¹⁸F-FDG PET: Early postoperative period of oro-maxillo-facial flaps

Aim: We addressed the feasibility of FDG-PET to differentiate between viability and non-viability in the immediate postoperative assessment of flaps (autologous microvascular anastomosed pedicled flaps) in oro-maxillofacial surgery. Methods: 3-7 days after surgery, FDG-PET was done in 38 patients who had received flaps for reconstruction of the mandible after partial resection. The studies were done on a dedicated full ring PET-scanner (ECAT EXACT HR+, Siemens/CTI). Acquisition started between 60 and 80 min post injection. The findings of the soft tissue component of the flaps were grouped using a three point scale: (I) no defect, (II) small defects, (III) one large defect. The results of PET were compared with the clinical course for at least 3 months. Results: "No defect" on the FDG-PET study identified viability of the flap and predicted normal clinical follow-up (22/38 patients). "Small defects" visualized areas of decreased perfusian and decreased glucose metabolism indicating risk of non-viability (13/38 patients); adapting the postsurgical management led to delayed but uncomplicated healing of the flaps in these patients. "One large defect" demonstrated early necrosis of the flap (3/38 patients). After removal and replacement of this necrotic portion of the flap the second FDG-PET scan of these 3 patients demonstrated the uncomplicated post-operative healing. Conclusion: FDG-PET facilitated the assessment of viability and non viability of flaps in the immediate postsurgical period, and demonstrated the usefulness of FDG-PET for postoperative care and prognosis.