Biograph mct flow pet ct scanner

PET/CT image acquisition was performed 45 to 60 minutes after IV administration of approximately 40 μCi/kg ⁶⁸Ga-DOTATATE. Patients were instructed to drink at least 500 mL of water and to urinate before the scan. Until October 2017, the Gemini Time-of-Flight PET/CT scanner (Philips, the Netherlands) was used. Diagnostic contrast-enhanced (100 mL IV Ultravist 300; Bayer, Germany) CT was performed in the portal phase from the skull base to the thigh (120 kV, 150 mAs, 16 × 1.5 collimation, 0.8013 pitch). Then, PET acquisition was performed with a scan time of 2.5 minutes per bed. From October 2017, a Biograph mCT Flow PET/CT scanner (Siemens, Germany) equipped with an enhanced axial field of view (TrueV) scanner was used. Diagnostic contrast-enhanced CT was performed in the portal phase with automatic modulation in current and voltage. Reference values were set at 120 kV and 160 mA, 128 × 0.6 collimation, and 0.9 pitch. CT was performed after administration of 90 mL IV iodinated contrast medium (Xenetix 350; Guerbet, France). PET was performed with continuous bed motion at 1.5 mm/s.
For both scanners, CT data were used for PET attenuation correction and PET data reconstruction. Iodinated contrast medium was only administered on clinical indication and when there were no contraindications for administration.

Imaging of 8 patients was performed under the conditions of the updated Declaration of Helsinki, section 37 (unproven interventions in clinical practice) and in accordance with the German Pharmaceuticals Law, section 13 (2b), for medical reasons using ⁶⁸Ga-FAPI-21 and -46, which were applied intravenously (20 nmol, 210–267 MBq for FAPI-21 and 216–242 MBq for FAPI-46). Imaging took place at 10 min, 1 h, and 3 h after tracer administration. The PET/CT scans were obtained with a Biograph mCT Flow PET/CT scanner (Siemens Medical Solutions) using the following parameters: slice thickness of 5 mm, increment of 3–4 mm, soft-tissue reconstruction kernel, and CARE Dose. Immediately after CT scanning, a whole-body PET scan was acquired in 3 dimensions (matrix, 200 × 200) in FlowMotion with 0.7 cm/min. The emission data were corrected for randoms, scatter, and decay. Reconstruction was conducted with an ordered-subset expectation maximization algorithm with 2 iterations and 21 subsets and Gauss-filtered to a transaxial resolution of 5 mm in full width at half maximum. Attenuation was corrected using the low-dose nonenhanced CT data. SUVs were quantitatively assessed using a region-of-interest technique. The data were analyzed retrospectively with approval of the local ethics committee (approval S016/2018).

All patients gave written informed consent for undergoing ⁶⁸Ga-FAPI PET-CT. The radiopharmaceutical was administered intravenously (80 nmol/GBq) followed by image acquisition 30 min after tracer administration. The PET/CT scans were performed with a Biograph mCT Flow PET/CT-Scanner (Siemens Medical Solutions). A low-dose whole body CT scan (130 keV, 30 mAs, CareDose; reconstructed with a soft-tissue kernel to a slice thickness of 5 mm) was used for attenuation correction and image fusion. A 3-D emission scan (matrix 200 × 200) was performed, subsequently using FlowMotion (Siemens). The emission data was corrected for randoms, scatter and decay. Reconstruction was performed with an ordered subset expectation maximisation (OSEM) algorithm with two iterations/21 subsets and Gauss-filtered to a transaxial resolution of 5 mm at full width at half maximum (FWHM).
Circular volumes of interest were used inside tumour lesions and healthy tissues to quantify the radiotracer biodistribution in patients. This resulted in SUV_max and SUV_mean.

Diagnostic imaging was performed under the conditions of the updated Declaration of Helsinki, § 37 (unproven interventions in clinical practice) and in accordance with German Pharmaceuticals Law §13 (2b) for medical reasons. FAPI tracers (FAPI-02, FAPI-46 and FAPI-74 with eight patients each) were labelled with ⁶⁸Ga as previously described [22 (link),23 (link)] and applied intravenously (80 nmol/GBq). CT scans were performed within the first 10 min after tracer injection with a Biograph mCT Flow™ PET/CT-Scanner (Siemens Medical Solutions) using the following parameters: slice thickness of 5 mm, increment of 3–4 mm, soft-tissue reconstruction kernel, and care dose. PET scans were acquired exactly 10, 22, 34, 46 and 58 min post tracer administration (timepoints 1, 2, 3, 4 and 5) with a standardized field of view allowing whole-body scans within 12 min in 3D (matrix 200 × 200) in FlowMotion™ with 1.6 cm/min. Emission data were corrected for random, scatter and decay. Reconstruction was conducted with an ordered subset expectation maximization (OSEM) algorithm with 2 iterations/21 subsets and Gauss-filtered to a transaxial resolution of 5 mm at full-width half-maximum. Attenuation correction was applied based on low-dose non-enhanced CT data.

Chemical synthesis and labeling of ⁶⁸Ga-FAPI-04 (6), ⁶⁸Ga-FAPI-46 (5), and ⁶⁸Ga-FAPI-74 (4) followed the methods as described in previous publications [6 (link), 7 (link), 14 ]. The radiopharmaceutical was administered intravenously followed by image acquisition 60 min after tracer application. The injected activity ranged from 127 to 308 MBq (2–3 MBq per kg bodyweight). Patients were requested to self-report any new symptoms or abnormalities up to 30 min after the end of the examination. PET imaging was performed with a Biograph mCT Flow PET/CT Scanner (Siemens Medical Solutions). PET scans were conducted according to previously published protocols [9 (link), 15 (link)]. Consequently, a low-dose CT without contrast was performed, followed by PET scans in 3-dimensional mode (matrix, 200 × 200). The emission data were corrected for random, scatter, and decay and subsequently reconstructed.

[¹⁸F]AlF-FAPI-74 (16.2 GBq/µmol at time of injection) was applied intravenously (20 nmol; 323 MBq) to a 68 y old patient with NSCLC. The PET/CT scans were performed 1 and 3 h post tracer administration with a Biograph mCT Flow™ PET/CT-Scanner (Siemens Medical Solutions). The parameters used were slice thickness of 5 mm, increment of 3–4 mm, soft-tissue reconstruction kernel and care dose. After CT scanning, a whole-body PET was acquired in 3D (matrix 200 × 200) in FlowMotion™ with 0.7 cm/min. The emission data were corrected for random, scatter and decay. Reconstruction was conducted with an ordered subset expectation maximization (OSEM) algorithm with 2 iterations/21 subsets and Gauss-filtered to a transaxial resolution of 5 mm at full-width half-maximum. Attenuation correction was performed using the low-dose non-enhanced CT data. The quantitative assessment of standardized uptake values (SUV) was done using a region of interest technique.