Factors Affecting Brain Metabolism Measured with ¹⁸FDG

Hongyun Zhu, Michael L. Goris

Department of Radiology, University of Arkansas for Medical Sciences (UAMS), Little Rock, USA.
Division of Nuclear Medicine, School of Medicine, Stanford University, Stanford, USA.

DOI: 10.4236/ojmi.2012.21003                

Abstract

An observational finding found a large variation in the brain SUV in patients with multiple myeloma undergoing PET/CT. The first hypothesis considered a toxic effect of chemotherapeutic agents, but no correlation was found with hematological signs of toxicity. Low brain FDG uptake has been described with anesthesia, but this was not relevant in this case. An alternative is the presence of a large FDG avid mass, but that was excluded. Since there was a question of chemotherapy toxicity, the metrics used for comparison were Hemoglobin levels (Hgb, g/dl), Erythrocyte count (RBC, M/μL), Lymphocytes absolute counts (Lymph#, K/μL) and % (lymph, %), Granulocytes Neutrophils, K/μL), age and C-reactive protein levels (CRP, g/L). The liver SUV (standardized uptake value) was included to eliminate unexpected global effects on the SUV values, since FDG uptake is a competitive system with a single source (plasma FDG levels). There was in fact no correlation between brain SUV and hepatic SUV, eliminating the so-called super scan effect. Further analysis, however, revealed a strong positive correlation with hemoglobin or RBC levels, but an inverse effect with Neutrophils, C-reactive proteins and age (in years). The results suggest that brain metabolism strongly depends on oxygen supply and may be depressed by general inflammatory diseases and independently with age. If the variation of glucose metabolism correlates with cognitive deficits (CD), considering general measures of good health may be a first step for relief of age related CD.

Keywords

Brain 18-FDG Uptake; Anemia; Inflammation

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	M. T. Alkire, C. J. Pomfrett, R. J. Haier , M. V. Gianzero, C. M. Chan, B. P. Jacobsen and J. H. Fallon “Functional Brain Imaging during Anesthesia in Humans: Effects of Halothane on Global and Regional Cerebral Glucose Metabolism,” Anesthesiology, Vol. 90, No. 3, 1999, pp. 701-709. doi:10.1097/00000542-199903000-00011
[2]	M. Boly, C. Phillips, L. Tshibanda, A. Vanhaudenhuyse, M. Schabus, T. T. Dang-Vu, G. Moonen, R. Hustinx, P. Maquet and S. Laureys, “Intrinsic Brain Activity in Altered States of Consciousness,” Annals of the New York Academy of Sciences, Vol. 1129, 2008, pp. 119-129. doi:10.1196/annals.1417.015
[3]	R. Meierhans, M. Béchir, S. Ludwig, J Sommerfeld, G. Brandi, C. Haberthür, R. Stocker,and J. F. Stover, “Brain Metabolism Is Significantly Impaired at Blood Glucose below 6 mM and Brain Glucose below 1 mM in Patients with Severe Traumatic Brain Injury,” Critical Care, Vol. 14, No. 1, 2010, p. R13. doi:10.1186/cc8869
[4]	N. Nakayama, A. Okumura, J. Shinoda, T. Nakashima and T. Iwama, “Relationship between Regional Cerebral Metabolism and Consciousness Disturbance in Traumatic Diffuse Brain Injury without Large Focal Lesions: An FDG-PET Study with Statistical Parametric Mapping Analysis,” Journal of Neurology, Neurosurgery & Psychiatry, Vol. 77, No. 7, 2006, pp. 856-862. doi:10.1136/jnnp.2005.080523
[5]	D.-W. Kim, C. G. Kim, S.-A. Park, S.-A. Jung and S-H. Yang, “Metabolic Super Scan in 18F-FDG PET/CT Imaging,” Journal of Korean Medical Science, Vol. 25, No. 8, 2010, pp. 1256-1257. doi:10.3346/jkms.2010.25.8.1256