Magnetic Resonance Imaging Signal Research Articles

Novel frequency selective B1focusing passive Lenz resonators for substantial MRI signal-to-noise ratio amplification.

The need for increased sensitivity in magnetic resonance imaging (MRI) is crucial for its advancement as an imaging modality. The development of passive Lenz Resonators for effective RF magnetic field focusing will improve MRI sensitivity via local amplification of MRI signal, thereby leading to more efficient diagnosis and patient treatment. While there are methods for amplifying the signal from specific nuclei in MRI, such as hyperpolarization, a general solution will be more advantageous and would work in combination with these preexisting methods. While the Lenz Lens proposed such a general solution based on Lenz's law and the reciprocity principle, it came at the cost of limited signal enhancement. In this work, the first-in-kind prototype Lenz Resonator was conceived and examined as a general frequency-selective passive flux-focusing element for significant MRI signal enhancement. A 3.0 T Philips Achieva MRI was used to compare the signal from a phantom in the presence of Lenz Lenses, Lenz Resonators, and control trials with neither component. An MRI investigation demonstrated an experimental amplification of the signal-to-noise ratio up to 80% using an MRI insert of two coaxial Lenz Resonators due to superior B1 magnetic field focusing. The resonators displayed consistent amplification, nearly independent of their x-position within the MRI bore. This behavior demonstrates the feasibility of imaging large objects of varying shapes without penalties for signal amplification using Lenz Resonators. The Lenz Resonators versatility in geometrical design and consistent signal amplifying abilities between pulse sequences should allow for the development of Lenz Resonators suitable for most commonly used MRI setups.

NIMG-62. SEX-DISTINCT TRANSCRIPTOMIC SIGNATURES UNDERLY MRI-DEFINED EDEMA PATTERNS IN HUMAN GLIOMAS

Abstract Magnetic resonance imaging (MRI) is key to clinically managing brain tumor patients, however connecting the biology to imaging remains challenging. We previously developed a two-compartment model of MRI signal intensity to quantitatively estimate relative edema abundance from T2-weighted MRIs. Using this model, we previously identified the fatty acid metabolism (FAM) and oxidative phosphorylation (OxPhos) pathways as sex-distinct, with both pathways amplified for high edema in males and low edema in females. The purpose of this project was to further delineate sex-distinct biology associated with MRI-estimated brain tumor edema abundance. We analyzed 179 multiregional samples (Female: 75; Male: 104) from 55 high grade glioma patients (Female: 21; Male: 34) for bulk RNA-Seq. Patients’ pre-surgical multiparametric MRIs were preprocessed and segmented for abnormal regions and normal tissue. Utilizing the segmentations and preprocessed images we estimated the relative fractions of extracellular and intracellular space based on the edema mathematical model. Samples were characterized by their edema scores, which were analyzed using differential expression for high and low edema, gene set enrichment analysis (GSEA) using MSigDB hallmarks, and leading edge interpretation. Based on transcriptomic leading edge analyses of high and low edema samples from sex-separated cohorts, we identified common and sex-distinct enrichment of the FAM and OxPhos pathways underlying edema patterns. Of the OxPhos pathway leading edge genes, 45 were common, 36 were unique to females, and 66 were unique to males. Of the FAM pathway leading edge genes, 8 were common, 39 were unique to females, and 29 were unique to males. Notably, expression of both IDH1 and IDH2 were increased for males in regions of high edema in the OxPhos pathway. IDH3a was decreased for females in regions of low edema in the OxPhos pathway. These data suggest that there may be sex-distinct metabolism underlying MRI measurable edema formation.

Brain connectomes in youth at risk for serious mental illness: a longitudinal perspective.

