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  1. Article ; Online: Estimate and compensate head motion in non-contrast head CT scans using partial angle reconstruction and deep learning.

    Chen, Zhennong / Li, Quanzheng / Wu, Dufan

    Medical physics

    2024  Volume 51, Issue 5, Page(s) 3309–3321

    Abstract: Background: Patient head motion is a common source of image artifacts in computed tomography (CT) of the head, leading to degraded image quality and potentially incorrect diagnoses. The partial angle reconstruction (PAR) means dividing the CT projection ...

    Abstract Background: Patient head motion is a common source of image artifacts in computed tomography (CT) of the head, leading to degraded image quality and potentially incorrect diagnoses. The partial angle reconstruction (PAR) means dividing the CT projection into several consecutive angular segments and reconstructing each segment individually. Although motion estimation and compensation using PAR has been developed and investigated in cardiac CT scans, its potential for reducing motion artifacts in head CT scans remains unexplored.
    Purpose: To develop a deep learning (DL) model capable of directly estimating head motion from PAR images of head CT scans and to integrate the estimated motion into an iterative reconstruction process to compensate for the motion.
    Methods: Head motion is considered as a rigid transformation described by six time-variant variables, including the three variables for translation and three variables for rotation. Each motion variable is modeled using a B-spline defined by five control points (CP) along time. We split the full projections from 360° into 25 consecutive PARs and subsequently input them into a convolutional neural network (CNN) that outputs the estimated CPs for each motion variable. The estimated CPs are used to calculate the object motion in each projection, which are incorporated into the forward and backprojection of an iterative reconstruction algorithm to reconstruct the motion-compensated image. The performance of our DL model is evaluated through both simulation and phantom studies.
    Results: The DL model achieved high accuracy in estimating head motion, as demonstrated in both the simulation study (mean absolute error (MAE) ranging from 0.28 to 0.45 mm or degree across different motion variables) and the phantom study (MAE ranging from 0.40 to 0.48 mm or degree). The resulting motion-corrected image,
    Conclusions: We demonstrate that using PAR and our proposed deep learning model enables accurate estimation of patient head motion and effectively reduces motion artifacts in the resulting head CT images.
    MeSH term(s) Deep Learning ; Humans ; Tomography, X-Ray Computed/methods ; Image Processing, Computer-Assisted/methods ; Artifacts ; Head/diagnostic imaging ; Head Movements ; Phantoms, Imaging
    Language English
    Publishing date 2024-04-03
    Publishing country United States
    Document type Journal Article
    ZDB-ID 188780-4
    ISSN 2473-4209 ; 0094-2405
    ISSN (online) 2473-4209
    ISSN 0094-2405
    DOI 10.1002/mp.17047
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: End-to-end deep learning for interior tomography with low-dose x-ray CT.

    Han, Yoseob / Wu, Dufan / Kim, Kyungsang / Li, Quanzheng

    Physics in medicine and biology

    2022  Volume 67, Issue 11

    Abstract: Objective. ...

    Abstract Objective.
    MeSH term(s) Algorithms ; Artifacts ; Deep Learning ; Humans ; Image Processing, Computer-Assisted/methods ; Tomography, X-Ray Computed/methods ; X-Rays
    Language English
    Publishing date 2022-05-16
    Publishing country England
    Document type Journal Article
    ZDB-ID 208857-5
    ISSN 1361-6560 ; 0031-9155
    ISSN (online) 1361-6560
    ISSN 0031-9155
    DOI 10.1088/1361-6560/ac6560
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Texture preserving low dose CT image denoising using Pearson divergence.

    Oh, Jieun / Wu, Dufan / Hong, Boohwi / Lee, Dongheon / Kang, Minwoong / Li, Quanzheng / Kim, Kyungsang

    Physics in medicine and biology

    2024  

    Abstract: Objective: The mean squared error (MSE), also known as $L_2$ loss, has been widely used as a loss function to optimize image denoising models due to its strong performance as a mean estimator of the Gaussian noise model. Recently, various low-dose ... ...

