Assessment of tumor blood flow using C-11 butanol

This study was undertaken to evaluate C-11 butanol as a possible radioagent for flow quantitation in human neoplasia. 100-120 mCi of no-carrier added C-11-n-butanol were obtained in 1.0 ml solution, the radiochemical purity was >99%. In the dog, only 3% of decay-corrected activity was released from the organism within 20 min. Following injection, 80% of the label was cleared from the blood within less than 1 min. HPLC analysis did not reveal any metabolites after a 1 min incubation time of the radiotracer with blood or when C-11 butanol was injected into the femoral vein of the rabbit and samples were taken from the left atrium. Single-pass extraction fraction in tumor (VX 2) and muscle was 100%. Tumor:muscle uptake of C-11 butanol was correlated (r=0.86) with the retention of I-121 microspheres (N=10; 5 tumor lines). A close correlation (r=0.96) was found when uptake data in 17 tumor transplants (3 lines) were compared with Xe-133 washout rates. Differences between two consecutive uptake measurements: one after i.v., and one after intra-aortic tracer injection did not exceed 10% (12 rats). High diffusion capacity, lack of intravascular and intrapulmonary metabolism and appreciable retention in tissue make C-11 butanol an appropriate radiotracer for non-invasive monitoring of tumor blood flow