Dataset Information

SUV variability in EARL-accredited conventional and digital PET.

ABSTRACT: BACKGROUND:A high SUV-reproducibility is crucial when different PET scanners are in use. We evaluated the SUV variability in whole-body FDG-PET scans of patients with suspected or proven cancer using an EARL-accredited conventional and digital PET scanner. In a head-to-head comparison we studied images of 50 patients acquired on a conventional scanner (cPET, Ingenuity TF PET/CT, Philips) and compared them with images acquired on a digital scanner (dPET, Vereos PET/CT, Philips). The PET scanning order was randomised and EARL-compatible reconstructions were applied. We measured SUVmean, SUVpeak, SUVmax and lesion diameter in up to 5 FDG-positive lesions per patient. The relative difference ?SUV between cPET and dPET was calculated for each SUV-parameter. Furthermore, we calculated repeatability coefficients, reflecting the 95% confidence interval of ?SUV. RESULTS:We included 128 lesions with an average size of 19 ± 14?mm. Average ?SUVs were 6-8% with dPET values being higher for all three SUV-parameters (p < 0.001). ?SUVmax was significantly higher than ?SUVmean (8% vs. 6%, p = 0.002) and than ?SUVpeak (8% vs. 7%, p = 0.03). Repeatability coefficients across individual lesions were 27% (?SUVmean and ?SUVpeak) and 33% (?SUVmax) (p < 0.001). CONCLUSIONS:With EARL-accredited conventional and digital PET, we found a limited SUV variability with average differences up to 8%. Furthermore, only a limited number of lesions showed a SUV difference of more than 30%. These findings indicate that EARL standardisation works. TRIAL REGISTRATION:This prospective study was registered on the 31th of October 2017 at ClinicalTrials.cov. URL: https://clinicaltrials.gov/ct2/show/NCT03457506?id=03457506&rank=1.

SUBMITTER: Koopman D

PROVIDER: S-EPMC6904705 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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SUV variability in EARL-accredited conventional and digital PET.

Koopman Daniëlle D Jager Pieter L PL Slump Cornelis H CH Knollema Siert S van Dalen Jorn A JA

EJNMMI research 20191210 1

<h4>Background</h4>A high SUV-reproducibility is crucial when different PET scanners are in use. We evaluated the SUV variability in whole-body FDG-PET scans of patients with suspected or proven cancer using an EARL-accredited conventional and digital PET scanner. In a head-to-head comparison we studied images of 50 patients acquired on a conventional scanner (cPET, Ingenuity TF PET/CT, Philips) and compared them with images acquired on a digital scanner (dPET, Vereos PET/CT, Philips). The PET s ...[more]

PMID: 31823097

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Project description:BACKGROUND:Today, the standardized uptake value (SUV) is essentially the only means for quantitative evaluation of static [18F-]fluorodeoxyglucose (FDG) positron emission tomography (PET) investigations. However, the SUV approach has several well-known shortcomings which adversely affect the reliability of the SUV as a surrogate of the metabolic rate of glucose consumption. The standard uptake ratio (SUR), i.e., the uptake time-corrected ratio of tumor SUV to image-derived arterial blood SUV, has been shown in the first clinical studies to overcome most of these shortcomings, to decrease test-retest variability, and to increase the prognostic value in comparison to SUV. However, it is unclear, to what extent the SUR approach is vulnerable to observer variability of the additionally required blood SUV (BSUV) determination. The goal of the present work was the investigation of the interobserver variability of image-derived BSUV. METHODS:FDG PET/CT scans from 83 patients (72 male, 11 female) with non-small cell lung cancer (N = 46) or head and neck cancer (N = 37) were included. BSUV was determined by 8 individuals, each applying a dedicated delineation tool for the BSUV determination in the aorta. Two of the observers applied two further tools. Altogether, five different delineation tools were used. With each used tool, delineation was performed for the whole patient group, resulting in 12 distinct observations per patient. Intersubject variability of BSUV determination was assessed using the fractional deviations for the individual patients from the patient group average and was quantified as standard deviation (SD is), 95% confidence interval, and range. Interobserver variability of BSUV determination was assessed using the fractional deviations of the individual observers from the observer-average for the considered patient and quantified as standard deviations (SD p, SD d) or root mean square (RMS), 95% confidence interval, and range in each patient, each observer, and the pooled data respectively. RESULTS:Interobserver variability in the pooled data amounts to RMS = 2.8% and is much smaller than the intersubject variability of BSUV (SD is= 16%). Averaged over the whole patient group, deviations of individual observers from the observer average are very small and fall in the range [ -?0.96, 1.05]%. However, interobserver variability partly differs distinctly for different patients, covering a range of [0.7, 7.4]% in the investigated patient group. CONCLUSION:The present investigation demonstrates that the image-based manual determination of BSUV in the aorta is sufficiently reproducible across different observers and delineation tools which is a prerequisite for accurate SUR determination. This finding is in line with the already demonstrated superior prognostic value of SUR in comparison to SUV in the first clinical studies.

