Postoperative changes after surgical mesh hernia repair: a pitfall in interpretation of 18F-FDG PET-CT

Objective: A number of case reports have demonstrated FDG uptake around mesh prostheses after hernia repair surgery. This study characterizes FDG PET-CT findings after hernia repair with synthetic mesh in a series of cancer patients. Materials and methods: FDG PET-CT studies were reviewed for increased FDG uptake consistent with CT appearances of post-surgical hernia repair in cancer patients. The findings were correlated with clinical data and follow-up studies. Results: 53 PET-CT studies in 22 patients (18 males, 31–79 years) were identified. Surgery for repair of inguinal (n = 14), ventral (n = 5) or umbilical (n = 3) hernia was performed, 4–204 months prior to PET-CT. FDG avidity was focal or linear in the region of the anterior abdominal or pelvic wall (mean SUV max 4.0 ± 2.3). Corresponding nonspecific CT findings included soft tissue thickening (n = 18), fat infiltration (n = 20) and fluid collection (n = 19) in the region of the omentum, adjacent to or in the inner abdominal or pelvic wall at the surgical site. Linear hyper-dense structures (n = 9) or metallic clips (n = 8) seen on CT suggested benign postoperative changes. In 10/12 (83.3%) patients with repeat PET-CT, FDG uptake remained unchanged, one showed more diffuse uptake and another showed reduced uptake on follow-up. There was neither significant change in CT appearance at the surgical site in these 12 patients, nor in 3 additional patients with only CT follow-up. Another 3 patients had previous CT demonstrating hernia at the same location. Conclusion: With increasing use of synthetic mesh, awareness of variations in FDG PET-CT appearance is important to avoid false interpretation in cancer patients.