Intraoperative gamma hand-held probe navigation in resection of osteoid osteoma tumor--report of two cases.

Two cases of osteoid osteoma tumor (OO) are presented and our early experience with intraoperative gamma probing to localize OO during surgery is reported. The concept of radioguided surgery was developed 60 years ago and the gamma detection probe technology for radioguided biopsy and/or resection of bone lesions has been applied since the early 1980s. Bone scintigraphy is very important for initial diagnosis of OO with almost 100% sensitivity. The bone scan finding is specific, with so called double density appearance, very intense accumulation of radiopharmaceutical in the nidus and therefore great difference between the nidus and the surrounding healthy bone, thus making possible to treat this lesion with probe guided surgery. Three phase bone scintigraphy and single photon emission computed tomography were conducted in our patients for initial diagnosis of OO. A second bone scintigraphy was performed before surgery. The surgery followed 12-15 hours later by intraoperative nidus detection with a hand-held gamma probe. Gamma hand-held probe is a system that detects gamma photons. The count rate in the nidus area on the day of surgery was 3 to 4 times higher than in the healthy bone area. Drilling was performed until the counts decreased to the level of the surrounding bone counts, thereby confirming complete excision. This is the method of choice for minimizing bone resection, the risk of pathologic fracture, the need of bone grafting, and reducing the period of convalescence. Evidence for the treatment efficiency is pain disappearance after the surgery.