Biograph 64 hd pet ct

The scanning equipment used is Siemens Biograph 64 HD PET/CT (Siemens, Erlangen, Germany)

In preparation before scanning, all subjects should fast over 6 hours and withdrew anti-Parkinsonian and antipsychotics drugs for more than 12 hours before clinical assessment and each imaging acquisition. And other drugs that may affect glucose metabolism also need to withdrew over 12 h before the ¹⁸F-FDG PET imaging

The acquisition protocols of PET imaging are shown in Table 2.

Acquisition for patients was performed in a resting state in a quiet and dimly lit room to avoid sensory, auditory, and motor stimulation to the patient.

All patients stopped taking anti-parkinsonian medications (if used) at least 12 h before PET imaging and received an intravenous injection of the [¹¹C]CFT (370 MBq). A 15-min three-dimensional emission scan was acquired one hour after the injection using the Biograph™ 64 HD PET/CT (Siemens Healthcare, Erlangen, Germany). The low-dose computed tomography was employed for the attenuation correction before the emission scan. PET images were then reconstructed using the three-dimensional ordered subset expectation maximization algorithm after the corrections for scatter, dead time and random coincidences. After that, the SPM5 software (Wellcome Department of Imaging Neuroscience, Institute of Neurology, London, UK), implemented in Matlab 7.4.0 (Mathworks Inc, Sherborn, MA), was utilized to spatially normalize these PET images into the Montreal Neurological Institute (MNI) brain space as previously described in [24 (link), 25 (link)]. Individual MRI scans were not used for image preprocessing since these scans were performed in the routine clinical workup but not acquired according to a standardized protocol [25 (link)]. Finally, a three-dimensional Gaussian filter (10 mm full width at half maximum (FWHM)) was involved to smoothen the normalized PET images.

All patients had fasted for at least 4 hours before imaging. 20 minutes after an intravenous bonus injection of ¹⁸F-FET (370 ± 30 MBq), a static PET scan was collected for 20 minutes with a Siemens Biograph 64 HD PET/CT (Siemens, Erlangen, Germany) in 3-dimensional (3D) mode for 50 patients in this cohort. 8 patients underwent dynamic ¹⁸F-FET PET scanning lasted longer than 40 minutes after the tracer injection; 20–40 minutes images were reconstructed for diagnosis and analysis. Attenuation correction was performed using a low-dose CT (tube current 150mAs, voltage 120kV, Acq. 64*0.6mm, convolution kernel H30s, slice thickness 5mm, interslice gap 1.5mm) before the emission scan. After acquisition, the PET images were reconstructed by filtered back projection algorithm with Gaussian filter and full-width-at-half-maximum at the center of the field of view of 3.5mm). The reconstructed brain PET image matrix size was 168*168 with voxel size of 2.04*2.04mm. And the reconstructed brain CT image matrix size was 512*512 with voxel size of 0.59*0.59 mm.

¹⁸F-FDG PET/CT was performed using integrated PET-CT scanner (Siemens Biograph 64HD PET/CT, Siemens, Germany). During the procedure, the subjects were fixed, and attenuation correction was applied with a low-dose CT (150 mAs, 120 kV, Acq. 64 × 0.6 mm). Following corrections for scatter, dead time, and random coincidences, PET images were reconstructed by 3D filtered back projection and a Gaussian Filter (FWHM 3.5 mm), providing 64 continuous trans-axial slices of 5-mm-thick spacing. PET-CT images were interpreted by experienced radiologists. The FDG uptake was normalized using the standardized uptake value (SUV) by dividing the radioactivity (kBq/mL) in the brain by the radioactivity injected per gram of body weight. The background area is defined in the symmetrical cerebellar cortex. SUVmax was used as the reference measurement and was determined by considering the tumor uptake given by the maximum pixel value within the gliomas [26 (link)].

All subjects underwent ¹⁸F-FDG PET examination at resting state. PET scans were performed with a Siemens Biograph 64 HD PET/CT (Siemens, Germany) in three-dimensional (3D) mode. All subjects were fasted for at least 6 h before scanning. After intravenous injection of 185 MBq ¹⁸F-FDG, the PET scan was started after a 45-min rest in a quiet and dimly lit environment. Prior to the PET scan, a low-dose CT transmission scan was performed for attenuation correction. The PET scan was performed in 3D mode for 10 min. All PET data were reconstructed using a 3D ordered subset expectation maximization algorithm and corrected for random coupling, scattering, and radioactive decay.