A new approach of 3D SPECT reconstruction for near-field coded aperture imaging

Hong, Baoming; Zhang, Mu; Liu, Yi-Hwa

doi:10.1117/12.653300

Cited by 7 publications

(10 citation statements)

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“…While our previous results were quite encouraging, the objects we imaged were comprised of rods or capillary tubes that were with strong contrast and sharp edges [1][2][3]. It would be of interest to see how the proposed methods perform on objects with low contrast and slow variations that are common in small animal and medical imaging.…”

Section: Introduction S Ingle Photon Emission Computerized Tomogramentioning

confidence: 89%

Recent progress on SPECT imaging with near-field coded aperture collimation: A small animal study

Zhang¹,

Dobrucki

et al. 2010

IEEE Nuclear Science Symposuim &Amp; Medical Imaging Conference

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A small animal study of three-dimensional (3-D) single photon emission computerized tomography (SPECT) imaging with near-field coded aperture collimation is reported. In our early effort to develop high-sensitivity and high-resolution SPECT technology, we introduced an imaging protocol and a reconstruction method for 3-D near-field coded aperture SPECT, and obtained good SPECT reconstructions of 3-D objects, including a micro hot-rod phantom with complex structures. In this study, we aim to reconstruct low contrast and slow-varying radioactivity distribution in an ex vivo rat heart, in contrast to point-like distributions such as that in the micro hot-rod phantom that we previously reported. In our new experiment, the rat underwent an open-chest surgery and its left anterior descending coronary artery was ligated to induce permanent myocardial infarction in the left ventricular (LV) myocardium. After the surgical procedures the rat was injected with 6.29 mCi of 99m Tc-Tetrofosmin via the jugular vein. One hour post the radiotracer injection, the rat was sacrificed and the LV was dissected from the heart. Dental alginate paste was subsequently injected into the LV to sustain its shape for imaging. Coded aperture projections with a magnification factor of 2.6 were acquired from 64 evenly distributed angles over a 360 degree camera rotation on a micro-SPECT system equipped with NaI detectors. Images of cross-sectional slices were successfully reconstructed using our four-step reconstruction algorithm, and special care was taken to account for the wide projection angle in the small animal imaging system. In the reconstructed images, the donut-shape of the LV was well visualized, and the surgically induced infarct, resulting in myocardial perfusion defect in the apical anterior regions of the LV, could be clearly identified, further demonstrating the feasibility of the near-field coded aperture SPECT imaging methods we proposed.

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Section: Introduction S Ingle Photon Emission Computerized Tomogramentioning

confidence: 89%

Recent progress on SPECT imaging with near-field coded aperture collimation: A small animal study

Zhang¹,

Dobrucki

et al. 2010

IEEE Nuclear Science Symposuim &Amp; Medical Imaging Conference

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“…In this article, we extend our previous research 14,22 and present a novel 3D image reconstruction approach to SPECT based on near-field coded aperture collimation and maximum likelihood estimation. The article is organized as follows.…”

Section: Introductionmentioning

confidence: 96%

“…To account for this depth dependent magnification, we developed a modified MLEM method to reconstruct a 3D image stack from a single coded aperture projection. In this method, the image slice at depth z is updated by 14,22 …”

Section: Iia1 Partial Reconstruction Of 3d Image Stack From Singlementioning

confidence: 99%

A novel three‐dimensional image reconstruction method for near‐field coded aperture single photon emission computerized tomography

