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Hydrophilic Quantum Dots Functionalized with Gd(III)-DO3A Monoamide Chelates as Bright and Effective T1-weighted Bimodal Nanoprobes
摘要： Magnetic resonance imaging (MRI) is a powerful non-invasive diagnostic tool that enables distinguishing healthy from pathological tissues, with high anatomical detail. Nevertheless, MRI is quite limited in the investigation of molecular/cellular biochemical events, which can be reached by fluorescence-based techniques. Thus, we developed bimodal nanosystems consisting in hydrophilic quantum dots (QDs) directly conjugated to Gd(III)-DO3A monoamide chelates, a Gd(III)-DOTA derivative, allowing for the combination of the advantages of both MRI and fluorescence-based tools. These nanoparticulate systems can also improve MRI contrast, by increasing the local concentration of paramagnetic chelates. transmetallation assays, optical characterization, and relaxometric analyses, showed that the developed bimodal nanoprobes have great chemical stability, bright fluorescence, and high relaxivities. Moreover, fluorescence correlation spectroscopy (FCS) analysis allowed us to distinguish nanosystems containing different amounts of chelates/QD. Also, inductively coupled plasma optical emission spectrometry (ICP – OES) indicated a conjugation yield higher than 75%. Our nanosystems showed effective longitudinal relaxivities per QD and per paramagnetic ion, at least 5 times [per Gd(III)] and 100 times (per QD) higher than the r1 for Gd(III)-DOTA chelates, suitable for T1-weighted imaging. Additionally, the bimodal nanoparticles presented negligible cytotoxicity, and efficiently labeled HeLa cells as shown by fluorescence. Thus, the developed nanosystems show potential as strategic probes for fluorescence analyses and MRI, being useful for investigating a variety of biological processes.
关键词： Quantum Dots,Gd(III)-DO3A monoamide chelates,Fluorescence,MRI,Bimodal nanoprobes
更新于2025-11-21 11:08:12
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<sup>129</sup> Xe Hyper-CEST/ <sup>19</sup> F MRI Multimodal Imaging System for Sensitive and Selective Tumor Cells Detection
摘要： Heteronuclear MRI offers broad potential for specific detection and quantification of molecularly targeted agents in diagnosis and therapy planning or monitoring. Here we report a novel method for simultaneous acquisition of dual-nuclei hyper-CEST 129Xe and 19F tumor targeting MRI. 129Xe hyper-CEST MRI, 19F MRI and fluorescent imaging were integrated into PFOB nanoemulsion as multimodal imaging system for sensitive and selective tumor cells detection. The dual-nuclei MR data could offer sensitive and selective tumor cells detection. Based on contemporaneous 1H signals. As the complementary to 1H MRI, 129Xe and 19F signals can also provided efficient and precise anatomical localization of tumors.
关键词： nanoemulsion,tumor,hyper-CEST,19F MRI,129Xe MRI
更新于2025-09-23 15:23:52
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Optimization of a parallel-plate RF probe for high resolution thin film imaging
摘要： Choosing an MR probe with the correct dimensions and high sensitivity is critical for magnetic resonance imaging, especially high resolution thin film imaging. In this work, a parallel‐plate resonator has been optimized for strength and uniformity of the B1 magnetic field. The parallel‐plate resonator is designed for high resolution imaging in the direction perpendicular to the plates. The optimization process was undertaken through simulation with CST Micro Wave Studio, followed by experiment. A 400 μm capillary tube, filled with doped water, was used for testing the optimized probe in a 2.4 T magnet. It is shown that increasing the width of the copper leads connected to the plates increases the homogeneity of the B1 magnetic field by almost 90%. The best approach to increase the sensitivity and the homogeneity of the probe was to maintain the dimensions of the plates and copper leads but to add additional capacitors at the corners to distribute the current. This approach produces a 40% stronger B1 magnetic field and increases the homogeneity by almost 85%. The experimental B1 magnetic field of the parallel‐plate prototype agrees within 20% of the value found through simulation, for specified power. The experimental MRI results show that it is possible to achieve a nominal resolution of 10 μm between the plates for suitable samples using the optimized probe. The optimized parallel‐plate resonator, combined with a phase encode SE SPI method, may be used for high resolution studies of lithium‐ion transport in the electrolyte solution of lithium‐ion batteries.
