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PICTORIAL ESSAY
Year : 2015  |  Volume : 30  |  Issue : 4  |  Page : 320-322  

Patterns of brown fat uptake of 18F-fluorodeoxyglucose in positron emission tomography/computed tomography scan


1 Department of Nuclear and Experimental Medical Sciences, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
2 Department of Nuclear Medicine and PET, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Date of Web Publication1-Sep-2015

Correspondence Address:
Dhritiman Chakraborty
Department of Nuclear and Experimental Medical Sciences, Institute of Post Graduate Medical Education and Research, Kolkata - 700 020, West Bengal
India
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Source of Support: Nil., Conflict of Interest: None declared.


DOI: 10.4103/0972-3919.164147

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   Abstract 


Fluorodeoxyglucose (FDG) positron emission tomography (PET) has become the common imaging modality in oncological practice. FDG uptake is seen in brown adipose tissue in a significant number of patients. Recognizing the uptake patterns is important for optimal FDG PET interpretation. The introduction of PET/computed tomography (PET/CT) revolutionized PET imaging, bringing much-needed anatomical information. Careful review and correlation of FDG PET images with anatomical imaging should be performed to characterize accurately any lesion having high FDG uptake.

Keywords: Brown adipose tissue, brown fat, fluorodeoxyglucose positron emission tomography


How to cite this article:
Chakraborty D, Bhattacharya A, Mittal BR. Patterns of brown fat uptake of 18F-fluorodeoxyglucose in positron emission tomography/computed tomography scan. Indian J Nucl Med 2015;30:320-2

How to cite this URL:
Chakraborty D, Bhattacharya A, Mittal BR. Patterns of brown fat uptake of 18F-fluorodeoxyglucose in positron emission tomography/computed tomography scan. Indian J Nucl Med [serial online] 2015 [cited 2019 Dec 15];30:320-2. Available from: http://www.ijnm.in/text.asp?2015/30/4/320/164147




   Introduction Top


Brown adipose tissue (BAT) functions as a thermogenic organ by producing heat to maintain body temperature in many mammals, especially in the young.[1],[2] It is involved in nonshivering thermogenesis and in diet-induced thermogenesis. This tissue has elevated cellular density, rich vascularization, innervations, and multilocular intracellular lipid droplets. BAT overexpress uncoupling protein (UCP1) more than white fat. Fluorodeoxyglucose (FDG) uptake in this hypermetabolic BAT can be confused with nodal uptake, leading to false positive results.[3] It not only can leads to false-positive findings but also can decrease the sensitivity of the tumor uptake by decreasing the pool of FDG availability.[4] BAT requires glucose not as a direct source of heat production but as a source of adenosine triphosphate. The adenosine triphosphate resulting from glycolysis is required for continued fatty acid oxidation in the mitochondrial UCPs in BAT, which is a main mechanism for heat production.[5] It is richly innervated by sympathetic nervous system predominantly expressing β3-adrenergic receptor and glucose accumulation of brown fat is increased by sympathetic stimulation.[6] Brown fat uptake is noted in neck, shoulder, paravertebral region, mediastinum, perirenal, and perigastric regions [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6].[7],[8] Positron emission tomography/computed tomography (PET/CT) allows to verify BAT uptake (standardized uptake value max = 1.9–20) foci have no corresponding anatomic soft-tissue mass detectable by computed tomography (CT) scanning. Rather, the FDG–avid focus fused to tissues of fat density. The corresponding hounsfield are within the reported fat-density range (−150 to −50).[9] It seems improbable that malignant pathologic foci of this intensity and size shown by positron emission tomography (PET) imaging could have no corresponding CT findings. The PET findings could help in recognizing this artifact. The intensity and standardized uptake value are not reliable tools for differentiating among these categories. Several pharmacologic methods have been tried to reduce FDG uptake by hypermetabolic BAT, e.g., use of propranolol, fentanyl, etc. Among the nonpharmacologic approaches use of high-fat, very low-carbohydrate, protein-permitted diet, and warming are the useful approach for significant reduction of the frequency of BAT hypermetabolism. None has been reliable, and most have involved pharmacologic intervention, which is especially undesirable in the pediatric population. Warming has been used, as has administration of benzodiazepines, propranolol, and even fentanyl.[10],[11],[12],[13] Nicotine has been found to increase uptake of hypermetabolic BAT.[14] We present some patterns of brown fat uptake.
Figure 1: Positron emission tomography/computed tomography images, of a 25-year-old male who presented with chondrosarcoma of left inferior pubic ramus, showing supraclavicular, and paravertebral brown fat fluorodeoxyglucose uptake

