Lymphangiography causes false-positive findings on 18F-FDG PET imaging

18F-FDG positron emission tomography (PET) may alter therapeutic management of patients with cervical cancer because 18F-FDG-positive pelvic and para-aortic lymph nodes are associated with lower progression-free survival and vice versa. However, the accuracy of 18F-FDG PET might be impaired by a preceding lymphangiography (LAG).

LAG, magnetic resonance (MR)-imaging and 18F-FDG PET were performed in 6 patients with cervical cancer stage FIGO IB and II. All patients were scheduled for radical hysterectomy and pelvic and para-aortic lymphadenectomy. The results of LAG, MR-imaging and 18F-FDG PET were compared with histological findings.

18F-FDG PET showed false-positive foci in both patients who had LAG before PET-study but not in 4 patients who had LAG thereafter. Histology confirmed false-positive 18F-FDG accumulation in lymphnodes to be consistent with granulomateous changes as induced by foregoing LAG.

Whenever 18F-FDG PET and LAG are performed in the same patient to assess the extent of lymph-node metastases, LAG should always be done after the 18F-FDG PET study to obviate false-positive results.