Identifying biomarkers for serious mental illnesses (SMI) has significant implications for prevention and early intervention. In the current study, changes in whole brain structural and functional connectomes were investigated in youth at transdiagnostic risk over a one-year period. Based on clinical assessments, participants were assigned to one of 5 groups: healthy controls (HC; n = 33), familial risk for serious mental illness (stage 0; n = 31), mild symptoms (stage 1a; n = 37), attenuated syndromes (stage 1b; n = 61), or discrete disorder (transition; n = 9). Constrained spherical deconvolution was used to generate whole brain tractography maps, which were then used to calculate connectivity matrices for graph theory analysis. Graph theory was also used to analyze correlations of functional magnetic resonance imaging (fMRI) signal between pairs of brain regions. Linear mixed models revealed structural and functional abnormalities in global metrics of small world lambda, and resting state networks involving the fronto-parietal, default mode, and deep grey matter networks, along with the visual and dorsal attention networks. Machine learning analysis additionally identified changes in nodal metrics of betweenness centrality in the angular gyrus and bilateral temporal gyri as potential features which can discriminate between the groups. Our findings further support the view that abnormalities in large scale networks (particularly those involving fronto-parietal, temporal, default mode,and deep grey matter networks) may underlie transdiagnostic risk for SMIs.

Novel MRI Signs in Atlantodental Space Predict Reduction Degree of Atlantoaxial Dislocation.

The type of atlantodental space tissue in patients with atlantoaxial dislocation (AAD) can help doctors understand the possibility of reduction before surgery. However, relevant research on this topic is lacking. This study aimed to summarize cases of AAD, classified based on the atlantodental space using magnetic resonance imaging (MRI), and preliminarily explore its impact on the degree of reduction. Preoperative T2-weighted MRIs and dynamic digital radiographs of patients who underwent posterior reduction and fixation surgery for congenital AAD between September 2012 and February 2023 were collected. The patients were classified into flexible and inflexible tissue sign groups based on T2-weighted imaging. Patients with an atlantodental interval < 3 mm on extension digital radiography were considered radiographically reducible. Three radiologists read and recorded the MRI results using standard protocols. Kappa and Fleiss kappa values were used to evaluate intra- and inter-observer agreements for MRI signs and dynamic digital radiography findings. Multivariate logistic regression and receiver operating characteristic curves were used to analyze the relationships between imaging parameters and the reduction degree. In total, 118 patients with AAD were included in the analysis. Inter-observer agreement among the three readers was higher for MRI than for dynamic digital radiography (0.816 vs. 0.668). The intra-observer consistency for MRI signs was also better than that of dynamic digital radiography. Both the flexible tissue sign and radiographically reducible groups showed a higher rate of satisfactory reduction. However, only the flexible tissue sign showed positive results in the multivariate regression. The receiver operating characteristic curve for MRI signs as a predictor of satisfactory reduction yielded an area under the curve of 0.776 (95% confidence interval, 0.667-0.875, p < 0.0001). Novel MRI signs of the atlantodental space exhibited high inter- and intra-observer agreement. Patients with flexible tissue signs were more likely to achieve satisfactory reduction after direct posterior surgery.

T1- and T2-weighted MRI signal and histology findings in suboptimally fixed human brains

Neuroscientific research that requires brain tissue depends on brain banks that provide very small tissue samples fixed by immersion in neutral-buffered formalin (NBF), while anatomy laboratories could provide full brain specimens. However, these brains are generally fixed by perfusion of the full body with solutions other than NBF generally used by brain banks, such as an alcohol-formaldehyde solution (AFS) that is typically used for dissection and teaching. Therefore, fixation quality of these brains needs to be assessed to determine their usefulness in post-mortem investigations through magnetic resonance imaging (MRI) and histology, two common neuroimaging modalities. Here, we report the characteristics of five brains fixed by full body perfusion of an AFS from our Anatomy Laboratory suspected of being poorly fixed, given the altered signal seen on T1w MRI scans in situ. We describe 1- the characteristics of the donors; 2- the fixation procedures applied for each case; 3- the tissue contrast characteristics of the T1w and T2w images; 4- the macroscopic tissue quality after extraction of the brains; 5- the macroscopic arterial characteristics and presence or absence of blood clots; and 6- four histological stains of the areas that we suspected were poorly fixed. We conclude that multiple factors can affect the fixation quality of the brain. Nevertheless, cases in which brain fixation is suboptimal, consequently altering the T1w signal, still have T2w of adequate gray-matter to white-matter contrast and may also be used for histology stains with sufficient quality.

