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  • 1
    Online-Ressource
    Online-Ressource
    A new dental CBCT metal artifact reduction method based on a dual-domain processing framework
    IOP Publishing ; 2023
    In:  Physics in Medicine & Biology Vol. 68, No. 17 ( 2023-09-07), p. 175016-
    Details
    In: Physics in Medicine & Biology, IOP Publishing, Vol. 68, No. 17 ( 2023-09-07), p. 175016-
    Kurzfassung: Objective. Cone beam computed tomography (CBCT) has been wildly used in clinical treatment of dental diseases. However, patients often have metallic implants in mouth, which will lead to severe metal artifacts in the reconstructed images. To reduce metal artifacts in dental CBCT images, which have a larger amount of data and a limited field of view compared to computed tomography images, a new dental CBCT metal artifact reduction method based on a projection correction and a convolutional neural network (CNN) based image post-processing model is proposed in this paper . Approach. The proposed method consists of three stages: (1) volume reconstruction and metal segmentation in the image domain, using the forward projection to get the metal masks in the projection domain; (2) linear interpolation in the projection domain and reconstruction to build a linear interpolation (LI) corrected volume; (3) take the LI corrected volume as prior and perform the prior based beam hardening correction in the projection domain, and (4) combine the constructed projection corrected volume and LI-volume slice-by-slice in the image domain by two concatenated U-Net based models (CNN1 and CNN2). Simulated and clinical dental CBCT cases are used to evaluate the proposed method. The normalized root means square difference (NRMSD) and the structural similarity index (SSIM) are used for the quantitative evaluation of the method. Main results. The proposed method outperforms the frequency domain fusion method (FS-MAR) and a state-of-art CNN based method on the simulated dataset and yields the best NRMSD and SSIM of 4.0196 and 0.9924, respectively. Visual results on both simulated and clinical images also illustrate that the proposed method can effectively reduce metal artifacts. Significance . This study demonstrated that the proposed dual-domain processing framework is suitable for metal artifact reduction in dental CBCT images.
    Materialart: Online-Ressource
    ISSN: 0031-9155 , 1361-6560
    URL: Article
    DOI: 10.1088/1361-6560/acec29
    RVK:
    WA 15000
    Sprache: Unbekannt
    Verlag: IOP Publishing
    Publikationsdatum: 2023
    ZDB Id: 1473501-5
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 2
    Online-Ressource
    Online-Ressource
    Serum osteocalcin concentrations in relation to glucose and lipid metabolism in Chinese individuals
    Oxford University Press (OUP) ; 2009
    In:  European Journal of Endocrinology Vol. 161, No. 5 ( 2009-11), p. 723-729
    Details
    In: European Journal of Endocrinology, Oxford University Press (OUP), Vol. 161, No. 5 ( 2009-11), p. 723-729
    Kurzfassung: Osteocalcin, a bone-derived protein, has recently been reported to affect energy metabolism. We investigated the relationship between serum osteocalcin and parameters of adiposity, glucose tolerance, and lipid profile in Chinese subjects. Methods Serum osteocalcin was measured by electrochemiluminescence immunoassay in 254 men (128 with newly diagnosed type 2 diabetes mellitus (T2DM) and 126 with normal glucose tolerance (NGT)), 66 premenopausal women (33 with T2DM and 33 with NGT) as well as 180 postmenopausal women (92 with T2DM and 88 with NGT). Their associations with parameters of adiposity, glucose tolerance, and lipid profile were examined. Results Serum osteocalcin concentrations in diabetic patients were significantly lower than those in NGT subjects after adjusted for age, gender, and body mass index ( P =0.003). Postmenopausal women had higher osteocalcin concentrations than premenopausal women and men (both P 〈 0.001). Multiple stepwise regression analysis showed that age, %fat, high-density lipoprotein cholesterol, fasting plasma glucose, and fasting serum insulin were independently associated with osteocalcin in men ( P 〈 0.05). Age and HbA1c were independently correlated with osteocalcin in postmenopausal women. Besides age and HbA1c, serum triglyceride was also an independent factor influencing osteocalcin in premenopausal women. In addition, osteocalcin was also positively associated with homeostasis model assessment of β-cell function. Furthermore, multiple logistic regression analysis demonstrated that osteocalcin was independently associated with T2DM. Conclusions Serum osteocalcin was closely associated with not only fat and glucose metabolism but also with lipid metabolism.
