Salunke GCRI-Ahmedabad radionuclide-guided surgery: Intraoperative gamma-camera mapping for giant cell tumors around the knee.

BACKGROUND Giant cell tumor (GCT) of bone is locally aggressive with a high recurrence rate following intralesional curettage. This study assessed early outcomes of Technetium (Tc-99 m) guided intraoperative gamma-camera margin mapping for the detection of residual tumor in GCT around the knee.

METHODS This prospective study included twenty consecutive patients with histologically confirmed GCT of the distal femur (n = 11), proximal tibia (n = 9) treated with extended curettage and cementing. Tc-99 m MIBI (10 mCi) was administered 2-4 h preoperatively. Sequential gamma-camera readings (R1-R5) were obtained from baseline to post-curettage using grid sampling. Curettage was continued until final activity was <1.5 × baseline, confirming tumor clearance. The mean follow-up was 16.5 months (6-30).

RESULTS The mean patient age was 30 years (17-61), with equal gender distribution. The mean tumor size was 6.49 cm (3.1-9.7 cm). Serial intraoperative metabolic readings demonstrated a progressive decline, with mean values of 13.7 (R1:baseline), 84.9 (R2), 98.8 (R3), 93.7 (R4), 29.3 (R5), and 19.1 at final assessment. The mean R5 Final/R1 ratio was 1.46 (SD 0.33; range, 0.94-2.40), reflecting effective tumor clearance. No perioperative or postoperative complications were observed. Local recurrence occurred in 2 patients (10%) at 7,10 months following primary surgery.

CONCLUSION Salunke technique of radionuclide -guided gamma-camera margin mapping provides objective intraoperative guidance supplementing conventional visual and tactile assessment during intralesional curettage surgery. Larger prospective studies are needed to define its role in contemporary orthopaedic oncologic practice.