A Macrocyclic Hybrid PET/MRI Probe for Quantitative Perfusion Imaging In Vivo.

Perfusion dynamics play a vital role in delivering essential nutrients and oxygen to tissues while removing metabolic waste products. Imaging techniques such as magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET) use contrast agents to visualize perfusion and clearance patterns; however, each technique has specific limitations. Hybrid PET/MRI combines the quantitative power and sensitivity of PET with the high functional and anatomical detail of MRI and holds great promise for precision in molecular imaging. However, the development of dual PET/MRI probes has been hampered by challenging synthesis and radiolabeling. Here, we present a novel PET/MRI probe, [18F][Gd(FL1)], which exhibits excellent stability comparable to macrocyclic MRI contrast agents used in clinical practice. The unique molecular design of [18F][Gd(FL1)] allows selective and expeditious radiolabeling of the gadolinium chelate in the final synthetic step. Leveraging the strengths of MRI and PET signals, the probe enables quantitative in vivo mapping of perfusion and excretion dynamics through an innovative voxel-based analysis. The diagnostic capabilities of [18F][Gd(FL1)] were demonstrated in a pilot study on healthy mice, successfully detecting early cases of unilateral renal dysfunction, a condition that is typically challenging to diagnose. This study introduces a new approach for PET/MRI and emphasizes a streamlined probe design for practical synthesis and improved diagnostic accuracy.

Novel ultrathin ferrous sulfide nanosheets: Towards replacing black phosphorus in anticancer nanotheranostics

Biodegradable two-dimensional nanomaterials could be a significant breakthrough in the field of oncology nanotheranostic agents, which are rapidly emerging as promising candidates for tumor theranostic applications. Herein, a novel biodegradable ferrous sulfide nanosheet (FeS NS) is developed. Compared to the traditional photothermal material, black phosphorus nanosheet (BP NS), FeS demonstrates superior degradability and enhanced photothermal performance, and making it ideal for efficient photothermal therapy (PTT) of tumors. In the acidic tumor microenvironment, FeS degrades and releases H2S, which inhibits mitochondrial respiration and ATP production. This process leads to a reduction in heat shock protein expression, lowering the resistance of tumor cells to photothermal stimulation, and improving the efficacy of PTT. The released Fe2+ exhibits efficient peroxidase activity, triggering ferroptosis in tumor cells. Furthermore, due to its superparamagnetic nature, FeS NSs could accumulate at the tumor site and provide a strong magnetic resonance imaging (MRI) signal for imaging-guided tumor therapy. Overall, as a promising alternative to BP, the FeS NSs are a potentially innovative nanotheranostic agent of tumors, offering a synergistic approach to ferroptosis−PTT with MRI guidance.

Uterine layers hypervascularization in atypical placentation: the comparison of magnetic resonance imaging with vascular pathomorphology

