Aortitis as Cause of Chest Pain: Role of FDG-PET in a Multimodal Diagnostic Approach

Abstract

Diagnostic imaging plays a critical role in identifying aortitis. (1) Computed tomography (CT) angiography of the aorta and thoracic magnetic resonance imaging (MRI) are essential resources to discriminate the different causes of chest pain. Nonetheless, once the aorta is identified as responsible for the symptoms, there are several conditions that can cause confusion in the diagnosis of aortitis, such as acute aortic syndrome (intramural hematoma, aortic dissection, and penetrating atherosclerotic ulcer) and different types of stent-graft leaks. Inflammation of the aortic wall may be caused by inflammatory, infectious, paraneoplastic or idiopathic diseases. Use of radioisotope techniques such as 18-fluorodeoxyglucose positron emission tomography (18 F-FDG PET) is an accurate tool for the diagnosis of this infectious or noninfectious inflammation. (2) We report the case of a patient with chest pain, where PET/CT scan revealed an aortic inflammatory process that redefined the diagnosis and treatment. This 74-year-old male patient was a heavy smoker and had hypertension and dyslipidemia. A control chest CT scan after radiation therapy for laryngeal cancer revealed an atherosclerotic, penetrating aortic ulcer, with maximum diameter of 22 mm in the lower wall of the juxtaductal region, which was treated with a thoracic stent-graft. The patient progressed with recurrent chest pain requiring new hospitalization. The condition was interpreted as of coronary etiology, and a coronary angiography (CA) with angioplasty and stent placement in the mid-circumflex artery was therefore performed. The patient was always afebrile, but was admitted in our center due to persistent chest pain. Lab tests on admission showed white blood cell count of 10 600/mm 3; erythrocyte sedimentation rate (ESR), 92 mm/h; C-reactive protein (CRP), 12.7 mg/ dL; high-sensitivity troponin T, 117 mg/dL; and negative blood cultures. A new CA showed no lesions and a patent stent. Thoracic aortography ruled out aortic dissection and stent-graft endoleaks. An 18 F-FDG PET/CT scan (Figure 1) exposed a thickened aortic arch wall, with intravenous contrast enhancement and radiotracer uptake with a maximum standardized uptake value (SUVmax) of 14.4, predominantly in the medial sector and, to a lesser extent, in the inferior sector. The ulcer was properly excluded with no evidence of endoleaks or expansion. The aortic stent showed no signs of pathological uptake. Due to suspected diagnosis of inflammatory aortitis, systemic inflammatory markers were requested, including VDRL, FTA-Abs, FAN in Hep-2, ANCA c and p, HLA-B*51 (for Behçet’s disease), and IgG4, with negative results. The condition was thus interpreted as isolated aortitis after aortic stent graft placement in the context of preexisting inflammatory aortic disease. Although giant cell arteritis —an entity accounting for 70% of aortitis in patients >50 years of age, and involving the aortic wall in 15-22% of cases in a diffuse or segmental form, with high probability of causing aortic aneurysms— cannot be definitively ruled out as a differential diagnosis, (3) this diagnosis is unlikely in our case as the patient did not meet the classification criteria or the typical clinical manifestations. The patient was started on meprednisone and made good progress, with resolution of symptoms and normalization of inflammatory parameters (ESR and CRP). A follow-up 18 F-FDG PET/CT scan at 2 months (Figure 2) showed persistent metabolic activity in the medial and inferior wall of the aortic arch, extending to the lateral sector, and the same uptake values as in the previous study. Aortitis is a nonspecific term that refers to inflammatory changes in the aortic wall, often caused by a systemic inflammatory, infectious or non-infectious disease, with different clinical variables and presentation. Therefore, the diagnosis often requires a multimodal imaging approach. (4) In our patient, after an initial CT angiography and two invasive procedures, a PET/CT scan made it possible to redefine the diagnosisinitially oriented to a coronary disease, as aortitis. FDG PET for the diagnosis of inflammatory aortic disease has 98% specificity, a positive predictive value of 93%, and a negative predictive value of 80%. (5) These data are also relevant for the follow-up and treatment of these patients, based on the inflammatory activity provided by the images and the evolving clinical and serological data. (6)

Conflicts of interest None declared.
(See authors’ conflicts of interest forms on the website/Supplementary material).