    Abstract Objective: The mean squared error (MSE), also known as $L_2$ loss, has been widely used as a loss function to optimize image denoising models due to its strong performance as a mean estimator of the Gaussian noise model. Recently, various low-dose computed tomography (LDCT) image denoising methods using deep learning combined with the MSE loss have been developed; however, this approach has been observed to suffer from the regression-to-the-mean problem, leading to over-smoothed edges and degradation of texture in the image. Approach: To overcome this issue, we propose a stochastic function in the loss function to improve the texture of the denoised CT images, rather than relying on complicated networks or feature space losses. The proposed loss function includes the MSE loss to learn the mean distribution and the Pearson divergence loss to learn feature textures. Specifically, the Pearson divergence loss is computed in an image space to measure the distance between two intensity measures of denoised low-dose and normal-dose CT images. The evaluation of the proposed model employs a novel approach of multi-metric quantitative analysis utilizing relative texture feature distance. Results: Our experimental results show that the proposed Pearson divergence loss leads to a significant improvement in texture compared to the conventional MSE loss and generative adversarial network (GAN), both qualitatively and quantitatively. Significance: Achieving consistent texture preservation in LDCT is a challenge in conventional GAN-type methods due to adversarial aspects aimed at minimizing noise while preserving texture. By incorporating the Pearson regularizer in the loss function, we can easily achieve a balance between two conflicting properties. Consistent high-quality CT images can significantly help clinicians in diagnoses and supporting researchers in the development of AI-diagnostic models.
    Language English
    Publishing date 2024-04-30
    Publishing country England
    Document type Journal Article
    ZDB-ID 208857-5
    ISSN 1361-6560 ; 0031-9155
    ISSN (online) 1361-6560
    ISSN 0031-9155
    DOI 10.1088/1361-6560/ad45a4
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: The first mobile photon-counting detector CT: the human images and technical performance study.

    Park, Su-Jin / Park, Junyoung / Kim, Doil / Lee, Duhgoon / Lee, Chang-Lae / Bechwati, Ibrahim / Wu, Dufan / Gupta, Rajiv / Jung, Jinwook

    Physics in medicine and biology

    2023  Volume 68, Issue 9

    Abstract: ... ...

    Abstract Objective
    MeSH term(s) Humans ; Photons ; Tomography, X-Ray Computed/methods ; Tomography Scanners, X-Ray Computed ; Head ; Phantoms, Imaging ; Iodine
    Chemical Substances Iodine (9679TC07X4)
    Language English
    Publishing date 2023-04-25
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 208857-5
    ISSN 1361-6560 ; 0031-9155
    ISSN (online) 1361-6560
    ISSN 0031-9155
    DOI 10.1088/1361-6560/acc8b3
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Low-dose CT reconstruction with Noise2Noise network and testing-time fine-tuning.

    Wu, Dufan / Kim, Kyungsang / Li, Quanzheng

    Medical physics

    2021  Volume 48, Issue 12, Page(s) 7657–7672

    Abstract: Purpose: Deep learning-based image denoising and reconstruction methods demonstrated promising performance on low-dose CT imaging in recent years. However, most existing deep learning-based low-dose CT reconstruction methods require normal-dose images ... ...