Rationale: One in five women worldwide delivers through cesarean section, which is associated to a high rate of placenta previa and abnormal placenta attachment to the uterine wall. The grade of placenta accreta spectrum (PAS) correlates with blood loss volume, which could be related to vascularization characteristics. Up to now, there have been no studies on the diagnostic value of magnetic resonance criteria for hypervascularization of the uterine wall and their correlation with an assumed grade of PAS according to the International Federation of Gynecology and Obstetrics (FIGO) classification. Also, abnormal vessels location and their wall structure have not been studied with state-of-the-art pathomorphological methods. Aim: To develop a classification for various types of the uterine wall hypervascularization depending on the depth of placental invasion assessed by magnetic resonance imaging (MRI). Methods: We retrospectively analyzed medical files of 66 patients aged 18 to 45 years, who were assumed to have PAS based on their sonography results. To clarify the extent and localization of the placental invasion, all patients had MRI performed at 24 to 32 weeks of gestation. In all patients, the PAS grade was verified pathologically; in 30 of them (45,5%), a detailed pathological examination was additionally performed. The PAS grades were classified according to Morbidly Adherent Placenta Imaging Reporting and Data System (MAPI-RADS). The MRI data were correlated with the PAS (FIGO) grade estimated from intraoperative data and with intraoperative blood loss. At the final study step, the MRI data was correlated with abnormal pathomorphology, with the assessment of the degree of vascularization and the visual picture of abnormal uteroplacental vasculature. Results: We have proposed a classification of MRI signs of hypervascularization in the lower uterine segment correlating with the depth of placenta accreta. Type 1. Single small vessels in the myometrium, medium caliber arteries in the projection of the uterine serosa (normal variation for the 3rd trimester of gestation). Type 2. Numerous small confluent vessels, mainly in the uteroplacental region, and retroplacental hematomas (typical for placenta accreta, or FIGO PAS 1). Type 3. Intrauterine hypervascularization with a deficient myometrium thickness, predominantly vessels of the middle layer (typical for placenta increta, or FIGO PAS 2). Type 4. Thinning of the lower uterine segment due to significant bulging of the placenta in the presence of curved anastomosing vessels of vast caliber over 4 mm (typical for placenta increta – FIGO PAS 2, as well as placenta percreta – FIGO PAS 3a). Type 5. Hypervascularization outside the uterus, over its surface and in the parametrial tissues: at the border with the bladder, uterine isthmus, including signs of fibrosis and growing into the posterior bladder wall (typical for various grades of placenta percreta – FIGO PAS 3b, 3c). Conclusion: The proposed classification of uterine wall hypervascularization in accordance with the grades of placenta accreta spectrum (FIGO PAS) could be useful for its practical implementation by radiologists.

Federated learning and deep learning framework for MRI image and speech signal-based multi-modal depression detection

Adolescence is a significant period for developing skills and knowledge and learning about managing relationships and emotions by gathering attributes for maturity. Recently, Depression arises as a common mental health issue in adolescents and this affects the daily life of the person. This leads to educational and social impairments and this acts as a major risk for suicide. As a result, the identification and treatment for this disorder are essential. By applying Deep learning (DL) algorithms to medical data, the mental condition of a person can be predicted. However, the traditional deep learning models face the challenge in processing the huge sized data. Hence, FL has emerged as an efficient solution for addressing the data size issue of DL. Here, Depression detection in adolescents is carried out by considering the FL framework, which comprises two modules, namely the local module and the Global module. The detection process is done in the local module using the proposed Exponential African Pelican Optimization based Deep Convolutional Neural Network (ExpAPO-DCNN), whereas the Global module produces the aggregated output of the local module. In this research, FL utilizes the DL model in producing the output, where the DL model considered two modalities of inputs, such as speech signal and Magnetic Resonance Imaging (MRI) image. The processing steps used for this research are pre-processing, feature extraction and detection. For MRI and speech signals, all the above processes are carried out individually. Finally, both the outputs are fused utilizing the overlap coefficient. The ExpAPO-DCNN obtained accuracy, Loss, Root mean Squared error (RMSE), Mean Squared error (MSE), True Negative rate (TNR), and True Positive rate (TPR) of 98.00 %, 0.023, 0.058, 0.240, 97.90 %, and 96.30 %, respectively.

Magnetic Resonance Imaging of Anterior Cruciate Ligament Injury.

The Anterior Cruciate Ligament (ACL) is considered the most commonly injured ligament of the knee. Magnetic Resonance Imaging (MRI) has become an indispensable imaging tool and modality of choice for assessing and managing knee conditions. This article outlines an effective MRI imaging technique that improves the diagnostic accuracy of ACL injuries of the knee, covering the appropriate pulse sequences and optimal imaging planes. Furthermore, the article provides a comprehensive review of the appearance of complete and partial ACL tears on MRI in the acute and chronic phases. In addition, it identifies and illustrates the primary MRI signs (signs related to the absence or abnormal visualization of the ACL fibers) and secondary MRI signs (signs related to the mechanism of injury or associated knee injuries) of ACL injury.

Imageable Brachytherapy with Chelator-Free Radiolabeling Hydrogel.

