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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/m 2 ) and nine obese (BMI 36±1 kg/m 2 ) young men. On a separate day, a placebo was administered to the same participants. BAT activity was assessed by measuring glucose uptake with [ 18 F]fluorodeoxyglucose and positron emission tomography-computed tomography imaging.

Objective To compare the accuracy of 68gallium prostate‐specific membrane antigen positron emission tomography/computed tomography (68Ga‐PSMA PET/CT) with multiparametric MRI (mpMRI) in detecting and localising primary prostate cancer when compared with radical prostatectomy (RP) specimen pathology. Patients and methods Retrospective review of men who underwent 68Ga‐PSMA PET/CT and mpMRI for primary prostate cancer before RP across four centres between 2015 and 2018. Patients undergoing imaging for recurrent disease or before non‐surgical treatment were excluded. We defined pathological index tumour as the lesion with highest International Society of Urological Pathology Grade Group (GG) on RP specimen pathology. Our primary outcomes were rates of accurate detection and localisation of RP specimen pathology index tumour using 68Ga‐PSMA PET/CT or mpMRI. We defined tumour detection as imaging lesion corresponding with RP specimen tumour on any imaging plane, and localisation as imaging lesion matching RP specimen index tumour in all sagittal, axial, and coronal planes. Secondary outcomes included localisation of clinically significant and transition zone (TZ) index tumours. We defined clinically significant disease as GG 3–5. We used descriptive statistics and the Mann–Whitney U‐test to define and compare demographic and pathological characteristics between detected, missed and localised tumours using either imaging modality. We used the McNemar test to compare detection and localisation rates using 68Ga‐PSMA PET/CT and mpMRI. Results In all, 205 men were included in our analysis, including 133 with clinically significant disease. There was no significant difference between 68Ga‐PSMA PET/CT and mpMRI in the detection of any tumour (94% vs 95%, P > 0.9). There was also no significant difference between localisation of all index tumours (91% vs 89%, P = 0.47), clinically significant index tumours (96% vs 91%, P = 0.15) or TZ tumours (85% vs 80%, P > 0.9) using 68Ga‐PSMA PET/CT and mpMRI. Limitations include retrospective study design and non‐central review of imaging and pathology. Conclusion We found no significant difference in the detection or localisation of primary prostate cancer between 68Ga‐PSMA PET/CT and mpMRI. Further prospective studies are required to evaluate a combined PET/MRI model in minimising tumours missed by either modality.

ClinicalTrials.gov NCT02236962 FUNDING: This study was funded by the National Health and Medical Research Council of Australia Program Grant (1036352) and the OIS scheme from the Victorian State Government.

BackgroundTo evaluate the effects of long-acting somatostatin analogue (SSA) therapy on 68Ga-DOTA-octreotate (GaTate) uptake at physiological and metastatic sites in neuroendocrine tumour (NET) patients.MethodsTwenty-one patients who underwent GaTate PET/CT before and after commencement of SSA therapy were reviewed. Maximum standardized uptake values (SUVmax) were measured in normal organs. Changes in uptake of 49 metastatic lesions in 12 patients with stable disease were also compared. Serum chromogranin-A (CgA) levels were available for correlation between scans in 17/21 patients.ResultsMean thyroid, spleen and liver SUVmax decreased significantly following SSA therapy from a baseline of 5.9 to 3.5, 30.3 to 23.1 and 10.3 to 8.0, respectively (p = < 0.0001 for all). Pituitary SUVmax increased from 10.2 to 11.0 (p = 0.004) whereas adrenal and salivary gland SUVmax did not change. Tumour SUVmax increased in 7 of 12 patients with stable disease; CgA was stable or decreasing in 5 of these patients. 30/49 (61%) metastatic lesions had an increase in SUVmax and lesion-to-liver uptake ratio increased in 40/49 (82%) following SSA therapy.ConclusionLong-acting SSA therapy decreases GaTate uptake in the thyroid, spleen and liver but in most cases increases intensity of uptake within metastases. This has significant implications for interpretation of GaTate PET/CT following commencement of therapy as increased intensity alone may not represent true progression. Our findings also suggest pre-dosing with SSA prior to PRRT may enable higher doses to be delivered to tumour whilst decreasing dose to normal tissues.Electronic supplementary materialThe online version of this article (10.1186/s40644-018-0136-x) contains supplementary material, which is available to authorized users.