Journal of Computer Assisted Tomography 7(5):919—924, October © 1983 Raven Press, New York Technical Note Quantitation of Regional Cerebral Glucose Metabolism Gordon L. Brownell, Kimberlee J. Kearfott, Anna-Liisa Kairento, David R. Elmaleh, Nathaniel M. Alpert, John A. Correia, Lawrence Wechsler, and Robert H. Ackerman Abstract: Kinetic analysis of ‘ 8 F-labeled 2-fluoro-2-deoxy-n-glucose (2FDG) has been carried out in 28 studies on 25 subjects. The object of the analysis was to determine the practical problems of quantitation of glucose metabolic rate (GMR) using the Sokoloff model with 2FDG. We found that arterial and venous plasma concentration of 2FDG yielded equivalent values of the inte grated plasma concentration (IPC*) and that one arterial or venous plasma sample at 30 mm serves to predict IPC* to within ± 7%. These observations suggest that quantitation is indeed possible in such subjects without using complex arterial or venous sampling procedures. The average values of K 1 , K 2 , and K 3 are observed to be 0.14 ± 0.08, 0.20 ± 0.10, and 0.030 ± 0.012 min’. The data are consistent with a value of lumped constant of 0.4 and a considerable spread in global values of GMR (30%) in an unselected group of subjects. Index Terms: Metabolism, glucose—Attenuation values—Computed tomography. Regional cerebral glucose metabolic rate (GMR) was first reported on a global basis in 1948 (1). So koloff demonstrated that ‘ 4 C-labeled 2-deoxy-D-glu- cose (2DG), an analog of glucose, combined with autoradiography could measure GMR on a quanti tative regional basis. The method has been widely used to map functional pathways within the animal brain and to determine metabolic rates of discrete brain structures. The model developed by Sokoloff et al. (2) uses three rate constants representing the rates of transfer of glucose from arterial blood to the precursor pool in tissue, transfer of glucose from the precursor pooi to blood, and the rate of phosphorylation of glucose in the precursor pool to the hexaphosphate form. Although the model refers to glucose metabolism, it can be used in modified form to quantitate GMR using analogs of glucose such as 2DG. Reivich et al. (3,4) applied the technique in man From the Department of Radiology, Massachusetts General Hospital, Boston, MA (G. L. Brownell, D. R. Elmaleh, N. M. Alpert, 3. A. Correia, L. Wechsler, and R. H. Ackerman); Cot zias Laboratory of Neuro-Oncology, Memorial Sloan Kettering Center, New York, NY (K. 3. Kearfott); and University Central Hospital, Meilahti Hospital, Laboratory Department, Helsinki, Finland (A.-L. Kairento). Address correspondence and reprint requests to Dr. Brownell, Physics Research Laboratory, Mas sachusetts General Hospital, Boston, MA 02114. by using 18 F-labeled 2-fluoro-2-deoxy-D-glucose (2FDG). By combining the principles of positron detection (5) with the principles of tomographic re construction developed for X-ray computed tomog raphy, regional activity concentrations of ‘ 8 F trapped in brain tissue can be obtained. Using the model of Sokoloff, Reivich et al. demonstrated the relevance of the technique to obtain quantitative values of GMR using 2FDG (3). Phelps et al. (6) further re fined the model to include the dephosphorylation of 2-fluoroglucose-6-P0 4 . We have analyzed data from 28 studies on 25 human subjects. These constitute the bulk of the 2FDG studies carried out at Massachusetts General Hospital (MGH) over the last 2 years and include all studies in which serial plasma samples were ob tained. In most cases serial tissue concentrations were also obtained. Information on dosimetry and other aspects of the use of 2FDG has been previ ously reported (7). The object of this study is to determine the practical problems involved in quan titation of GMR in a series of unselected subjects. FDG MODEL Figure 1 shows the three compartment model used by Sokoloff and subsequently by other investigators 919