This study evaluates the performance of the Siemens Biograph Vision digital PET/CT system (Siemens Healthineers, Knoxville, USA) according to the NEMA NU 2-2012 standard (published by the National Electrical Manufacturers Association (NEMA)) to allow for a reliable, reproducible, and inter-system comparable performance measurement. Methods: The new digital PET/CT features silicon photomultiplier (SiPM)-based detectors with 3.2 mm lutetium oxyorthosilicate (LSO) crystals and full coverage of the scintillator area. The PET components incorporate eight rings of 38 detector blocks and each block contains 4x2 mini-blocks. Each mini-block consists of a 5x5 LSO-array of 3.2x3.2x20 mm crystals coupled to a SiPM-array of 16x16 mm, resulting in an axial field of view (FOV) of 26.1 cm. In this study PET/CT system performance will be evaluated conform the NEMA NU 2-2012 standard with additional measurements described in the new NEMA NU 2-2018 standard. Spatial resolution, sensitivity, count-rate performance, accuracy of attenuation and scatter correction, Time-of-Flight (TOF) performance, and image quality will be determined. Measurements will be directly compared to results from its predecessor, the Biograph mCT Flow, using existing literature. Moreover, feasibility to comply with the European Association of Nuclear Medicine (EANM) Research Ltd (EARL) criteria will be evaluated and some illustrative patient PET images will be shown. Results: The Biograph Vision shows a transverse (resp. axial) spatial resolution at Full Width Half Maximum (FWHM) of 3.6 mm (resp. 3.5 mm) at 1 cm offset of the center of the FOV (measured with a 22Na 0.25 mm point-source), a NEMA sensitivity of 16.4 kcps/MBq, and a NEMA peak NECR of 306 kcps at 32 kBq/mL. TOF resolution varied from 210 to 215 as count-rate increased up to the peak NECR. The overall image contrast seen with the NEMA image quality phantom ranged from 77.2% to 89.8%. Furthermore, the system was able to comply with the current and future EARL performance criteria. Conclusion: The Biograph Vision outperforms the analog Biograph mCT Flow and the system is able to meet European harmonizing performance standards.

In May 2018 the new Biograph Vision PET/CT (Siemens Healthineers, Knoxville, USA) was introduced at the University Medical Center Groningen. This study evaluated the initial experiences with this new PET/CT system in terms of perceived image quality and semi-quantitative analysis in comparison to the Biograph mCT (Siemens Healthineers, Knoxville, USA) as a reference. Methods: A total of 20 oncological patients were enrolled and received a single ¹⁸F-FDG injected dose of 3 MBq/kg followed by a dual-imaging PET protocol. Ten patients were scanned on the Biograph mCT first, while the other ten patients were scanned on the Biograph Vision first. The locally preferred clinical reconstructions were blindly reviewed by three nuclear medicine physicians and scored 1-5 on tumor lesion delineation, overall image quality, and image noise. In addition, these clinical reconstructions were used for semi-quantitative analysis; measurement of standardized uptake values (SUVs) in tumor lesions. Reconstructions conform the European Association of Nuclear Medicine Research Ltd (EARL) specifications were also used for measurements of SUVs in tumor lesions and healthy tissues for comparison between systems. Results: 20 oncological patients (14 men, 6 women; age 36-84, mean ± SD 61 ± 16 years) received a single ¹⁸F-FDG injected dose (range 145-405 MBq, mean ± SD 268 ± 59.3). Images acquired on the Biograph Vision were scored significantly higher on tumor lesion delineation, overall image quality, and image noise in comparison to images acquired on the Biograph mCT (P < 0.001). The overall inter-reader agreement showed a Fleiss kappa of 0.61 (95% CI 0.53 – 0.70). Furthermore, the measured SUVs in tumor lesions and healthy tissues showed a good agreement (within 95%) between PET/CT systems, in particular when using EARL compliant reconstructions on both systems. Conclusion: In this initial study it was found that the Biograph Vision PET/CT showed improved image quality compared with the Biograph mCT in terms of lesion demarcation, overall image quality, and visually assessed signal-to-noise ratio. The two systems are comparable in semi-quantitatively assessed image biomarkers in both healthy tissues and tumor lesions. Improved quantitative performance may, however, be feasible using the clinically optimized reconstruction settings.

