Postcontrast magnetic resonance imaging assessment of porous polyethylene orbital implant (medpor)

doi:10.1016/S0161-6420(00)00249-9

Ophthalmology

Volume 107, Issue 9, September 2000, Pages 1656-1660

Presented in part at the American Academy of Ophthalmology Annual Meeting, New Orleans, Louisiana, November 1998.

https://doi.org/10.1016/S0161-6420(00)00249-9 Get rights and content

Abstract

Objective

To evaluate the fibrovascular ingrowth progression within the porous polyethylene orbital implant (Medpor) with serial magnetic resonance imaging (MRI).

Design

Prospective, nonrandomized, comparative (self-controlled) trial.

Participants

Ten patients who underwent enucleation and implantation of a 20-mm porous polyethylene implant wrapped with heterologous sclera.

Methods

Serial precontrast and postcontrast T1-weighted MRI were obtained at 1.5, 3, 6, and 12 months after implantation. The percentage area of enhancement was calculated by use of manual planimetric contouring unenhanced areas at the equator of each sphere on axial and coronal planes.

Results

All the implants showed enhancing areas as early as 1.5 months after enucleation. In 8 of the 10 patients, the areas of enhancement at the equator of the implant consistently showed similar centripetal progression primarily during the first 6 months after enucleation. The presence of fibrovascular tissue at the equator was associated in all cases with enhancing zones at the anterior portion of the implant. None of the implants showed diffuse complete enhancement after 12 months. Two patients failed to demonstrate further enhancement progression 1.5 months after implantation. No histopathologic study to equate with the MRI findings was performed in this series.

Conclusions

Postcontrast magnetic resonance studies seem to be the best-suited imaging modality for assessing the fibrovascular tissue progression into porous polyethylene spheres after enucleation and for identifying patients in whom failure of vascularization occurs. Incomplete vascularization at the equator of the porous polyethylene sphere does not prove an absence of fibrovascular ingrowth in the anterior region. Prior ocular surgery and coexisting arterial hypertension may slow the progression of fibrovascular ingrowth.

Section snippets

Patients and methods

Ten patients in whom the high density PP sphere (Medpor; Porex Technologies Co., Fairburn, GA) was surgically placed into the orbit after enucleation were included in this prospective nonrandomized trial. A standard technique of enucleation was performed by the same surgeon (PDP). All six extraocular muscles were identified and tagged with double-armed 5-0 polyglactin 910 (Vicryl) sutures. Retrobulbar vasoconstrictors were not used. Hemostasis after eye removal was achieved with digital

Results

The 10 patients (8 men and 2 women) ranged in age between 18 and 68 years (mean, 47 years) at the time of enucleation. The clinical data are summarized in Table 1.

The specific diagnoses before enucleation included choroidal melanoma in five cases, blind painful eye with phthisis bulbi in four cases, and endophthalmitis after glaucoma surgery in one case. Five patients (50%) underwent enucleation without prior surgical procedures. Five patients had had prior ocular surgeries, including

Discussion

An essential factor in determining the success of porous allograft material such as hydroxyapatite and polyethylene is the development of fibrovascular tissue within it to ensure its integration into the surrounding orbital tissues and theoretically reduce the incidence of complications such as exposure, extrusion, and infection. In anophthalmic socket reconstruction, the presence of fibrovascularization within the hydroxyapatite sphere is desirable before considering drilling of the implant

