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Diagnosis of vascular prosthesis infection with FDG-PET/CT

2004; Elsevier BV; Volume: 40; Issue: 6 Linguagem: Inglês

10.1016/j.jvs.2004.09.032

1097-6809

P Štádler, Otakar Bìlohlávek, Miroslav Špaček, Pavel Michálek,

Infectious Aortic and Vascular Conditions

Fluorodeoxyglucose positron emission tomography (FDG-PET) is on the verge of becoming an established imaging tool in the fields of clinical oncology, cardiology, and neurology. Because of the high glucose uptake of inflammatory cells, FDG scanning is an appropriate tool for use in tracing suspected inflammation or to evaluate infection. PET, although highly sensitive, often lacks the ability to define the precise anatomic location of abnormal FDG accumulation. The new PET/computed tomography (CT) technology provides precise registration of metabolic and structural imaging data in a single session. We report positive FDG-PET/CT findings in an infected vascular prosthesis 6 months after grafting. Our experience and a few available case reports support the hypothesis that FDG-PET/CT may have a promising role in future noninvasive diagnosis of infected vascular grafts. Fluorodeoxyglucose positron emission tomography (FDG-PET) is on the verge of becoming an established imaging tool in the fields of clinical oncology, cardiology, and neurology. Because of the high glucose uptake of inflammatory cells, FDG scanning is an appropriate tool for use in tracing suspected inflammation or to evaluate infection. PET, although highly sensitive, often lacks the ability to define the precise anatomic location of abnormal FDG accumulation. The new PET/computed tomography (CT) technology provides precise registration of metabolic and structural imaging data in a single session. We report positive FDG-PET/CT findings in an infected vascular prosthesis 6 months after grafting. Our experience and a few available case reports support the hypothesis that FDG-PET/CT may have a promising role in future noninvasive diagnosis of infected vascular grafts. Vascular prosthesis infection ranks among the most serious complications in vascular surgery. Vascular graft infection is usually diagnosed with computed tomography (CT) or magnetic resonance imaging. Ultrasound scanning with labeled white blood cell scanning and gallium scanning may be used as ancillary methods to establish vascular graft infection.1Orton D.F. Leveen R.F. Saigh J.A. Culp W.C. Fidler J.L. Lynch T.J. et al.Aortic prosthetic graft infections: radiologic manifestations and implications for management.RadioGraphics. 2000; 20: 977-993Crossref PubMed Scopus (178) Google Scholar Positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-d-glucose (FDG) has become an important imaging tool in clinical oncology, cardiology, and neurology, and has recently been used in the diagnosis of infectious diseases with elevated intracellular glucose metabolism.2Cook G.J. Fogelman I. Maisey M.N. Normal physiological and benign pathological variants of 18-fluoro-2-deoxyglucose positron-emission tomography scanning: potential for error in interpretation.Semin Nucl Med. 1996; 26: 308-314Abstract Full Text PDF PubMed Scopus (332) Google Scholar Glucose accumulates in malignant and inflammatory cells.3De Winter F. Vogelaers D. Gemmel F. Dierckx R.A. Promising role of 18-F-fluoro-d-deoxyglucose positron emission tomography in clinical infectious diseases.Eur J Clin Microbiol Infect Dis. 2002; 21: 247-257Crossref PubMed Scopus (175) Google Scholar The uptake mechanism in infectious and inflammatory diseases has not yet been fully elucidated, but it appears to be related to the fact that glucose is the sole energy source of granulocytes and macrophages during their metabolic burst.4Brown R.S. Leung J.Y. Fisher S.J. Frey K.A. Ethier S.P. Wahl R.L. Intratumoral distribution of tritiated fluorodeoxyglucose in breast carcinoma: are inflammatory cells important?.J Nucl Med. 1995; 36: 1854-1861PubMed Google Scholar Therefore PET, with capability to detect increased glucose levels, represents a new method for use in diagnosing vascular prosthesis infection. Although MEDLINE includes hundreds of references to the key word “infection, vascular prosthesis,” only a few reports relate to the use of FDG-PET for diagnosis of vascular prosthesis infection.5Keidar Z. Engel A. Nitecki S. Bar Shalom R. Hoffman A. Israel O. PET/CT using 2-deoxy-2-[18F]fluoro-d-glucose for the evaluation of suspected infected vascular graft.Mol Imag Biol. 2003; 5: 23-25Crossref PubMed Scopus (32) Google Scholar, 6Krupnick A.S. Lombardi J.V. Engels F.H. Kreisel D. Zhuang H. Alavi Carpenter J.P. 18-fluorodeoxyglucose positron emission tomography as a novel imaging tool for the diagnosis of aortoenteric fistula and aortic graft infection: a case report.Vasc Endovasc Surg. 2003; 37: 363-366Crossref PubMed Scopus (49) Google Scholar, 7Rohde H. Horstkotte M.A. Loeper S. Aberle J. JenickeL Lampidis R. et al.Recurrent Listeria monocytogenes aortic graft infection: confirmation of relapse by molecular subtyping.Diagn Microbiol Infect Dis. 2004; 48: 63-67Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar PET is an imaging technique that enables identification of abnormalities by analyzing cellular metabolic properties rather than their anatomic density. The fusion of FDG-PET and CT scans, acquired in a single session, enables precise localization of any abnormal FDG uptake.8Chacko T.K. Zhuang H. Nakhoda K.Z. Moussavian B. Alavi A. Applications of fluorodeoxyglucose positron emission tomography in the diagnosis of infection.Nucl Med Commun. 