Dynamic contrast-enhanced computed tomography for the quantification of tumor response to vasoactive agents in a rat
Rachel E Pollard1, Richard F Larson
1University of California, Davis, School of Veterinary Medicine, Veterinary Medical Teaching Hospital, Department of Surgical and Radiological Sciences, 95616, USA. repollard@ucdavis.edu
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.
