Comments on the NEMA NU 4-2008 Standard on Performance Measurement of Small Animal Positron Emission Tomographs

Hallen, P.; Schug, David; Schulz, Volkmar

doi:10.1186/s40658-020-0279-2

Cited by 31 publications

(41 citation statements)

References 41 publications

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“…Additionally, we must be clear that 3D‐OSEM method we have implemented use a positivity constraint that prevents the images taking on negative values 34 . This is inaccurate for measuring point sources in air and will give unrealistically good spatial resolution results 14,35,36 . Hallen et al pointed out that for the measurement of system spatial resolution, the NEMA standard requires the use of FBP algorithm to reconstruct the point source image, but it does not specify a clear projection window size.…”

Section: Discussionmentioning

confidence: 99%

Technical Note: Performance evaluation of a small‐animal PET/CT system based on NEMA NU 4–2008 standards

Liu

Liu³

et al. 2021

Medical Physics

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Purpose The MetisTM PET/CT is a self‐developed, silicon photomultiplier (SiPM) detector‐based, rodent PET/CT system. The objective of this study was to evaluate the performance of the system using the National Electrical Manufacturers Association (NEMA) NU 4–2008 standard protocol. Methods Energy resolution, spatial resolution, sensitivity, scatter fraction (SF), noise‐equivalent count rate (NECR), and image quality (IQ) characteristics were measured. A micro Derenzo phantom experiment was performed to evaluate the spatial resolution using three‐dimensional ordered‐subsets expectation maximization (3D‐OSEM) and maximum likelihood expectation maximization (MLEM) reconstructed images. In addition, the CT imaging agent Ioverol 350 was mixed with fluorine‐18 (18F)‐fluorodeoxyglucose (FDG) and then injected into the micro Derenzo phantom to evaluate the PET/CT imaging. In vivo PET/CT imaging studies were also conducted in a healthy mouse and rat using 18F‐FDG. Results The mean energy resolution of the system was 15.3%. The tangential resolution was 0.82 mm full‐width half‐maximum (FWHM) at the center of the field of the view (FOV), and the radial and axial resolution were generally lower than 2.0 mm FWHM. The spatial resolution was significantly improved when using 3D‐OSEM, especially the axial FWHM could be improved by up to about 57%. The system absolute sensitivity was 7.7% and 6.8% for an energy window of 200–750 and 350–750 keV respectively. The scatter fraction was 8.2% and 12.1% for the mouse‐ and rat‐like phantom respectively. The peak NECR was 1343.72 kcps at 69 MBq and 640.32 kcps at 53 MBq for the mouse‐ and rat‐like phantom respectively. The 1‐mm fillable rod in the IQ phantom can be clearly observed. We can identify the 0.6‐mm aperture of the micro Derenzo phantom image clearly using 3D‐OSEM (10 subsets, 5 iterations). We also performed the fusion of the PET and CT images of the mouse and the brain imaging of the rat. Conclusions The results show that the system has the characteristics of high‐resolution, high‐sensitivity, and excellent IQ and is suitable for rodent imaging‐based research.

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Section: Discussionmentioning

confidence: 99%

Technical Note: Performance evaluation of a small‐animal PET/CT system based on NEMA NU 4–2008 standards

Liu

Liu³

et al. 2021

Medical Physics

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“…This result is slightly higher than VR at FOV quarter in comparison to other integrated scanners (Table VII). As noted by [30], the use of FBP, as required by NEMA, can be inadequate with some specific geometries and can lead to broad artefacts. To overcome this problem, some authors have implemented strategies to deal with the histogramming of data to be used with FBP, trying to preserve DOI information [31].…”

Section: A Pet Performancementioning

confidence: 99%

Performance Evaluation and Compatibility Studies of a Compact Preclinical Scanner for Simultaneous PET/MR Imaging at 7 Tesla

