Correlation of histological findings with gadolinium enhanced MRI scans during healing of a PHEMA orbital implant in rabbits

• Published in: British journal of ophthalmology Vol. 83; no. 5; pp. 616 - 621
• Main Authors: Hicks, Celia R, Morris, Ian T, Vijayasekaran, Sarojini, Fallon, Michael J, McAllister, Jordana, Clayton, Anthony B, Chirila, Traian V, Crawford, Geoffrey J, Constable, Ian J
• Format: Journal Article
• Language: English
• Published: BMA House, Tavistock Square, London, WC1H 9JR BMJ Publishing Group Ltd 01.05.1999; BMJ; BMJ Publishing Group LTD; BMJ Group
• Subjects: Animals; biointegration; Biological and medical sciences; Contrast Media - administration & dosage; Fibroblasts; gadolinium; Gadolinium DTPA - administration & dosage; histology; Hydroxyapatite; magnetic resonance imaging; Magnetic Resonance Imaging - methods; Medical imaging; Medical sciences; Microscopy; NMR; Nuclear magnetic resonance; orbital implant; Orbital Implants; Original articles - Laboratory science; PHEMA; Polyhydroxyethyl Methacrylate - therapeutic use; Prostheses; Rabbits; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the eye and orbit; Transplants & implants; Wound Healing - physiology; Integration; Implant; Rabbit; Exploration; Gadolinium; Histology; Lagomorpha; Orbit(eye); Nuclear magnetic resonance imaging; Hydroxyethyl methacrylate polymer; Vertebrata; Mammalia; Surgery; Animal; Medical imagery; Biomaterial; Experimental surgery; Contrast media
• ISSN: 0007-1161; 1468-2079
• DOI: 10.1136/bjo.83.5.616

BACKGROUND/AIMS To investigate a poly(2-hydroxyethyl methacrylate) (PHEMA) orbital implant with a spongy anterior hemisphere and a smooth gel posterior hemisphere, by histology correlated with magnetic resonance images. METHODS Following enucleation, eight rabbits received PHEMA implants to which the muscles were directly sutured, and underwent gadolinium enhanced magnetic resonance imaging (MRI) from 3 to 52 weeks. After the rabbits were killed, the implants were removed, cut in a plane corresponding to the scan, and processed for light and electron microscopy. RESULTS All eight rabbits retained their implant to the end of the study period without complications. The scans demonstrated muscle attachment to the anterior half of the implant, and enhancement was seen on injection of gadolinium chelate. Histology confirmed muscle attachment, and cellular and vascular ingrowth. Over time, a transformation from reactive inflammatory to relatively non-vascular scar tissue was seen within the implant. Calcium deposits in one implant were detected by imaging and histology. CONCLUSION The implants are readily visualised on MRI. Muscle attachment and fibrovascular ingrowth into the anterior hemisphere are seen, while encapsulation of the posterior hemisphere is minimal. Histological findings confirm the progress of the healing response, with initial inflammation and marked vascularisation, developing later into quiescent scar tissue predominantly of fibroblasts.