POSITRON EMISSION TOMOGRAPHY-BASED BORON NEUTRON-CAPTURE THERAPY USING BORONOPHENYLALANINE FOR HIGH-GRADE GLIOMAS - PART-II

Based on pharmacokinetic findings of fluorine-18-labeled L-fluoroboron ophenylalanine by positron emission tomography (PET), methods for esti mating tumor B-10 concentration were devised. In clinical practice of boron neutron capture therapy (BNCT) for high-grade gliomas, a large a mount of L-boronophenylalanine (L-B-10-BPA)-fructose solution is used. Under these conditions, a slow i.v. infusion of L-B-10-BPA-fructose s olution should be performed for BNCT; therefore, the changes over time in B-10 concentration in the target tissue were estimated by convolut ing the actual time course of changes in plasma B-10 concentration wit h a PET-based weight function including the proper rate constants [K-1 (ml/g/min), k(2) (min(-1)), k(3) (min(-1)), and k(4) (min(-1))]. With this method, the estimated values of B-10 concentration in gliomas we re very close to the B-10 levels in surgical specimens. This demonstra ted the similarity in pharmacokinetics between fluorine-18-labeled L-f luoroboronophenylalanine and L-B-10-BPA, This method, using the approp riate rate constant, permits the determination of tumor B-10 concentra tion and is widely suitable for clinical BNCT, because the averaged PE T data are enough to use in future patients without individual PET stu dy.