Brachytherapy stands as an essential clinical approach for combating locally advanced tumors. Here, an injectable brachytherapy hydrogel is developed for the treatment of both local and metastatic tumor. Fe-tannins nanoparticles are efficiently and stably radiolabeled with clinical used therapeutic radionuclides (such as 131I, 90Y, 177Lu, and 225Ac) without a chelator, and then chemically cross-linked with 4-armPEG-SH to form brachytherapy hydrogel. Upon intratumoral administration, magnetic resonance imaging (MRI) signal from ferric ions embedded within the hydrogel directly correlates with the retention dosage of radionuclides, which can real-time monitor radionuclides emitting short-range rays in vivo without penetration limitation during brachytherapy. The hydrogel's design ensures the long-term tumor retention of therapeutic radionuclides, leading to the effective eradication of local tumor. Furthermore, the radiolabeled hydrogel is integrated with an adjuvant to synergize with immune checkpoint blocking therapy, thereby activating potent anti-tumor immune responses and inhibiting metastatic tumor growth. Therefore, this work presents an imageable brachytherapy hydrogel for real-time monitoring therapeutic process, and expands the indications of brachytherapy from treatment of localized tumors to metastatic tumors.

Correlation between post-chemotherapy MRI and histopathology of malignant bone tumors treated with extra-articular resection.

Magnetic resonance imaging (MRI) remains the gold standard for diagnosing tumoral joint involvement; however, its interpretation remains uncertain due to the presence of perilesional edema that can lead to unjustified arthrectomy. The aim of the study is to identify precise MRI signs that are predictive of joint involvement. This retrospective multicenter study included 25 patients who underwent extra-articular resection for malignant bone tumor with suspected joint involvement at the shoulder, hip, or knee, between January 2004 and July 2023. Joint resection was indicated based on preoperative MRI examination. MRI signs of joint involvement were joint effusion, capsuloligamentous invasion, disruption of articular cartilage, and intra-articular tumor mass. We then compared histopathological "true" joint involvement of the resected specimen with its preoperative MRI diagnosis. Extra-articular resection was performed in 9 shoulders, 4 hips, and 12 knees. Histological analysis confirmed wide resections for all patients. Based on histopathological analysis, extra-articular resection was unjustified in 40% (44%, 0%, and 50%, respectively). The most specific iconographic criteria were intra-capsular cortical breach and the presence of a tumor mass inside the joint. Articular cartilage disruption is often the most accurate sign. Our results suggest that MRI has a poor ability to accurately diagnose joint involvement. To date, however, this is the best tool available. In addition to obvious signs of joint involvement, MRI analysis must be performed with a thorough understanding of capsular anatomy and its particularities for each joint so as not to miss other signs, such as intra-capsular cortical effraction.

Magnetic resonance imaging signal changes at the intramuscular injection site in dogs: Comparison of medetomidine and saline.

Intramuscular administration is a commonly used method for delivering sedatives and anesthetics in veterinary medicine. Previous studies have reported inflammation at the intramuscular injection site in laboratory animals and observed signal changes on MRI following intramuscular injections in humans. We hypothesized that following intramuscular injection, the site would exhibit T2 hyperintensity and contrast enhancement on MRI. To investigate this, this prospective study evaluated the pattern of signal changes and grade of T2 signal intensity and contrast enhancement over time after the intramuscular injection of medetomidine at a premedication dosage, comparing it to saline. MRI scans were performed immediately postinjection into the biceps femoris and quadriceps femoris muscles, as well as at 2, 8, 24, and 72h, and 7 days postinjection. A semiquantitative scale was utilized to grade signal intensity and contrast enhancement. Both medetomidine and saline injections showed T2 hyperintensity immediately after injection and contrast enhancement from 2h postinjection, manifesting as flame-shaped. These signal changes decreased up to 24h postinjection (p<.05). The signal changes induced by medetomidine showed higher T2 hyperintense change and stronger contrast enhancement compared with saline at most time points, with the signal changes persisting for a longer duration (p<.05). These findings suggest that intramuscular administration of medetomidine induces a more severe tissue reaction compared with saline, and the results are expected to aid in the differentiation of various muscle diseases that present with similar MRI findings.

Magnetic resonance imaging and clinicopathological findings of primary hepatic angiosarcoma.

