Article Figures & Data
Figures
- FIGURE 1.
Vereos sensitivity: axial sensitivity profile for measurements with line source in center of FOV and at 10-cm radial offset.
- FIGURE 2.
Vereos count rate performance: prompts, trues, randoms, and scatter count rates (A); trues, randoms, and scatter counts as function of total number of coincidences recorded (B).
- FIGURE 3.
Vereos NEC rate. (A) NEC rate as function of activity concentration in phantom calculated according to NEMA NU2-2012. Peak NEC rate was 153.4 kcps at 54.9 kBq/mL. (B) Scatter fraction for same range of activities. Scatter fraction at peak NEC rate was 33.9%.
- FIGURE 4.
Vereos count rate accuracy: maximum and minimum relative count rate errors for different activity distributions. First and last slices of acquisitions were excluded from this evaluation.
- FIGURE 5.
Vereos image quality: central slice of image-quality phantom for 4:1 (A) and 8:1 (B) sphere-to-background ratio.
- FIGURE 6.
Maximum-intensity projection of 18F-FDG PET/CT examination of 68-y-old patient. Imaging was performed first on Vereos PET/CT system (at 69 min) (A) and subsequently on Gemini PET/CT system (at 156 min) (B) after injection of 260 MBq of 18F-FDG. Both examinations were performed using clinical standard acquisition parameters: blob ordered-subsets TOF reconstruction using 3 iterations and 33 subsets into a 144 × 144 matrix on Vereos PET/CT system, and ordered-subsets expectation-maximization reconstruction using 2 iterations and 10 subsets into a 288 × 288 matrix on Gemini system. Better image contrast was observed in Vereos images. However, objective comparison of imaging capabilities of the two systems is not possible because of differences in reconstruction protocols as predetermined by acquisition software.
Tables
- TABLE 1
Spatial Resolution Measured for PET Component of Vereos PET/CT System (NEMA NU2-2012)
Vereos Parameter Distance (cm) FWHM (mm) FWTM (mm) Discovery MI FWHM (mm) (8) mCT Flow FWHM (mm) (20) Transverse 1 4.24* ± 0.07 8.40* ± 0.15 4.15* 4.33* Axial 1 4.17 ± 0.17 8.80 ± 0.21 4.48 4.25 Transverse radial 10 4.55 ± 0.09 8.87 ± 0.13 5.47 5.16 Transverse tangential 10 4.35 ± 0.01 8.97 ± 0.04 4.49 4.72 Axial 10 4.39 ± 0.00 9.08 ± 0.02 6.01 5.85 Transverse radial 20 5.84 ± 0.06 10.43 ± 0.04 7.53 5.55 Transverse tangential 20 4.92 ± 0.01 9.96 ± 0.12 4.90 6.48 Axial 20 4.60 ± 0.13 9.21 ± 0.26 6.10 7.80 ↵* Average value of radial and tangential measurements.
FWTM = full width at tenth maximum.
Data are average ± SD of the measurements at the axial center an off center position. Reported spatial resolutions of Discovery MI (SiPM-based system with 20-cm axial FOV (8)) and mCT Flow (PMT-based system with 22.1-cm axial FOV (20)) are shown for comparison. Spatial resolution measurements for 15-cm axial FOV Discovery MI and 16.2-cm axial FOV mCT Flow are not available but are expected to be similar to those of extended-axial-FOV systems (25,35).
Discovery MI (8) Biograph mCT Distance (cm) Vereos 20 cm 15 cm 22.1 cm (20) 16.2 cm (36) 1 5.1 13.7 7.5 9.6 5.4 10 5.2 9.6 5.9 Data are cps kBq−1. Sensitivity of state-of-art PET/CT systems are shown for comparison: Discovery MI with axial FOVs of 20 and 15 cm, Biograph mCT Flow 4R with axial FOV of 22.1 cm, and Biograph mCT 3R with axial FOV of 16.2 cm.
- TABLE 3
Measured Count Rates and Scatter Fractions for Vereos PET/CT System (NEMA NU2-2012)
Discovery MI Parameter Vereos 20 cm (8) 15 cm (35) mCT flow, 22.1 cm (20) Peak trues rate 733 kcps at 64.6 kBq/mL 876 kcps at 35.4 kBq/mL NA 634 kcps at42.4 kBq/mL Peak NEC rate 153.4 kcps at 54.9 kBq/mL 193.4 kcps at 21.9 kBq/mL 100 kcps at 20.6 kBq/mL 185.4 kcps at 29.0 kBq/mL NEC rate at 5.3 kBq/mL 47.2 kcps NA NA NA Scatter fraction at low count rates 31.7% at 0.4 kBq/mL NA NA 33.5% Scatter fraction at Peak NEC rate 33.9% at 54.9 kBq/mL 40.6% at 21.9 kBq/mL NA 33.4% at 29.0 kBq/mL NA = not applicable.
For comparison, measurements from SiPM-based Discovery MI PET/CT system with axial FOVs of 15 cm (35) and 20 cm (8), as well as data from PMT-based mCT Flow with 22.1-cm axial FOV (20), are shown.
- TABLE 4
Image Quality Results for 4:1 and 8:1 Sphere-to-Background Ratios for Vereos PET/CT System (NEMA NU2-2012)
Contrast recovery Background variability Sphere diameter (mm) 4:1 8:1 4:1 8:1 10 54.3 (48.6–61.5) 54.4 (53.2–55.4) 8.8 (7.7–10.2) 9.3 (8.9–9.8) 13 75.3 (68.6–78.8) 75.9 (74.3–79.0) 7.2 (6.2–8.3) 7.5 (7.1–7.9) 17 80.4 (78.5–83.1) 81.6 (80.0–83.4) 5.7 (5.0–6.3) 5.7 (5.2–6.1) 22 83.9 (80.7–88.3) 86.5 (86.2–87.1) 4.4 (4.1–4.7) 4.3 (3.9–4.8) 28 81.4 (08.2–82.8) 82.5 (82.1–83.3) 3.3 (3.1–3.6) 3.5 (3.2–3.9) 37 87.0 (86.8–87.3) 85.8 (86.1–85.4) 2.5 (2.5–2.3) 2.6 (2.1–2.9) Lung residual 6.35 6.36 Data are mean percentages followed by ranges in parentheses.
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