The strong but nonspecific relationship between 18F-FDG uptake in the lower-extremity veins and venous thromboembolism.

Venous thromboembolism (VTE) can present as deep vein thrombosis (DVT) and/or acute pulmonary embolism (PE). In fluorine-18 fluorodeoxyglucose (18F-FDG) PET/CT, 18F-FDG activity along the deep veins of the lower extremities (LE) is often observed and, unless it is associated with focal intense activity, is not considered abnormal. However, anecdotally it has been associated with the placement of an inferior vena cava filter. In this short paper we intend to investigate this association. We found 10 patients who were investigated in the vascular laboratory by means of either LE or upper-extremity duplex or a chest computed tomography with PE protocol, or who had undergone the placement of an inferior vena cava filter between 27 April 2010 and 7 January 2013 and who had also undergone one or more 18F-FDG-PET scan(s) that included the LE. Seventeen patients without venous 18F-FDG uptake were added as controls. 18F-FDG uptake visualized in the LE was scored as the number of positive LE veins and the extent of the radiotracer uptake. The time intervals between the VTE event and the 18F-FDG-PET scan(s) were recorded. The time intervals between the most remote and the closest 18F-FDG-PET before a VTE event averaged 79 ± 101 and 49 ± 82 days, respectively, and the closest and the most remote 18F-FDG-PET after the VTE event averaged 58 ± 50 and 122 ± 124 days. The extent of uptake in the LE veins averaged 7 ± 2 for the patients with an acute DVT on LE duplex and 5 ± 3 for those with negative or chronic DVT on LE duplex (P=nonsignificant). Two patients (n=3 and 10) were negative for VTE events and had an extent of 0. The number of positive events correlated slightly with the extent of venous uptake (r=0.69). The 17 control patients without venous uptake on 18F-FDG-PET had no history of VTE. There was an association between LE venous uptake of 18F-FDG and risk for VTE. The association was not related to the location of the VTE, nor to the timing of the VTE.