    Abstract Purpose: Deep learning-based image denoising and reconstruction methods demonstrated promising performance on low-dose CT imaging in recent years. However, most existing deep learning-based low-dose CT reconstruction methods require normal-dose images for training. Sometimes such clean images do not exist such as for dynamic CT imaging or very large patients. The purpose of this work is to develop a low-dose CT image reconstruction algorithm based on deep learning which does not need clean images for training.
    Methods: In this paper, we proposed a novel reconstruction algorithm where the image prior was expressed via the Noise2Noise network, whose weights were fine-tuned along with the image during the iterative reconstruction. The Noise2Noise network built a self-consistent loss by projection data splitting and mapping the corresponding filtered backprojection (FBP) results to each other with a deep neural network. Besides, the network weights are optimized along with the image to be reconstructed under an alternating optimization scheme. In the proposed method, no clean image is needed for network training and the testing-time fine-tuning leads to optimization for each reconstruction.
    Results: We used the 2016 Low-dose CT Challenge dataset to validate the feasibility of the proposed method. We compared its performance to several existing iterative reconstruction algorithms that do not need clean training data, including total variation, non-local mean, convolutional sparse coding, and Noise2Noise denoising. It was demonstrated that the proposed Noise2Noise reconstruction achieved better RMSE, SSIM and texture preservation compared to the other methods. The performance is also robust against the different noise levels, hyperparameters, and network structures used in the reconstruction. Furthermore, we also demonstrated that the proposed methods achieved competitive results without any pre-training of the network at all, that is, using randomly initialized network weights during testing. The proposed iterative reconstruction algorithm also has empirical convergence with and without network pre-training.
    Conclusions: The proposed Noise2Noise reconstruction method can achieve promising image quality in low-dose CT image reconstruction. The method works both with and without pre-training, and only noisy data are required for pre-training.
    MeSH term(s) Algorithms ; Humans ; Image Processing, Computer-Assisted ; Neural Networks, Computer ; Phantoms, Imaging ; Research Design ; Tomography, X-Ray Computed
    Language English
    Publishing date 2021-11-17
    Publishing country United States
    Document type Journal Article
    ZDB-ID 188780-4
    ISSN 2473-4209 ; 0094-2405
    ISSN (online) 2473-4209
    ISSN 0094-2405
    DOI 10.1002/mp.15101
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: The Evolution of Image Reconstruction in PET: From Filtered Back-Projection to Artificial Intelligence.

    Gong, Kuang / Kim, Kyungsang / Cui, Jianan / Wu, Dufan / Li, Quanzheng

    PET clinics

    2021  Volume 16, Issue 4, Page(s) 533–542

    Abstract: PET can provide functional images revealing physiologic processes in vivo. Although PET has many applications, there are still some limitations that compromise its precision: the absorption of photons in the body causes signal attenuation; the dead-time ... ...

    Abstract PET can provide functional images revealing physiologic processes in vivo. Although PET has many applications, there are still some limitations that compromise its precision: the absorption of photons in the body causes signal attenuation; the dead-time limit of system components leads to the loss of the count rate; the scattered and random events received by the detector introduce additional noise; the characteristics of the detector limit the spatial resolution; and the low signal-to-noise ratio caused by the scan-time limit (eg, dynamic scans) and dose concern. The early PET reconstruction methods are analytical approaches based on an idealized mathematical model.
    MeSH term(s) Algorithms ; Artificial Intelligence ; Humans ; Image Processing, Computer-Assisted ; Positron-Emission Tomography ; Signal-To-Noise Ratio
    Language English
    Publishing date 2021-09-17
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 2764575-7
    ISSN 1879-9809 ; 1556-8598
    ISSN (online) 1879-9809
    ISSN 1556-8598
    DOI 10.1016/j.cpet.2021.06.004
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Dual energy computed tomography cannot effectively differentiate between calcium pyrophosphate and basic calcium phosphate diseases in the clinical setting.

    Jarraya, Mohamed / Bitoun, Olivier / Wu, Dufan / Balza, Rene / Guermazi, Ali / Collins, Jamie / Gupta, Rajiv / Nielsen, Gunnlaugur Petur / Guermazi, Elias / Simeone, F Joseph / Omoumi, Patrick / Melnic, Christopher M / Yee, Seonghwan

    Osteoarthritis and cartilage open

    2024  Volume 6, Issue 1, Page(s) 100436

    Abstract: Background: Recent reports suggested that dual-energy CT (DECT) may help discriminate between different types of calcium phosphate crystals : Purpose: Our aim was to test the hypothesis that DECT can effectively differentiate basic calcium phosphate ( ...

