Usefulness of 99mTc-MDP Bone Scintigraphy for Assessing Vascular Ingrowth on Hydroxyapatite Ocular Implant

Kang, Bong Joo; Sohn, Hyung Sun

Abstract

PURPOSE: This study was to evaluate the clinical usefulness of 99mTc-MDP bone scintigraphy for assessing vascular ingrowth into the ocular implants after enucleation or evisceration.
MATERIALS AND METHODS
Twenty-four patients (M:F=7:17, mean age: 36 years), who buried a coralline hydroxyapatite after uncomplicated enucleation or evisceration surgery were studied. Dynamic and static scintigraphy on the orbit fossa were obtained after injection of 740 MBq 99mTc-MDP to evaluate the status of vascularization. The study was performed from the 3 to 33 weeks after surgery. According to the visual analysis, activity greater than nasal bridge was graded as 4, equal to the nasal bridge as 3, less than nasal bridge but greater than normal orbit as 2, greater than normal orbit but less than grade 2 as 1. Uptake ratio was also calculated by measuring the implants activity (H) and contralateral orbit activity (N). Grading score and uptake ratio were compared with clinical outcome of vascularization. Additionally, we also analyzed the vascularization status as time lapse between primary surgery and scintigraphic study and surgical methods.
RESULTS
Twenty-one patients who had bone scintigraphy at 11 weeks after surgery showed increased uptake above grade 2 and greater H/N ratio than 1.56. Of these, 19 patients who had drilling surgery for permanent peg application showed adequate bleeding during the procedure. The activity grade and uptake ratio were inversely correlated with vascular ingrowth. Higher than grade 2 or greater than 1.56 in H/N ratio seemed to be an indicator for better prognosis. Accomplishment of vascularization was not affected by the surgical way such as enucleation or evisceration.
CONCLUSION
99mTc-MDP bone scintigraphy can be a useful method to evaluate the vascularized status of implants. Adequate time for 99mTc-MDP bone scintigraphy may be 11-20 weeks after enucleation or evisceration.