An 18-year-old man was preoperatively assessed for a varicocele and found to be hypoxemic. A Tc-99m macroaggregated albumin lung perfusion scan showed right-to-left shunting, evidenced by increased radiotracer uptake in the brain, kidneys, thyroid gland, and bilateral supraclavicular areas, a typical location for brown adipose tissue. Chest computerized tomography angiogram study showed supraclavicular fat density areas and multiple pulmonary arteriovenous malformations. The authors report a rare case of brown fat visualization on a lung perfusion scan in a patient with right-to-left shunting, likely because of increased perfusion to activated brown adipose tissue

Marashdeh, Wael

Wahl, Richard L

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Wael Marashdeh

Richard L. Wahl

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Case Report

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Washington University School of MedicineDigital Commons@BeckerOpen Access Publications2015Case report: brown fat accumulation of Tc-99mmacroaggregated albumin in a lung perfusion studyin a patient with multiple lung arteriovenousmalformations and right-to-left shuntingWael MarashdehJohns Hopkins UniversityRichard L. WahlWashington University School of MedicineFollow this and additional works at: http://digitalcommons.wustl.edu/open_access_pubsThis Open Access Publication is brought to you for free and open access by Digital Commons@Becker. It has been accepted for inclusion in OpenAccess Publications by an authorized administrator of Digital Commons@Becker. For more information, please contact engeszer@wustl.edu.Recommended CitationMarashdeh, Wael and Wahl, Richard L., ,"Case report: brown fat accumulation of Tc-99m macroaggregated albumin in a lungperfusion study in a patient with multiple lung arteriovenous malformations and right-to-left shunting." Medicine.94,42. . (2015).http://digitalcommons.wustl.edu/open_access_pubs/4902Case Report: Brown Fat Accumulation of Tc-99mMacroaggregated Albumin in a Lung Perfusion Study in aPatient With Multiple Lung Arteriovenous Malformationsand Right-to-Left ShuntingWael Marashdeh, MD and Richard L. Wahl, MDAbstract: An 18-year-old man was preoperatively assessed for avaricocele and found to be hypoxemic. A Tc-99m macroaggregatedalbumin lung perfusion scan showed right-to-left shunting, evidencedby increased radiotracer uptake in the brain, kidneys, thyroid gland, andbilateral supraclavicular areas, a typical location for brown adiposetissue. Chest computerized tomography angiogram study showed supra-clavicular fat density areas and multiple pulmonary arteriovenousmalformations.The authors report a rare case of brown fat visualization on a lungperfusion scan in a patient with right-to-left shunting, likely because ofincreased perfusion to activated brown adipose tissue.(Medicine 94(42):e1820)Abbreviations: AVM = arteriovenous malformation, BAT = brownadipose tissue, CTA = computerized tomography angiogram, FDG= flourodeoxyglucose, MAA = macroaggregated albumin, SPECT= single photon emission tomography.INTRODUCTIONB rown adipose tissue (BAT) is type of adipose tissue that hasa role in thermogenesis, especially in neonates and youngchildren during cold exposure, by aging BAT becomes whiteadipose tissue; however, a lesser amount of persistent brown fatis present in adults, which also has a some role in energymetabolism, in the last decade due it to common use of F-18fluorodeoxyglucose (FDG) BAT is commonly seen on thesescans, especially in the supraclavicular, axilla, and paraverteb-ral regions; however it can also be seen adjacent to visceralorgans in the mediastinum and abdomen. In cases of coldexposure, BAT becomes activated and ultimately becomesmore apparent on F18 FDG scans.1,2,3,4METHODSNo Institutional Review Board approval was requestedbecause such approval is not required for single case reportsat the Johns-Hopkins Medical Institution. No consent wasobtained because this publication contains no identifiableinformation.This publication methodology included review of theelectronic medical record and review of the available imagesfor our case.Patient InformationAn 18-year-old patient was preoperatively assessed andfound to be hypoxemic. The patient was