Association of Heat Production with FDG Accumulation by Murine Brown Adipose Tissue (BAT) After Stress

• Published in: The Journal of nuclear medicine (1978) Vol. 52; no. 10; pp. 1616 - 1620
• Main Authors: Carter, Edward A., Bonab, Ali A, Paul, Kasie, Yerxa, John, Tompkins, Ronald G., Fischman, Alan J.
• Format: Journal Article
• Language: English
• Published: 13.09.2011
• ISSN: 0161-5505; 1535-5667
• DOI: 10.2967/jnumed.111.090175

Previous studies have demonstrated that cold stress results in increased accumulation of 18 FDG in brown adipose tissue (BAT). Although it has been assumed that this effect is associated with increased thermogenesis by BAT, direct measurements of this phenomenon have not been reported. In the current investigation we evaluated the relationship between stimulation of 18 FDG accumulation in BAT by three stressors and heat production measured in vivo by thermal imaging. Male SKH-1 hairless mice were subjected to full-thickness thermal injury (30% total body surface area), cold stress (4°C for 24 hours), or cutaneous wounds. Groups of 6 animals with each treatment were fasted over night and injected with 18 FDG. Sixty minutes after injection the mice were sacrificed and biodistribution was measured. Other groups of six animals subjected to the three stressors were studied by thermal imaging and the difference in temperature between BAT and adjacent tissue was recorded (ΔT). Additional groups of 6 animals were studied by both thermal imaging and 18 FDG biodistribution in the same animals. Accumulation of 18 FDG by BAT was significantly (p <0.0001) increased by all 3 treatments (burn ~5 fold, cold: ~15 fold, and cutaneous wound ~15 fold) whereas accumulation by adjacent white adipose tissue (WAT) was unchanged. Compared with sham control mice; ΔTs in animals exposed to all three stressors showed significant (p<0.001) increases in temperature between BAT and adjacent tissue. The difference in ΔT between stressor groups was not significant, however, there was a highly significant linear correlation (r 2 =0.835, p<0.0001) between the ΔT measured in BAT vs. adjacent tissue and 18 FDG accumulation. These results establish, for the first time, that changes in BAT temperature determined in vivo by thermal imaging parallel increases in 18 FDG accumulation.