关键词： lithium-ion battery,optimization,MRI,parallel-plate resonator
更新于2025-09-23 15:23:52
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Dose distribution verification in high-dose-rate brachytherapy using a highly sensitive normoxic N-vinylpyrrolidone polymer gel dosimeter
摘要： Rapid technological advances in high-dose-rate brachytherapy have led to a requirement for greater accuracy in treatment planning system calculations and in the verification of dose distributions. In high-dose-rate brachytherapy, it is important to measure the dose distribution in the low-dose region at a position away from the source in addition to the high-dose range in the proximity of the source. The aim of this study was to investigate the accuracy of a treatment plan designed for prostate cancer in the low-dose range using a normoxic N-vinylpyrrolidone-based polymer gel (VIPET gel) dosimeter containing inorganic salt as a sensitizer (iVIPET). The dose response was evaluated on the basis of the transverse relaxation rate (R2) measured by magnetic resonance scanning. In the verification of the treatment plan, gamma analysis showed that the dose distributions obtained from the polymer gel dosimeter were in good agreement with those calculated by the treatment planning system. The gamma passing rate according to the 2%/2 mm criterion was 97.9%. The iVIPET gel dosimeter provided better accuracy for low doses than the normal VIPET gel dosimeter, demonstrating the potential to be a useful tool for quality assurance of the dose distribution delivered by high-dose-rate brachytherapy.
关键词： Iridium-192,MRI,High-dose-rate brachytherapy,Polymer gel dosimeter
更新于2025-09-23 15:23:52
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Two-dimensional frequency-swept pulse with resilience to both B1 and B0 inhomogeneity
摘要： Applications of multidimensional spatially-selective pulses are sometimes limited by their long pulse durations resulting from the need to execute a modulated gradient waveform in concert with RF transmission. Here, we introduce a method to design two-dimensional selective adiabatic pulses using a Cartesian k-space trajectory. The full pulse can be sampled using various undersampled segments to create a multidimensional pulse resilient to large off-resonances. Moreover, the pulse can be designed to be resilient to B1 inhomogeneity. Experimental demonstrations of fully segmented and single-shot k-space sampling patterns are presented.
关键词： MRI,B1 inhomogeneity,B0 inhomogeneity,Adiabatic pulse,Frequency-modulated,Radiofrequency pulse,2D pulse
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Krakow, Poland (2018.10.16-2018.10.18)] 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Application of ANN and ANFIS for detection of brain tumors in MRIs by using DWT and GLCM texture analysis
摘要： In this work we combine different methodologies in order to develop algorithms for Computer-Aided Diagnosis (CAD) for brain tumors from the axial plane (T2 MRI). All methods utilize texture analysis by extracting features from raw data, without post-processing, based on different techniques, such as Gray Level Co-Occurrence Matrix (GLCM), or Discrete Wavelet Transform (DWT) and different classification methods, based on ANN or ANFIS. All of our proposed methodologies are developed, validated and verified on various sub data including 65% non-healthy MRIS. The total used database consists of 202 MRIs from non-healthy patients and 18 from healthy, segmented visually by an experienced neurosurgeon. Combining different subsets of features, our best results are by using 4 GLCM features for a 4 input and two hidden layers ANN, giving sensitivity 100%, specificity 77.8% accuracy 94.3%. It is proved that the input data to train such a CAD are considered to be unbiased if the ratio between healthy/un-healthy tissue MRIs is about 35%/65%, respectively.
关键词： MRI tumor CAD diagnosis,DWT,ANFIS,GLCM,ANN
更新于2025-09-23 15:23:52
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Imaging extracellular vesicles: current and emerging methods
摘要： Extracellular vesicles (EVs) are lipid bilayer-enclosed nanoparticles released by cells. They range from 30 nm to several micrometers in diameter, and ferry biological cargos such as proteins, lipids, RNAs and DNAs for local and distant intercellular communications. EVs have since been found to play a role in development, as well as in diseases including cancers. To elucidate the roles of EVs, researchers have established different methods to visualize and study their spatiotemporal properties. However, since EV are nanometer-sized, imaging them demands a full understanding of each labeling strategy to ensure accurate monitoring. This review covers current and emerging strategies for EV imaging for prospective studies.