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Figure 2: A 23-year-old female presented with right subretinal granuloma was subjected to positron emission tomography/computed tomography that shows supraclavicular, paravertebral, and perirenal brown fat fluorodeoxyglucose uptake

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Figure 3: Positron emission tomography/computed tomography imaging in a 20-year-old male case of nonHodgkin lymphoma post six cycles of salvage chemotherapy showing supraclavicular, paravertebral, perisplenic, and perirenal brown fat fluorodeoxyglucose uptake

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Figure 4: Positron emission tomography/computed tomography imaging in a 34-year-old male patient of left-sided seminoma testis post six cycles of chemotherapy and radiotherapy showing supraclavicular, axillary, and paravertebral brown fat fluorodeoxyglucose uptake

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Figure 5: Positron emission tomography/computed tomography imaging in a 22-year-old male patient with Hodgkin's disease showing asymmetrical, perisplenic, and perirenal brown fat fluorodeoxyglucose uptake

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Figure 6: Positron emission tomography/computed tomography images of a 48-year-old female who presented with right carcinoma breast post total mastectomy and axillary clearance, chemotherapy, and radiotherapy. Small area of brown fat fluorodeoxyglucose uptake is seen in the neck

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   Conclusion Top


Unexpected and varied FDG uptake is seen in whole body FDG PET/CT studies. During interpretation of FDG PET/CT scan it should be kept in mind and PET images are correlated with CT images and Hounsfield Units, which will minimize the false positive findings.

Nil.

None declared.



 
   References Top

1.
Cannon B, Houstek J, Nedergaard J. Brown adipose tissue. More than an effector of thermogenesis? Ann N Y Acad Sci 1998;856:171-87.  Back to cited text no. 1
    
2.
Himms-Hagen J. Does brown adipose tissue (BAT) have a role in the physiology or treatment of human obesity? Rev Endocr Metab Disord 2001;2:395-401.  Back to cited text no. 2
    
3.
Shreve PD, Anzai Y, Wahl RL. Pitfalls in oncologic diagnosis with FDG PET imaging: Physiologic and benign variants. Radiographics 1999;19:61-77.  Back to cited text no. 3
    
4.
Bogsrud TV, Lowe V. Normal variants and pitfalls in whole body PET imaging with 18F FDG. Appl Radiol 2006;35:16-30.  Back to cited text no. 4
    
5.
Himms-Hagen J. Brown adipose tissue thermogenesis: Interdisciplinary studies. FASEB J 1990;4:2890-8.  Back to cited text no. 5
    
6.
Hull D, Segall MM. Sympathetic nervous control of brown adipose tissue and heat production in the new-born rabbit. J Physiol 1965;181:458-67.  Back to cited text no. 6
    
7.
Hany TF, Gharehpapagh E, Kamel EM, Buck A, Himms-Hagen J, von Schulthess GK. Brown adipose tissue: A factor to consider in symmetrical tracer uptake in the neck and upper chest region. Eur J Nucl Med Mol Imaging 2002;29:1393-8.  Back to cited text no. 7
    
8.
Cohade C, Osman M, Pannu HK, Wahl RL. Uptake in supraclavicular area fat ("USA-Fat"): Description on 18F-FDG PET/CT. J Nucl Med 2003;44:170-6.  Back to cited text no. 8
    
9.
Kim S, Lee GH, Lee S, Park SH, Pyo HB, Cho JS. Body fat measurement in computed tomography image. Biomed Sci Instrum 1999;35:303-8.  Back to cited text no. 9
    
10.
Christensen CR, Clark PB, Morton KA. Reversal of hypermetabolic brown adipose tissue in F-18 FDG PET imaging. Clin Nucl Med 2006;31:193-6.  Back to cited text no. 10
    
11.
Tatsumi M, Engles JM, Ishimori T, Nicely O, Cohade C, Wahl RL. Intense (18) F-FDG uptake in brown fat can be reduced pharmacologically. J Nucl Med 2004;45:1189-93.  Back to cited text no. 11
    
12.
Söderlund V, Larsson SA, Jacobsson H. Reduction of FDG uptake in brown adipose tissue in clinical patients by a single dose of propranolol. Eur J Nucl Med Mol Imaging 2007;34:1018-22.  Back to cited text no. 12
    
13.
Gelfand MJ, O'hara SM, Curtwright LA, Maclean JR. Pre-medication to block [(18) F] FDG uptake in the brown adipose tissue of pediatric and adolescent patients. Pediatr Radiol 2005;35:984-90.  Back to cited text no. 13
    
14.
Baba S, Tatsumi M, Ishimori T, Lilien DL, Engles JM, Wahl RL. Effect of nicotine and ephedrine on the accumulation of 18F-FDG in brown adipose tissue. J Nucl Med 2007;48:981-6.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]



 

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