Clin Rheumatol DOI 10.1007/s10067-014-2648-5

ORIGINAL ARTICLE

The value of FDG-PET in the diagnosis of thromboangiitis obliterans—a case series Gerald Hackl & Robert Milosavljevic & Klara Belaj & Thomas Gary & Peter Rief & Franz Hafner & Rainer W. Lipp & Marianne Brodmann

Received: 3 April 2014 / Revised: 21 April 2014 / Accepted: 22 April 2014 # Clinical Rheumatology 2014

Abstract Thromboangiitis obliterans (TAO) is an inflammatory vascular disease affecting dominantly the vessels of the extremities and is etiologically strongly associated with tobacco consumption. Different imaging techniques are generally used to exclude potential differential diagnoses. We investigated the value of 18 F-flourodeoxyglucose positron emission tomography ([18 F]FDG-PET) in the diagnosis of TAO. All consecutive patients with diagnosed TAO between Nov 2001 and Nov 2003 at our institution who underwent [18 F]FDGPET in the diagnostic workup were analyzed retrospectively. Whole-body scans were conducted after a fasting period of at least 6 h and blood glucose levels lower than 180 mg/dl. The primary endpoint was defined as significantly increased vascular FDG uptake. Tracer uptake was visually determined and, in accordance with strength, divided into grades 0 to 3. In total, ten patients were statistically evaluated. The median patient age at the date of the first [18 F]FDG-PET was 41.5 years. Repetitive FDG-PET imaging was performed in seven out of ten patients (70 %). The endpoint was objectified in one of the initial examinations (10 %) and in another one out of seven follow-up scans (14.3 %). One positive [18 F]FDG-PET was observed in the pelvic vessels and the other in the infrapopliteal arteries. Therefore, increased tracer uptake could be observed in two examinations on two different patients (both with grade 3 tracer uptake) out of 17 conducted [18 F]FDG-PETs in total. The [18 F]FDG-PET was

G. Hackl (*) : R. Milosavljevic : K. Belaj : T. Gary : P. Rief : F. Hafner : M. Brodmann Division of Angiology, Department of Internal Medicine, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria e-mail: [email protected] R. W. Lipp Division of Nuclear Medicine, Department of Radiology, Medical University of Graz, Graz, Austria

not a suitable investigative procedure for the diagnosis of TAO in the present patient cohort. Keywords Buerger’s disease . Diagnosis . F-18-FDG-PET . Thromboangiitis obliterans . Vasculitis

Introduction Positron emission tomography (PET) is a noninvasive imaging technique that visualizes body regions with the aid of radioactively labeled tracers. Based on the distribution of 18 F-flourodeoxyglucose ([18 F]FDG), tissues with increased glucose metabolism and, consequently, increased cellular activity, can be depicted. [18 F]FDG is a glucose labeled with 18fluorine, which constitutes a positron emission source that can be utilized for imaging purposes. The labeled glucose is transported into the cells via the GLUT-1 transporter mechanism like normal glucose. There, the labeled glucose is phosphorylated into FDG-6 phosphate via the hexokinase pathway and cannot leave the cell before it is subject of radioactive decay [1]. This radioactive decay can be detected with the help of a PET camera, and the locations of glucose turnover can be illustrated on sectional images. In case of malignant tumors and inflammatory diseases in particular, the glucose metabolism is increased. Therefore, the [18 F]FDG-PET is a good option for the diagnosis of these diseases. Additionally, the [18 F]FDG-PET has been firmly established in the diagnosis of large vessel vasculitis [2]. However, the value of [18 F]FDG-PET for the diagnosis of small and medium vessel vasculitis is unclear so far. Thromboangiitis obliterans (TAO) is a disease that is etiologically strongly associated with tobacco consumption. The prevalence of the disease among peripheral arterial disease patients ranges from 0.5 to 5.6 % in Western Europe to 45 to 63 % in India, 16 to 66 % in Korea and Japan, and 80 %

Clin Rheumatol

among Jews of Ashkenazi ancestry living in Israel [3]. It leads typically to a nonatherosclerotic, segmental, inflammatory affection of the small- and medium-sized arteries, veins, and nerves in the upper and lower extremities [4]. To date, ultrasound, computed tomography angiography, magnetic resonance angiography, and digital subtraction angiography are the imaging techniques used for diagnostic purposes. However, none of these imaging techniques can reproduce inflammatory vascular changes directly. Therefore, we investigated the value of [18 F]FDG-PET for the diagnosis of TAO retrospectively.

Material and methods Patients All patients who were diagnosed with TAO between Nov 2001 and Nov 2003 and who underwent a [18 F]FDG-PET within the diagnostic workup were included in the present retrospective study. In most cases, imaging was repeated after 2 to 8 months. All patients were given an antiplatelet therapy with ASA of 100 mg per day, and none of the patients received immunosuppressive therapy at the time of the [18 F]FDG-PET. Within the diagnostic workup, antinuclear antibodies, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), as well as blood count were determined for each patient. Important differential diagnoses were excluded by color-coded duplex sonography, magnetic resonance angiography, as well as digital subtraction angiography. Regarding the aspect of the underlying morphology of the arterial lesions, endovascular revascularizations were unfeasible. TAO was diagnosed by means of the established Shionoya criteria (onset of disease prior to age of 50 years, history of smoking, involvement of the infrapopliteal arteries, involvement of the upper extremity or migrating phlebitis, and the absence of atherosclerotic risk factors other than smoking respectively) [5]. In accordance with these criteria, no patient was suffering from diabetes. The study was approved by the International Review Board (IRB) of the Medical University Graz, Austria (IRB No. 26– 083 ex 13/14), and all patients gave their written informed consent for the [18 F]FDG-PET procedure. Therefore, procedures have been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. [18 F]FDG-PET All [18 F]FDG-PET examinations were conducted after a fasting period of at least 6 h as well as with blood glucose levels lower than 180 mg/dl. An hour prior to the examination, 6.5 Mbq/kg of [18 F]FDG was injected intravenously. Whole-

body scans were executed via full-ring PET camera system (ECAT V 7,2,1; Siemens Erlangen, Germany) with an axial field of view of 10.1 cm. The endpoint was defined as a significantly increased vascular FDG uptake, which was clearly set apart from the background. Thereby, the tracer uptake was visually detected and, in accordance with strength, divided into grades 0 to 3 (0 = no tracer uptake; 1 = slight tracer uptake: uptake comparable with normal chest uptake; 2 = moderate tracer uptake: uptake between chest uptake and normal liver uptake; and 3 = high tracer uptake: higher than physiological liver uptake). The scintigraphic recordings were assessed by experts in nuclear medicine. Statistics Descriptive statistics were conducted via explorative data analysis. To evaluate the distribution of continuous variables, a one-sample Kolmogorov-Smirnov test was performed. In case of normal distribution, a t test was used to evaluate differences between the two groups ([ 18 F]FDG-PET positive/negative). In case of nonparametrical data, a Mann– Whitney U test was utilized. Qualitative command variables were compared via crosstabs, as well as the chi-square and Fisher exact tests if indicated. Statistical significance was defined as a p value of

The value of FDG-PET in the diagnosis of thromboangiitis obliterans--a case series.

Thromboangiitis obliterans (TAO) is an inflammatory vascular disease affecting dominantly the vessels of the extremities and is etiologically strongly...
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