2.2. Image Acquisition

During this follow-up period, computed tomography (CT) and BS were used to evaluate treatment response for metastatic bone lesions. BS was performed 3 to 5 h after intravenous injection of 740 MBq (20 mCi) technetium −99 m hydroxymethylene diphosphonate (HDP). Anterior and posterior planar whole-body images were acquired using a dual-headed gamma camera equipped with a low-energy high-resolution collimator (Infinia, GE, Milwaukee, WI, USA) and using 128 × 128 matrices and a 15% energy window around the 140 keV. Additional static images of areas of interest were obtained as needed. BS was reviewed retrospectively by an experienced nuclear medicine physician who was blinded to the clinical data.

Pre and posttreatment contrast-enhanced CT of the chest and abdomen were performed on all patients using a Siemens Somatom Sensation 10 scanner (Siemens, Forchheim, Germany) with a 3 mm slice thickness. For contrast enhancement, intravenous contrast medium (Ultravist 370; Shering AG, Berlin, Germany) was administered. The CT confirmed metastatic bone lesions that had been revealed on BS and also revealed extraosseous metastasis. All patients were divided typically into three subgroups classified by the radiologic pattern of bone metastasis: osteolytic, osteosclerotic, or mixed type [6].