Publications by authors named "Qiegen Liu"

Photoacoustic tomography, a novel non-invasive imaging modality, combines the principles of optical and acoustic imaging for use in biomedical applications. In scenarios where photoacoustic signal acquisition is insufficient due to sparse-view sampling, conventional direct reconstruction methods significantly degrade image resolution and generate numerous artifacts. To mitigate these constraints, a novel sinogram-domain priors guided extremely sparse-view reconstruction method for photoacoustic tomography boosted by enhanced diffusion model is proposed.

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Purpose: Multi-contrast magnetic resonance imaging is a significant and essential medical imaging technique. However, multi-contrast imaging has longer acquisition time and is easy to cause motion artifacts. In particular, the acquisition time for a T2-weighted image is prolonged due to its longer repetition time (TR).

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Digital holography can reconstruct the amplitude and phase information of the target light field. However, the reconstruction quality is largely limited by the size of the hologram. Multi-plane holograms can impose constraints for reconstruction, yet the quality of the reconstructed images continues to be restricted owing to the deficiency of effective prior information constraints.

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Three-dimensional (3D) display can provide more information than two-dimensional display, and real-time 3D reconstruction of the real-world environment has broad application prospects as a key technology in the field of meta-universe and Internet of Things. 3D holographic display is considered to be an ideal 3D display scheme, thus enhancing the computational speed and reconstruction quality of 3D holograms can offer substantial support for real-time 3D reconstruction. Here, we proposed a real-time 3D holographic photography for real-world scenarios driven by both physical model and artificial intelligence.

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Optical metasurfaces have revolutionized analog computing and image processing at subwavelength scales with faster speed and lower power consumption. They typically involve spatial differentiation with an engineered angular dispersion. Quasi-bound states in the continuum (quasi-BICs) have emerged as powerful tools for customizing optical resonances.

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Article Synopsis
  • Photoacoustic tomography (PAT) is a cutting-edge imaging technique that creates high-resolution images of biological tissues, but often struggles with artifact issues in limited-view scenarios.
  • This study introduces a new reconstruction strategy that uses multiple diffusion models and alternating iteration methods to fill in missing data, which leads to improved image quality and stability.
  • When tested on a dataset with only 60° views, the method showed a significant increase in image clarity with improvements in peak signal-to-noise ratio and structural similarity, indicating a promising advancement for clinical applications of PAT.
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Recently, diffusion models have shown considerable promise for MRI reconstruction. However, extensive experimentation has revealed that these models are prone to generating artifacts due to the inherent randomness involved in generating images from pure noise. To achieve more controlled image reconstruction, we reexamine the concept of interpolatable physical priors in k-space data, focusing specifically on the interpolation of high-frequency (HF) k-space data from low-frequency (LF) k-space data.

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Article Synopsis
  • Recent advancements in diffusion models have improved magnetic resonance imaging (MRI), but challenges like long iteration times and slow convergence remain.* -
  • The proposed GM-SDE model addresses these issues by optimizing initial values in an iterative algorithm, utilizing mean-reverting stochastic differential equations (SDE) for better performance.* -
  • GM-SDE can adapt to different k-space data structures and combines with traditional constraints, leading to faster reconstruction times and superior image quality in experiments compared to existing methods.*
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The multi-source stationary CT, where both the detector and X-ray source are fixed, represents a novel imaging system with high temporal resolution that has garnered significant interest. Limited space within the system restricts the number of X-ray sources, leading to sparse-view CT imaging challenges. Recent diffusion models for reconstructing sparse-view CT have generally focused separately on sinogram or image domains.

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Article Synopsis
  • Temporal compressive coherent diffraction imaging is a lensless technique designed for capturing fast-moving small objects, but struggles with image accuracy due to lost frequency information.
  • The dual-domain mean-reverting diffusion model-enhanced method (DMDTC) improves image quality by recovering missing data in both frequency and spatial domains through advanced sample learning.
  • DMDTC shows significantly better structural similarity and peak signal-to-noise ratios in reconstructed images compared to traditional methods, offering high temporal frame rates and resolution.
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Photoacoustic tomography (PAT) regularly operates in limited-view cases owing to data acquisition limitations. The results using traditional methods in limited-view PAT exhibit distortions and numerous artifacts. Here, a novel limited-view PAT reconstruction strategy that combines model-based iteration with score-based generative model was proposed.

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Traditional methods under sparse view for reconstruction of photoacoustic tomography (PAT) often result in significant artifacts. Here, a novel image to image transformation method based on unsupervised learning artifact disentanglement network (ADN), named PAT-ADN, was proposed to address the issue. This network is equipped with specialized encoders and decoders that are responsible for encoding and decoding the artifacts and content components of unpaired images, respectively.