关键词： Bioluminescence,MRI,Microvesicles,SPECT,Biodistribution,Imaging,Extracellular vesicles,Fluorescence,Dyes,exosomes
更新于2025-09-23 15:23:52
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Imaging and Biomechanics
摘要： Over the past 3 decades, our ability to noninvasively image structures of the musculoskeletal system has facilitated clinical diagnoses and provided insight into the success of various therapeutic interventions. As imaging modalities are refined and novel approaches are introduced, imaging technologies can provide objective measures to better understand the natural history and mechanisms of diseases and optimize and evaluate their treatment. While traditional radiography and computed tomography are commonly used to evaluate the integrity of bony structures, recent advances include biplanar videoradiography, which can now be used to directly track 3-dimensional joint motion in vivo with a high degree of accuracy.11 As such, biplanar videoradiography has been applied to study the progression of arthrosis after anterior cruciate ligament (ACL) injury.4 Based on recent technological advances, ultrasound is now being used to measure cartilage thickness to study the progression of arthrosis in vivo after ACL injury.8 Likewise, there has been a real boon in the use of magnetic resonance imaging (MRI) to evaluate anatomic, biomechanical, and compositional interactions among the structures of an injured joint. For example, MRI has been used to evaluate compositional changes of the articular cartilage in the injured joint in relation to changes in loading during gait.13 These kinds of studies provide opportunities to better understand mechanisms of posttraumatic osteoarthritis following joint injury. Furthermore, MRI has been recently applied to gain insight into the mechanisms of ACL injury.9 By using the projections of the bone bruises that occurred during ligament rupture onto the articular surfaces within the 2 compartments of the knee via models derived from 3-dimensional MRI scans, the position of the tibia relative to the femur at the time of injury can be determined.9 MRI has also been used to evaluate the structural and mechanical integrity of the menisci3 and ACL grafts after surgery.1
关键词： biomechanics,knee,MRI,imaging
更新于2025-09-23 15:23:52
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Electronic Medical Record Context Signatures Improve Diagnostic Classification using Medical Image Computing
摘要： Composite models that combine medical imaging with electronic medical records (EMR) improve predictive power when compared to traditional models that use imaging alone. The digitization of EMR provides potential access to a wealth of medical information, but presents new challenges in algorithm design and inference. Previous studies, such as PheWAS (Phenome Wide Association Study), have shown that EMR data can be used to investigate the relationship between genotypes and clinical conditions. Here, we introduce PheDAS (Phenome-Disease Association Study) to extend the statistical capabilities of the PheWAS software through a custom Python package which creates diagnostic EMR signatures to capture system-wide co-morbidities for a disease population within a given time interval. We investigate the effect of integrating these EMR signatures with radiological data to improve diagnostic classification in disease domains known to have confounding factors because of variable and complex clinical presentation. Specifically, we focus on two studies: (1) a study of four major optic nerve related conditions and (2) a study of diabetes. Addition of EMR signature vectors to radiologically-derived structural metrics improves the area under the curve (AUC) for diagnostic classification using elastic net regression, for diseases of the optic nerve. For glaucoma, the AUC improves from 0.71 to 0.83, for intrinsic optic nerve disease it increases from 0.72 to 0.91, for optic nerve edema it increases from 0.95 to 0.96, and for thyroid eye disease from 0.79 to 0.89. The EMR signatures recapitulate known comorbidities with diabetes, such as abnormal glucose but do not significantly modulate image-derived features. In summary, EMR signatures present a scalable and readily applicable approach for using EMR context to increase the statistical power of image derived features.
关键词： CT,MRI,Electronic medical records,Optic nerve
更新于2025-09-23 15:22:29
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Manganese-Enhanced MRI for Preclinical Evaluation of Retinal Degeneration Treatments
摘要： PURPOSE. Apply manganese-enhanced magnetic resonance imaging (MEMRI) to assess ion channel activity and structure of retinas from mice subject to light-induced retinal degeneration treated with prophylactic agents. METHODS. Abca4?/?Rdh8?/? double knockout mice with and without prophylactic retinylamine (Ret-NH2) treatment were illuminated with strong light. Manganese-enhanced MRI was used to image the retina 2 hours after intravitreous injection of MnCl2 into one eye. Contrast-enhanced MRIs of the retina and vitreous humor in each experimental group were assessed and correlated with the treatment. Findings were compared with standard structural and functional assessments of the retina by optical coherence tomography (OCT), histology, and electroretinography (ERG). RESULTS. Manganese-enhanced MRI contrast in the retina was high in nonilluminated and illuminated Ret-NH2–treated mice, whereas no enhancement was evident in the retina of the light-illuminated mice without Ret-NH2 treatment (P < 0.0005). A relatively high signal enhancement was also observed in the vitreous humor of mice treated with Ret-NH2. Strong MEMRI signal enhancement in the retinas of mice treated with retinylamine was correlated with their structural integrity and function evidenced by OCT, histology, and a strong ERG light response. CONCLUSIONS. Manganese-enhanced MRI has the potential to assess the response of the retina to prophylactic treatment based on the measurement of ion channel activity. This approach could be used as a complementary tool in preclinical development of new prophylactic therapies for retinopathies.
关键词： manganese-enhanced MRI,efficacy evaluation,retinal degeneration,retinylamine
更新于2025-09-23 15:22:29