To investigate the magnetic resonance imaging (MRI) and clinicopathological features of primary hepatic angiosarcoma (PHA) and enhance preoperative diagnosis. MRI and clinicopathological information of 12 cases proved PHA were reviewed. Summarize the MRI characteristics of PHA combined with literature reviews. Among 12 cases (6 males and 6 females; age range, 23-70 years; mean, 53.3 years), one presented as a large mass, two as a diffuse infiltrating tumor, and nine as a mixed pattern of large masses with multiple nodules, all involving both lobes of the liver and ranging from 0.1cm to 11cm in diameter. A total of 63 lesions were analyzed, including 21 masses and 42 nodules. 13 masses (61.9%) demonstrated intratumoral hemorrhage. 18 masses (85.7%) demonstrated heterogeneous patchy, ring-shaped, septate, or irregular shaped enhancing foci on late arterial phase (LAP). On dynamic contrast-enhanced MRI (DCE-MRI), 14 masses (66.7%) showed a centripetal or centrifugal pattern of incomplete progressive enhancement. 6 nodules (14.3%) appeared intratumoral hemorrhage. 31 nodules (73.8%) showed no enhancing foci on LAP images and 27 nodules (64.3%) showed enhancement pattern of complete filling, either centripetal or centrifugal pattern. Moreover, 12 cases (100%) exhibited prominent vessels within or adjacent to at least one lesion. PHA exhibits diverse appearances on MRI. Typical MRI signs include multifoci with intratumoral hemorrhage, prominent vessels within or adjacent to the foci, as well as varied degrees of progressive enhancement with incomplete filling in dominant masses of PHA.

Fourier Convolution Block with global receptive field for MRI reconstruction

Reconstructing images from under-sampled Magnetic Resonance Imaging (MRI) signals significantly reduces scan time and improves clinical practice. However, Convolutional Neural Network (CNN)-based methods, while demonstrating great performance in MRI reconstruction, may face limitations due to their restricted receptive field (RF), hindering the capture of global features. This is particularly crucial for reconstruction, as aliasing artifacts are distributed globally. Recent advancements in Vision Transformers have further emphasized the significance of a large RF. In this study, we proposed a novel global Fourier Convolution Block (FCB) with whole image RF and low computational complexity by transforming the regular spatial domain convolutions into frequency domain. Visualizations of the effective RF and trained kernels demonstrated that FCB improves the RF of reconstruction models in practice. The proposed FCB was evaluated on four popular CNN architectures using brain and knee MRI datasets. Models with FCB achieved superior PSNR and SSIM than baseline models and exhibited more details and texture recovery. The code is publicly available at https://github.com/Haozhoong/FCB.

Viral capsid-mediated efficient cell labeling of micron-sized magnetic particles for highly sensitive long-term in vivo tumor cells MRI tracking

As a contrast agent, micron-sized iron oxide particles (MPIO) offer major advantages for monitoring tumor cells in vivo—applications crucial for studies of tumorigenesis and metastasis. However, labeling tumor cells with MPIO is often dependent on phagocytosis, which limits the labeling efficiency of the cells and thus affects in vivo tumor cell tracking. To address this issue, we prepared a virus-like particle (VLP) consisting of the SV40 VP1 protein modified on the surface of a MPIO (vMPIO). The vMPIO can enter cells via a pathway similar to that of viral infection (caveolae-dependent endocytosis pathway). This approach increased the number of vMPIO in individual labeled cells, which in turn enhances magnetic resonance imaging (MRI) signal intensity and the number of vMPIO in daughter cells. These vMPIO-labeled cells can be detected by MRI in vitro and in vivo even in very small numbers (≤10 cells). Furthermore, vMPIO-labeled cells were successfully applied to long-term tracing of tumor tissue and detection of early metastatic lesions. This VLP-mediated MPIO labeling strategy (vML) not only enables highly sensitive in vivo MRI but also introduces a useful technical tool for investigating tumor invasion and early metastasis.

Cu/Gd co-doped hydroxyapatite/poly lactic-co-glycolic acid composites enhance MRI imaging and bone defect regeneration.