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Gadolinium-enhanced magnetic resonance imaging assessment of hydroxyapatite orbital implants
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2022, Neuroimaging Clinics of North America
Citation Excerpt :
Porous materials enable fibrovascular growth from the surrounding tissues into the porous implant, which ensures integration into the surrounding orbital tissues and reduces the incidence of complications such as exposure, extrusion, and infection. Postcontrast MR imaging can depict fibrovascular tissue ingrowth within the porous implants (Fig. 13).15 This should not be mistaken for infection or recurrent tumor, which would be expected to appear as enhancement beyond the implant.
Imaging of the Postoperative Eye and Orbit
2022, Neuroimaging Clinics of North America
Citation Excerpt :
There is a variety of materials that are used for globe implants (Fig. 12). Of note, porous implants, such as MEDPOR (Stryker Corp, Kalamazoo, MI), can display internal enhancement because of fibrovascular ingrowth (Fig. 13).12 Exenteration of the orbit, which consists of removing the eye globe and surrounding tissues, is most often indicated for malignant tumors.
Clinical Significance of Optic Nerve Enhancement on Magnetic Resonance Imaging in Enucleated Retinoblastoma Patients
2017, Ophthalmology Retina
The aim of this 8-year retrospective review was to determine the clinical significance of gadolinium-enhanced magnetic resonance imaging (MRI) findings in retinoblastoma patients after enucleation, particularly the presence of abnormal contrast enhancement of the transected optic nerve.
Retrospective chart review.
A review was done on 88 patients with retinoblastoma undergoing 90 enucleations between January 2008 and December 2015.
These patients underwent 233 MRI scans: 90 preoperative and 143 postoperative that were included for review.
The primary outcome measure assessed was abnormal MRI findings in the preoperative and postoperative MRI scans, specifically enhancement of the optic nerve and correlations between abnormal MRI findings and clinical outcomes for the 88 patients.
On the preoperative MRI, 4 optic nerves out of 90 scans showed positive enhancement. Fifty orbits had ≥1 postoperative MRI. Overall, 41 of 50 orbits (82%) of enucleated patients demonstrated postoperative contrast enhancement on MRI after enucleation, at a mean interval of 10 months after surgery. The percentage of MRI scans with optic nerve enhancement was 77% from 0 to 6 months after enucleation and 68% at >24 months after surgery. Postenucleation optic nerve enhancement did not correlate with preoperative optic nerve enhancement, chemotherapy administration, or the presence of optic nerve invasion on histopathology. No child required an orbital biopsy. None of the 88 patients were found to have subsequent orbital or metastatic disease at the last clinical follow-up visit (average, 29 months; range, 1–71).
Optic nerve contrast enhancement on follow-up MRI after enucleation for retinoblastoma seems to be a common, benign radiographic finding; none of the patients in this series developed extraocular tumor relapse. The presence of postenucleation enhancement on MRI did not correlate with preoperative chemotherapy or the presence of optic nerve invasion on histopathology. Based on our findings, intervention for isolated optic nerve enhancement on MRI is not indicated in the absence of other abnormal clinical or radiographic signs. A prospective trial with a validated radiographic grading system would be helpful to clarify the MRI features to differentiate orbital recurrence from benign postoperative enhancement.
High-resolution magnetic resonance imaging can reliably detect orbital tumor recurrence after enucleation in children with retinoblastoma
2016, Ophthalmology
Orbital tumor recurrence is a rare but serious complication in children with retinoblastoma, leading to a high risk of metastasis and death. Therefore, we assume that these recurrences have to be detected and treated as early as possible. Preliminary studies used magnetic resonance imaging (MRI) to evaluate postsurgical findings in the orbit. In this study, we assessed the diagnostic accuracy of high-resolution MRI to detect orbital tumor recurrence in children with retinoblastoma in a large study cohort.
Consecutive retrospective study (2007–2013) assessing MRI findings after enucleation.
A total of 103 MRI examinations of 55 orbits (50 children, 27 male/23 female, mean age 16.3±12.4 months) with a median time of 8 months (range, 0–93) after enucleation for retinoblastoma.
High-resolution MRI using orbital surface coils was performed on 1.5 Tesla MRI systems to assess abnormal orbital findings.
Five European experts in retinoblastoma imaging evaluated the MRI examinations regarding the presence of abnormal orbital gadolinium enhancement and judged them as “definitive tumor,” “suspicious of tumor,” “postsurgical condition/scar formation,” or “without pathologic findings.” The findings were correlated to histopathology (if available), MRI, and clinical follow-up.
