Dynamic bone scintigraphy for evaluation of tumor response after preoperative chemotherapy

Abstract

Dynamic bone scintigraphy with 2-second scintigrams for 6 minutes after the injection of Tc-99m-MDP, may be regarded as a kind of angiography. We investigated the vascularity and early uptake of MDP in 39 osteosarcoma and 12 Ewing sarcoma patients before and after preoperative chemotherapy, and compared them to the histological tumor response. Early appearance of activity in the feeding arteries and rapid clearance from the arterial to the venous side give a distinct early activity peak on histograms over the tumor region. We calculated a tumor-tonontumor (t) ratio at 6 minutes after the injection. In osteosarcoma patients, a persistent peak or a Tratio decrease of less than 40%, without disappearance of the peak, identified 23 of the 24 poor responders. Peak disappearance occurred in 14 of the 15 good responders. In Ewing's sarcoma peak disappearance and a t-ratio decrease of more than 60% identified the good responders.