    Materialart: Online-Ressource
    ISSN: 0804-4643 , 1479-683X
    URL: Article
    DOI: 10.1530/EJE-09-0585
    RVK:
    WA 15000
    Sprache: Unbekannt
    Verlag: Oxford University Press (OUP)
    Publikationsdatum: 2009
    ZDB Id: 1485160-X
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 3
    Online-Ressource
    Online-Ressource
    An improved dual-domain network for metal artifact reduction in CT images using aggregated contextual transformations
    IOP Publishing ; 2023
    In:  Physics in Medicine & Biology Vol. 68, No. 17 ( 2023-09-07), p. 175021-
    Details
    In: Physics in Medicine & Biology, IOP Publishing, Vol. 68, No. 17 ( 2023-09-07), p. 175021-
    Kurzfassung: Objective . Metal artifact reduction (MAR) remains a challenging task due to the difficulty of removing artifacts while preserving anatomical details of the tissue. Although current dual-domain networks have shown promising performance in MAR, they heavily rely on the image domain, which can be too smooth and lose important information in the metal-affected area. To address this problem, we propose an improved dual domain network framework. Approach . We enhance sinogram completion performance by utilizing an aggregated contextual transformations network in the sinogram domain. Furthermore, we utilize a prior -projection-based linearized correction method to obtain images with beam-hardening artifacts removed, which are incorporated into the input of the image post-processing network to assist in training the image domain network. Finally, we train the sinogram domain network and the image domain network separately to their respective convergences. Main results . In experiments conducted on a simulated dataset, our method achieves the best average RMSE of 25.1, SSIM of 0.973, and PSNR of 42.1, respectively. Significance . The proposed method is capable of preserving tissue structures near metallic objects while eliminating metal artifacts from the reconstructed images. Related codes will be released at https://github.com/Corinna-China/AOTDudoNet
    Materialart: Online-Ressource
    ISSN: 0031-9155 , 1361-6560
    URL: Article
    DOI: 10.1088/1361-6560/aced78
    RVK:
    WA 15000
    Sprache: Unbekannt
    Verlag: IOP Publishing
    Publikationsdatum: 2023
    ZDB Id: 1473501-5
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 4
    Online-Ressource
    Online-Ressource
    Dose reduction in dynamic synaptic vesicle glycoprotein 2A PET imaging using artificial neural networks
    IOP Publishing ; 2023
    In:  Physics in Medicine & Biology Vol. 68, No. 24 ( 2023-12-21), p. 245006-
    Details
    In: Physics in Medicine & Biology, IOP Publishing, Vol. 68, No. 24 ( 2023-12-21), p. 245006-
    Kurzfassung: Objective . Reducing dose in positron emission tomography (PET) imaging increases noise in reconstructed dynamic frames, which inevitably results in higher noise and possible bias in subsequently estimated images of kinetic parameters than those estimated in the standard dose case. We report the development of a spatiotemporal denoising technique for reduced-count dynamic frames through integrating a cascade artificial neural network (ANN) with the highly constrained back-projection (HYPR) scheme to improve low-dose parametric imaging. Approach . We implemented and assessed the proposed method using imaging data acquired with 11 C-UCB-J, a PET radioligand bound to synaptic vesicle glycoprotein 2A (SV2A) in the human brain. The patch-based ANN was trained with a reduced-count frame and its full-count correspondence of a subject and was used in cascade to process dynamic frames of other subjects to further take advantage of its denoising capability. The HYPR strategy was then applied to the spatial ANN processed image frames to make use of the temporal information from the entire dynamic scan. Main results . In all the testing subjects including healthy volunteers and Parkinson’s disease patients, the proposed method reduced more noise while introducing minimal bias in dynamic frames and the resulting parametric images, as compared with conventional denoising methods. Significance . Achieving 80% noise reduction with a bias of −2% in dynamic frames, which translates into 75% and 70% of noise reduction in the tracer uptake (bias, −2%) and distribution volume (bias, −5%) images, the proposed ANN+HYPR technique demonstrates the denoising capability equivalent to a 11-fold dose increase for dynamic SV2A PET imaging with 11 C-UCB-J.
    Materialart: Online-Ressource
    ISSN: 0031-9155 , 1361-6560
    URL: Article
    DOI: 10.1088/1361-6560/ad0535
    RVK:
    WA 15000
    Sprache: Unbekannt
    Verlag: IOP Publishing
    Publikationsdatum: 2023
    ZDB Id: 1473501-5
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
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