Ephedrine activates brown adipose tissue in lean but not obese humans.

AIMS/HYPOTHESIS: Brown adipose tissue (BAT) activation increases energy consumption and may help in the treatment of obesity. Cold exposure is the main physiological stimulus for BAT thermogenesis and the sympathetic nervous system, which innervates BAT, is essential in this process. However, cold-induced BAT activation is impaired in obese humans. To explore the therapeutic potential of BAT, it is essential to determine whether pharmacological agents can activate BAT. METHODS: We aimed to determine whether BAT can be activated in lean and obese humans after acute administration of an orally bioavailable sympathomimetic. In a randomised, double-blinded, crossover trial, we administered 2.5 mg/kg of oral ephedrine to nine lean (BMI 22 ± 1 kg/m²) and nine obese (BMI 36 ± 1 kg/m²) young men. On a separate day, a placebo was administered to the same participants. BAT activity was assessed by measuring glucose uptake with [¹8F]fluorodeoxyglucose and positron emission tomography-computed tomography imaging. RESULTS: BAT activity was increased by ephedrine compared with placebo in the lean, but unchanged in the obese, participants. The change in BAT activity after ephedrine compared with placebo was negatively correlated with various indices of body fatness. CONCLUSIONS/INTERPRETATION: BAT can be activated via acute, oral administration of the sympathomimetic ephedrine in lean, but not in obese humans.

18 F-FDG PET/CT influences management in patients with known or suspected pancreatic cancer.

BACKGROUND: The aims of this study were (i) to assess and validate the incremental information of positron emission tomography/computed tomography (PET/CT) over conventional staging investigations (CSI) and (ii) to assess the management impact of PET/CT in patients with known or suspected pancreatic cancer. METHODS: Between October 2007 and September 2008, 22 PET/CT scans were performed using a dedicated PET/CT scanner in 21 patients with known or suspected pancreatic cancer. Follow up was used to reconcile discordance between PET/CT and CSI. The pre-PET/CT management plan and/or intent were prospectively recorded in all scans. The post-PET/CT management plan was determined from the medical record and/or discussions with treating clinicians. The management impact of PET/CT was classified as high, medium, low or none defined using Australian and New Zealand Association of Physicians in Nuclear Medicine PET data collection project criteria. RESULTS: PET/CT and CSI were discordant in 14/22 (64%: 95% CI; 43-84%) scans. Of the 14 discordant scans, PET/CT assessment was correct in eight, conventional imaging in four and there was insufficient information in two. Overall, PET/CT management impact was classified as high (n= 6), medium (n= 3), low (n= 9) or none (n= 4). Significant changes in management (high or medium impact) were induced by PET/CT in 9/22 scans (41%: 95% CI; 20-62%) predominantly by correctly modifying the disease extent. CONCLUSION: PET/CT has an incremental benefit over CSI and has a significant impact on management in patients with known or suspected pancreatic cancer. PET/CT merits consideration as part of the non-invasive evaluation of patients with known or suspected pancreatic cancer.

Evaluation of pulmonary nodules and lung cancer with one-inch crystal gamma coincidence positron emission tomography/CT versus dedicated positron emission tomography/CT.

Dedicated positron emission tomography (PET)/CT scanners using BGO and related detectors (d-PET) have become standard imaging instruments in many malignancies. Hybrid gamma camera systems using NaI detectors in coincidence mode (g-PET) have been compared to d-PET but reported usefulness has been variable when gamma cameras with half-inch to three-fourth-inch thick crystals have been used without CT. Our aim was to compare g-PET with a 1-in.-thick crystal and inbuilt CT for lesion localization and attenuation correction (g-PET/CT) and d-PET/CT in patients presenting with potential and confirmed lung malignancies. One hour after (18)F-fluorodeoxyglucose (FDG), patients underwent BGO d-PET/CT from jaw to proximal thigh. This was followed by one to two bed position g-PET/CT 194 +/- 27 min after FDG. Each study pair was independently analysed with concurrent CT. d-PET/CT was interpreted by a radiologist experienced in both PET and CT, and g-PET/CT by consensus reading of an experienced PET physician and an experienced CT radiologist. A TNM score was assigned and studies were then unblinded and compared. Fifty-seven patients underwent 58 scan pairs over 2 years. Eighty-nine per cent concordance was shown between g-PET/CT and d-PET/CT for the assessment of intrapulmonary lesions, with 100% concordance for intrapulmonary lesions >10 mm (36 of 36). Eighty-eight per cent (51 of 58) concordance was shown between g-PET/CT and d-PET/CT for TNM staging. Coincidence imaging using an optimized dual-head 1-in.-thick crystal gamma camera with inbuilt CT compares reasonably well with dedicated PET/CT for evaluation of indeterminate pulmonary lesions and staging of pulmonary malignancies and may be of some value when d-PET/CT is not readily available.