Zhang

Hong

et al. 2009

Medical Physics

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Coded aperture imaging for two-dimensional ͑2D͒ planar objects has been investigated extensively in the past, whereas little success has been achieved in imaging 3D objects using this technique. In this article, the authors present a novel method of 3D single photon emission computerized tomography ͑SPECT͒ reconstruction for near-field coded aperture imaging. Multiangular coded aperture projections are acquired and a stack of 2D images is reconstructed separately from each of the projections. Secondary projections are subsequently generated from the reconstructed image stacks based on the geometry of parallel-hole collimation and the variable magnification of near-field coded aperture imaging. Sinograms of cross-sectional slices of 3D objects are assembled from the secondary projections, and the ordered subset expectation and maximization algorithm is employed to reconstruct the cross-sectional image slices from the sinograms. Experiments were conducted using a customized capillary tube phantom and a micro hot rod phantom. Imaged at approximately 50 cm from the detector, hot rods in the phantom with diameters as small as 2.4 mm could be discerned in the reconstructed SPECT images. These results have demonstrated the feasibility of the authors' 3D coded aperture image reconstruction algorithm for SPECT, representing an important step in their effort to develop a high sensitivity and high resolution SPECT imaging system.

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“…Among conventional methods, high-resolution collimations (e.g., pinhole) often yield low sensitivity, while high-sensitivity collimations (e.g., parallel-hole) generate images with poor resolution. To accommodate both, coded aperture (CA) collimation has been proposed as a potential method to achieve reasonably high sensitivity and high resolution in SPECT imaging [ 9 – 14 ]. This collimation technique was originally devised for astronomical imaging, where incoming projections from a given source (such as a star) are parallel [ 15 – 17 ].…”

Section: Introductionmentioning

confidence: 99%

“…In previous studies [ 9 , 11 , 12 ], it was discovered that the angular artifacts due to the aperture collimation effect of CA imaging is mostly neglected by researchers in the field. A solution has been proposed to correct for this collimation effect [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

SPECT Imaging of 2-D and 3-D Distributed Sources with Near-Field Coded Aperture Collimation: Computer Simulation and Real Data Validation

2016

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The imaging of distributed sources with near-field coded aperture (CA) remains extremely challenging and is broadly considered unsuitable for single-photon emission computerized tomography (SPECT). This study proposes a novel CA SPECT reconstruction approach and evaluates the feasibilities of imaging and reconstructing distributed hot sources and cold lesions using near-field CA collimation and iterative image reconstruction. Computer simulations were designed to compare CA and pinhole collimations in two-dimensional radionuclide imaging. Digital phantoms were created and CA images of the phantoms were reconstructed using maximum likelihood expectation maximization (MLEM). Errors and the contrast-to-noise ratio (CNR) were calculated and image resolution was evaluated. An ex vivo rat heart with myocardial infarction was imaged using a micro-SPECT system equipped with a custom-made CA module and a commercial 5-pinhole collimator. Rat CA images were reconstructed via the three-dimensional (3-D) MLEM algorithm developed for CA SPECT with and without correction for a large projection angle, and 5-pinhole images were reconstructed using the commercial software provided by the SPECT system. Phantom images of CA were markedly improved in terms of image quality, quantitative root-mean-squared error, and CNR, as compared to pinhole images. CA and pinhole images yielded similar image resolution, while CA collimation resulted in fewer noise artifacts. CA and pinhole images of the rat heart were well reconstructed and the myocardial perfusion defects could be clearly discerned from 3-D CA and 5-pinhole SPECT images, whereas 5-pinhole SPECT images suffered from severe noise artifacts. Image contrast of CA SPECT was further improved after correction for the large projection angle used in the rat heart imaging. The computer simulations and small-animal imaging study presented herein indicate that the proposed 3-D CA SPECT imaging and reconstruction approaches worked reasonably well, demonstrating the feasibilities of achieving high sensitivity and high resolution SPECT using near-field CA collimation.

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A new approach of 3D SPECT reconstruction for near-field coded aperture imaging

Cited by 7 publications

References 0 publications

Recent progress on SPECT imaging with near-field coded aperture collimation: A small animal study

Recent progress on SPECT imaging with near-field coded aperture collimation: A small animal study

A novel three‐dimensional image reconstruction method for near‐field coded aperture single photon emission computerized tomography

SPECT Imaging of 2-D and 3-D Distributed Sources with Near-Field Coded Aperture Collimation: Computer Simulation and Real Data Validation

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