Fluorine-18–Labeled Deoxyglucose Positron Emission Tomography in the Diagnosis and Management of Aortitis With Pulmonary Artery Involvement
A 58-year-old woman presented with a complex history of constitutional symptoms, heart block requiring pacemaker, and subsequent heart failure. Initial echocardiograms reported some periaortic thickening but no definite vegetations. The patient had received antibiotic therapy before initial presentation. She had multiple negative serial blood cultures and was treated for culture-negative endocarditis. Over the ensuing months, however, her condition progressively worsened. At the time of her presentation to our facility, she had persistent elevations of her C-reactive protein (CRP; 66 mg/dL), an accelerated erythrocyte sedimentation rate (ESR; 60 mm/h), and a P-antineutrophil cytoplasmic antibody (ANCA) immunofluorescence assay that was positive. She had negative serology for bartonella, coxiella, and brucella, as well as nonreactive syphilis and human immunodeficiency virus tests. C-ANCA, rheumatoid factor, anticardiolipin antibodies, and complement levels were also negative. Contrast-enhanced CT scan of her chest demonstrated significant inflammatory tissue at the root of the aorta extending into the interventricular septum but no other large-vessel involvement (Figures 1A and 2⇓A). An 18F-labeled deoxyglucose (FDG) positron emission tomography (PET) scan of the thorax was performed after a 12-hour fast. Increased FDG uptake was noted in the proximal aorta over the site of inflammatory tissue (Figures 1B and 2⇓B). Fusion of the CT and FDG PET images confirmed the location and extent of the inflammatory area but also identified an area of inflammation in the pulmonary artery not previously appreciated on the CT scan (Figures 1C and 2⇓C). The patient was diagnosed with aortitis and began high-dose prednisolone, with clinical improvement and subsequent normalization of CRP and ESR to 1 mg/dL and 4 mm/h, respectively. Follow-up echocardiograms showed improvement in aortic root thickening, and repeat FDG PET demonstrated resolution of the abnormal FDG uptake seen on the previous PET study (Figure 3B). The case demonstrates the utility of FDG PET (particularly when fused with CT imaging) to detect and monitor active aortitis. In this case, the FDG PET scan identified unsuspected active inflammation in the pulmonary artery that also responded to therapy.
Dr Beanlands is a research scientist supported by the Canadian Institutes of Health Research and the Premier’s Research Excellence Award.