ECG-gated pinhole SPECT in mice with millimeter spatial resolution

Wu, Max C.; Tang, H.R.; Gao, Dongwei; Ido, Akira; O’Connell, Joe; Hasegawa, B.H.; Dae, Michael W.

doi:10.1109/23.856572

Cited by 57 publications

(28 citation statements)

References 15 publications

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“…1, we see that an image resolution approaching the pinhole diameter can be obtained when the pinhole to detector distance is sufficiently large and the object is close to the pinhole. The smallest pinhole diameters reported so far are about 0.5 mm, and have resulted in a SPET image resolution of about 1 mm [6,7,8].…”

Section: Methodsmentioning

confidence: 97%

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Towards in vivo nuclear microscopy: iodine-125 imaging in mice using micro-pinholes

et al. 2002

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Position-sensitive gamma-radiation detectors equipped with collimators have been used for in vivo imaging of the distribution of radiolabelled molecules in laboratory animals and humans for several decades. To date, the best image resolution achieved in a rodent is on the order of 1 mm. Here we demonstrate how a basic and compact gamma camera can be constructed for in vivo radionuclide imaging in small animals, at much higher spatial resolution. Resolution improvements were obtained by combining dense, shaped, micro-pinhole apertures with iodine-125, an isotope with low energy emissions, ease of incorporation into a wide range of molecules, and straightforward translation into the clinic via other isotopes of iodine that are suitable for nuclear medicine imaging. (125)I images of test distributions and a mouse thyroid have been obtained at a resolution of as high as 200 microm using this simple bench-top camera. Possible future applications and extension to ultra-high-resolution emission tomography are discussed.

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Section: Methodsmentioning

confidence: 97%

“…1) offers the ability to obtain high-resolution images of gamma-emitting tracers in small objects like the human thyroid and small animals [6,7,8]. However, a fundamental factor limiting image resolution is the penetration of gammaradiation along the edge of the pinhole collimator.…”

Section: Introductionmentioning

confidence: 98%

Towards in vivo nuclear microscopy: iodine-125 imaging in mice using micro-pinholes

et al. 2002

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“…2) Central pixel of the voxel's projection , which is located where the line passing through the center of the voxel and the center of the pinhole intersects the detection plane. 3) Fraction of activity that reaches the detector, and depends on the voxel position according to (3) where is the effective pinhole diameter, according to Anger [17], is the angle between the line perpendicular to the detector and passing through the pinhole and the line passing through the pinhole and voxel j, and is the distance of the voxel from the plane of the pinhole (we suppose that the voxel is localized at its center) (see [18] for details of (3)). The quantity is also modified by attenuation with a circular symmetric model, assuming a 0.11 uniformly attenuating medium.…”

Section: B Discrete Psf Factorizationmentioning

confidence: 99%

Pinhole SPECT imaging: compact projection/backprojection operator for efficient algebraic reconstruction

Israël-Jost

Choquet

Salmon

et al. 2006

IEEE Trans. Med. Imaging

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We describe the efficient algebraic reconstruction (EAR) method, which applies to cone-beam tomographic reconstruction problems with a circular symmetry. Three independant steps/stages are presented, which use two symmetries and a factorization of the point spread functions (PSFs), each reducing computing times and eventually storage in memory or hard drive. In the case of pinhole single photon emission computed tomography (SPECT), we show how the EAR method can incorporate most of the physical and geometrical effects which change the PSF compared to the Dirac function assumed in analytical methods, thus showing improvements on reconstructed images. We also compare results obtained by the EAR method with a cubic grid implementation of an algebraic method and modeling of the PSF and we show that there is no significant loss of quality, despite the use of a noncubic grid for voxels in the EAR method. Data from a phantom, reconstructed with the EAR method, demonstrate 1.08-mm spatial tomographic resolution despite the use of a 1.5-mm pinhole SPECT device and several applications in rat and mouse imaging are shown. Finally, we discuss the conditions of application of the method when symmetries are broken, by considering the different parameters of the calibration and nonsymmetric physical effects such as attenuation.

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“…This has prohibited in vivo studies of small animals involving disease progression, drug treatment, and genetic modification. In spite of the difficulties in imaging a mouse positioned vertically, SPECT pinhole studies have reported significant spatial resolution [7] and even electrocardiography (ECG)-gated temporal resolution [3]. More recently, micro SPECT cameras have featured a stationary mouse with a rotating camera in order to make in vivo imaging simpler [8].…”

Section: Introductionmentioning

confidence: 98%

First results from the high-resolution mouseSPECT annular scintillation camera

Goertzen

Jones

Seidel

et al. 2005

IEEE Trans. Med. Imaging

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High-resolution single-photon emission computed tomography (SPECT) imaging in small animals tends to use long imaging times and large injected doses due to the poor sensitivity of single pinhole gamma cameras. To increase sensitivity while maintaining spatial resolution, we designed and constructed a multipinhole collimator array to replace the parallel hole collimators of a Ceraspect human SPECT brain scanner. The Ceraspect scanner is composed of an annular NaI(TI) crystal within which the eight pinhole collimators (1-mm-diameter holes) rotate while projecting nonoverlapping images of the object onto the stationary annular crystal. In this manner, only one-eighth of a collimator rotation is required to acquire a full circle orbit tomographic data set. The imaging field of view (FOV) has a diameter of 25.6 mm in the transverse direction, which is sufficient to encompass a mouse in the transverse direction. The axial FOV is 25.6 mm at the center of the FOV and 13.9 mm at the edge of the transverse FOV. Data are currently acquired in step-and-shoot mode; however, the system is capable of list mode acquisition with the collimator continuously rotating. Images are reconstructed using a cone-beam ordered subsets expectation maximization method. The reconstructed spatial resolution of the system is 1.7 mm and the sensitivity at the center of the FOV is 13.8 cps/microCi. A whole-body bone scan of a mouse injected with [Tc-99 m]MDP clearly revealed skeletal structures such as the ribs and vertebral bodies. These preliminary results suggest that this approach is a good tradeoff between resolution and sensitivity and, with further refinement, may permit dynamic imaging in living animals.

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ECG-gated pinhole SPECT in mice with millimeter spatial resolution

Cited by 57 publications

References 15 publications

Towards in vivo nuclear microscopy: iodine-125 imaging in mice using micro-pinholes

Towards in vivo nuclear microscopy: iodine-125 imaging in mice using micro-pinholes

Pinhole SPECT imaging: compact projection/backprojection operator for efficient algebraic reconstruction

First results from the high-resolution mouseSPECT annular scintillation camera

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