MRI Findings of Hydroxyapatite Orbital Implants

ABSTRACT

PURPOSE: To assess MR findings of hydroxyapatite orbital implants and their usefulness for the evaluation of fibrovascular ingrowth. MATERIALS AND METHODS: MR images of 32 hydroxyapatite orbital implants were obtained six months after implantation surgery. We retrospectively analysed MR images for signal intensity and contrast enhancement in both central and peripheral zones of the implants. The degree of contrast enhancement in an implant was compared with that of the temporalis muscle on contrast enhanced fat suppressed T1 weighted images. RESULTS: On T1-weighted images, implants showed a higher signal intensity than that of the vitreous body in the opposite globe. All implants showed peripheral contrast enhancement, densely enhanced in 30 cases and faintly in two. Three implants showed dense central contrast enhancement, and in the remainder, enhancement was similar to that of gray matter. On T2 weighted images, bright signal intensity was noted in 29 implants, focally in 19 and diffusely in ten. In most cases, areas of peripheral iso- to low signal intensity on T2-weighted images corresponded well with the contrast-enhanced area on T1 weighted images. CONCLUSION: At six months ofter surgery, Gd-enhanced MR imaging was useful for the evaluation of fibrovascular ingrowth in hydroxyapatite orbital implants.