RT Journal Article
SR Electronic
T1 Combining <sup>123</sup>I-Metaiodobenzylguanidine SPECT/CT and <sup>18</sup>F-FDG PET/CT for the Assessment of Brown Adipose Tissue Activity in Humans During Cold Exposure
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 208
OP 212
DO 10.2967/jnumed.112.111849
VO 54
IS 2
A1 Admiraal, Wanda M.
A1 Holleman, Frits
A1 Bahler, Lonneke
A1 Soeters, Maarten R.
A1 Hoekstra, Joost B.
A1 Verberne, Hein J.
YR 2013
UL http://jnm.snmjournals.org/content/54/2/208.abstract
AB Brown adipose tissue (BAT) has become a focus of research in the hope of finding a new target to fight obesity. Metabolic BAT activity can be visualized with 18F-FDG PET/CT. Furthermore, the sympathetic innervation of BAT can be visualized with the radiolabeled norepinephrine analog 123I-metaiodobenzylguanidine (123I-MIBG). We aimed to determine whether 123I-MIBG SPECT/CT and 18F-FDG PET/CT identify the same anatomic regions as active BAT in adult humans. Furthermore, we investigated whether the magnitude of BAT activity measured by these techniques correlated. Finally, we tried to establish the optimal time interval between 123I-MIBG administration and subsequent SPECT/CT acquisition to visualize sympathetic stimulation of BAT. Methods: Ten lean (body mass index, 19–25 kg/m2), healthy Caucasian men (age, 18–32 y) underwent one 18F-FDG PET/CT and two 123I-MIBG-SPECT/CT scans within a 2-wk interval. On 2 separate occasions, the subjects were exposed to mild cold (17°C) for 2 h after an overnight fast. After 1 h of cold exposure, 18F-FDG (one occasion) or 123I-MIBG (other occasion) was administered. 18F-FDG PET/CT was performed at 1 h after 18F-FDG administration, and 123I-MIBG-SPECT/CT was performed at 4 and 24 h after 123I-MIBG injection. Results: 18F-FDG uptake in BAT was observed in 8 of 10 subjects, whereas 123I-MIBG uptake was observed in 7 of 10 subjects in both the SPECT/CT scans acquired at 4 h after 123I-MIBG administration and the SPECT/CT scans acquired at 24 h after 123I-MIBG administration. All subjects who showed 123I-MIBG uptake in BAT also showed 18F-FDG uptake in BAT. There was no statistically significant correlation between maximal standardized uptake value of 18F-FDG and semiquantitative uptake of 123I-MIBG at 4 h after administration. However, a positive correlation was found between the maximal standardized uptake value of 18F-FDG and semiquantitative uptake of 123I-MIBG at 24 h after administration (r = 0.64, P = 0.04). Conclusion: 123I-MIBG SPECT/CT, as a marker of sympathetic activity, and 18F-FDG PET/CT, as a marker of metabolic activity, identified the same anatomic regions as active BAT. Moreover, when 123I-MIBG SPECT/CT was performed at 24 h after 123I-MIBG administration, the magnitude of BAT activity measured with these techniques correlated strongly. This finding not only supports that BAT activity in humans is sympathetically influenced but also identifies 123I-MIBG SPECT/CT, when performed 24 h after 123I-MIBG injection, as a method to visualize and quantify sympathetic stimulation of BAT.