Symbia intevo

721 ± 25 MBq DPD were injected intravenously 2.5 h prior to whole body planar imaging on the same hybrid SPECT/CT system as the phantom experiments were conducted (Symbia Intevo, Siemens Medical Solutions AG, Erlangen, Germany). Directly after the planar scan, a SPECT/CT of the thorax was performed. Image acquisition and reconstruction was done using the same parameters as for the phantom experiments utilizing the xSPECT/CT QUANT technology, which uses a 3% National Institute of Standards and Technology (NIST) traceable precision source for standardization of uptake values across different cameras, dose calibrators, and facilities [31 ].

USG examinations were carried out by different operators and using different scanners (the patients provided the results). The scintigraphy images were obtained using the planar technique and SPECT-CT projections with Siemens Symbia Intevo (Siemens Healthineers, Erlangen, Germany). All the scintigraphy images were evaluated by the same physician.

All patients underwent planar imaging and SPECT/CT 1 and 3 hours after intravenous injection of 555 MBq ^99mTc-PYP. Images were acquired using a dual Anger detector large field-of-view rotating SPECT/CT system equipped with low-energy high-resolution collimators and an integrated 6-slice diagnostic-quality CT unit (Symbia Intevo, Siemens Medical Solutions AG, Erlangen, Germany). The primary energy peak was centered at 140 keV (15% energy window) and the scatter correction peak was centered at 119 keV (18% energy window).
One-hour anterior and posterior planar images were acquired as 128 × 128 matrices with 750 × 10³ counts (Fig. 1). SPECT/CT images were acquired as 256 × 256 matrices for 128 projections for 35 seconds per projection. SPECT reconstructions by ordered subset expectation maximization (8 subsets, 3 iterations) were performed for this data, without attenuation correction, to emulate data that would be acquired on SPECT systems (Fig. 2). CT data were acquired immediately after SPECT acquisition using the CT acquisition parameters recommended by the manufacturer. Data were reconstructed using ordered subset expectation maximization (8 subsets, 3 iterations) and corrected for radiation scatter and attenuation using CT parameters and the reconstruction algorithm provided by the manufacturer (Fig. 3).

All patients received 450–750 MBq [^99mTc]Tc-HDP intravenously for each of both scans. Bone scintigraphies were performed on dedicated SPECT/CT systems (Symbia T2, Symbia T16 and Symbia Intevo, Siemens Healthineers, Erlangen, Germany) equipped with a low-energy high-resolution collimator. Planar whole-body scans were obtained 3 h after injection from posterior and anterior view. Acquisition time was 12 min in total, and 6 min per view. SPECT images were acquired using a 180° configuration, 64 views, 20 s per view and a 128 × 128 matrix. Planar images were compared with single-photon emission computed tomography (SPECT) images to rule out blood pool activity. Anterior planar images were scored according to the Perugini scale [17 (link)], and a free-handed region of interest (ROI) was placed over the heart, oval ROIs were placed over the kidneys, and bladder and a free-handed ROI was placed around the outline of the body. Heart/whole-body (H/WB) ratio was calculated [18 (link)].

Bone scans were performed on a dedicated SPECT/CT system (Symbia Intevo, Siemens Medical Solutions AG, Erlangen, Germany) equipped with a low-energy high-resolution collimator. Planar images were acquired from anterior and posterior with a continuous table feed of 20 to 25 cm per min (ca. 1.000.000 cts) using a 1024 × 256 matrix and a 20% energy window around the 140 keV peak. Tracer activities of 713 ± 15 MBq [Tc^99m]-DPD were injected intravenously prior to bone scintigraphy SPECT imaging as recently described^{15 (link)} was performed using a 180° configuration, 64 views, 20 s per view, 256 × 256 matrix and an energy window of 15% around the 99mTc photopeak of 141 keV. Subsequent to the SPECT acquisition, a low-dose CT scan was acquired for attenuation correction (130 kV, 35 mAs, 256 × 256 matrix, step-and-shoot acquisition with body-contour). SPECT/CT images were reconstructed with the iterative xSPECT/CT QUANT algorithm (eight iterations, four subsets, 3.0 mm smoothing filter, and a 20 mm Gaussian filter) using a 3% National Institute of Standards and Technology (NIST) traceable precision source.