Using the NEMA NU 4 PET Image Quality Phantom in Multipinhole Small-Animal SPECT

Harteveld, Anita A.; Meeuwis, Antoi P.W.; Disselhorst, Jonathan A.; Slump, Cornelis H.; Oyen, Wim J.G.; Boerman, Otto C.; Visser, Eric P.

doi:10.2967/jnumed.110.087114

Cited by 33 publications

(27 citation statements)

References 15 publications

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“…However, the number of iterations obtained in the present study may not be truly predictive for the number of iterations needed for a mouse or rat scan, which need some specific adjustments. All this is in line with the proposal of Harteveld et al (18) about the development of a NEMA NU 5 standard for SPECT and, more specifically, the use of an additional phantom with smaller internal structures and smaller outer diameter to better mimic mouse acquisitions such as the one proposed by Visser et al (23).…”

Section: Discussionsupporting

confidence: 79%

“…We first observed that more iterations were required to reach convergence (and maximum RCs) for the smaller rods because high frequencies converge more slowly than low frequencies. Harteveld et al (18) reported the same observation for the U-SPECT-II using also the IQ phantom.…”

Section: Discussionsupporting

confidence: 56%

“…A task force has recently been assigned to establish what could be the new NEMA NU 5, also including a new phantom, adapted to small-animal SPECT systems and to define the IQ parameters. In anticipation of this possible NEMA NU 5, the IQ phantom (NU 4 IQ phantom) defined by the NU 4 2008 standard was used in previous studies to characterize the performance of small-animal SPECT scanners and, more particularly, the IQ (10,18).…”

Section: Discussionmentioning

confidence: 99%

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Imaging Capabilities of the Inveon SPECT System Using Single-and Multipinhole Collimators

et al. 2013

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The Inveon small-animal SPECT system comes with several types of multipinhole collimator plates. We evaluate here the performance measurements of the Inveon SPECT system using 6 different collimators: 3 dedicated for mouse imaging and 3 for rat imaging. Methods: The measured performance parameters include the sensitivity, the spatial resolution using line sources, the ultra-micro Derenzo phantom, the recovery coefficient and the noise measurements using the National Electrical Manufacturers Association NU-4 image quality phantom, obtained with the 2 reconstruction algorithms available with the Inveon Acquisition Workplace, version 1.5-the 3-dimensional ordered-subset expectation maximization (3DOSEM) and the 3-dimensional maximum a posteriori (3DMAP). Further, the overall performance of the system is illustrated by an animal experiment. Results: The results show that the Inveon SPECT scanner offers a spatial resolution, measured at the center of the field of view, ranging from 0.6 to 1 mm with the collimator plates dedicated to mouse imaging and from 1.2 to less than 2 mm with rat collimator plates. The system sensitivity varies from 29 to 404 cps/MBq for mouse collimators and from 53 to 175 cps/MBq for rat collimators. The image quality study showed that 3DMAP allows better noise reduction while preserving the recovery coefficient, compared with other regularization strategies such as the premature termination of the 3DOSEM reconstruction or 3DOSEM followed by gaussian filtering. Conclusion: The acquisition parameters, such as the collimator set and the radius of rotation, offer a wide range of possibilities to apply to a large number of biologic studies. However, special care must be taken because this increase in sensitivity can be offset by image degradation, such as image artifacts caused by projection overlap and statistical noise due to a higher number of iterations required for convergence. 3DMAP allowed better noise reduction while maintaining relatively constant recovery coefficients, as compared with other reconstruction strategies. Smal l-animal SPECT systems typically use pinhole collimation, which presents a conical geometry, leading to high magnification and high spatial resolution (1-3). Higher detection efficiency can be obtained using multipinhole collimation (4-9) without theoretically trading the resolution. The Inveon small-animal SPECT system (Siemens Medical Solution) comes with several types of multipinhole collimator plates, which can be mounted on the detector heads. These collimators are designed to rotate at specific radii of rotation (RORs). The combination of the collimator geometric design (number and placement of the pinholes, collimator length, aperture, and degree of multiplexing) and the ROR used fixes many characteristics such as the active field of view (FOV) and the performance of the system in terms of resolution, sensitivity, and resulting reconstruction image quality (IQ). This is different from PET imaging, for which there are no collimation-related parameters to optimiz...

