Optimal MRI protocol for the evaluation of vitreoretinal disease in eyes with intraocular silicone oil

Introduction: To define the optimal orbital protocol for MR imaging in globes containing silicone oil. The presence of silicone oil occasionally makes both the direct and ultrasonographic evaluation of eyes subject to significant artifacts. While standard magnetic resonance imaging has been recommended in these cases, it too is subject to a chemical shift artifact at the oil-retina interface. Methods: Eight eyes of seven patients who previously underwent vitrectomy followed by silicone oil tamponade were imaged using an orbital coil. Intraoperative perfluorooctane was used in four eyes. The following protocols were used: T1 and fast T2 weighted sequences, with and without fat and silicone saturation, spin density, with and without silicone saturation, gradient echo and STIR. Results: Two of the eight globes with intraocular silicone had postoperative complications demonstrated on MR imaging. Redetachment of the retina was well demonstrated in one case. Retained perfluorooctane was demonstrated on T1 sequences in the second case. In the second case, the absence of signal from perfluorooctane blended with the signal loss from silicone on the fat and silicone saturation scans. Therefore detection of this complication was best done on companion sequences without fat or silicone saturation. The fat or silicone-saturated fast T2 sequences showed the best pathologic/anatomic detail in all other cases. Conclusions: We recommend the silicone saturated T2 weighted imaging technique in cases requiring MR scanning. If silicone saturation is unavailable, the fat saturated fast T2 protocol is an excellent alternative. We also recommend a companion T1 weighted image.