mm²/s (range, 76.5-102.1 × 10-5 mm²/s) (P = .02). The Pearson correlation coefficient for the ADC in surrounding edema and hematoma volume was 0.7 (P = .04). The correlation coefficient between hematoma volume and contralateral hemisphere ADC was 0.8 (P = .02). CONCLUSION: We report a significant direct correlation between ICH volume and degree of ADC elevation in perihematoma and ADC values in contralateral corresponding brain tissue. These findings suggest a dose-effect interaction between volume and concentration of blood products and intensity of response that brain tissue exhibits in blood-mediated edema. Prospective natural history and interventional studies are required to confirm this biologically meaningful correlation in patients with ICH.