Feasibility of Whole-Body Functional Mouse Imaging Using Helical Pinhole SPECT

Metzler, S.; Vemulapalli, Sreekanth; Jaszczak, R.J.; Akabani, Gamal; Chin, Bennett B.

doi:10.1007/s11307-009-0234-z

Cited by 17 publications

(12 citation statements)

References 37 publications

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“…As of March 2011, no initiative has been taken up yet by NEMA for small-animal SPECT guidelines. Most of the scientific literature on image quality in small-animal SPECT is based on qualitative demonstrations of the effective spatial resolution using Derenzo-like phantoms with hot and cold rods (2,(4)(5)(6)(7)(8)(9). An anatomic phantom to mimic rat brain structures has been described by Beekman et al (10).…”

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confidence: 99%

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

Harteveld¹,

Meeuwis²,

Disselhorst³

et al. 2011

J Nucl Med

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Several commercial small-animal SPECT scanners using multipinhole collimation are presently available. However, generally accepted standards to characterize the performance of these scanners do not exist. Whereas for small-animal PET, the National Electrical Manufacturers Association (NEMA) NU 4 standards have been defined in 2008, such standards are still lacking for small-animal SPECT. In this study, the image quality parameters associated with the NEMA NU 4 image quality phantom were determined for a small-animal multipinhole SPECT scanner. Methods: Multiple whole-body scans of the NEMA NU 4 image quality phantom of 1-h duration were performed in a U-SPECT-II scanner using 99m Tc with activities ranging between 8.4 and 78.2 MBq. The collimator contained 75 pinholes of 1.0-mm diameter and had a bore diameter of 98 mm. Image quality parameters were determined as a function of average phantom activity, number of iterations, postreconstruction spatial filter, and scatter correction. In addition, a mouse was injected with 99m Tc-hydroxymethylene diphosphonate and was euthanized 6.5 h after injection. Multiple whole-body scans of this mouse of 1-h duration were acquired for activities ranging between 3.29 and 52.7 MBq. Results: An increase in the number of iterations was accompanied by an increase in the recovery coefficients for the small rods (RC rod ), an increase in the noise in the uniform phantom region, and a decrease in spillover ratios for the cold-air-and water-filled scatter compartments (SOR air and SOR wat ). Application of spatial filtering reduced image noise but lowered RC rod . Filtering did not influence SOR air and SOR wat . Scatter correction reduced SOR air and SOR wat . The effect of total phantom activity was primarily seen in a reduction of image noise with increasing activity. RC rod , SOR air , and SOR wat were more or less constant as a function of phantom activity. The relation between acquisition and reconstruction settings and image quality was confirmed in the 99m Tc-hydroxymethylene diphosphonate mouse scans. Conclusion: Although developed for small-animal PET, the NEMA NU 4 image quality phantom was found to be useful for small-animal SPECT as well, allowing for objective determination of image quality parameters and showing the tradeoffs between several of these parameters on variation of acquisition and reconstruction settings.

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confidence: 99%

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

Harteveld¹,

Meeuwis²,

Disselhorst³

et al. 2011

J Nucl Med

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“…This means a trade-off between resolution and acceptable noise level in the image must be established. 6 As a result, when we limit the number of iterations, differences in resolution appear depending on the position of the point source in the FOV and on the ROR. The worst cases are found in the center of the FOV and for high ROR.…”

Section: Discussionmentioning

confidence: 99%

“…One of these uses clinical gamma cameras equipped with multiple pinhole collimators, which, due to their high magnification and high sensitivity, allows a high resolution to be achieved. [3][4][5][6] Another involves the use of small cameras. [7][8][9][10] These are low-cost systems, and due to their flexibility and size, they are suitable for molecular imaging multimodality.…”

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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“…Since the pinhole SPECT around a circular orbit can only scan a cubic-like volume, it can merely provide a very limited field-of-view (FOV). If one needs to scan a longer object, it may require to scan multiple bed positions to cover the whole object [5]. The advantage of multi-bed method is that the data acquired in each bed position can be reconstructed independently and then the resultant images can be stacked up into the final image volume.…”

Section: Introductionmentioning

confidence: 99%

“…A helical SPECT can not only increase the FOV, but also provides many other advantages [5,7]. First, the image truncations of multi-bed pinhole SPECT will not occur in helical pinhole SPECT.…”

Section: Introductionmentioning

confidence: 99%

Fast iterative reconstruction for helical pinhole SPECT imaging

Huang

Hsu

2015

BME

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Abstract. Pinhole SPECT for small animal has become a routine procedure in many applications of molecular biology and pharmaceutical development. There is an increasing demand in the whole body imaging of lab animals. A simple and direct solution is to scan the object along a helical trajectory, similar to a helical CT scan. The corresponding acquisition time can be greatly reduced, while the over-lapping and gap between consecutive bed positions can be avoided. However, helical pinhole SPECT inevitably leads to the tremendous increase in computational complexity when the iterative reconstruction algorithms are applied. We suggest a novel voxel-driven (VD) system model which can be integrated with geometric symmetries from helical trajectory for fast iterative image reconstruction. Such a model construction can also achieve faster calculation and lower storage requirement of the system matrix. Due to the independence among various symmetries, it permits parallel coding to further boost computation efficiency of forward/backward projection. From phantom study, the results also indicate that the proposed VD model can adequately model the helical pinhole SPECT scanner with manageable storage size of system matrix and clinically acceptable computation loading of reconstruction.

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Feasibility of Whole-Body Functional Mouse Imaging Using Helical Pinhole SPECT

Cited by 17 publications

References 37 publications

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

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

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

Fast iterative reconstruction for helical pinhole SPECT imaging

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