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Image Reconstruction Using Analysis Model Prior
摘要： The analysis model has been previously exploited as an alternative to the classical sparse synthesis model for designing image reconstruction methods. Applying a suitable analysis operator on the image of interest yields a cosparse outcome which enables us to reconstruct the image from undersampled data. In this work, we introduce additional prior in the analysis context and theoretically study the uniqueness issues in terms of analysis operators in general position and the specific 2D finite difference operator. We establish bounds on the minimum measurement numbers which are lower than those in cases without using analysis model prior. Based on the idea of iterative cosupport detection (ICD), we develop a novel image reconstruction model and an effective algorithm, achieving significantly better reconstruction performance. Simulation results on synthetic and practical magnetic resonance (MR) images are also shown to illustrate our theoretical claims.
关键词： cosparsity,iterative cosupport detection,magnetic resonance imaging,analysis model,image reconstruction
更新于2025-09-09 09:28:46
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Perfluorocarbon‐Based <sup>19</sup> F?MRI Nanoprobes for In?Vivo Multicolor Imaging
摘要： In vivo multicolor imaging is important for monitoring multiple biomolecular or cellular processes in biology. 19F magnetic resonance imaging (MRI) is an emerging in vivo imaging technique because it can non-invasively visualize 19F nuclei without endogenous background signals. Therefore, 19F MRI probes capable of multicolor imaging are in high demand. Herein, we report five types of perfluorocarbon-encapsulated silica nanoparticles that show 19F NMR peaks with different chemical shifts. Three of the nanoprobes, which show spectrally distinct 19F NMR peaks with sufficient sensitivity, were selected for in vivo multicolor 19F MRI. The nanoprobes exhibited 19F MRI signals with three colors in a living mouse. Our in vivo multicolor system could be utilized for evaluating the effect of surface functional groups on the hepatic uptake in a mouse. This novel multicolor imaging technology will be a practical tool for elucidating in vivo biomolecular networks by 19F MRI.
关键词： multicolor imaging,fluorine,magnetic resonance imaging,nanoparticles,imaging agents
更新于2025-09-04 15:30:14
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Initial experience of correlating diffusion spectral parameters with histopathologic indexes in murine colorectal tumor homografts
摘要： Purpose: To determine the correlation between continuously distributed diffusion-weighted image (DWI)-derived parameters and histopathologic indexes. Methods: Fifty-four mice bearing HCT-116 colorectal tumors were included for analysis; 12 mice were used for continuous observation, and the other 42 mice were used for break-point observation. All mice were randomly divided into radiotherapy and non-radiotherapy groups. Optical imaging and MRI were performed at different time points according to radiotherapy regimen (baseline, 24 h, 48 h, 72 h, 7 d, 14 d, and 28 d). Continuous observation data were analyzed to show the difference of dynamic changing trends of optical and MR-DWI–derived parameters between radiotherapy and non-radiotherapy groups (photon numbers, D_max, full width half maximum [FWHM], and apparent diffusion coefficient [ADC] value). Break-point observation data were used to analyze the correlation between histopathologic indices and DWI-derived parameters. Results: There was a significant difference in the changing trends of photon numbers, D_max, FWHM, and ADC value between radiotherapy and non-radiotherapy groups, especially at early time points. There was moderate negative correlation between Ki67 and percentage changes of D_max, FWHM, and ADC values (the correlation coefficients were 0.632, 0.449, and 0.586, P,0.001, P=0.008, and P,0.001, respectively). There was moderate negative correlation between survivin and percentage changes of D_max and ADC values (correlation coefficients were 0.496 and 0.473, P=0.004 and P=0.006, respectively). Conclusion: The continuously distributed DWI-derived parameters could reflect histological behavior to some extent and, thus, are potential markers for early noninvasive monitoring of tumor cell apoptosis and proliferation.
关键词： magnetic resonance imaging,colorectal cancer,murine homografts,diffusion-weighted imaging,continuously distributed
更新于2025-09-04 15:30:14
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Synthesis of gadolinium-based Bi<sub>2</sub>S<sub>3</sub> nanoparticles as cancer theranostics for dual-modality computed tomography /magnetic resonance imaging-guided photothermal therapy
摘要： Development of a safe, efficient and inexpensive multifunctional nanoplatform using a facile approach for multimodal imaging and therapeutic functions becomes more and more practically relevant but challenging. In this work, we demonstrated a novel nanocomposites (Bi2S3-Gd) for computed tomography (CT)/magnetic resonance (MR) imaging-guided photothermal therapy for cancer in vitro. It was achieved by modification of hydrophobic Bi2S3 with a smart amphiphilic gadolinium-chelated ligand. The as-prepared nanocomposites composed of low cost Bi2S3 and gadolinium complexes, showed high stability, excellent biocompatibility and good photostability. It was observed that Bi2S3-Gd nanocomposites can efficiently convert the NIR light into heat, and then suppressed the growth of tumor cells under NIR laser irradiation. Apart from serving as an effective photothermal agent, the as-prepared nanomaterials could induce an efficient contrast enhancement for both CT and MRI imaging at low concentrations of Bi and Gd, rendering more accurate diagnosis. This work suggests the potential of Bi2S3-Gd nanomaterials as a novel multifunctional nanoplatform for CT/MRI imaging-guided photothermal therapy for cancer.
