Optimising the detection and reproducibility of human brown adipose tissue by PET-CT in a subtropical climate. — ASN Events
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Optimising the detection and reproducibility of human brown adipose tissue by PET-CT in a subtropical climate. (#325)

Sandya Jalapu 1 2 , Christina Jang 1 2 , Phillip Law 2 3 , Susanne Jeavons 3 , Ken Ho 1 2
  1. Diabetes and Endocrinology, Princess Alexandra Hospital, Woolloongabba, Qld, Australia
  2. School of Medicine, University of Queensland, Brisbane, Qld, Australia
  3. Medical Imaging, Princess Alexandra Hospital, Brisbane, Qld, Australia

Background: The detection rate of brown adipose tissue (BAT) by Positron Emission Tomography (PET)-CT is influenced by environmental temperature. It is 6 fold higher in winter than in summer and 4 fold lower in tropical than in cooler regions (1-2). These factors are likely to contribute to the poor reproducibility of BAT detection by PET-CT (3).
Aim: To develop a standardised protocol for improved detection of BAT by PET-CT
Method: We undertook two studies. The first examined the detection rate under ambient conditions in PET-CT scans for oncological indications at a tertiary hospital located in subtropical environment during 2011-2013. The second involved two cold stimulation protocols in healthy volunteers: a) 6 subjects (3M/3F, age 36 ± 6 years, BMI 20.9 ± 0.9 kg/m2) underwent PET-CT scans between October 2011-February 2012, with hands and feet immersed in ice water for 30-60 minutes in a room at 24oC prior to scanning, and b) 9 subjects, (7M/2F, age 39 ±4 years, BMI 27.6 ±2.6 kg/m2) stayed in an air-conditioned room at 19°C for 3h prior to scanning from June 2012-February 2013. Scanning was repeated in these 9 subjects under identical conditions within 6 weeks.
Results: In the first study BAT was detected in 0.7% of 2284 clinical scans performed in 2202 patients at room temperature.
From ice water immersion, BAT was detected in 1 of 6 subjects (16.7%). From cool room exposure, BAT was detected in 6 of 9 scans (66.7%). On repeat scanning in the latter, 8 were concordant and one discordant.
Summary: Protocol involving 3h of cold stimulation in an air-conditioned room improved the rate of detection from 0.7% to 67% with 89% reproducibility.
Conclusion: Standardised preparation involving 3h of cold stimulation markedly enhances the sensitivity and reproducibility of BAT detection by PET-CT in subtropical environment.

Supported by the Princess Alexandra Hospital Research Support Scheme and the NHMRC of Australia.

References:
1. Huang YC , Hsu CC, Wang PW, Chang YH, Chen TB, Lee BF, Chiu NT 2012
Scientific world journal 2012:793039
2. Au-Yong IT, Thorn N ,Ganatra R,Perkins AC,Symonds ME Diabetes 2009
Nov;58(11):2583-7
3. Lee P, Swarbrick MM, Ho KK. 2013 Endocr Rev. Jun;34(3):413-38

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