Added Value of Abnormal Lymph Nodes Detected with FDG-PET/CT in Suspected Vascular Graft Infection

Simple Summary Patients with a suspected vascular graft and endograft infection regularly undergo a medical imaging examination with radioactive labelled glucose as a tracer (F-18-fluorodeoxyglucose positron emission tomography/computed tomography) for diagnosis. Nuclear medicine physicians currently use the intensity and uptake pattern of the tracer around the prosthesis as an indication for infection. This study aimed to investigate the added value of possibly present lymph nodes in the diagnosis of vascular graft infection. Uptake and enlargement of lymph nodes is highly indicative for vascular graft infections but does not add to existing interpretation criteria. Vascular graft and endograft infections (VGEI) cause a serious morbidity and mortality burden. F-18-fluorodeoxyglucose positron emission tomography/computed tomography (F-18-FDG PET/CT) imaging is frequently used in the diagnostic workup, but the additional value of abnormal (F-18-FDG active and/or enlarged) locoregional lymph nodes is unknown. In this retrospective study, the additional diagnostic value of abnormal locoregional lymph nodes on F-18-FDG PET/CT imaging for VGEI was evaluated, including 54 patients with a culture-proven VGEI (defined according to the Management of Aortic Graft Infection [MAGIC] group classification) and 25 patients without VGEI. F-18-FDG PET/CT was qualitatively and quantitatively assessed for tracer uptake and pattern at the location of the vascular graft, and locoregional lymph node uptake and enlargement (>10 mm). F-18-FDG uptake intensity and pattern independently predicted the presence of VGEI by logistic regression (X-2: 46.19, p < 0.001), with an OR of 7.38 (95% CI [1.65, 32.92], p = 0.009) and 18.32 (95% CI [3.95, 84.88], p < 0.001), respectively. Single visual assessment of abnormal locoregional lymph nodes predicted the presence of VGEI with a sensitivity of 35%, specificity of 96%, PPV of 95%, and NPV of 41%. The visual assessment of abnormal lymph nodes after qualitative assessment of F-18-FDG uptake intensity and pattern at the vascular graft location did not independently predict the presence of VGEI by logistic regression (X-2: 3.60, p = 0.058; OR: 8.25, 95% CI [0.74, 63.37], p = 0.096). In conclusion, detection of abnormal locoregional lymph nodes on F-18-FDG PET/CT has a high specificity (96%) and PPV (95%) for VGEI. However, it did not add to currently used F-18-FDG PET/CT interpretation criteria.