NW/. Med. Biol. Vol. 16, No. 5, pp. 449-453. 1989 Inr. J. Radial. Appl. Imrrum. Parr B Printed in Great Britain. All rights reserved 0883-2897/89 $3.00 + 0.00 Copyright 0 1989 Maxwell Pergamon Macmillan plc Imaging of Rats with Mammary Cancer with Two 2-Deoxy-2-[‘*F]fluoro-D-hexoses ROBERT PAUL,‘,** KIMMO AH0,3 JiSRGEN BERGMAN,3 MERJA HAAPARANTA: JARMO KULMALA,4 ANN1 REISSELL’ and OLOF SOLIN ‘Department of Internal Medicine, Turku University Central Hospital, SF-20520 Turku, Finland, ‘Turku Medical Cyclotron Project, Porthaninkatu 3, SF-20500 Turku, Finland, ‘Accelerator Laboratory, Abe Akademi, Porthansgatan 3, SF-20500 Abe, Finland and 4Department of Radiotherapy, Turku University Central Hospital, SF-20520 Turku, Finland zyxwvutsrqponml (Received 10 January 1989) Rats with mammary cancer were imaged by scintigraphy: 10 rats with 2-deoxy-2-[“F]fluoro-D-glucose ([‘sF]FDG) and IO rats with [‘sF]F-D-galactose. The uptake of both tracers was similar in the tumors-the tumor-to-normal tissue ratio was 2.7 f 1.1 for [‘aF]FDG and 2.3 f 0.9 for [taF]FDGal at 120 min after injection. In addition to the tumors [‘*F]FDG accumulated in the brain, bladder and heart, [‘*F]FDGal in the brain, bladder and liver. [‘*F]FDGal may be useful for tumor imaging in man; further studies should be addressed to elucidate the mechanism of [‘*F]FDGal uptake into tumors. Introduction Galactose is almost exclusively metabolized in the liver, where it is either converted to glucose via UDPgalactose or used for glycoprotein synthesis. Glycoprotein synthesis is enhanced in malignant growth and characteristic glycoproteins can be iden- tified in the surface structures of many malignant cell clones, e.g. in the leukemias. Thus, one would expect galactose to be taken up at enhanced rates in malig- nant cells and tumors. There is a vast literature on the metabolism of glucose in malignant cells. It has generally been found that glucose is used in high amounts in malignant tissue, where it is the preferential source of energy. For external imaging the ‘*F labeled 2-deoxy analogs of glucose and galactose may be used. There is much information on the association between the radiopharmacokinetics of 2-deoxy-2-[‘*F]fluoro- D-ghCOSe ([“FIFDG) and glucose, and the metabolic rate of glucose in the brain can be measured from studies with [“F]FDG in conjunction with positron emission tomography (PET) (Phelps et al., 1979). This may also be true for tumors (DiChiro et al., 1982) although the peculiar internal milieu of malignant cells must be considered, when extrapo- ___-_-___ *All correspondence should be addressed to: Dr Robert Paul, MD, Department of Internal Medicine, Mikkeli Central Hospital, SF-50100 Mikkeli, Finland. (Tel. int + 358-55-351 I). lating kinetic data on [“F]FDG to rates of tumor glucose utilization. There is no doubt, however, that [‘*F]FDG may well be used for tumor detection (Paul et al., 1986), and for grading of metabolic activity (DiChiro et al., 1982). Much less information is available on the vizualization of tumors with [‘*F]FDGal (Yamaguchi et al., 1986). In this paper we report on the imaging results of [‘*F]FDG and [“F]FDGal in rats with mammary carcinoma. Our attempt was only to compare the imaging potential of these two agents, and especially to see how [18F]FDGal fares in comparison with [“FIFDG. We know from previous experience that rat mammary cancer is well visualized with [@FJFDG (Paul and Parviainen, 1986). Materials and Methods Synthesis The labeling synthesis of [18F]FDGal followed an electrophilic fluorination method (Haaparanta et al., 1984; Tada et al., 1987). The specific radio- activity was 1.5 Ci/mmol. The preparation had high radiochemical and epimeric purity (> 98%). Test animals Twenty female rats of the Sprague-Dawley strain (Alab, Sollentuna, Sweden) were used, 10 for imaging with (18F]FDG and 10 for imaging with [18F]FDGal; half of the rats bore mammary cancers. Mammary cancer was induced by peroral administration of 449