title: Dynamic contrast-enhanced computed tomography for the quantification of tumor response to vasoactive agents in a rat tumor model: preliminary results.
abstract: OBJECTIVE
  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.
  
  
  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.
authors.affiliation: University of California, Davis, School of Veterinary Medicine, Veterinary Medical Teaching Hospital, Department of Surgical and Radiological Sciences, 95616, USA. repollard@ucdavis.edu
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Pollard
authors.forename: Richard F
authors.initials: RF
authors.lastname: Larson
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003287:Contrast Media; D004195:Disease Models, Animal; D006830:Hydralazine / Q000494:pharmacology; D008297:Male; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000473:pathology; D010101:Oxygen Consumption / Q000187:drug effects; D010865:Pilot Projects; D011379:Prognosis; D051381:Rats; D011916:Rats, Inbred F344; D012039:Regional Blood Flow / Q000187:drug effects; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D003287:Contrast Media; D014665:Vasodilator Agents; D006830:Hydralazine