Intraoperative echographic localization of iodine-125 episcleral plaque for brachytherapy of choroidal melanoma.

PURPOSE

To report intraoperative echographic localization of iodine-125 episcleral plaque for brachytherapy of choroidal melanoma.

METHODS

In a retrospective study, 117 eyes with medium-sized choroidal melanoma in 117 patients not participating in the Collaborative Ocular Melanoma Study underwent iodine-125 episcleral plaque radiotherapy with intraoperative echographic verification of plaque placement between January 1992 and December 1998 at the Bascom Palmer Eye Institute.

RESULTS

After initial plaque placement using standard localization techniques, intraoperative echography demonstrated satisfactory tumor-plaque apposition in 76% of eyes (89 of 117). In the 28 eyes (28 of 117, 24%) that required repositioning of the plaque, the extent of misplacement was less than 1 mm in 10 eyes, 1.1 to 3.0 mm in six eyes, and greater than 3 mm in eight eyes. Two eyes had tilting of the plaque, and in two additional eyes, although the plaque covered all tumor margins, the centration was considered suboptimal. Repositioning was necessary in 1 eye with an anteriorly located tumor (1 of 13, 7.7%) and in 20 eyes with peripapillary or posterior pole tumors (20 of 67, 26.3%). Anteriorly located tumors required plaque repositioning significantly less frequently than did posteriorly located tumors (P = .041). Misalignment involved one tumor margin in 23 eyes and two margins in five eyes. The most commonly misaligned margins were the lateral (35%) and posterior margins (26%). In no case was an anterior marginal misalignment documented. At a mean follow-up of 37 months, no tumor-related death or metastatic disease was noted. Two of the 117 patients (1.7%) had local tumor recurrence and underwent enucleation.

CONCLUSIONS

Intraoperative echography is an effective adjunct for localization and confirmation of tumor-plaque relationship. This technique facilitates the identification and correction of suboptimal plaque placement at the time of surgery, potentially minimizing treatment failures.