The first Siemens Biograph Vision PET/CT system (Siemens Healthineers, Knoxville, USA) was installed at the University Medical Center Groningen. Improved performance of this system could allow for a reduction in activity administration and/or scan duration. This study evaluates the effects of reduced scan duration in oncological ¹⁸F-FDG PET imaging on quantitative and subjective imaging parameters and its influence on clinical image reading. Methods: Patients referred for a clinical PET/CT scan were enrolled in this study, received a weight-based ¹⁸F-FDG injected activity, and underwent a 180 seconds per bed position (s/bp) list-mode PET acquisition. Acquired PET data were reconstructed using the clinically vendor recommended reconstruction protocol (hereinafter referred to as Clinical), using the Clinical protocol with additional 2 mm Gaussian filtering (hereinafter referred to as Clinical+G2) as well as conform European Association of Nuclear Medicine Research Ltd (EARL) specifications using different scan durations per bed position (180, 120, 60, 30, and 10 s). Reconstructed images were quantitatively assessed for comparison of standardized uptake values (SUVs) and noise. In addition, Clinically reconstructed images were qualitatively evaluated by three nuclear medicine physicians. Results: In total, 30 oncological patients (22 men, 8 women; age 48-88, mean ± SD 67 ± 9.6 years) received a single weight-based (3 MBq/kg) ¹⁸F-FDG injected activity (weight 45-123 kg, mean ± SD 81 ± 15; activity 135-380 MBq, mean ± SD 241 ± 46.5). Significant differences in lesion SUV_max were found between the 180 s/bp images and the 30 and 10 s/bp images reconstructed using the Clinical protocols, whereas no differences were found in lesion SUVpeak. EARL compliant images did not show differences in lesion SUV_max or SUVpeak between scan durations. Quantitative parameters showed minimal deviation (~5%) in the 60 s/bp images. Further subjective image quality assessment was therefore conducted using the 60 s/bp images. Qualitative assessment revealed the influence of personal preference on physicians’ willingness to adopt the 60 s/bp images in clinical practice. Although quantitative PET parameters differed minimally, an increase in noise was observed. Conclusion: Using the Biograph Vision PET/CT for oncological ¹⁸F-FDG imaging, scan duration and/or activity administration could be reduced by a factor of three or more when using the Clinical+G2 or the EARL compliant reconstruction protocol, respectively.

Purpose: Current European Association of Nuclear Medicine (EANM) Research Ltd. (EARL) guidelines for the standardisation of PET imaging developed for conventional systems have not yet been adjusted for long axial field-of-view (LAFOV) systems. In order to use the LAFOV Siemens Biograph Vision Quadra PET/CT (Siemens Healthineers, Knoxville, TN, USA) in multicentre research and harmonised clinical use, compliance to EARL specifications for ¹⁸F-FDG tumour imaging was explored in the current study. Additional tests at various locations throughout the LAFOV and the use of shorter scan durations were included. Furthermore, clinical data were collected to further explore and validate the effects of reducing scan duration on semi-quantitative PET image biomarker accuracy and precision when using EARL-compliant reconstruction settings. Methods: EARL compliance phantom measurements were performed using the NEMA image quality phantom both in the centre and at various locations throughout the LAFOV. PET data (maximum ring difference (MRD) = 85) were reconstructed using various reconstruction parameters and reprocessed to obtain images at shorter scan durations. Maximum, mean and peak activity concentration recovery coefficients (RC) were obtained for each sphere and compared to EARL standards specifications. Additionally, PET data (MRD = 85) of 10 oncological patients were acquired and reconstructed using various reconstruction settings and reprocessed from 10 min listmode acquisition into shorter scan durations. Per dataset, SUVs were derived from tumour lesions and healthy tissues. ANOVA repeated measures were performed to explore differences in lesion SUV_max and SUV_peak. Wilcoxon signed-rank tests were performed to evaluate differences in background SUV_peak and SUV_mean between scan durations. The coefficient of variation (COV) was calculated to characterise noise. Results: Phantom measurements showed EARL compliance for all positions throughout the LAFOV for all scan durations. Regarding patient data, EARL-compliant images showed no clinically meaningful significant differences in lesion SUV_max and SUV_peak or background SUV_mean and SUV_peak between scan durations. Here, COV only varied slightly. Conclusion: Images obtained using the Vision Quadra PET/CT comply with EARL specifications. Scan duration and/or activity administration can be reduced up to a factor tenfold without the interference of increased noise.

