Vue point hd

¹⁸F-FDG was synthesized with an in-house cyclotron and automated synthesis system (F200; Sumitomo Heavy Industries, Shinagawa, Tokyo, Japan). PET/CT images were acquired 60 min after an intravenous injection of ¹⁸F-FDG, fixed at 5.0 MBq/kg. Patients were instructed to urinate before scanning to reduce tracer accumulation in the bladder. All PET/CT images were obtained using a Discovery PET/CT 600 (GE Healthcare, Pewaukee, WI) with a multi-detector-row CT component (16 detectors). Scanning covered an area from the head to the mid-thigh. Low dose CT with shallow breathing was performed first and used for attenuation correction and image fusion. CT acquisition was performed with 120 kVp using an auto exposure control system, beam pitch of 0.938, slice thickness of 3.75 mm. Emission images were acquired in three-dimensional mode for 2.5 min per bed position. The 3D-OSEM reconstruction method (VUE point HD; GE Healthcare) was used both for (a) conventional PET (16 subsets; 3 iterations), and (b) PSF-PET [(16 subsets; 5 iterations) + PSF algorithm (Sharp IR, GE Healthcare)]. For both reconstructions, the matrix size was 192 × 192, resulting in a 3.65 × 3.65 × 3.65 mm voxel size, and a 4 mm Gaussian filter was used.

All image acquisition was done with a GE Discovery 690 PET/CT scanner (General Electric, Pewaukee, WI, USA). Software and algorithms were supplied with the scanner. The patients were injected with 1-[¹¹C]-acetate (5.0 MBq/kg body weight, mean dose 436 MBq, range 304 to 577 MBq) i.v., and a CT scan with low dose for PET attenuation was acquired, followed by a PET scan 10 min post-injection and finally a diagnostic CT with or without i.v. contrast media. The attenuation CT was a helical 0.5-s rotation time scan, employing 120 kV and 30 mA. The PET scan was performed in time-of-flight mode with an acquisition time of 2 min/bed position, including the abdomen, thorax and neck. The PET images were reconstructed with the OSEM-based VuePoint HD (GE Healthcare, Pewaukee, WI, USA) (2 iterations, 24 subsets, 6.4 mm Gaussian filter), to a 128 × 128 pixel matrix with 50-cm field-of-view, giving a voxel size of 5.5 × 5.5 × 3.27 mm³. The diagnostic CT included the neck, thorax and abdomen, using 120 kV, with beam current controlled by the Auto-mA algorithm (noise index 35, current limited to the range 150 to 750 mA). The CECT was done after i.v. injection of iodine contrast (Omnipaque 350 mgI/ml 0.5 g I/kg, rendering a patient mean volume of 137 ml, range 108 to 167 ml).