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

Israël-Jost, Vincent; Choquet, Philippe; Salmon, Stéphanie; Blondet, C.; Sonnendrücker, Éric; Constantinesco, A.

doi:10.1109/tmi.2005.861707

Cited by 28 publications

(24 citation statements)

References 22 publications

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“…In our experiments, an isotropic spatial resolution of 1 mm was obtained by pinhole SPECT with a reconstructed voxel of 0.47 · 0.47 · 0.47 mm 3 (14,23). It is also obvious that isotropic voxel MR images are recommended for optimal coregistration with SPECT.…”

Section: Discussion Spatial Resolution Of Spect and Mrimentioning

confidence: 93%

“…For small-animal SPECT image acquisition, a 20% window centered on the 140-keV photopeak was used, and 60 projections of 1 min over an arch of 180°in a 128 · 128 format were obtained using a 4-cm radius of rotation around the imaging cell. Images were reconstructed with an inhouse efficient algebraic cone beam reconstruction method based on an algebraic reconstruction technique (ART) algorithm that takes into account the variation of the radius of rotation and is able to achieve an isotropic 1 · 1 · 1 mm 3 spatial resolution (efficient algebraic reconstruction [EAR] method (14)). The size of the isotropic reconstructed voxel was 0.47 · 0.47 · 0.47 mm 3 .…”

Section: Spect System and Image Reconstructionmentioning

confidence: 99%

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SPECT Low-Field MRI System for Small-Animal Imaging

Goetz¹,

Breton²,

Choquet³

et al. 2007

J Nucl Med

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Localization of regions with increased uptake of radiotracer in small-animal SPECT is greatly facilitated when using coregistration with anatomic images of the same animal. As MRI has several advantages compared with CT (soft-tissue contrast and lack of ionizing radiation) we developed a SPECT/low-field MRI hybrid device for small-animal imaging. Methods: A small-animal single-pinhole g-camera (pinhole, 1.5 mm in diameter and 12 cm in focal length) adjacent to a dedicated low-field (0.1 T) small MR imager (imaging volume, 10 · 10 · 6 cm 3 ) was used. The animal was placed in a warmed nonmagnetic polymethyl methacrylate imaging cell for MR acquisition, which was followed immediately by SPECT after translation of the imaging cell from one modality to the other. 3-Dimensional T1-weighted sequences were used for MRI. Phantom studies enabled verification of a low attenuation (10%) for 99m Tc and 201 Tl and a very slight increase in Compton scattering due to the radiofrequency coil and polymethyl methacrylate imaging cell. Results: SPECT/ MRI data acquisition and image coregistration of selected examples using different radiotracers for lungs, kidneys, and brain were obtained in 3 nude mice with isotropic spatial resolutions of 0.5 · 0.5 · 0.5 mm 3 for MRI and 1 · 1 · 1 mm 3 for SPECT. The total acquisition time for combined SPECT and MRI lasted 1 h 45 min. Conclusion: A low-magnetic-field strength of 0.1 T is a simple and useful solution for a small-animal dual-imaging device combining pinhole SPECT with the adjacent MR imager. Among small-animal imaging techniques, SPECT provides a unique possibility to follow and measure in vivo, and noninvasively, the biodistribution of a 10 29 molar concentration of a wide range of radiolabeled biomolecules commonly available in nuclear medicine departments (1). However, one essential drawback in SPECT images is the lack of anatomic references related to the tissue uptake of tracer. Therefore, localization of regions with increased uptake of radiotracer is greatly facilitated when using coregistration of SPECT with anatomic images of the same animal, from CT or MRI. Over the last few years, SPECT/ CT dual modality has been widely proposed by manufacturers but MRI presents specific advantages compared with CT, including lack of ionizing radiation, high soft-tissue contrast, and sensitivity to tissue alterations evidenced by specific imaging sequences (2,3). Yet, compared with CT, the use of MRI for coregistration of both functional and structural information has, to our knowledge, essentially served to demonstrate the potential interest of using coregistration of images after data acquisition in separate nuclear and MR rooms. However, as experienced for rat and mice, the strategy of pinhole SPECT followed by MRI in a clinical scanner is a long and complicated task (4-7), requiring a careful transfer of the animal in a specially designed bed equipped with multimodality fiducial markers helping in the coregistration of images (4,5). In addition, separate dual-modality scans (follow...