investigated by a chestcomputerized tomography angiogram (CTA) and a Tc-99mmacroaggregated albumin (MAA) lung perfusion study toevaluate for possibility of arteriovenous malformations (AVMs)within the lung.Diagnostic FindingsThe findings on an anterior perfusion view of the head andupper chest using Tc-99m MAA shows increased radiotraceruptake in the brain, thyroid, and bilateral supra-clavicularregions (Fig. 1). It has been demonstrated previously that inthe presence of shunting in the lungs, a portion of the Tc-99mMAA particles bypass the lung capillary circulation and appearin the systemic circulation.5,6,7,8The uptake in the supra-clavicular region is presumed to bebrown fat because of its location and anatomic correlation withthe expected location of BAT.9,10A chest CTA image shows an AVM in the right lowerlobe (Fig. 2). Other axial slices showed multiple AVMs. Themultiplicity of these lesions suggested a diagnosis of hereditaryhemorrhagic telangiectasia, which was subsequently treatedsuccessfully by vascular embolization, which improved thepatient’s hypoxemia.11,12A coronal chest CTA image shows structures that have fatdensity in the supraclavicular regions as shown in (Figure 3);these areas of well-perfused fat correspond to the areas of Tc-99MAA accumulation seen on the perfusion scan and likelyrepresent areas of BAT perfusion because of brown fat activation.DISCUSSIONBrown adipose tissue uptake has been demonstrated pre-viously with multiple radiotracers, such as Tl-201 chloride, I-123 metaiodobenzylguandine, Tc-99m sestamib, F-18 and H-3FDG, H-3 L-methionine, and H-3 thymidine. The regions ofEditor: Dwight Achong.Received: August 16, 2015; revised: September 20, 2015; accepted:September 22, 2015.From the Department of Radiology and Radiological Science, Division ofNuclear Medicine, Russell H. Morgan, Johns-Hopkins University SchoolofMedicine, Baltimore, MD (WM)., and the Mallinckrodt Institute ofRadiology, Washington University in St. Louis School Of Medicine, St.Louis, MO (RLW).Correspondence: Wael Marashdeh, MD, Russell H. Morgan Department ofRadiology and Radiological Science, Division of Nuclear Medicine,Johns-Hopkins University School of Medicine, 601 N. Caroline Streetsuite 3223, Baltimore, MA 21287 (e-mail: wmarash1@jhmi.edu).The authors have no conflicts of interest to disclose.Copyright # 2015 Wolters Kluwer Health, Inc. All rights reserved.This is an open access article distributed under the Creative CommonsAttribution-NonCommercial-NoDerivatives License 4.0, where it ispermissible to download, share and reproduce the work in any medium,provided it is properly cited. The work cannot be changed in any way orused commercially.ISSN: 0025-7974DOI: 10.1097/MD.0000000000001820Medicine®CLINICAL CASE REPORTMedicine  Volume 94, Number 42, October 2015 www.md-journal.com | 1BAT uptake in these radiotracers are usually the supraclavicularand paravertebral adipose tissues 13,14. The available images wehave, however, show only Tc-99m MAA accumulation in thesupraclavicular adipose tissue with no definite evidence ofaccumulation in the paravertebral adipose tissues, which ifpresent may be obscured by the lung activity.Although we do not have a single-photon emission com-puted tomography image to show the accumulation of Tc-99mMAA in the supraclavicular brown fat, it can be considered thatthe supraclavicular region of uptake on the perfusion images is asite of brown fat accumulation of Tc-99m MAA because of thetypical location and the presence of fat tissue in the supracla-vicular region as shown on the chest CTA coronal imageprovided.The presence of intrapulmonary shunting causing uptakein highly perfused organs including activated brown fat may bean important factor that allowed visualization of the activatedbrown fat in the supraclavicular regions in this patient. Giventhe fact that the examination was performed in a summer month(August) and although we do not have information regarding theenvironment surrounding the patient during the examinationday, we believe the brown fat uptake is attributed to thepresence of metabolically active brown fat with increasedvascularity, which is mainly because of young age (18 yearsold) with the possibility of being because of a surrounding coldenvironment less likely.Although the shunt fraction should have been estimated forthis study, it was not calculated because the clinical concern wasto evaluate for the presence of pulmonary embolism and theimages were sufficient to suggest the diagnosis of intrapulmonaryshunting.We report a rare case of Tc-99m MAA accumulation inBAT in the supraclavicular region, which will help resolvediagnostic dilemma’s in the future if a similar case is encoun-tered.REFERENCES1. Sacks H, Symonds ME. Anatomical locations of human brownadipose tissue: functional relevance and implications in obesity andtype 2 diabetes. Diabetes. 