Background: The hydroxyapatite (HA)/poly(lactide-co-glycolide) acid (PLGA) composite material is a widely used orthopedic implant due to its excellent biocompatibility and plasticity. Recent advancements in cation doping have expanded its potential biological applications. However, conventional HA/PLGA composites are not visible under X-rays post-implantation and have limited osteogenic induction capabilities. Copper (Cu) is known to regulate osteoblast proliferation and differentiation, while gadolinium (Gd) can significantly enhance the magnetic resonance imaging (MRI) capabilities of materials. Methods: This study aimed to investigate whether incorporating Cu and Gd into an HA/PLGA composite could enhance the osteogenic properties, in vivo bone defect repair, and MRI characteristics. We prepared a Cu/Gd@HA/PLGA composite and assessed its performance. Results: Material characterization confirmed that Cu/Gd@HA retained the morphology and crystal structure of HA. The Cu/Gd@HA/PLGA composite exhibited excellent nuclear magnetic imaging capabilities, porosity, and hydrophilicity, which are conducive to cell adhesion and implant detection. In vitro experiments demonstrated that the Cu/Gd@HA/PLGA composite enhanced the proliferation, differentiation, and adhesion of MC3T3-E1 cells, and upregulated COL-1 and BMP-2 expression at both gene and protein levels. In vivo studies showed that the Cu/Gd@HA/PLGA composite maintained strong T1-weighted MRI signals and significantly improved the bone defect healing rate in rats. Conclusion: These findings indicate that the Cu/Gd@HA/PLGA composites significantly enhance T1-weighted MRI capabilities, promote osteoblast proliferation and differentiation in vitro, and accelerate bone defect healing in vivo.

Clinical Utility of Radiographic Signs in Neuroradiology

Several characteristic radiographic signs associated with various diseases are useful in neuroradiological practice; however, their clinical usefulness varies widely. This article presents some common signs and the associated pathological features, particularly those observed on computed tomography and magnetic resonance imaging or pathognomonic signs that are useful for accurate diagnosis, even in patients with rare diseases.

Brain network analysis in Parkinson's disease patients based on graph theory

Development of Parkinson's disease causes functional impairment in the brain network of Parkinson's patients. The aim of this study is to analyze brain networks of people with Parkinson's disease based on higher resolution parcellations and newer graphical features. The topological features of brain networks were investigated in Parkinson's patients (19 individuals) compared to healthy individuals (17 individuals) using graph theory. In addition, four different methods were used in graph formation to detect linear and nonlinear relationships between functional magnetic resonance imaging (fMRI) signals. The functional connectivity between the left precuneus and the left amygdala, as well as between the vermis 1-2 and the left temporal lobe was evaluated for the healthy and the patient groups. The difference between the healthy and patient groups was evaluated by parametric t-test and nonparametric U-test. Based on the results, Parkinson's patients exhibited a noteworthy reduction in centrality criterion compared to healthy subjects. Moreover, alterations in the regional features of the brain network were evident. Applying centrality criteria and correlation coefficients revealed significant distinctions between healthy subjects and Parkinson's patients across various brain areas. The results obtained for topological features indicate changes in the functional brain network of Parkinson's patients. Finally, similar areas obtained by all three methods of graph formation in the evaluation of connectivity between paired regions in the brain network of Parkinson's patients increased the reliability of the results.

Nonparametric distributions of tensor-valued Lorentzian diffusion spectra for model-free data inversion in multidimensional diffusion MRI.

Magnetic resonance imaging (MRI) is the method of choice for noninvasive studies of micrometer-scale structures in biological tissues via their effects on the time- and frequency-dependent (restricted) and anisotropic self-diffusion of water. While new designs of time-dependent magnetic field gradient waveforms have enabled disambiguation between different aspects of translational motion that are convolved in traditional MRI methods relying on single pairs of field gradient pulses, data analysis for complex heterogeneous materials remains a challenge. Here, we propose and demonstrate nonparametric distributions of tensor-valued Lorentzian diffusion spectra, or "D(ω) distributions," as a general representation with sufficient flexibility to describe the MRI signal response from a wide range of model systems and biological tissues investigated with modulated gradient waveforms separating and correlating the effects of restricted and anisotropic diffusion.