Dynamic contrast-enhanced computed tomography for the quantification of tumor response to vasoactive agents in a rat tumor model: preliminary results

Rationale and Objectives: The purpose of this pilot study was to establish the ability of dynamic contrast enhanced computed tomography (DCE-CT) to detect changes in tumor blood flow (BF) and oxygenation induced by vasoactive substances in rats. Materials and Methods: Under ultrasound guidance, a fiber-optic probe was guided into thigh tumors in eight rats and attached to an oxygenation/blood flow-sensing device. A DCE-CT sequence was acquired at the oxygen-sensing probe tip during injection of iodinated contrast media. Group 1 rats (n = 6) were administered a vasodilator (hydralazine, 5 mg/kg i.v.) and group 2 rats (n = 2) were given physiologic saline in a similar volume. DCE-CT was repeated at the probe tip after 30 min. BF in the whole tumor and at the probe tip were estimated pre- and post-drug administration and the percentage change was calculated. Results: DCE-CT defined significant differences between pre- and post-drug BF in the whole tumor (p = 0.007) and at the probe tip (p = 0.03). Estimates of percentage change in BF in the whole tumor agreed with fiber-optic measure of percentage change perfusion (r(2) = 0.60; p = 0.02) and pO(2) (r(2) = 0.65; p 0.02). Estimates of percentage change in BF at the probe tip agreed with fiber-optic measures of percentage change in perfusion (r(2) = 0.83; p = 0.001) and pO(2) (r(2) = 0.62; p 0.02). Conclusions: Preliminary results indicate that DCE-CT is capable of identifying alterations in tumor BF in rats. The percentage change in BF agrees with a validated estimate of tumor perfusion and oxygenation. This research technique may prove useful for assessment of tumor BF during combined chemotherapeutic and radiation therapy to improve outcome. Copyright (C) 2010 John Wiley & Sons, Ltd.