MRI Applications Research Articles

Thermal studies on cryocooler thermal masses from 4 K to 300 K for MRI applications

AbstractGifford–McMahon (GM) cryocoolers are pivotal for maintaining the temperature of MRI magnets, necessitating regular servicing for optimal performance and longevity. This study explores the geometric dimensions and shapes of superconducting magnets utilized in MRI for system cooling. The investigation demonstrates that warm-up time is contingent on heat capacity rather than geometric shapes. As a result, the design of magnets can be customized to specific shapes and sizes in accordance with favorable conditions, given that warm-up time is solely dependent on heat capacity. The primary focus is to deliberately prolong the warm-up time of the magnet relative to the GM cryocooler, consequently minimizing service intervals. Laboratory evaluations explore the use of thermal masses equivalent to MRI magnets, employing typical materials such as copper and aluminum. These masses are cooled to 4 K and then subjected to different heating powers to evaluate warm-up characteristics. Various configurations and shapes of thermal masses are numerically studied for warm-up analysis. Comparative assessments between experimental results and simulations reveal that, for cylindrical thermal masses, 80 W heating power facilitates a 76% reduction in warm-up time compared to 20 W heating across all cases. In the exploration of different geometric thermal masses, aluminum demonstrates a remarkable 35% decrease in warm-up time compared to copper. A noteworthy finding emerges, indicating that warm-up time is contingent on heat capacity rather than geometric shapes. These insights hold substantial relevance, particularly in systems with large thermal capacities, such as superconducting magnets. The study contributes valuable knowledge to the optimization of GM cryocoolers for enhanced MRI magnet performance and extended operational life.

Using High-Pass Filter to Enhance Scan Specific Learning for MRI Reconstruction without Any Extra Training Data.

In accelerated MRI, the robust artificial-neural-network for k-space interpolation (RAKI) method is an attractive learning-based reconstruction that does not require additional training data. This study was focused on obtaining high quality MR images from regular under-sampled multi-coil k-space data using a high-pass filtered RAKI (HP-RAKI) reconstruction without any extra training data. MRI scan from human subjects was under-sampled with a regular pattern using skipped phase encoding and a fully sampled k-space center. A high-pass (HP) filter was applied in k-space to reduce image support to facilitate linear prediction. The HP filtered k-space center was used to train the RAKI network without any extra training data. The unacquired k-space data can be predicted from a trained RAKI network with optimized parameters. Final reconstruction was obtained after performing an inverse HP filtering for the predicted k-space data. This HP-RAKI method can be extended to corresponding residual structure (HP-rRAKI). HP-RAKI was compared with GRAPPA, HP-GRAPPA, RAKI and MW-RAKI algorithms, and HP-rRAKI was compared with corresponding residual extensions, including rRAKI and MW-rRAKI, all qualitatively and quantitatively using visual inspection and such metrics as SSIM and PSNR. HP-RAKI and HP-rRAKI were found to be effective in reconstructing MR images even at high acceleration factors. HP-RAKI and HP-rRAKI compared favorably with other algorithms. Using high-pass filtered central k-space data for training, HP-RAKI offers higher reconstruction quality for regularly under-sampled multi-coil k-space data without any extra training data. It has shown promising capabilities for fast MRI applications, especially those lacking fully sampled training data.

The Clinical Application of Dynamic Contrast-Enhanced MRI in Canine Masses of Mesenchymal and Epithelial Origin: A Preliminary Case Series

Evaluating masses of mesenchymal and epithelial origin accurately using computed tomography (CT) has several limitations in dogs. This study aimed to present dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters to aid in improving the diagnostic accuracy for masses of mesenchymal and epithelial origin in veterinary medicine. Four dogs diagnosed with benign and malignant soft tissue sarcoma (STS), cholesteatoma, or squamous cell carcinoma underwent CT, conventional MRI, and DCE-MRI. Ktrans is a quantitative DCE-MRI parameter representing vascular permeability and tissue perfusion and is related to the potential for malignancy. Hemangiopericytomas (Grade II, STS) showed a higher Ktrans than normal muscle tissue and myxosarcoma (Grade I, STS). Squamous cell carcinoma (a malignant epithelial tumor) also showed a higher Ktrans than normal muscle tissue and cholesteatoma (a mass originating from keratinized squamous epithelium). These results suggest that higher Ktrans values may indicate a greater likelihood that a lesion is more malignant. In conclusion, Ktrans might be useful as a biomarker for evaluating the malignancy of a mass and as an indicator of lesion characteristics in dogs.