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Section: Discussion Spatial Resolution Of Spect and Mrimentioning

confidence: 93%

Section: Spect System and Image Reconstructionmentioning

confidence: 99%

SPECT Low-Field MRI System for Small-Animal Imaging

Goetz¹,

Breton²,

Choquet³

et al. 2007

J Nucl Med

View full text Add to dashboard Cite

show abstract

“…The first symmetry is the rotational symmetry (RS) as conventional circular trajectory pinhole SPECT [19,20]. Since the pinhole SPECT has a cubic field of view (FOV), after rotating 90 degrees, the detection probabilities will be exactly the same as those probabilities of the0 degree except for different voxel indecies.…”

Section: Geometric Symmetries and Multi-threaded Computationmentioning

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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“…Finally, iterative algorithms can compensate the radionuclide data for parallax errors and errors in positioning individual events when g-rays strike the detector surface at oblique angles. Iterative reconstruction now is the dominant method of image reconstruction for both preclinical and clinical SPECT, because of its ability to recover or correct for some imagedegrading effects and to generally offer images of higher visual quality and better quantitative accuracy than analytic reconstruction methods (9,10). Commercial small-animal SPECT systems typically claim up to submillimeter resolution using iterative reconstruction, but reconstructed resolutions based on FBP are more easily compared between systems.…”

Section: Tomographic Reconstructionmentioning

confidence: 99%

Small-Animal SPECT and SPECT/CT: Important Tools for Preclinical Investigation

Franc¹,

Acton²,

Marì³

et al. 2008

J Nucl Med

206

122

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The need to study dynamic biologic processes in intact smallanimal models of disease has stimulated the development of highresolution nuclear imaging methods. These methods are capable of clarifying molecular interactions important in the onset and progression of disease, assessing the biologic relevance of drug candidates and potential imaging agents, and monitoring therapeutic effectiveness of pharmaceuticals serially within a single-model system. Single-photon-emitting radionuclides have many advantages in these applications, and SPECT can provide 3-dimensional spatial distributions of g-(and x-) ray-emitting radionuclide imaging agents or therapeutics. Furthermore, combining SPECT with CT in a SPECT/CT system can assist in defining the anatomic context of biochemical processes and improve the quantitative accuracy of the SPECT data. Over the past decade, dedicated small-animal SPECT and SPECT/CT systems have been developed in academia and industry. Although significant progress in this arena has been realized through system development and biologic application, further innovation continues to address challenges in camera sensitivity, spatial resolution, and image reconstruction and quantification. The innumerable applications of small-animal SPECT and SPECT/CT in drug development, cardiology, neurology, and oncology are stimulating further investment in education, research, and development of these dedicated small-animal imaging modalities. Rapi dly evolving knowledge of molecular biology has stimulated exploration of novel therapies targeting specific points in molecular pathways associated with cardiac disease, neurologic disorders, cancer, and many other pathologic processes. However, identifying the role of a molecule in a disease process modeled in vitro does not necessarily translate to an understanding of its interactions with other molecular processes in vivo. On the other hand, few of all disease processes can be fully studied in human patients because of logistical and ethical concerns. Small-animal models represent a critical bridge between discoveries at the molecular level and implementation of clinically relevant diagnostics or therapeutics. Emphasis is ever increasing that these models accurately recapitulate both the disease itself and the environment in which the key molecular processes take place. For example, xenograft mouse models of cancer are simple to develop but are not considered particularly useful in understanding molecular interactions involved in carcinogenesis. More sophisticated approaches, such as transgenic models using oncogene activation or tumor suppressor inactivation, have evolved to the point at which cancers may be induced in a spatially and temporally defined manner using deletion of specified genetic sequences with Cre recombinase (1,2). Sophisticated infrastructures have been developed to manage data related to small-animal models of disease and provide greater access to various mouse models for all investigators, exemplified by the Mouse Models of Human Cancer Cons...

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

Cited by 28 publications

References 22 publications

SPECT Low-Field MRI System for Small-Animal Imaging

SPECT Low-Field MRI System for Small-Animal Imaging

Fast iterative reconstruction for helical pinhole SPECT imaging

Small-Animal SPECT and SPECT/CT: Important Tools for Preclinical Investigation

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