2003; 24: 615-624Crossref PubMed Scopus (107) Google Scholar This hybrid PET/CT method, while providing precise metabolic and structural imaging data, may enhance the potential use of FDG in diagnosis and management of infected vascular grafts. A 54-year-old man had fever accompanying a minor defect in the right lower limb heel and multiple defects in the left lower limb. The medical history revealed that a right-sided patent femoropopliteal polytetrafluoroethylene (Gore-Tex; W. C. Gore and Associates) distal bypass had been performed 6 months previously. The operation wounds were completely healed. Blood cultures were obtained, and methicillin-resistant Staphylococcus aureus (MRSA) was found. Ultrasound examination proved reduced flow in the bypass graft, with no exudate around the graft. Magnetic resonance angiograms showed wall thrombi and left-sided superficial femoral artery obliteration. MRSA was also cultivated from all defects, and vancomycin treatment was consequently initiated. Leukocyte count was close to the upper limit of normal. Because of persistently high temperature, vascular graft infection was suspected, and FDG-PET/CT examination was performed. Ninety minutes after intravenous administration of 375 MBq of FDG, data acquisition at CT was started, with intravenous administration of 95 mL of Omipaque 300. Without moving the patient, 3-dimensional PET was subsequently performed with the Biograph duo LSO hybrid PET/CT scanner (Siemens). The field of investigation extended from the mesogastrium to below the knees in multiple 3-minute bed positions. CT scans alone revealed no specific signs of graft infection, except for a faint, partially developed, nonspecific hypodense rim around some parts of the graft (Fig 1). However, intense abnormal FDG uptake along the vascular graft was recorded with PET (Fig 2). On the basis of a clearly positive combined FDG-PET/CT investigation, the graft was removed and substituted with a vein from the left lower limb. The graft was found to be infected and incompletely incorporated into the surrounding tissues. There was a small quantity of slightly cloudy liquid around the prosthesis. The explanted vascular graft was sent for culture and genetic examination, which confirmed the presence of MRSA.Fig 2Positron emission tomography scan demonstrates intense abnormal fluorodeoxyglucose uptake from groin to knee. Uptake is more prominent in central part of thigh. On FDG-PET/CT fused image, focus is precisely localized to vascular graft.View Large Image Figure ViewerDownload (PPT) Graft infection is a serious complication of vascular surgery, with high morbidity and mortality. FDG-PET is becoming a new examining method, especially when symptoms of infection are minimal. Combined FDG-PET/CT may potentially have an incremental benefit over PET alone, because of its ability to accurately localize the tracer uptake in the infected anatomic structure.5Keidar Z. Engel A. Nitecki S. Bar Shalom R. Hoffman A. Israel O. PET/CT using 2-deoxy-2-[18F]fluoro-d-glucose for the evaluation of suspected infected vascular graft.Mol Imag Biol. 2003; 5: 23-25Crossref PubMed Scopus (32) Google ScholarFDG-PET can rapidly provide anatomically clear images of defined areas of inflammation with elevated glucose metabolism. Prompt diagnosis is particularly important for detection of vascular prosthesis infection by a life-threatening aortoenteric fistula.6Krupnick A.S. Lombardi J.V. Engels F.H. Kreisel D. Zhuang H. Alavi Carpenter J.P. 18-fluorodeoxyglucose positron emission tomography as a novel imaging tool for the diagnosis of aortoenteric fistula and aortic graft infection: a case report.Vasc Endovasc Surg. 2003; 37: 363-366Crossref PubMed Scopus (49) Google Scholar This method may also prove useful for diagnosis of rare vascular prosthesis infection caused by Listeria monocytogenes.7Rohde H. Horstkotte M.A. Loeper S. Aberle J. JenickeL Lampidis R. et al.Recurrent Listeria monocytogenes aortic graft infection: confirmation of relapse by molecular subtyping.Diagn Microbiol Infect Dis. 2004; 48: 63-67Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar The literature offers a retrospective analysis of 167 FDG-PET investigations of inflammation. All 3 vascular cases, according to the article, showed accurate PET results.8Chacko T.K. Zhuang H. Nakhoda K.Z. Moussavian B. Alavi A. Applications of fluorodeoxyglucose positron emission tomography in the diagnosis of infection.Nucl Med Commun. 2003; 24: 615-624Crossref PubMed Scopus (107) Google ScholarThe possibility of false positive findings must be kept in mind. Venous thrombosis, sterile inflammation, vasculitis, chronic polyarthritis, or retroperitoneal fibrosis may all lead to an abnormal accumulation of FDG. Furthermore, the early phase of wound healing is physiologically accompanied by an increased accumulation of FDG. However, according to our experience, a wound will heal in 6 weeks, after which the FDG level subsequently decreases. When FDG-PET findings are positive after this initial healing period, the possibility of vascular prosthesis infection should be considered. FDG is not specific for infection, and a sterile inflammation, such as macrophage infiltration of atherosclerotic plaque, can also cause an accumulation of FDG. Published case reports emphasize the problem of vascular prosthesis infection and the potential opportunity for early diagnosis with FDG-PET. The FDG-PET/CT combination can precisely specify the anatomic location of pathologic FDG accumulation.9Townsend D.W. Carney J.P. Yap J.T. Hall N.C. PET/CT today and tomorrow.J Nucl Med. 2004; 45(Suppl 1 (S4-14): S4-S14PubMed Google Scholar In conclusion, FDG-PET/CT may enhance the promising role of FDG in evaluation and management of infected vascular grafts and provide a useful tool for noninvasive diagnosis of this clinical problem. Consequently, an extensive study should be undertaken to determine the role of FDG-PET in diagnosis of vascular prosthesis infection compared with the standard methods currently applied.