Measurement of blood-brain hexose transport with dynamic PET: comparison of [18F]2-fluoro-2-deoxyglucose and [11C]O-methylglucose.

Blood-to-tissue transport of [18F]2-fluoro-2-deoxyglucose (FDG) and [11C]O-methylglucose (CMG) was compared by dynamic positron emission tomography in four patients with recent ischemic infarcts and in three patients with intracerebral tumors. Local blood volume, tracer transport from tissue to blood, and FDG phosphorylation rates were also determined. A regional analysis of parametric images showed a close correlation of FDG and CMG transport rate constants in pathological tissue. Transport rates of FDG and CMG showed correspondingly less asymmetric remote effects than FDG phosphorylation rates. Transport rate constants were consistently higher for FDG than for CMG in pathological and normal tissue, in accordance with the higher affinity of carrier enzymes to FDG. There was a significant correlation between fitted regional blood volume values and correspondence of average absolute values with both tracers. It is concluded that dynamic FDG PET for measurement of cerebral glucose metabolism is also useful to measure alterations of hexose transport and local blood volume in pathological tissue.