FLUDEOXYGLUCOSE F 18 INJECTION IS A POSITRON EMITTING RADIOPHARMACEUTICAL USED FOR DIAGNOSTIC PURPOSES IN CONJUNCTION WITH POSITRON EMISSION TOMOGRAPHY (PET SCAN).
FLUDEOXYGLUCOSE F 18 IS A GLUCOSE ANALOG THAT CONCENTRATES IN CELLS THAT RELY UPON GLUCOSE AS AN ENERGY SOURCE, OR IN CELLS WHOSE DEPENDENCE ON GLUCOSE INCREASES UNDER PATHOPHYSIOLOGICAL CONDITIONS. FLUDEOXYGLUCOSE F 18 IS TRANSPORTED THROUGH THE CELL MEMBRANE BY FACILITATIVE GLUCOSE TRANSPORTER PROTEINS AND IS PHOSPHORYLATED WITHIN THE CELL TO [18F] FDG-6- PHOSPHATE BY THE ENZYME HEXOKINASE. ONCE PHOSPHORYLATED IT CANNOT EXIT UNTIL IT IS DEPHOSPHORYLATED BY GLUCOSE-6-PHOSPHATASE. THEREFORE, WITHIN A GIVEN TISSUE OR PATHOPHYSIOLOGICAL PROCESS, THE RETENTION AND CLEARANCE OF FLUDEOXYGLUCOSE F 18 REFLECT A BALANCE INVOLVING GLUCOSE TRANSPORTER, HEXOKINASE AND GLUCOSE-6-PHOSPHATASE ACTIVITIES. WHEN ALLOWANCE IS MADE FOR THE KINETIC DIFFERENCES BETWEEN GLUCOSE AND FLUDEOXYGLUCOSE F 18 TRANSPORT AND PHOSPHORYLATION (EXPRESSED AS THE "LUMPED CONSTANT" RATIO), FLUDEOXYGLUCOSE F 18 IS USED TO ASSESS GLUCOSE METABOLISM.