Large improvement in RF magnetic fields and imaging SNR with whole-head high-permittivity slurry helmet for human-brain MRI applications at 7 T.

To optimize the design and demonstrate the integration of a helmet-shaped container filled with a high-permittivity material (HPM) slurry with RF head coil arrays to improveRF coil sensitivity and SNR for human-brain proton MRI. RF reception magneticfields ( ) of a 32-channel receive-only coil array with various geometries and permittivity values of HPM slurry helmet are calculated with electromagnetic simulation at 7 T. A 16-channel transmit-only coil array, a 32-channel receive-only coil array, and a 2-piece HPM slurry helmet were constructed and assembled. RF transmission magnetic field ( ), , and MRI SNR maps from the entire human brain were measured and compared. Simulations showed that averaged improvement with the HPM slurry helmet increased from 57% to 87% as the relative permittivity (εr) of HPM slurry increased from 110 to 210. In vivo experiments showed that the average improvement over the human brain was 14.5% with the two-piece HPM slurry (εr ≈ 170) helmet, and the average and SNR were improved 63% and 34%, respectively, because the MRI noise level was increased by the lossy HPM. The RF coil sensitivity and MRI SNR were largely improved with the two-piece HPM slurry helmet demonstrated by both electromagnetic simulations and in vivo human head experiments at 7 T. The findings demonstrate that incorporating an easily producible HPM slurry helmet into the RF coil array significantly enhances human-brain MRI SNRhomogeneity and quality at ultrahigh field. Greater SNR improvement is anticipated using the less lossy HPM and optimal design.

An Effective Liposome-Based Nanodelivery System for Naphthalene Derivative Polyamines with Antitumor Activity

This study focuses on the development of a novel liposome-based nanodelivery system designed to encapsulate polyamine-1, a compound with potential anti-tumor properties. The main objective of this work was to enhance the therapeutic and imaging potential of polyamine-1 by incorporating it into liposome-based nanoparticles, which were functionalized with a gadolinium complex for imaging purposes and a fluorescent phospholipid for tracking applications. These nanoparticles were characterized by measuring their size, shape, polydispersity index, zeta potential and encapsulation efficiency. In vitro experiments were conducted to evaluate the antitumor activity, specifically determining the cytotoxicity of both free and encapsulated polyamine-1 in cancerous and non-cancerous cell lines. Additionally, the study shows the enhanced signal intensity of gadolinium-loaded liposomes by T1-weighted MRI, highlighting their imaging potential. The experimental results suggest that this liposome-based nanodelivery system not only has therapeutic potential in targeted cancer therapy but also could be advantageous for diagnostic imaging, particularly in MRI applications.

MRI recovery with self-calibrated denoisers without fully-sampled data.

Acquiring fully sampled training data is challenging for many MRI applications. We present a self-supervised image reconstruction method, termed ReSiDe, capable of recovering images solely from undersampled data. ReSiDe is inspired by plug-and-play (PnP) methods, but unlike traditional PnP approaches that utilize pre-trained denoisers, ReSiDe iteratively trains the denoiser on the image or images that are being reconstructed. We introduce two variations of our method: ReSiDe-S and ReSiDe-M. ReSiDe-S is scan-specific and works with a single set of undersampled measurements, while ReSiDe-M operates on multiple sets of undersampled measurements and provides faster inference. Studies I, II, and III compare ReSiDe-S and ReSiDe-M against other self-supervised or unsupervised methods using data from T1- and T2-weighted brain MRI, MRXCAT digital perfusion phantom, and first-pass cardiac perfusion, respectively. ReSiDe-S and ReSiDe-M outperform other methods in terms of peak signal-to-noise ratio and structural similarity index measure for Studies I and II, and in terms of expert scoring for Study III. We present a self-supervised image reconstruction method and validate it in both static and dynamic MRI applications. These developments can benefit MRI applications where the availability of fully sampled training data is limited.

