Discovery st pet ct system

PET/CT scans were completed using a Discovery ST PET/CT system (GE Medical Systems, Milwaukee, WI, USA) for 18 patients and a Biograph mCT (Siemens Healthcare Molecular Imaging, Knoxville, TN, USA) for 31 patients. FDG was injected after 5 h of fasting and blood glucose measurement (median: 5.8 mmol/L). The injected activity was 5–7 MBq/kg for acquisitions performed on the Discovery ST PET system and 3 MBq/kg for acquisitions performed on the Biograph PET system. PET images were reconstructed using the algorithm provided by the manufacturer; OSEM without PSF correction, 2 iterations, 28 subsets and a Gaussian post-filtering of 5.45 mm FWHM for the Discovery ST, and OSEM with PSF correction and TOF information, 3 iterations, 21 subsets and a Gaussian post-filtering of 2.0 mm FWHM for the Biograph.

PET scans of all patients were obtained in the interictal state with the same protocols as healthy subjects. The ¹⁸FDG-PET examinations were performed under standard resting conditions using the GE Discovery ST PET-CT system (300 mm FOV, matrix 192 × 192, 3.27 mm slice thickness). The ¹⁸FDG was injected via IV at a mean dose of 310 MBq/70 kg body weight. The reconstructed images were corrected for attenuation using transmission scans obtained from a germanium source. PET scans of all patients were obtained within 6 months before epilepsy surgery evaluation. No patients had clinical seizures less than 6 h before or during the PET scan.

MRI scans were performed on a 3T Siemens Verio scanner (Siemens Medical System, South Iselin, NJ), including a 3D-T1 sagittal magnetization prepared rapid gradient echo sequence (MPRAGE, TR/TE 1900/2.53, TI 900, matrix 256 × 256, 1.0 mm thickness), T2 axial (TR/TE 7030/110, matrix 256 × 320, 3 mm thickness), FLAIR axial (TR/TE 8000/94, TI 2371.5, matrix 424 × 512, 3 mm thickness), FLAIR sagittal (TR/TE 8000/96, TI 2371.2, matrix 236 × 256, 3 mm thickness), and FLAIR coronal (TR/TE 8000/96, TI 2371.2, matrix 408 × 512, 3 mm thickness) imaging. The 18FDG-PET examination was performed using a GE Discovery ST PET-CT system (300 mm FOV, matrix 192 × 192, and 3.27 mm slice thickness). An IV injection of 18FDG at a mean dose of 220 MBq/70 kg body weight was administered. Reconstructed images were corrected for attenuation using transmission scans obtained from a germanium source. PET scans of all patients were obtained within 6 months before the epilepsy surgery evaluation. No patients had ictal events <6 h before or during the PET scanning.

MRI scans were performed on a 3T Siemens Verio scanner including a 3D T1 sagittal magnetization prepared rapid gradient echo sequence (MPRAGE; TR = 1,900 milliseconds, TE = 2.53 milliseconds, TI = 900 milliseconds, flip angle = 12°, slice thickness = 1 mm, no gap, matrix = 256 × 256, voxel size = 0.98 × 0.98 × 1 mm³).
PET scans of all patients were obtained in the interictal state with the same protocols as healthy subjects. The ¹⁸FDG-PET examinations were performed under standard resting conditions using the GE Discovery ST PET-CT system (300 mm FOV, matrix 192 × 192, 3.27 mm slice thickness). Patients were required to rest quietly in a dimly lit room during the 40 min following 18F-FDG intravenous administration of a mean dose of 310 MBq/70 kg body weight. Ordered subset expectation maximization (OSEM) algorithm (16 subsets and six iterations) was used for PET data reconstruction. The reconstructed images were corrected for attenuation using transmission scans obtained from a germanium source. PET scans of all patients were obtained within 6 months before epilepsy surgery evaluation. No patients had clinical seizures <6 h before or during the PET scan.

All of the patients underwent ¹⁸F-FDG PET/CT using a Discovery ST PET/CT system (GE Healthcare), consisting of a bismuth germanate full scanner and a 16-detector-row CT scanner. The patients fasted for at least 6 h prior to the intravenous administration of ¹⁸F-FDG (7.4 MBq per body weight) to ensure a serum glucose level below 7.2 mmol/L. At 60 min after ¹⁸F-FDG administration, transmission data were acquired using low-dose CT (120 kV, automated from 10 to 130 mA, a 512 × 512 matrix, a 50-cm field of view (FOV), 3.75-mm slice thickness, and a rotation time of 0.8 s), extending from the base of the skull to the proximal thighs. Immediately after CT acquisition, PET emission scans were acquired in the same anatomic locations with a 15.7-cm axial FOV acquired in the two-dimensional mode with a 128 × 128 matrix. The CT data were used for attenuation correction. The images were reconstructed using a conventional iterative algorithm (OSEM). A workstation (AW Volume Share™) providing multi-planar reformatted images was also used for image display and analysis. The initial and final conventional CT and PET/CT were assessed according to the revised International Workshop Criteria (IWC) [22 (link)]. The PET/CT scans were read by two nuclear medicine physicians who had no knowledge of subject or clinical information.