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Deep learning (DL) has emerged as a leading approach in accelerating MRI. It employs deep neural networks to extract knowledge from available datasets and then applies the trained networks to reconstruct accurate images from limited measurements. Unlike natural image restoration problems, MRI involves physics-based imaging processes, unique data properties, and diverse imaging tasks.

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The x-ray radiation dose in computed tomography (CT) examination has been a major concern for patients. Lowing the tube current and exposure time in data acquisition is a straightforward and cost-effective strategy to reduce the x-ray radiation dose. However, this will inevitably increase the noise fluctuations in measured projection data, and the corresponding CT image quality will be severely degraded if noise suppression is not performed during image reconstruction.

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Given the obstacle in accentuating the reconstruction accuracy for diagnostically significant tissues, most existing MRI reconstruction methods perform targeted reconstruction of the entire MR image without considering fine details, especially when dealing with highly under-sampled images. Therefore, a considerable volume of efforts has been directed towards surmounting this challenge, as evidenced by the emergence of numerous methods dedicated to preserving high-frequency content as well as fine textural details in the reconstructed image. In this case, exploring the merits associated with each method of mining high-frequency information and formulating a reasonable principle to maximize the joint utilization of these approaches will be a more effective solution to achieve accurate reconstruction.

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Pretreatment patient-specific quality assurance (prePSQA) is conducted to confirm the accuracy of the radiotherapy dose delivered. However, the process of prePSQA measurement is time consuming and exacerbates the workload for medical physicists. The purpose of this work is to propose a novel deep learning (DL) network to improve the accuracy and efficiency of prePSQA.

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To improve the efficiency of multi-coil data compression and recover the compressed image reversibly, increasing the possibility of applying the proposed method to medical scenarios. A deep learning algorithm is employed for MR coil compression in the presented work. The approach introduces a variable augmentation network for invertible coil compression (VAN-ICC).

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The trade-off between imaging efficiency and imaging quality has always been encountered by Fourier single-pixel imaging (FSPI). To achieve high-resolution imaging, the increase in the number of measurements is necessitated, resulting in a reduction of imaging efficiency. Here, a novel high-quality reconstruction method for FSPI imaging via diffusion model was proposed.

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Diffusion model has emerged as a potential tool to tackle the challenge of sparse-view CT reconstruction, displaying superior performance compared to conventional methods. Nevertheless, these prevailing diffusion models predominantly focus on the sinogram or image domains, which can lead to instability during model training, potentially culminating in convergence towards local minimal solutions. The wavelet transform serves to disentangle image contents and features into distinct frequency-component bands at varying scales, adeptly capturing diverse directional structures.

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Article Synopsis
  • Photoacoustic tomography combines optical and acoustic imaging for better clarity and depth but faces quality issues with standard reconstruction methods under sparse views.
  • A new model-based reconstruction method using a score-based diffusion model was developed to enhance image quality by incorporating prior information as a constraint in the reconstruction process.
  • Test results showed that this method significantly outperforms traditional techniques, particularly under extreme sparse conditions, improving image clarity and potentially reducing both acquisition time and costs in photoacoustic imaging.
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Article Synopsis
  • Photoacoustic tomography (PAT) often struggles with data limitations in sparse view, leading to reconstruction issues like artifacts.
  • A new accelerated model-based iterative reconstruction strategy integrates multi-channel autoencoder priors to improve reconstruction quality and speed.
  • The method showed significantly improved performance in sparse-view scenarios, outperforming traditional U-Net techniques with better PSNR and SSIM results on both simulated and experimental data.
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  • The score-based generative model (SGM) shows great promise in solving tough inverse problems in medical imaging, but it struggles with noisy or incomplete data typical in low-dose CT and under-sampled MRI scans.
  • To tackle this challenge, the authors propose a wavelet-improved denoising technique that integrates a wavelet sub-network with the standard SGM framework, enhancing training stability and accuracy even with noisy samples.
  • Experiments demonstrate that this combined approach significantly improves image reconstruction quality across various medical imaging scenarios, achieving results similar to those with clean data despite training on noisy samples.
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. Performing pre-treatment patient-specific quality assurance (prePSQA) is considered an essential, time-consuming, and resource-intensive task for volumetric modulated arc radiotherapy (VMAT) which confirms the dose accuracy and ensure patient safety. Most current machine learning and deep learning approaches stack excessive convolutional/pooling operations (CPs) to predict prePSQA with two-dimensional or one-dimensional information input.

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Deep learning based parallel imaging (PI) has made great progress in recent years to accelerate MRI. Nevertheless, it still has some limitations: for example, the robustness and flexibility of existing methods are greatly deficient. In this work, we propose a method to explore the k-space domain learning via robust generative modeling for flexible calibrationless PI reconstruction, coined the weighted k-space generative model (WKGM).

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