Retrospective Evaluation of GEC-ESTRO Constraints for Definitive Radiochemotherapy with Brachytherapy and Correlation with Oncologic Outcome in Cervical Cancer: A Monocenter Study.

This study aims to evaluate patients with locally advanced cervical cancer who underwent definitive radiochemotherapy, including brachytherapy, at the University Hospital of Muenster (UKM), focusing on target volume coverage, oncologic outcome parameters, and organs at risk (OAR) toxicities. Results are compared with the Gyn GEC-ESTRO (GGE) recommendations. Of a cohort of 48 patients, treated between 2013 and 2023, the physical radiation treatment planning with application of CT and MRI and oncologic follow-up data was analyzed. Target volume structures, comprising the high-risk clinical target volume (HR-CTV), intermediate-risk clinical target volume (IR-CTV), Point A, and corresponding EQD2(α/β=10) doses were determined. Endpoints included local tumor control, overall survival (OS), recurrence-free survival (RFS), and progression-free survival (PFS). Total OAR (D2cc) EQD2(α/β=3) doses were correlated with adverse events defined by CTCAE v5.0 and LENT-SOMA criteria. Median follow-up was 58.0 months (95% CI [27.6, 88.4]). FIGO stage I was present in 7 (15%) patients, II in 13 (27%), and III in 28 (58%) patients. A total of 38 (79%) patients showed a complete remission 3 months after treatment. The 5-year event-free rate was 67.4% (95% CI [49.3, 80.3]) for OS, 77.0% (95% CI [56.7, 88.6]) for RFS and 68.1% (95% CI [49.7, 80.9]) for PFS. Incomplete radiation treatment and advanced tumor stages led to worse outcomes. Meeting Point A GGE recommendations increased chances for complete remission and could decrease chances of an event occurring for OS, PFS, and RFS. Compliance with GGE recommendations lowered the chances of OAR toxicity occurring. MRI-based target volume definition for brachytherapy in cervical cancer may improve patients' OS, PFS, and RFS. Time-to-event endpoints are consistent with comparable studies, and adherence to current ESGO/ESTRO/ESP guidelines is endorsed.

Physics-guided self-supervised learning: Demonstration for generalized RF pulse design.

To introduce a new method for generalized RF pulse design using physics-guided self-supervised learning (GPS), which uses the Bloch equations as the guiding physics model. The GPS framework consists of a neural network module and a physics module, where the physics module is a Bloch simulator for MRI applications. For RF pulse design, the neural network module maps an input target profile to an RF pulse, which is subsequently loaded into the physics module. Through the supervision of the physics module, the neural network module designs an RF pulse corresponding to the target profile. GPS was applied to design 1D selective, -insensitive, saturation, and multidimensional RF pulses, each conventionally requiring dedicated design algorithms. We further demonstrate our method's flexibility and versatility by compensating for experimental and scanner imperfections through online adaptation. Both simulations and experiments show that GPS can design a variety of RF pulses with corresponding profiles that agree well with the target input. Despite these verifications, GPS-designed pulses have unique differences compared to conventional designs, such as achieving -insensitivity using different mechanisms and using non-sampled regions of the conventional design to lower its peak power. Experiments, both ex vivo and in vivo, further verify that it can also be used for online adaptation to correct system imperfections, such as / inhomogeneity. This work demonstrates the generalizability, versatility, and flexibility of the GPS method for designing RF pulses and showcases its utility in several applications.

RF coil that minimizes electronic components while enhancing performance for rodent MRI at 7 Tesla.