    Abstract Background: Recent reports suggested that dual-energy CT (DECT) may help discriminate between different types of calcium phosphate crystals
    Purpose: Our aim was to test the hypothesis that DECT can effectively differentiate basic calcium phosphate (BCP) from calcium pyrophosphate (CPP) deposition diseases.
    Methods: Discarded tissue after total knee replacement specimens in a 71 year-old patient with knee osteoarthritis and chondrocalcinosis was scanned using DECT at standard clinical parameters. Specimens were then examined on light microscopy which revealed CPP deposition in 4 specimens (medial femoral condyle, lateral tibial plateau and both menisci) without BCP deposition. Regions of interest were placed on post-processed CT images using Rho/Z maps (Syngo.via, Siemens Healthineers, VB10B) in different areas of CPP deposition, trabecular bone BCP (T-BCP) and subchondral bone plate BCP (C-BCP).
    Results: Dual Energy Index (DEI) of CPP was 0.12 (SD ​= ​0.02) for reader 1 and 0.09 (SD ​= ​0.03) for reader 2, The effective atomic number (Z
    Conclusion: Differentiation of different types of calcium crystals using DECT is not feasible in a clinical setting.
    Language English
    Publishing date 2024-01-24
    Publishing country England
    Document type Journal Article
    ISSN 2665-9131
    ISSN (online) 2665-9131
    DOI 10.1016/j.ocarto.2024.100436
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Point-of-care AI-assisted stepwise ultrasound pneumothorax diagnosis.

    Kim, Kyungsang / Macruz, Fabiola / Wu, Dufan / Bridge, Christopher / McKinney, Suzannah / Al Saud, Ahad Alhassan / Sharaf, Elshaimaa / Sesic, Ivana / Pely, Adam / Danset, Paul / Duffy, Tom / Dhatt, Davin / Buch, Varun / Liteplo, Andrew / Li, Quanzheng

    Physics in medicine and biology

    2023  Volume 68, Issue 20

    Abstract: ... ...

    Abstract Objective
    MeSH term(s) Humans ; Pneumothorax/diagnostic imaging ; Retrospective Studies ; Point-of-Care Systems ; Artificial Intelligence ; Ultrasonography/methods
    Language English
    Publishing date 2023-10-06
    Publishing country England
    Document type Journal Article
    ZDB-ID 208857-5
    ISSN 1361-6560 ; 0031-9155
    ISSN (online) 1361-6560
    ISSN 0031-9155
    DOI 10.1088/1361-6560/acfb70
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Computationally efficient deep neural network for computed tomography image reconstruction.

    Wu, Dufan / Kim, Kyungsang / Li, Quanzheng

    Medical physics

    2019  Volume 46, Issue 11, Page(s) 4763–4776

    Abstract: Purpose: Deep neural network-based image reconstruction has demonstrated promising performance in medical imaging for undersampled and low-dose scenarios. However, it requires large amount of memory and extensive time for the training. It is especially ... ...

    Abstract Purpose: Deep neural network-based image reconstruction has demonstrated promising performance in medical imaging for undersampled and low-dose scenarios. However, it requires large amount of memory and extensive time for the training. It is especially challenging to train the reconstruction networks for three-dimensional computed tomography (CT) because of the high resolution of CT images. The purpose of this work is to reduce the memory and time consumption of the training of the reconstruction networks for CT to make it practical for current hardware, while maintaining the quality of the reconstructed images.
    Methods: We unrolled the proximal gradient descent algorithm for iterative image reconstruction to finite iterations and replaced the terms related to the penalty function with trainable convolutional neural networks (CNN). The network was trained greedily iteration by iteration in the image domain on patches, which requires reasonable amount of memory and time on mainstream graphics processing unit (GPU). To overcome the local-minimum problem caused by greedy learning, we used deep UNet as the CNN and incorporated separable quadratic surrogate with ordered subsets for data fidelity, so that the solution could escape from easy local minimums and achieve better image quality.
    Results: The proposed method achieved comparable image quality with state-of-the-art neural network for CT image reconstruction on two-dimensional (2D) sparse-view and limited-angle problems on the low-dose CT challenge dataset. The difference in root-mean-square-error (RMSE) and structural similarity index (SSIM) was within [-0.23,0.47] HU and [0,0.001], respectively, with 95% confidence level. For three-dimensional (3D) image reconstruction with ordinary-size CT volume, the proposed method only needed 2 GB graphics processing unit (GPU) memory and 0.45 s per training iteration as minimum requirement, whereas existing methods may require 417 GB and 31 min. The proposed method achieved improved performance compared to total variation- and dictionary learning-based iterative reconstruction for both 2D and 3D problems.
    Conclusions: We proposed a training-time computationally efficient neural network for CT image reconstruction. The proposed method achieved comparable image quality with state-of-the-art neural network for CT reconstruction, with significantly reduced memory and time requirement during training. The proposed method is applicable to 3D image reconstruction problems such as cone-beam CT and tomosynthesis on mainstream GPUs.
    MeSH term(s) Deep Learning ; Image Processing, Computer-Assisted/methods ; Imaging, Three-Dimensional ; Quality Control ; Radiation Dosage ; Time Factors ; Tomography, X-Ray Computed
    Language English
    Publishing date 2019-09-21
    Publishing country United States
    Document type Journal Article
    ZDB-ID 188780-4
    ISSN 2473-4209 ; 0094-2405
    ISSN (online) 2473-4209
    ISSN 0094-2405
    DOI 10.1002/mp.13627
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Risk assessment for acute kidney injury and death among new COVID-19 positive adult patients without chronic kidney disease: retrospective cohort study among three US hospitals.