Project description:INTRODUCTION:11C-acetate (ACE)-PET/CT is used for staging of high-risk prostate cancer. PET data is reconstructed with iterative algorithms, such as VUEPointHD ViP (VPHD) and VUEPoint HD Sharp IR (SharpIR), the latter with additional resolution recovery. It is expected that the resolution recovery algorithm should render more accurate maximum and mean standardized uptake values (SUVmax and SUVmean) and functional tumor volumes (FTV) than the ordinary OSEM. Performing quantitative analysis, choice of volume-of-interest delineation algorithm (SUV threshold) may influence FTV. Optimizing PET acquisition time is justified if image quality and quantitation do not deteriorate. The aim of this study is to identify the optimal reconstruction algorithm, SUV threshold and acquisition time for ACE-PET/CT. METHODS:ACE-PET/CT data acquired with a General Electric Discovery 690 PET/CT from 16 consecutive high-risk prostate cancer patients was reconstructed with VPHD and SharpIR. Forty pelvic lymph nodes (LNs) and 14 prostate glands were delineated with 42% and estimated threshold. SUVmax, SUVmean, FTV and total lesion uptake were measured. Default acquisition time was four minutes per bed position. In a subset of lesions, acquisition times of one, two and four minutes were evaluated. Structural tumor volumes (STV) of the LNs were measured with CT for correlation with functional volumetric parameters. To validate SUV quantification under different conditions with SharpIR 42%, recovery coefficients (RCs) of SUVmean and FTV were calculated from a phantom with 18F-fluoro-deoxy-glucose (FDG)-filled volumes 0.1-9.2cm3 and signal-to-background (S/B) ratios 4.3-15.9. RESULTS:With SharpIR, SUVmax and SUVmean were higher and FTV lower compared with VPHD, regardless of threshold method, in both prostates and LNs. Total lesion uptake determined with both threshold methods was lower with SharpIR compared with VPHD with both threshold methods, except in subgroup analysis of prostate targets where estimated threshold returned higher values. Longer acquisition times returned higher FTV for both threshold methods, regardless of reconstruction algorithm. The FTV difference was most pronounced with one minute's acquisition per bed position, which also produced visually the highest noise. SUV parameters were unaffected by varying acquisition times. FTV with SharpIR 42% showed the best correspondence with STV. SharpIR 42% gave higher RCs of SUVmean and FTV with increasing phantom size and S/B-ratio, as expected. CONCLUSIONS:Delineation with SharpIR 42% seems to provide the most accurate combined information from SUVmax, SUVmean, FTV and total lesion uptake. Acquisition time may be shortened to two minutes per bed position with preserved image quality.