This study introduces a novel volume coil design that features two slotted end-plates connected by six rungs, resembling the traditional birdcage coil. The end rings are equipped with six evenly distributed circular slots, inspired by Mansfield's cavity resonator theory, which suggests that circular slots can generate a baseline resonant frequency. One notable advantage of this proposed coil design is its reduced reliance on electronic components compared to other volume coils, making it more efficient. Additionally, the dimensions of the coil can be theoretically computed in advance, enhancing its practicality. To evaluate the performance and safety of the coil, electromagnetic field and specific absorption rate simulations were simulated using a cylindrical saline phantom and the finite element method. Furthermore, a transceiver coil prototype optimized for 7 Tesla and driven in quadrature was constructed, enabling whole-body imaging of rats. The resonant frequency of the coil prototype obtained through experimental measurements closely matched the theoretical frequency derived from Mansfield's theory. To validate the coil design, phantom images were acquired to demonstrate its viability and assess its performance. These images also served to validate the magnetic field simulations. The experimental results aligned well with the simulation findings, confirming the reliability of the proposed coil design. Importantly, the prototype coil showcased significant improvements over a similarly-sized birdcage coil, indicating its potential for enhanced performance. The noise figure was lower in the prototype versus the birdcage coil (NFbirdcage-NFslotcage= 0.7). Phantom image data were also used to compute the image SNR, giving SNRslotcage/SNRbirdcage= 34.36/24.34. By proving the feasibility of the coil design through successful rat whole-body imaging, the study provides evidence supporting its potential as a viable option for high-field MRI applications on rodents.

Free-breathing time-resolved 4D MRI with improved T1-weighting contrast.

This work proposes MP-Grasp4D (magnetization-prepared golden-angle radial sparse parallel 4D) MRI, a free-breathing, inversion recovery (IR)-prepared, time-resolved 4D MRI technique with improved T1-weighted contrast. MP-Grasp4D MRI acquisition incorporates IR preparation into a radial gradient echo sequence. MP-Grasp4D employs a golden-angle navi-stack-of-stars sampling scheme, where imaging data of rotating radial stacks and navigator stacks (acquired at a consistent rotation angle) are alternately acquired. The navigator stacks are used to estimate a temporal basis for low-rank subspace-constrained reconstruction. This allows for the simultaneous capture of both IR-induced contrast changes and respiratory motion. One temporal frame of the imaging volume in MP-Grasp4D MRI is reconstructed from a single stack and an adjacent navigator stack on average, resulting in a nominal temporal resolution of 0.16 seconds per volume. Images corresponding to the optimal inversion time (TI) can be retrospectively selected for providing the best image contrast. Reader studies were conducted to assess the performance of MP-Grasp4D MRI in liver imaging across 30 subjects in comparison with standard Grasp4D MRI without IR preparation. MP-Grasp4D MRI received significantly higher scores (P < 0.05) than Grasp4D in all assessment categories. There was a moderate to almost perfect agreement (kappa coefficient from 0.42 to 0.9) between the two readers for image quality assessment. When the scan time is reduced, MP-Grasp4D MRI preserves image contrast and quality, demonstrating additional acceleration capability. MP-Grasp4D MRI improves T1-weighted contrast for free-breathing time-resolved 4D MRI and eliminates the need for explicit motion compensation. This method is expected to be valuable in different MRI applications such as MR-guided radiotherapy.

A Non-Invasive Technique to Unveil Renal Implications in Anderson-Fabry Disease.

