Neoadjuvant therapy is employed before the primary treatment of sarcomas. It is not uncommon that it fails due to multi-drug resistance gene causing unnecessary delays in surgery. Tc-99m MIBI, a radiopharmaceutical, is taken-up in these tumours. Being substrate of P-glycoprotein (Pgp), its washout from the malignant tissue may predict the response of sarcoma to neoadjuvant therapy. This book presents the author’s experience of in-vivo quantitative estimation of the washout rates of Tc-99m MIBI from nuclear medicine scans of various bone and soft-tissue sarcomas. These rates were then assessed for their ability to predict the effectiveness of neoadjuvant therapy initiated afterwards.