Courteau¹,

McGrath²,

Walker³

et al. 2021

IEEE Trans. Med. Imaging

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We present the design and performance of a new compact preclinical system combining positron emission tomography (PET) and magnetic resonance imaging (MRI) for simultaneous scans. The PET contains sixteen SiPM-based detector heads arranged in two octagons and covers an axial field of view (FOV) of 102.5 mm. Depth of interaction effects and detector's temperature variations are compensated by the system. The PET is integrated in a dry magnet operating at 7 T. PET and MRI characteristics were assessed complying with international standards and interferences between both subsystems during simultaneous scans were addressed. For the rat size phantom, the peak noise equivalent count rates (NECR) were 96.4 kcps at 30.2 MBq and 132.3 kcps at 28.4 MBq respectively with and without RF coil. For mouse, the peak NECR was 300.0 kcps at 34.5 MBq and 426.9 kcps at 34.3 MBq respectively with and without coil. At the axial centre of the FOV, spatial resolutions expressed as full width at half maximum / full width at tenth maximum (FWHM/FWTM) ranged from 1.69/3.19 mm to 2.39/4.87 mm. The peak absolute sensitivity obtained with a 250-750 keV energy window was 7.5% with coil and 7.9% without coil. Spill over ratios of the NEMA NU4-2008 image quality (NEMA-IQ) phantom ranged from 0.25 to 0.96 and the percentage of non-uniformity was 5.7%. The image count versus activity was linear up to 40 MBq. The principal magnetic field variation was 0.03 ppm/mm over 40 mm. The qualitative and quantitative aspects of data were preserved during simultaneous scans.

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“…It should also be noted that the NEMA protocol derives the %STD from the standard deviations of the line profiles along axial directions and the %STD uni assuming Gaussian error propagation. However, this is not the correct standard deviation of the RC as the %STD of the maximum value of a randomly distributed value is not the standard deviation of the underlying distribution [33]. This results in an artificial increase of RC for smaller sources.…”

Section: Recovery Coefficientsmentioning

confidence: 95%

Influence of Multiple Animal Scanning on Image Quality for the Sedecal SuperArgus2R Preclinical PET Scanner

et al. 2021

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Background: Increased throughput in small animal preclinical studies using positron emission tomography leads to reduced costs and improved efficiency of experimental design, however the presence of multiple off-centre subjects, as opposed to a single centered one, may affect image quality in several ways.Methods: We evaluated the count rate performance using a NEMA scatter phantom. A Monte Carlo simulation of the system was validated against this dataset and used to simulate the count rate performance for dual scatter phantoms. NEMA NU4 image quality phantoms were then scanned in the central and offset positions, as well as in the offset position next to a uniform activity phantom. Uniformity, recovery coefficients and spillover ratios were then compared, as were two time frames for acquisition.Results: Count rate performance assessed with a single NEMA scatter phantom was in line with previous literature, with simulated data in good agreement. Simulation of dual scatter phantoms showed an increase in scatter fraction. For the NEMA Image Quality phantom, uniformity and Recovery coefficients were degraded in the offset, and dual phantom cases, while spillover ratios were increased, notably when the chamber was placed nearest the gantry. Image quality metrics were comparable between the 20- and 10 min timeframes.Conclusion: Dual animal scanning results in some loss of image quality on the Sedecal Argus PET scanner; however, this degradation is within acceptable limits.

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Comments on the NEMA NU 4-2008 Standard on Performance Measurement of Small Animal Positron Emission Tomographs

Cited by 31 publications

References 41 publications

Technical Note: Performance evaluation of a small‐animal PET/CT system based on NEMA NU 4–2008 standards

Technical Note: Performance evaluation of a small‐animal PET/CT system based on NEMA NU 4–2008 standards

Performance Evaluation and Compatibility Studies of a Compact Preclinical Scanner for Simultaneous PET/MR Imaging at 7 Tesla

Influence of Multiple Animal Scanning on Image Quality for the Sedecal SuperArgus2R Preclinical PET Scanner

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