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

Summary:

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-maxillo-facial 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 perfusion 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.

Zusammenfassung:

Ziel: Untersuchung der Einsatzmöglichkeit von FDG-PET für die Diagnostik bzw. den Ausschluss der Frühnekrose von mikrovaskulär, gefäßgestielten Transplantaten (freien Lappen) in der Mund-, Kiefer- und Gesichtschirurgie. Patienten, Methoden: Die FDG-PET wurde an 38 Patienten, die freie Lappen erhalten hatten, 3-7 Tage post operationem durchgeführt. Die Untersuchungen wurden an einem ECAT EXACT HR+ Vollring-PET-Scanner durchgeführt. Die PET-Befunde der Weichteilkomponente wurden je nach Untersuchungsergebnis 3 Gruppen zugeordnet: (I) kein Defekt, (II) kleine Defekte, (III) ein großer Defekt. Diese Ergebnisse wurden mit dem klinischen Verlauf über mindestens 3 Monate verglichen. Ergebnisse: »Kein Defekt« bedeutete Vitalität und guter postoperativer Heilungsverlauf (22/38 Patienten). »Kleine Defekte« stellten Bezirke mit beeinträchtigtem Glukosestoffwechsel dar; dieser Befund bedeutete somit Risiko von Defektheilung resp. Frühnekrose (13/38 Patienten). Ein solitärer, großer Aktivitätsdefekt bedeutete definitiv Frühnekrose (3/38 Patienten). Nach chirurgischer Entfernung der nekrotischen Anteile demonstrierte der erneute PET-Scan dieser 3 Patienten den unkomplizierten Heilungsprozess. Schlussfolgerung: FDG-PET ist in der unmittelbar postoperativen Verlaufskontrolle resp. in der Vitalitätsdiagnostik von freien Lappen eine effektive Untersuchungsmodalität, die zudem eine verlässliche prognostische Beurteilung erlaubt.

Key words:

Flap - maxillo-facial - tumour - FDG - PET - viability

Schlüsselwörter:

Freier Lappen - Kieferchirurgie - Tumor - FDG - PET - Vitalität

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