AIM: To investigate the correlation between microvessel density and spiral CT perfusion imaging in colorectal carcinoma.METHODS: Thirty-seven patients, with histologically proven colorectal carcinoma, underwent water enema spiral CT scan. The largest axial surface of the primary tumor was searched on unenhanced spiral CT images. At this level, the enhanced dynamic scan series was acquired.Time-density curves (TDC) were created from the region of interest drawn over the tumor, target artery by Toshiba Xpress/SX spiral CT with perfusion functional software.Then the perfusion was calculated. Microvessel density(MVD) was evaluated using immunohistochemical staining of surgical specimens with anti-CD34, and then MVD was correlated with perfusion.RESULTS: MVD of colorectal carcinomas was 33.11-173.44,mean 87.28, and perfusion was 15.60-64.80 mL/min/100 g, mean 39.74 mL/min/100 g. MVD and perfusionwere not associated with invasive depth, metastasis and disease stage, and they all decreased with increasing Dukes stage, but no significant correlation was found between them (r= 0.L8, P = 0.29).CONCLUSION: There is no significant correlation between MVD and perfusion. Neovascularizaton and perfusion are highly presented in early colorectal carcinoma.CT perfusion imaging may be more suited for assessing tumorigenesis in colorectal carcinoma than histological MVD technique.