Project description:Quantitative assessment of radio- and chemotherapy response with 18F-FDG whole-body PET has attracted increasing interest in recent years. In most published work, SUV has been used for this purpose. In the context of therapy response assessment, the reliability of lesion SUVs, notably their test-retest stability, thus becomes crucial. However, a recent study demonstrated substantial test-retest variability (TRV) in SUVs. The purpose of the present study was to investigate whether the tumor-to-blood SUV ratio (SUR) can improve TRV in tracer uptake. Methods: 73 patients with advanced non-small cell lung cancer from the prospective multicenter trials ACRIN 6678 (n = 34) and MK-0646-008 (n = 39) were included in this study. All patients underwent two 18F-FDG PET/CT investigations on two different days (time difference, 3.6 ± 2.1 d; range, 1-7 d) before therapy. For each patient, up to 7 tumor lesions were evaluated. For each lesion, SUVmax and SUVpeak were determined. Blood SUV was determined as the mean value of a 3-dimensional aortic region of interest that was delineated on the attenuation CT image and transferred to the PET image. SURs were computed as the ratio of tumor SUV to blood SUV and were uptake time-corrected to 75 min after injection. TRV was quantified as 1.96 multiplied by the root-mean-square deviation of the fractional paired differences in SUV and SUR. The combined effect of blood normalization and uptake time correction was inspected by considering RTRV (TRVSUR/TRVSUV), a ratio reflecting the reduction in the TRV in SUR relative to SUV. RTRV was correlated with the group-averaged-value difference (?) in CFmean (?CFmean) of the quantity ?CF = |CF - 1|, where CF is the numeric factor that converts individual ratios of paired SUVs into corresponding SURs. This correlation analysis was performed by successively increasing a threshold value ?CFmin and computing ?CFmean and RTRV for the remaining subgroup of patients/lesions with ?CF ? ?CFminResults: The group-averaged TRVSUV and TRVSUR were 32.1 and 29.0, respectively, which correspond to a reduction of variability in SUR by an RTRV factor of 0.9 in comparison to SUV. This rather marginal improvement can be understood to be a consequence of the atypically low intrasubject variability in blood SUV and uptake time and the accordingly small ?CF values in the investigated prospective study groups. In fact, subgroup analysis with increasing ?CFmin thresholds revealed a pronounced negative correlation (Spearman ? = -0.99, P < 0.001) between RTRV and ?CFmean, where RTRV ? 0.4 in the ?CFmin = 20% subgroup, corresponding to a more than 2-fold reduction of TRVSUR compared with TRVSUVConclusion: Variability in blood SUV and uptake time has been identified as a causal factor in the TRV in lesion SUV. Therefore, TRV in lesion uptake measurements can be reduced by replacing SUV with SUR as the uptake measure. The improvement becomes substantial for the level of variability in blood SUV and uptake time typically observed in the clinical context.

Project description:BackgroundWe assessed and compared image quality obtained with clinical 18F-FDG whole-body oncologic PET protocols used in three different, state-of-the-art digital PET/CT and two conventional PMT-based PET/CT devices. Our goal was to evaluate an improved trade-off between administered activity (patient dose exposure/signal-to-noise ratio) and acquisition time (patient comfort) while preserving diagnostic information achievable with the recently introduced digital detector technology compared to previous analogue PET technology.MethodsWe performed list-mode (LM) PET acquisitions using a NEMA/IEC NU2 phantom, with activity concentrations of 5?kBq/mL and 25?kBq/mL for the background (9.5?L) and sphere inserts, respectively. For each device, reconstructions were obtained varying the image statistics (10, 30, 60, 90, 120, 180, and 300?s from LM data) and the number of iterations (range 1 to 10) in addition to the employed local clinical protocol setup. We measured for each reconstructed dataset: the quantitative cross-calibration, the image noise on the uniform background assessed by the coefficient of variation (COV), and the recovery coefficients (RCs) evaluated in the hot spheres. Additionally, we compared the characteristic time-activity-product (TAP) that is the product of scan time per bed position × mass-activity administered (in min·MBq/kg) across datasets.ResultsGood system cross-calibration was obtained for all tested datasets with <?6% deviation from the expected value was observed. For all clinical protocol settings, image noise was compatible with clinical interpretation (COV?<?15%). Digital PET showed an improved background signal-to-noise ratio as compared to conventional PMT-based PET. RCs were comparable between digital and PMT-based PET datasets. Compared to PMT-based PET, digital systems provided comparable image quality with lower TAP (from ~?40% less and up to 70% less).ConclusionsThis study compared the achievable clinical image quality in three state-of-the-art digital PET/CT devices (from different vendors) as well as in two conventional PMT-based PET. Reported results show that a comparable image quality is achievable with a TAP reduction of ~?40% in digital PET. This could lead to a significant reduction of the administered mass-activity and/or scan time with direct benefits in terms of dose exposure and patient comfort.

Dataset Information

SUV variability in EARL-accredited conventional and digital PET.

Publications

SUV variability in EARL-accredited conventional and digital PET.

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