Dynamic, contrast-enhanced CT of human brain tumors: quantitative assessment of blood volume, blood flow, and microvascular permeability: report of two cases.

We present two patients with metastatic brain tumors who underwent dynamic contrast-enhanced CT that yielded estimates of blood volume, blood flow, and microvascular permeability. For one patient, these CT-based quantifications were compared with contrast-enhanced MR-based assessments of fractional blood volume and permeability. Regional blood volume heterogeneity patterns were consistent between both CT- and MR imaging-based mapping. Permeability variations across the tumor, however, were less consistent, perhaps because of differences between ionic and non-ionic contrast agents. The advantages of dynamic contrast-enhanced CT in comparison with dynamic, contrast-enhanced MR imaging for microvascular quantifications are its availability and lower costs, applicability in the presence of MR imaging contraindications, and potentially more accurate analyses. The disadvantages are its limited anatomic coverage, radiation exposure, and the need for injection of a contrast agent.