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Section: Discussionsupporting

confidence: 79%

Section: Discussionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 99%

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Imaging Capabilities of the Inveon SPECT System Using Single-and Multipinhole Collimators

et al. 2013

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“…This phantom has been previously used for characterizing small-animal SPECT systems [23–25]. The phantom has three different sections: a section with two cold cylinders with a hot background, a larger uniform cylinder filled with radiotracer, and a hot rod section with five different rod diameters (1, 2, 3, 4 and 5 mm).…”

Section: Methodsmentioning

confidence: 99%

Development of a Germanium Small-Animal SPECT System

Johnson

Ovchinnikov

Shokouhi

et al. 2015

IEEE Trans. Nucl. Sci.

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Advances in fabrication techniques, electronics, and mechanical cooling systems have given rise to germanium detectors suitable for biomedical imaging. We are developing a small-animal SPECT system that uses a double-sided Ge strip detector. The detector’s excellent energy resolution may help to reduce scatter and simplify processing of multi-isotope imaging, while its ability to measure depth of interaction has the potential to mitigate parallax error in pinhole imaging. The detector’s energy resolution is <1% FWHM at 140 keV and its spatial resolution is approximately 1.5 mm FWHM. The prototype system described has a single-pinhole collimator with a 1-mm diameter and a 70-degree opening angle with a focal length variable between 4.5 and 9 cm. Phantom images from the gantry-mounted system are presented, including the NEMA NU-2008 phantom and a hot-rod phantom. Additionally, the benefit of energy resolution is demonstrated by imaging a dual-isotope phantom with 99mTc and 123I without cross-talk correction.

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“…3,[5][6][7][8][9] Recently, some authors have focused their attention on the quantification of system resolution as well as other quantitative parameters related to image quality, such as absolute quantification, [11][12][13] recovery coefficients (RC), and noise. 12,14 These studies characterize the image-quality parameters as a function of reconstruction settings and of the correction of attenuation and scatter in the object. The effect of the reconstruction algorithms on quantification has also been studied.…”

Section: Introductionmentioning

confidence: 99%

Improved image quality in pinhole SPECT by accurate modeling of the point spread function in low magnification systems

et al. 2015

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Purpose: Single photon emission computed tomography (SPECT) has become an important noninvasive imaging technique in small-animal research. Due to the high resolution required in small-animal SPECT systems, the spatially variant system response needs to be included in the reconstruction algorithm. Accurate modeling of the system response should result in a major improvement in the quality of reconstructed images. The aim of this study was to quantitatively assess the impact that an accurate modeling of spatially variant collimator/detector response has on image-quality parameters, using a low magnification SPECT system equipped with a pinhole collimator and a small gamma camera. Methods: Three methods were used to model the point spread function (PSF). For the first, only the geometrical pinhole aperture was included in the PSF. For the second, the septal penetration through the pinhole collimator was added. In the third method, the measured intrinsic detector response was incorporated. Tomographic spatial resolution was evaluated and contrast, recovery coefficients, contrast-to-noise ratio, and noise were quantified using a custom-built NEMA NU 4-2008 image-quality phantom. Results: A high correlation was found between the experimental data corresponding to intrinsic detector response and the fitted values obtained by means of an asymmetric Gaussian distribution. For all PSF models, resolution improved as the distance from the point source to the center of the field of view increased and when the acquisition radius diminished. An improvement of resolution was observed after a minimum of five iterations when the PSF modeling included more corrections. Contrast, recovery coefficients, and contrast-to-noise ratio were better for the same level of noise in the image when more accurate models were included. Ring-type artifacts were observed when the number of iterations exceeded 12. Conclusions: Accurate modeling of the PSF improves resolution, contrast, and recovery coefficients in the reconstructed images. To avoid the appearance of ring-type artifacts, the number of iterations should be limited. In low magnification systems, the intrinsic detector PSF plays a major role in improvement of the image-quality parameters. C 2015 American Association of Physicists in Medicine. [http://dx

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Using the NEMA NU 4 PET Image Quality Phantom in Multipinhole Small-Animal SPECT

Cited by 33 publications

References 15 publications

Imaging Capabilities of the Inveon SPECT System Using Single-and Multipinhole Collimators

Imaging Capabilities of the Inveon SPECT System Using Single-and Multipinhole Collimators

Development of a Germanium Small-Animal SPECT System

Improved image quality in pinhole SPECT by accurate modeling of the point spread function in low magnification systems

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