Contrast-enhanced computed tomography and ultrasound for the evaluation of tumor blood flow

Objective: We evaluated implanted rat mammary adenocarcinoma tumors during a 5-week period using ultrasound, computed tomography (CT), and histology. Materials and Methods: Contrast-enhanced ultrasound with a destruction- replenishment imaging scheme was used to derive estimates of blood volume and flow. These ultrasound-derived measures of microvascular physiology were compared with contrast-enhanced CT-derived measures of perfusion and vascular volume made by the Mullani-Gould formula and Patlak analysis, respectively. Results: The tumor cross-sectional area and necrotic core cross-sectional area determined by the 3 methods were correlated (r² > 0.8, P < 0.001, n = 15). The spatial integral of perfusion estimated by CT correlated with the spatial integral of flow from ultrasound (P < 0.05). The contrast-enhanced tumor area calculated from the ultrasound analysis was highly correlated with the contrast-enhanced area estimated by CT images (r² = 0.89, P < 0.001, n = 15). However, the fraction of the tumor area enhanced by the CT contrast agent was significantly larger than either the fraction enhanced by ultrasound contrast agent or than the viable area as estimated from histology slides. Conclusion: Destruction-replenishment ultrasound provides valuable information about the spatial distribution of blood flow and vascular volume in tumors and ultrasound analysis compares favorably with a validated contrast-enhanced CT method.