Xeleris imaging workstation

All SPECT/CT studies were obtained using a SPECT/CT scanner, NMCT/670 (GE Healthcare, Waukesha, WI, USA). Planar blood pool imaging was performed at 1 min after intravenous injection of 800–1,100 MBq of Tc-99 m hydroxymethylene diphosphonate. Four hours after injection of radiotracer, whole body image and planar spot image of the site of tumor were obtained followed by SPECT/CT. CT images were acquired by using the following parameters: 120 kVp, 110–130 mA with “autoMa” function, and 1.25-mm-thick sections. SPECT images were acquired by using the following parameters: peak energy at 140 keV with 10% window and step-and-shot mode acquisition (25 s per step and 30 steps per detector) with 6° angular increment. SPECT images reconstructions were performed using an iterative ordered subset expectation maximization algorithm (four iterations; 10 subsets) with CT-based attenuation correction, scatter correction, and resolution recovery on a Xeleris imaging workstation (version 4.0, GE Healthcare, Waukesha, WI, USA). The matrix size of reconstructed images was 128 × 128 with section thickness of 4.42 mm. The minimal source-to-collimator distance is 4 mm for parallel-hole collimation of Tc-99 m.

All SPECT/CT scans were conducted using an NMCT/670 SPECT/CT scanner (GE Healthcare, Waukesha, WI, USA). First, 800–1100 MBq of Tc-99m hydroxymethylene diphosphonate (HDP) was injected. SPECT/CT images of tumor site were obtained 4 h after radiotracer injection. CT acquisition was done by the following parameters: peak energy at 140 keV with 10% window and step-and-shot mode acquisition (25 s per step and 30 steps per detector) with 6° angular increments. For SPECT image reconstruction, an iterative ordered subset expectation maximization algorithm was employed (four iterations; 10 subsets), with CT-based attenuation correction, scatter correction, and resolution recovery carried out on a Xeleris imaging workstation (version 4.0, GE Healthcare, Waukesha, WI, USA). The reconstructed images had a matrix size of 128 × 128 with a section thickness of 4.42 mm. The minimal source-to-collimator distance for the parallel-hole collimation of Tc-99m was set at 4 mm.