Development of novel statistical reconstruction algorithms for poly-energetic X-ray computed tomography

Chueh, Ho-Shiang; Tsai, Wen-Kai; Chang, C. Allen; Chang, S. L.; Su, Kuan-Hao; Chen, Jyh-Cheng

doi:10.1016/j.cmpb.2008.04.002

Cited by 6 publications

(6 citation statements)

References 12 publications

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“…Alveolar bone density was quantified from a cone-beam micro-computed tomography system developed at National Yang-Ming University as previously described [6,7]. Briefly, four pairs of mandible bones were resected from sham and uremic rats, and each pair was examined simultaneously ex vivo.…”

Section: Alveolar Bone Density Measurementmentioning

confidence: 99%

Uremia Induces Dental Pulp Ossification but Reciprocally Inhibits Adjacent Alveolar Bone Osteogenesis

et al. 2015

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Uremic patients are predisposed to atrophy of the alveolar bone and narrowing of the dental pulp chamber. Such pulp chamber changes have only been diagnosed radiologically; however, this has not been supported by any pathological evidence. We used a uremic rat model with secondary hyperparathyroidism induced by 5/6 nephrectomy surgery and high-phosphate diet to examine the dental pulp and adjacent alveolar bone pathology. In addition, we collected pulp tissues for real-time PCR. We found an opposite histopathological presentation of the ossified dental pulp and the osteomalacic adjacent alveolar bone. Furthermore, pulp cells with positive staining for Thy-1, a surrogate stem cell marker, were significantly reduced in the pulp of uremic rats compared to the controls, indicating a paucity of stem cells. This was further evidenced by the reduced pulp expression of dickkopf-1 (Dkk-1), a Wnt/β-catenin signaling inhibitor produced by mesenchymal stem cells. In contrast, expressions of receptor activator of nuclear factor κB ligand (RANKL) and RANK in uremic pulp were up-regulated, probably to counteract the ossifying process of uremic pulp. In conclusion, uremic pulp ossifications were associated with a paucity of stem cells and dysregulated Dkk-1 and RANKL signaling systems, further shifting the imbalance toward osteogenesis. Strategies to counteract such an imbalance may offer a potential therapeutic target to improve dental health in uremic patients, which warrants further interventional studies.

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Section: Alveolar Bone Density Measurementmentioning

confidence: 99%

Uremia Induces Dental Pulp Ossification but Reciprocally Inhibits Adjacent Alveolar Bone Osteogenesis

et al. 2015

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“…This algorithm is based on several prior techniques. [15][16][17] However, our method is unique in its combination of both time and energy information in the same formula.…”

Section: Iid Iterative Refinementmentioning

confidence: 99%

“…As with temporal reconstruction, efforts have been made to exploit the substantial overlap of information between the two scans within the reconstruction process. [15][16][17] In this work, we present a technique to visualize the changing distribution of iodine in the body with a dual source micro-CT system, using a retrospectively gated dual energy scan with optimized filters and voltages, and a series of computational operations to reconstruct the data. This results in five-dimensional volumetric images that distinguish different materials at different points in time and can be used to segment regions containing iodinated blood and compute various measures of cardiac function, such as the stroke volume, the ejection fraction, and the cardiac output.…”

Section: Introductionmentioning

confidence: 99%

Temporal and spectral imaging with micro‐CT

2012

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Purpose: Micro-CT is widely used for small animal imaging in preclinical studies of cardiopulmonary disease, but further development is needed to improve spatial resolution, temporal resolution, and material contrast. We present a technique for visualizing the changing distribution of iodine in the cardiac cycle with dual source micro-CT. Methods: The approach entails a retrospectively gated dual energy scan with optimized filters and voltages, and a series of computational operations to reconstruct the data. Projection interpolation and five-dimensional bilateral filtration (three spatial dimensions + time + energy) are used to reduce noise and artifacts associated with retrospective gating. We reconstruct separate volumes corresponding to different cardiac phases and apply a linear transformation to decompose these volumes into components representing concentrations of water and iodine. Since the resulting material images are still compromised by noise, we improve their quality in an iterative process that minimizes the discrepancy between the original acquired projections and the projections predicted by the reconstructed volumes. The values in the voxels of each of the reconstructed volumes represent the coefficients of linear combinations of basis functions over time and energy. We have implemented the reconstruction algorithm on a graphics processing unit (GPU) with CUDA. We tested the utility of the technique in simulations and applied the technique in an in vivo scan of a C57BL/6 mouse injected with blood pool contrast agent at a dose of 0.01 ml/g body weight. Postreconstruction, at each cardiac phase in the iodine images, we segmented the left ventricle and computed its volume. Using the maximum and minimum volumes in the left ventricle, we calculated the stroke volume, the ejection fraction, and the cardiac output. Results: Our proposed method produces five-dimensional volumetric images that distinguish different materials at different points in time, and can be used to segment regions containing iodinated blood and compute measures of cardiac function. Conclusions: We believe this combined spectral and temporal imaging technique will be useful for future studies of cardiopulmonary disease in small animals.

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“…The information obtained at the different energies may then be used to estimate the concentrations of different materials in the object. The estimation can be performed before tomographic reconstruction [1], after reconstruction [2], or it can be integrated into the reconstruction process [3] [4].…”

Section: Introductionmentioning

confidence: 99%

A spectral calibration technique for x-ray CT

Johnston

Badea

2012

SPIE Proceedings

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Spectral reconstruction algorithms for x-ray CT require an accurate spectral model of the system, including the spectrum of the photons emitted by the source and the spectral sensitivity of the detector. Although these components of the spectral model have been characterized in previous studies, there might be additional components that are unaccounted for, such as the inherent filtration of the x-ray source and the detector. In this study, we present a technique for measuring the inaccuracies in the spectral model and accounting for them. This technique entails the acquisition of photon measurements with several materials placed between the source and the detector, and the solution of a linear system of equations. We test the accuracy of this technique in simulations, and demonstrate its potential to improve the results of spectral reconstruction.

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Development of novel statistical reconstruction algorithms for poly-energetic X-ray computed tomography

Cited by 6 publications

References 12 publications

Uremia Induces Dental Pulp Ossification but Reciprocally Inhibits Adjacent Alveolar Bone Osteogenesis

Uremia Induces Dental Pulp Ossification but Reciprocally Inhibits Adjacent Alveolar Bone Osteogenesis

Temporal and spectral imaging with micro‐CT

A spectral calibration technique for x-ray CT

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