关键词： photothermal therapy,magnetic resonance imaging,Bismuth sulfide,amphiphilic ligand,computed tomography imaging
更新于2025-09-04 15:30:14
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Diffusion-weighted imaging and diffusion tensor imaging as adjuncts to?conventional MRI for the diagnosis and management of peripheral nerve sheath tumors: current perspectives and future directions
摘要： Peripheral nerve sheath tumors (PNSTs) account for ~ 5% of soft tissue neoplasms and are responsible for a wide spectrum of morbidities ranging from localized neuropathy to fulminant metastatic spread and death. MR imaging represents the gold standard for identification of these neoplasms, however, current anatomic MR imaging markers do not reliably detect or differentiate benign and malignant lesions, and therefore, biopsy or excision is required for definitive diagnosis. Diffusion-weighted MR imaging (DWI) serves as a useful tool in the evaluation and management of PNSTs by providing functional information regarding the degree of diffusion, while diffusion tensor imaging (DTI) aids in determining the directional information of predominant diffusion and has been shown to be particularly useful for pre-operative planning of these tumors by delineating healthy and pathologic fascicles. The article focuses on these important neurogenic lesions, highlighting the current utility of diffusion MR imaging and future directions including computerized radiomic analysis.
关键词： Diffusion tensor imaging,Nerve sheath neoplasms,Diagnostic techniques, neurological,Diffusion magnetic resonance imaging,Peripheral nerves
更新于2025-09-04 15:30:14
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Pattern Recognition and Signal Analysis in Medical Imaging || Computer-Aided Diagnosis for Diagnostically Challenging Breast Lesions in DCE-MRI
摘要： Breast cancer is the most common cancer among women, but has an encouraging cure rate if diagnosed at an early stage. Thus, early detection of breast cancer continues to be the key for effective treatment. Magnetic resonance (MR) imaging is an emerging and promising new modality for detection and further evaluation of clinically, mammographically, and sonographically occult cancers [134,402]. Acquisition of temporal sequences of between three and six MR images depicting the kinetics of contrast agent molecules in the breast tissue allows for detecting and assessing suspicious tissue disorders with high sensitivity, even in the mammographically dense breasts of young women. Yet, the multitemporal nature of the three-dimensional image data poses new challenges to radiologists as the key-information, reflected by subtle temporal changes of the signal intensity, is only perceivable if all images of the temporal sequence are considered simultaneously.
关键词： Computer-aided diagnosis,Dynamic contrast-enhanced MR,Magnetic resonance imaging,Non-mass-enhancing lesions,Breast cancer
更新于2025-09-04 15:30:14
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Evaluation of renal dysfunction using texture analysis based on DWI, BOLD, and susceptibility-weighted imaging
摘要： Objective To explore the value of texture analysis based on diffusion-weighted imaging (DWI), blood oxygen level–dependent MRI (BOLD), and susceptibility-weighted imaging (SWI) in evaluating renal dysfunction. Methods Seventy-two patients (mean age 53.72 ± 13.46 years) underwent MRI consisting of DWI, BOLD, and SWI. According to their estimated glomerular filtration rate (eGFR), the patients were classified into either severe renal function impairment (sRI, eGFR < 30 mL/min/1.73 m2), non-severe renal function impairment (non-sRI, eGFR ≥ 30 mL/min/1.73 m2, and < 80 mL/min/1.73 m2), or control (CG, eGFR ≥ 80 mL/min/1.73 m2) groups. Thirteen texture features were extracted and then were analyzed to select the most valuable for discerning the three groups with each imaging method. A ROC curve was performed to compare the capacities of the features to differentiate non-sRI from sRI or CG. Results Six features proved to be the most valuable for assessing renal dysfunction: 0.25QuantileDWI, 0.5QuantileDWI, HomogeneityDWI, EntropyBOLD, SkewnessSWI, and CorrelationSWI. Three features derived from DWI (0.25QuantileDWI, 0.5QuantileDWI, and HomogeneityDWI) were smaller in sRI than in non-sRI; EntropyBOLD and CorrelationSWI were smaller in non-sRI than in CG (p < 0.05). 0.25QuantileDWI, 0.5QuantileDWI, and HomogeneityDWI showed similar capacities for differentiating sRI from non-sRI. Similarly, EntropyBOLD and CorrelationSWI showed equal capacities for differentiating non-sRI from CG. Conclusion Texture analysis based on DWI, BOLD, and SWI can assist in assessing renal dysfunction, and texture features based on BOLD and SWI may be suitable for assessing renal dysfunction during early stages.
