title: Fibrovascular ingrowth into porous polyethylene orbital implants (Medpor) after modified evisceration.
abstract: OBJECTIVE
  To evaluate, using MRI, the extent and pattern of fibrovascular ingrowth into Medpor implants after modified evisceration.
  
  
  METHODS
  Contrast T1-weighted images were performed in 21 patients within 1.5- to69-month intervals after modified evisceration with primary Medpor implantation. In 6 patients, the images were obtained separately following 1- and 5-minute delays after contrast administration.
  
  
  RESULTS
  No grade I enhancement occurred in these series. Grade II was observed in 2 patients (9.09%), grade III in 8 patients (36.36%), grade IV in 9 patients (40.91%), and grade V in 3 patients (13.64%). Significant correlation existed between the grade of enhancement and the postevisceration interval (r = 0.483, p = 0.023 < 0.05). The images demonstrated an enhancement pattern that started at the unwrapped posterior pole and anterior location of rectus muscles with progressive centripetal vascularization toward the center of the implant. At the early stage of recovery, the fibrous connective tissue was thick in front of Medpor spheres. In the 5-minute delay images of 6 patients, 2 patients failed to exhibit further enhancement; 2 patients exhibited enlarged and homogeneous enhancement; and 2 patients revealed more intense enhancement patterns. The medical ethics committee of Zhongshan Ophthalmic Center approved the study.
  
  
  CONCLUSIONS
  Fibrovascular ingrowth into Medpor implants was satisfactory after the modified evisceration and correlated with the duration of the implants. The double layers of sclera effectively prevented the implant extrusion and exposure. The authors recommend waiting at least 5 minutes before obtaining MR images after contrast administration.
authors.affiliation: *Oculoplasty Department, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. and †Diagnostic Radiology, the First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Danping
authors.initials: D
authors.lastname: Huang
authors.forename: Binbin
authors.initials: B
authors.lastname: Xu
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Yang
authors.forename: Bing
authors.initials: B
authors.lastname: Xu
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Lin
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Yang
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
mesh_terms: D000293:Adolescent; D000328:Adult; D001672:Biocompatible Materials; D001808:Blood Vessels; D002648:Child; D002675:Child, Preschool; D003239:Connective Tissue Cells / Q000502:physiology*; D003287:Contrast Media; D017234:Eye Evisceration; D005260:Female; D005682:Gadolinium; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018919:Neovascularization, Physiologic / Q000502:physiology*; D009915:Orbit / Q000601:surgery*; D020273:Orbital Implants; D011095:Polyethylenes; D016062:Porosity
chemical_list: D001672:Biocompatible Materials; D003287:Contrast Media; C084562:Medpor; D011095:Polyethylenes; D005682:Gadolinium