Abnormal orbital enhancement was a common finding after enucleation (100% in the first 3 months after enucleation, 64.3% >3 years after enucleation). All histopathologically confirmed tumor recurrences (3 of 55 orbits, 5.5%) were correctly judged as “definitive tumor” in MRI. Two orbits from 2 children rated as “suspicious of tumor” received intravenous chemotherapy without histopathologic confirmation; further follow-up (67 and 47 months) revealed no sign of tumor recurrence. In 90.2%, no tumor was suspected on MRI, which was clinically confirmed during follow-up (median follow-up after enucleation, 45 months; range, 8–126).
High-resolution MRI with orbital surface coils may reliably distinguish between common postsurgical contrast enhancement and orbital tumor recurrence, and therefore may be a useful tool to evaluate orbital tumor recurrence after enucleation in children with retinoblastoma. We recommend high-resolution MRI as a potential screening tool for the orbit in children with retinoblastoma to exclude tumor recurrence, especially in high-risk patients within the critical first 2 years after enucleation.
Postsurgical Imaging of the Globe
2011, Seminars in Ultrasound, CT and MRI
Citation Excerpt :
Ocular implants used include hydroxyapatite, aluminum oxide, and porous polyethylene (medpor), with all appearing hyperdense on CT (Fig. 7D-F) and low signal intensity on T1-weighted and T2-weighted imaging.9 MRI with intravenous contrast is the test of choice for postoperative evaluation of ocular implants with respect to vascularization.16,17 The Hydroxyapatite orbital implant is highly favored due its low rate of infection and extrusion when compared with the other motility implants, although these cannot be used in all patients.18
Interpretation of globe imaging after ophthalmologic surgical intervention, just like postoperative imaging in any location, can create a diagnostic dilemma if the radiologist is not familiar with the type of surgery performed and the nature and location of any implanted devices. Certain implants and devices may create artifacts on computed tomography or magnetic resonance imaging, and some contain ferromagnetic components that may be damaged if inadvertently placed in the magnetic resonance imaging. We review several common ocular surgical procedures, as well as a few orbital surgical procedures and discuss many implants and devices and their appearance on cross-sectional imaging. Familiarity with these procedures and their imaging appearance can diminish the chance of misinterpretation.
MRI exploration for the evaluation of orbital implant biocolonization in children enucleated for retinoblastoma
2009, Journal Francais d'Ophtalmologie
Evaluer l’apport de l’IRM dans la surveillance de la biocolonisation des implants intra-orbitaires.
Nous avons mené une étude rétrospective incluant 10 enfants (10 yeux) ayant eu une énucléation pour un rétinoblastome évolué. Les implants étaient tous en hydroxyapatite de synthèse. Nous avons réalisé une IRM en postopératoire à des délais différents allant de 2 mois à 1 an. L’exploration orbitaire a comporté, pour chaque patient, des séquences pondérées en T1 sans et avec injection de Gadolinium dans les plans axial et sagittal.
L’IRM montrait une prise de contraste de l’implant dans cinq cas, une prise de contraste nodulaire autour de l’implant en rapport avec une récidive du rétinoblastome dans un cas, et une absence de prise de contraste dans quatre cas. La prise de contraste de l’implant était périphérique dans deux cas et étendue au centre dans trois cas. Une dissémination méningée a été notée dans deux cas, mais aucun cas de rejet de l’implant n’a été détecté.
La colonisation fibrovasculaire de l’implant orbitaire réduit le risque d’expulsion et permet d’assurer une meilleure mobilité de la kératoprothèse superficielle. L’IRM est un moyen sensible pour objectiver cette biocolonisation et l’intégration de l’implant orbitaire.
To evaluate the contribution of MRI exploration for the evaluation of orbital prothesis biocolonization.
We studied ten eyes of ten children who underwent enucleation for retinoblastoma and synthetic hydroxyapatite orbital implantation. Each patient was examined by MRI imaging with gadolinium within 2 months to 1 year.
After gadolinium administration, five implants showed an enhancement. Nodular enhancement around the implant was noted in one patient with a recurrence of retinoblastoma, and brain metastases were shown in two cases. None of the orbital implants was rejected.
Fibrovascular colonization reduces the risk of orbital implant migration. Magnetic resonance imaging is safe and effective in detecting extrusion or tolerance of the orbital implant.

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¹: The authors have no proprietary interest in any of the materials used in this study.

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Postcontrast magnetic resonance imaging assessment of porous polyethylene orbital implant (medpor)1

Abstract

Objective

Design

Participants

Methods

Results

Conclusions

Section snippets

Patients and methods

Results

Discussion

Ophthalmology

Ophthalmology

Ophthalmology

Ophthalmology

Am J Ophthalmol

Postcontrast magnetic resonance imaging assessment of porous polyethylene orbital implant (medpor)¹