    Li, Daniel / Ren, Hui / Varelmann, Dirk J / Sarin, Pankaj / Xu, Pengcheng / Wu, Dufan / Li, Quanzheng / Lin, Xihong

    BMJ open

    2022  Volume 12, Issue 2, Page(s) e053635

    Abstract: Objective: To develop simple but clinically informative risk stratification tools using a few top demographic factors and biomarkers at COVID-19 diagnosis to predict acute kidney injury (AKI) and death.: Design: Retrospective cohort analysis, follow- ... ...

    Abstract Objective: To develop simple but clinically informative risk stratification tools using a few top demographic factors and biomarkers at COVID-19 diagnosis to predict acute kidney injury (AKI) and death.
    Design: Retrospective cohort analysis, follow-up from 1 February through 28 May 2020.
    Setting: 3 teaching hospitals, 2 urban and 1 community-based in the Boston area.
    Participants: Eligible patients were at least 18 years old, tested COVID-19 positive from 1 February through 28 May 2020, and had at least two serum creatinine measurements within 30 days of a new COVID-19 diagnosis. Exclusion criteria were having chronic kidney disease or having a previous AKI within 3 months of a new COVID-19 diagnosis.
    Main outcomes and measures: Time from new COVID-19 diagnosis until AKI event, time until death event.
    Results: Among 3716 patients, there were 1855 (49.9%) males and the average age was 58.6 years (SD 19.2 years). Age, sex, white blood cell, haemoglobin, platelet, C reactive protein (CRP) and D-dimer levels were most strongly associated with AKI and/or death. We created risk scores using these variables predicting AKI within 3 days and death within 30 days of a new COVID-19 diagnosis. Area under the curve (AUC) for predicting AKI within 3 days was 0.785 (95% CI 0.758 to 0.813) and AUC for death within 30 days was 0.861 (95% CI 0.843 to 0.878). Haemoglobin was the most predictive component for AKI, and age the most predictive for death. Predictive accuracies using all study variables were similar to using the simplified scores.
    Conclusion: Simple risk scores using age, sex, a complete blood cell count, CRP and D-dimer were highly predictive of AKI and death and can help simplify and better inform clinical decision making.
    MeSH term(s) Acute Kidney Injury/complications ; Acute Kidney Injury/diagnosis ; Adolescent ; COVID-19 ; COVID-19 Testing ; Cohort Studies ; Hospitals ; Humans ; Male ; Middle Aged ; Renal Insufficiency, Chronic/complications ; Renal Insufficiency, Chronic/diagnosis ; Retrospective Studies ; Risk Assessment ; Risk Factors ; SARS-CoV-2
    Language English
    Publishing date 2022-02-21
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2599832-8
    ISSN 2044-6055 ; 2044-6055
    ISSN (online) 2044-6055
    ISSN 2044-6055
    DOI 10.1136/bmjopen-2021-053635
    Database MEDical Literature Analysis and Retrieval System OnLINE

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