Background: Excellent performance characteristics of the Vision Quadra PET/CT, e.g. a substantial increase in sensitivity, allow for precise measurements of image-derived input functions (IDIF) and tissue time activity curves. Previously we have proposed a method for a reduced 30 min (as opposed to 60 min) whole body ¹⁸F-FDG Patlak PET imaging procedure using a previously published population-averaged input function (PIF) scaled to IDIF values at 30–60 min post-injection (p.i.). The aim of the present study was to apply this method using the Vision Quadra PET/CT, including the use of a PIF to allow for shortened scan durations. Methods: Twelve patients with suspected lung malignancy were included and received a weight-based injection of ¹⁸F-FDG. Patients underwent a 65-min dynamic PET acquisition which were reconstructed using European Association of Nuclear Medicine Research Ltd. (EARL) standards 2 reconstruction settings. A volume of interest (VOI) was placed in the ascending aorta (AA) to obtain the IDIF. An external PIF was scaled to IDIF values at 30–60, 40–60, and 50–60 min p.i., respectively, and parametric ¹⁸F-FDG influx rate constant (K_i) images were generated using a t* of 30, 40 or 50 min, respectively. Herein, tumour lesions as well as healthy tissues, i.e. liver, muscle tissue, spleen and grey matter, were segmented. Results: Good agreement between the IDIF and corresponding PIF scaled to 30–60 min p.i. and 40–60 min p.i. was obtained with 7.38% deviation in K_i. Bland–Altman plots showed excellent agreement in K_i obtained using the PIF scaled to the IDIF at 30–60 min p.i. and at 40–60 min p.i. as all data points were within the limits of agreement (LOA) (− 0.004–0.002, bias: − 0.001); for the 50–60 min p.i. K_i, all except one data point fell in between the LOA (− 0.021–0.012, bias: − 0.005). Conclusions: Parametric whole body ¹⁸F-FDG Patlak K_i images can be generated non-invasively on a Vision Quadra PET/CT system. In addition, using a scaled PIF allows for a substantial (factor 2 to 3) reduction in scan time without substantial loss of accuracy (7.38% bias) and precision (image quality and noise interference).

Whole-body Patlak images can be obtained from an acquisition of first 6 min of dynamic imaging over the heart to obtain the arterial input function (IF), followed by multiple whole-body sweeps up to 60 min pi. The use of a population-averaged IF (PIF) could exclude the first dynamic scan and minimize whole-body sweeps to 30–60 min pi. Here, the effects of (incorrect) PIFs on the accuracy of the proposed Patlak method were assessed. In addition, the extent of mitigating these biases through rescaling of the PIF to image-derived IF values at 30–60 min pi was evaluated. Methods: Using a representative IF and rate constants from the literature, various tumour time-activity curves (TACs) were simulated. Variations included multiplication of the IF with a positive and negative gradual linear bias over 60 min of 5, 10, 15, 20, and 25% (generating TACs using an IF different from the PIF); use of rate constants (K₁, k₃, and both K₁ and k₂) multiplied by 2, 1.5, and 0.75; and addition of noise (μ = 0 and σ = 5, 10 and 15%). Subsequent Patlak analysis using the original IF (representing the PIF) was used to obtain the influx constant (K_i) for the differently simulated TACs. Next, the PIF was scaled towards the (simulated) IF value using the 30–60-min pi time interval, simulating scaling of the PIF to image-derived values. Influence of variabilities in IF and rate constants, and rescaling the PIF on bias in K_i was evaluated. Results: Percentage bias in K_i observed using simulated modified IFs varied from − 16 to 16% depending on the simulated amplitude and direction of the IF modifications. Subsequent scaling of the PIF reduced these K_i biases in most cases (287 out of 290) to < 5%. Conclusions: Simulations suggest that scaling of a (possibly incorrect) PIF to IF values seen in whole-body dynamic imaging from 30 to 60 min pi can provide accurate Ki estimates. Consequently, dynamic Patlak imaging protocols may be performed for 30–60 min pi making whole-body Patlak imaging clinically feasible.