Abstract No. 474 A Pilot study of the feasibility of ultrasound-PET/CT fusion–guided supraclavicular brown adipose tissue biopsy

To determine the feasibility of ultrasound-PET/CT fusion imaging guidance for supra-clavicular adipose tissue biopsies This IRB-approved prospective study included seven healthy volunteers (5F/2M) who had a prior 18F-FDG PET/CT showing metabolically active BAT. Manual registration of the ipsilateral sterno-clavicular joint was performed using an electromagnetically tracked 15-7io probe. A 2D ultrasound sweep of the ipsilateral clavicle was then obtained after manual alignment of the electromagnetic tracking space to the patient. A 3D ultrasound volume was reconstructed and then registered to the CT portion of the PET/CT image. Manual correction of image fusion was carried out on an as-needed basis. Ultrasound/CT/PET fusion was displayed in real-time for biopsy guidance. Biopsies were performed with 14-16G Temno needles under direct ultrasound visualization in the fused image. BAT was confirmed via 1) the presence of mRNA for uncoupling protein 1 (UCP1), the thermogenic protein specific to brown adipocytes, and 2) comparison of levels obtained from adjacent subcutaneous white adipose tissue (WAT) obtained from each subject. From the seven subjects enrolled, deep supraclavicular brown fat was acquired from 6/7 and superficial white fat from 7/7. The deep biopsies had 40X higher levels of UCP1 (P<0.001), consistent with BAT, validating the accuracy of the fused imaging guidance. Complications included self-limited site erythema (1/7), pressure (1/7), and paresthesias (1/7). Ultrasound-PET/CT fusion is a feasible approach for site-specific sampling human supraclavicular BAT and WAT. This novel method should enable a new, wide range of studies of human BAT physiology.