The role of a positron- and high-energy gamma photon probe in intraoperative localization of recurrent melanoma.

PURPOSE

This preliminary study retrospectively evaluated the ability of intraoperative localization of recurrent melanoma using F-18 fluorodeoxyglucose (FDG) and a probe sensitive to both high-energy gamma rays and positrons to enable complete tumor resection and improved patient outcome.

MATERIALS AND METHODS

Three hours before surgery for resection of recurrent melanoma, 5 patients (mean age, 52 +/- 22 years) with a history of local surgery, radiation therapy, and/or large habitus received 14.6 +/- 3.2 mCi of F-18 FDG. Intraoperative tumor localization was performed with a radiation probe (PET-Probe; IntraMedical Imaging LLC, Los Angeles, CA). Intraoperative tumor tissue activities, background tissue activities, pathology results, and patient follow up (clinical/imaging) were recorded.

RESULTS

Eight of the 19 surgical specimens were identified by the probe as having increased FDG uptake when compared with the surrounding tissues before resection. All 8 specimens contained melanoma. Of the 11 specimens that were not identified using the probe, one contained melanoma, yielding a sensitivity of 89% (8 of 9) and a specificity of 100% (10 of 10). In 3 of the 5 cases, the probe allowed the identification of nonvisualized and nonpalpable tumor foci that were later confirmed pathologic. At an average follow up of 210 days (range, 30-515 days), 2 of 5 patients had no evidence of recurrent melanoma by clinical or radiographic evaluations.

CONCLUSION

In the setting of recurrent melanoma, there appear to be potential benefits to intraoperative detection with FDG and a positron-detecting probe, particularly in cases with challenging or altered anatomy.