关键词： Chronic kidney disease,Image processing, computer-assisted,Diffusion magnetic resonance imaging,Chronic renal insufficiency
更新于2025-09-04 15:30:14
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Comparison of different treatment schemes in 5-ALA interstitial photodynamic therapy for high-grade glioma in a preclinical model: An MRI study
摘要： Background: There is currently no therapy that prevents high-grade glioma recurrence. Thus, these primary brain tumors have unfavorable outcomes. Recently, 5-ALA photodynamic therapy (PDT) has been proposed to delay relapse and is highly expected to have potential synergistic effects with the current standard of care. However, PDT treatment delivery needs to be optimized by evaluating the impact of both the number of fractions and the light power used. Objectives: Our study aimed to compare MRI markers across different treatment schemes that use interstitial PDT in high-grade glioma in a preclinical model. Materials and Methods: Forty-eight “nude” rats were grafted with human U87 cells into the right putamen and subsequently submitted to interstitial PDT. The rats were randomized into six groups, including two different sham groups and four different treated groups (5 fractions at 5 mW or 30 mW and 2 fractions at 5 mW or 30 mW). After photosensitizer (PS) precursor (5-ALA) intake, an optical fiber was introduced into the tumor. Treatment effects were assessed with early high-field MRI to acquire T1 and T2 diffusion and perfusion images. Results: There was no difference in the variation of the diffusion coefficient among the six groups (p=0.0549, Kruskal-Wallis test). However, a significant difference was identified among the six groups in terms of variation in perfusion (p=0.048, Kruskal-Wallis test), supporting a lesional effect in the treated groups. Additionally, the sham groups had significantly smaller edema volumes than were observed in the treated groups. Moreover, the 5-fraction group treated with 30 mW was associated with edema volumes that were significantly greater than those in the 5-fraction group treated with 5 mW (p=0.019). Conclusion: Based on observations of MRI data and considering treatment effects, the 5-fraction group treated at 5 mW was not significantly different from the other treated groups in terms of cell deaths, characterized by diffusion imaging, or necrosis level. However, the significantly lower level of edema observed in this group indicated that this treatment scheme had limited toxicity.
关键词： Glioblastoma,Photodynamic Therapy,High-Grade Glioma,PDT,PpIX,MRI,5-ALA,Magnetic Resonance Imaging
更新于2025-09-04 15:30:14
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Hilbert Curve-Based Metasurface to Enhance Sensitivity of Radio Frequency Coils for 7-T MRI
摘要： In this paper, we propose a compact, lightweight, and easy-to-fabricate Hilbert curve-based metasurface resonator that can effectively increase the sensitivity (radio frequency (RF) field intensity) and penetration depth of an RF coil for 7-T magnetic resonance imaging scanner. A circuit model is proposed to accurately calculate the resonance frequency of Hilbert curve resonators of different orders. A single element of a transverse electromagnetic (EM) coil was used for this paper. The increase in the field sensitivity introduced by the proposed metasurface to an RF coil was successfully demonstrated through simulations and experiments. The EM field produced by the RF coil is redistributed due to the presence of the proposed metasurface. The key feature of the proposed structure is its significant increase in the penetration depth of magnetic fields into the imaging volume. An enhancement of the magnetic field by more than four times was observed at 13.5 cm away from the coil experimentally. Flexibility for matching the coil integrated with the proposed surface is shown.
关键词： metasurface,magnetic resonance imaging (MRI),radio frequency (RF) coil,Hilbert curve
更新于2025-09-04 15:30:14
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Contrast-Enhanced Mammography (CEM) for Detecting Residual Disease after Neoadjuvant Chemotherapy: A Comparison with Breast Magnetic Resonance Imaging (MRI)
摘要： Objective. To evaluate the performance of contrast-enhanced mammography (CEM) compared to magnetic resonance imaging (MRI) for estimating residual tumor size after neoadjuvant chemotherapy (NAC) in women with newly diagnosed breast cancer. Methods. The institutional review board approved this study. This prospective study included women with newly diagnosed breast cancer who underwent breast CEM and MRI at the end of the last cycle of NAC and before definitive surgery. Size of residual malignancy on post-NAC CEM and MRI was compared with surgical pathology. Agreements and correlations of CEM and MRI measurements with histological size were assessed. Results. Thirty-three patients were included with a mean age of 45 years (range 22–76). The sensitivity, specificity, and positive and negative predictive value for detection of residual disease of CEM were 76%, 87.5%, 95%, and 86.4%, and those of MRI were 92%, 75%, 92%, and 75%. Comparing CEM to MRI, the mean difference was ?0.8 cm, concordance coefficient was 0.7, and Pearson correlation was 0.7 (p = 0.0003). The concordance coefficient between measurements of each imaging modality and pathologic tumor size was 0.7 for CEM and 0.4 for MRI. Pearson correlation was 0.8 for CEM and 0.5 for MRI. Mean differences between CEM, MRI, and residual histopathological tumor size were 0.8 cm and 1.8 cm, respectively. Conclusions. CEM has good correlation and agreement with histopathology for measuring residual disease after NAC. CEM was comparable to MRI, showing high positive predictive value and specificity for detecting residual disease.
关键词： neoadjuvant chemotherapy,residual disease,magnetic resonance imaging,contrast-enhanced mammography,breast cancer
更新于2025-09-04 15:30:14