Gemini gxl 16 scanner

This step used the Gemini GXL 16 scanner (Philips, Netherlands) which integrates a PET scanner with a 16-detector spiral CT that can collect jointly registered CT and PET images in a single inspection. In addition, the ¹⁸F-FDG tracer was produced by our department using the Cyclone 10 isotope synthesis system from the Belgium IBA Company. The radiochemical purity of ¹⁸F-FDG was more than 95%. Notably, all the patients were required to fast for at least 6 h and urinated just before starting the PET/CT scan. After entering the waiting room, the patients received an intravenous injection of ¹⁸F-FDG at a dose of 5.18 MBq (0.14 mCi)/kg and after about 60 minutes, the PET/CT scan was performed from the upper thigh to the base of the skull. The parameters of the noncontrast CT scan were as follows: 120 kV, tube current-time product: 50 to 80 mAs depending on the patient's weight, a slice thickness of 5 mm, and a rotation time of 0.8 seconds. In the same range, PET images were collected in the 3-dimensional acquisition mode and 6-7 beds were scanned in the 90 seconds per bed position. Finally, images were reconstructed with 4 × 4 × 4 mm³ voxels using the LOR-Ramla algorithm with low-dose CT images for attenuation correction.

¹³N-ammonia and ¹¹C-MET were produced in our department by commercially available systems for isotope generation (Ion Beam Applications, Cyclone-10, Belgium) with standard methods. The radiochemical purity was>99%. PET/CT scans were performed with a Gemini GXL-16 scanner (Philips, Netherlands). Five minutes after intravenous injection of 7.4 MBq (0.20 mCi)/kg ¹³N-ammonia or ¹¹C-MET, a 10-min serial PET/CT scan using a brain imaging protocol (matrix: 128 × 128 pixels; slice thickness: 1.5 mm; FOV: 180 mm) was initiated. Images were attenuation-corrected with low-dose CT and reconstructed with the Line of Response RAMLA algorithm. ¹³N-ammonia and ¹¹C-MET PET/CT were performed with an interval of at least 24 h.