Case Report
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World J Radiol. Dec 28, 2013; 5(12): 498-502
Published online Dec 28, 2013. doi: 10.4329/wjr.v5.i12.498
Dynamic 18F-fluorodeoxyglucose positron emission tomography/CT in hibernoma: Enhanced tracer uptake mimicking liposarcoma
Christos Sachpekidis, Safwan Roumia, Matthias Schwarzbach, Antonia Dimitrakopoulou-Strauss
Christos Sachpekidis, Safwan Roumia, Antonia Dimitrakopoulou-Strauss, Medical Positron Emission Tomography Group-Biological Imaging, Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, 69115 Heidelberg, Germany
Matthias Schwarzbach, Surgical Clinic, Klinikum Frankfurt Höchst, 65929 Frankfurt, Germany
Author contributions: Sachpekidis C performed positron emission tomography/CT scanning and wrote paper; Roumia S was attending physician and wrote paper; Schwarzbach M performed surgical operations; Dimitrakopoulou-Strauss A performed positron emission tomography/CT evaluations, organized and overviewed the report.
Correspondence to: Christos Sachpekidis, MD, Medical Positron Emission Tomography Group -Biological Imaging, Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Im Neuenheimer Feld 280, 69115 Heidelberg, Germany. christos_saxpe@yahoo.g
Telephone: +49-62-21422477 Fax: +49-62-21422476
Received: September 3, 2013
Revised: October 14, 2013
Accepted: October 18, 2013
Published online: December 28, 2013
Abstract

We report on two cases of patients with fat-equivalent masses in computed tomography (CT), referred to our department for dynamic positron emission tomography/CT (dPET/CT) with 18F-fluorodeoxyglucose (18F-FDG) in order to investigate their dignity. Both qualitative and quantitative information, as derived from dPET/CTs, couldn’t exclude a high-grade liposarcoma: Visual evaluation, revealed a large hypermetabolic focus of intense 18F-FDG uptake in each patient (average SUVs 8.3 and 11.3). Regression-based parametric imaging demonstrated an enhanced distribution volume, which correlates to perfusion, and a high phosphorylation rate that correlates to cell viability. Kinetic analysis, based on a two-tissue compartment model demonstrated an enhanced FDG transport k1 and an enhanced phosphorylation rate k3. A non-compartmental approach based on fractal dimension revealed also enhanced values. However, final diagnosis was based on biopsy, which revealed hibernoma, a benign brown fat tumor. Brown adipose contains increased numbers of mitochondria and a high-rate of glucose metabolism. Therefore, they have increased FDG uptake. The evaluation of lipomatous lesions on CT, with high FDG uptake, should include the possibility of hibernoma as a differential diagnosis.

Keywords: Hibernoma, Dynamic positron emission tomography/CT, 18F-fluorodeoxyglucose, Kinetic Modeling, Parametric imaging

Core tip: We report on two cases of patients with fat-equivalent masses in computed tomography (CT), referred to our department for dynamic positron emission tomography/CT (dPET/CT) with 18F-fluorodeoxyglucose (18F-FDG) in order to investigate their dignity. Both qualitative and quantitative information, as derived from dPET/CTs, couldn’t exclude a high-grade liposarcoma. The evaluation of lipomatous lesions on CT, with high FDG uptake, should include the possibility of hibernoma as a differential diagnosis.