Purpose

To characterize, for the first time, the postoperative metabolic activity of orbital implants on ¹⁸F-FDG PET/CT, to compare quantitative metabolic parameters across implant types, and to correlate these findings with the clinical examination of the enucleated cavity.

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Methods

This retrospective, single-center study included 48 patients who underwent enucleation for choroidal melanoma at the University Hospital of Nice (2018–2025), received an orbital implant, and completed a four-month postoperative PET/CT. Three implant types were compared : porous polyethylene implants (MEDPOR®, Ezypor®, FCI S.A.S., France), bioceramic implants wrapped in a Vicryl mesh (FCI S.A.S., France), and alumina implants (Orbtex™, Novamed Ceramisys Ltd., Dundee, UK). All patients underwent ¹⁸F-FDG PET/CT 4 months postoperatively for the choroidal melanoma extension workup. Maximum standardized uptake values (SUVmax) and implant-to-liver SUV ratios were analyzed according to implant type, PET/CT uptake pattern (absent, diffuse, focal), and postoperative orbital findings including pathological secretions, orbital pain, and phantom eye syndrome.

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Results

Forty-eight patients were included (mean age 64 years, 60% men). Alumina implants (Orbtex™, Novamed Ceramisys Ltd.) were placed in 28 patients (58.3%), MEDPOR® implants (Ezypor®, FCI S.A.S.) in 18 patients (37.5%), and bioceramic implants wrapped in Vicryl mesh (FCI S.A.S.) in 2 patients (4.2%). The median implant SUVmax was 2.42. Implant material significantly influenced metabolic activity : MEDPOR® implants demonstrated markedly lower SUVmax than Orbtex™ alumina implants (1.67 ± 0.6 vs. 2.79 ± 0.9, p = 0.033). PET/CT uptake pattern was significantly associated with postoperative socket status (p = 0.006) : normal cavities uniformly displayed absent or diffuse uptake, whereas focal uptake was identified in 75% of pyogenic granuloma cases. Elevated SUVmax correlated with infection or granuloma (p = 0.05). Phantom eye syndrome occurred more frequently with bioceramic implants (p = 0.017).

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Conclusion

An implant that does not fix ¹⁸F-FDG should be considered a reassuring sign of uneventful integration. Among implant materials, porous polyethylene (MEDPOR®, Ezypor®) demonstrates significantly lower metabolic activity than alumina (Orbtex™), suggesting a more favorable tissue response. Focal or asymmetric hypermetabolism should raise suspicion for a pyogenic granuloma, generally synonymous with implant exposure and underlying infection, requiring prompt clinical evaluation.

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Additional Authors

First name	Last name	Base Hospital / Institution
Baptiste	VERDIER	Ophthalmology departement, Univeristy Hospital of Nice, France
Guillaume	NIVAGIONNI	Nuclear medicine department, University Hospital of Nice, France

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