2013;62:1783–1790.2. Poekes L, Lanthier N, Leclecrcq IA. Brown adipose tissue: apotential target in the fight against obesity and the metabolicsyndrome. Clin Sci. 2015;129:933–949.FIGURE 1. This is a perfusion scan using Tc-99 macroaggregatedalbumin of the head and upper chest showing uptake in the brain,thyroid gland, and bilateral supraclavicular regions (arrows).FIGURE 2. This is a representative slice of a chest computerizedtomography angiogram showing one of the multiple arteriove-nous malformations (arrow) detected on the study.FIGURE 3. This is a coronal image of a chest computerizedtomography angiogram showing fat tissue in the supraclavicularregions bilaterally (arrows).Marashdeh et al Medicine  Volume 94, Number 42, October 20152 | www.md-journal.com Copyright # 2015 Wolters Kluwer Health, Inc. All rights reserved.3. Hong TS, Shammas A, Charron M, et al. Brown adipose tissue 18F-FDG uptake in pediatric PET/CT imaging. Pediatr Radiol.2011;41:759–768.4. Chen KY, Brychta RJ, Linderman JD, et al. Brown fat activationmediates cold-induced thermogenesis in adult humans in response toa mild decrease in ambient temperature. J Clin Endocinol Metab.2013;98:1218–1223.5. Lu G, Shih WJ, Chou C, et al. Tc-99m MAA total-body imaging todetect intrapulmonary right-to-left shunts and to evaluate thetherapeutic effect in pulmonary arteriovenous shunts. Clin Nucl Med.1996;21:197–202.6. Palevsky HI, Alavi A. Ventilation perfusion lung scanning in theevaluation of right-to-left shunting. J Nucl Med. 1992;33:2036–2039.7. Salimi Z, Thomasson J, Vas W, et al. Detection of right-to-left shuntwith radionuclide angiocardiography in refractory hypoxemia. Chest.1985;88:784–786.8. Dolezal J. The scintigraphic 99mTc-MAA imaging quantification ofthe right-to-left shunt in a patients with multiple pulmonaryarteriovenous malformation and familial teleangiectasis. Vnitr Lek.2008;54:206–209.9. Hany TF, Gharehpapagh E, Kamel EM, et al. Brown adipose tissue: afactor to consider in symmetrical tracer uptake in the neck and upperchest region. Eur J Nucl Med Mol Imaging. 2002;29:1393–1398.10. Cohade C, Osman M, Pannu HK, et al. Uptake in supraclaviculararea fat (‘‘USA-Fat’’): description on 18F-FDG PET/CT. J NuclMed. 2003;44:170–176.11. Lacombe P, Lacout A, Marcy PY, et al. Diagnosis and treatment ofpulmonary arteriovenousmalformations in hereditary hemorrhagictelangiectasia: an overview. Diagn Interv Imaging. 2013;94:835–848.12. Cottin V, Dupuis-Girod S, Cordier JF, et al. Pulmonary vascularmanifestations of hereditary hemorrhagic telangiectasia (rendu-oslerdisease). Respiration. 2007;74:361–378.13. Fukuchi K, Tatsumi M, Ishida Y, et al. Radionuclide imagingmetabolic activity of brown adipose tissue in a patient withpheochromocytoma. Exp Clin Endocrinol Diabetes. 2004;112:601–603.14. Baba S, Engles JM, Huso DL, et al. Comparison of uptake ofmultiple clinical radiotracers into brown adipose tissue under cold-stimulated and nonstimulated conditions. J Nucl Med. 2007;48:1715–1723.Medicine  Volume 94, Number 42, October 2015 Brown Fat Accumulation in Lung Perfusion StudyCopyright # 2015 Wolters Kluwer Health, Inc. All rights reserved. www.md-journal.com | 3

Case report: brown fat accumulation of Tc-99m macroaggregated albumin in a lung perfusion study in a patient with multiple lung arteriovenous malformations and right-to-left shunting

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Case report: brown fat accumulation of Tc-99m macroaggregated albumin in a lung perfusion study in a patient with multiple lung arteriovenous malformations and right-to-left shunting

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