Anderson-Fabry disease (AFD) is a rare genetic disorder characterized by a deficiency of α-galactosidase A activity and the accumulation of glycosphingolipids in tissues, which leads to multiorgan damage. Cardiovascular magnetic resonance (CMR) and the T1 mapping technique are essential tools for the assessment of AFD cardiac involvement. Moreover, the T1 mapping technique has proved to be a successful non-invasive method for the early detection of patients most at risk for kidney disease. We evaluated the application of MRI in patients with AFD to assess renal involvement. We conducted a retrospective analysis of 19 patients (Group A) with histologically proven AFD who underwent routine CMR examinations for the evaluation of cardiac involvement, selecting specific sequences that also showed the left kidney, compared to a control population (Group B, 19 patients) without kidney disease. A Spearman's rank-order correlation was run to assess the relationship between the T1 mapping values of the heart and kidney in Group A and between the kidneys of Groups A and B. There was a positive correlation between the heart and kidney T1 values in Group A (rho = 0.32). More interestingly, we observed a negative correlation between the kidney values of both groups (Group A mean 1284 ± 137 ms, Group B mean 1073 ± 57 ms, rho = -0.38), which is probably related to the presence of microvascular damage and infiltrates in the kidneys of AFD patients. To our knowledge, these results are the first to highlight the key value of T1 mapping in assessing pathological changes and aiding in the non-invasive diagnosis of renal involvement in AFD.

Value of Optic Nerve MRI in Multiple Sclerosis Clinical Management: A MAGNIMS Position Paper and Future Perspectives.

The optic nerve is frequently involved in multiple sclerosis (MS). However, MRI of the optic nerve is considered optional in the differential diagnosis of optic neuropathy symptoms either at presentation or in established MS. In addition, unlike spinal cord imaging in comparable scenarios, no role is currently recommended for optic nerve MRI in patients presenting with optic neuritis for its confirmation, to plan therapeutic strategy, within the MS diagnostic framework, nor for the detection of subclinical activity in established MS. In this article, evidence related to these 3 aspects will be summarized and gaps in knowledge will be highlighted, including (1) the acquisition challenges and novel sequences that assess pathologic changes within the anterior visual pathways; (2) the clinical implications of quantitative magnetic resonance studies of the optic nerve, focusing on atrophy measures, magnetization transfer, and diffusion tensor imaging; and (3) the relevant clinical studies performed to date. Finally, an algorithm for the application of optic nerve MRI will be proposed to guide future studies aimed at addressing our knowledge gaps.

Moiré patterns of space-filling curves

It is shown on the examples of Moore and Gosper curves that two spatially shifted or twisted, preasymptotic space-filling curves can produce large-scale superstructures akin to moiré patterns. To study physical phenomena emerging from these patterns, a geometrical coupling coefficient based on the Neumann integral is introduced. It is found that moiré patterns appear most defined at the peaks of those coefficients. A physical interpretation of these coefficients as a measure for inductive coupling between radiofrequency resonators leads to a design principle for strongly overlapping resonators with vanishing mutual inductance, which might be interesting for applications in MRI. These findings are demonstrated in graphical, numerical, and physical experiments. Published by the American Physical Society 2024

Synthesis of higher-B0 CEST Z-spectra from lower-B0 data via deep learning and singular value decomposition.

Chemical exchange saturation transfer (CEST) MRI at 3 T suffers from low specificity due to overlapping CEST effects from multiple metabolites, while higher field strengths (B0) allow for better separation of Z-spectral "peaks," aiding signal interpretation and quantification. However, data acquisition at higher B0 is restricted by equipment access, field inhomogeneity and safety issues. Herein, we aim to synthesize higher-B0 Z-spectra from readily available data acquired with 3 T clinical scanners using a deep learning framework. Trained with simulation data using models based on Bloch-McConnell equations, this framework comprised two deep neural networks (DNNs) and a singular value decomposition (SVD) module. The first DNN identified B0 shifts in Z-spectra and aligned them to correct frequencies. After B0 correction, the lower-B0 Z-spectra were streamlined to the second DNN, casting into the key feature representations of higher-B0 Z-spectra, obtained through SVD truncation. Finally, the complete higher-B0 Z-spectra were recovered from inverse SVD, given the low-rank property of Z-spectra. This study constructed and validated two models, a phosphocreatine (PCr) model and a pseudo-in-vivo one. Each experimental dataset, including PCr phantoms, egg white phantoms, and in vivo rat brains, was sequentially acquired on a 3 T human and a 9.4 T animal scanner. Results demonstrated that the synthetic 9.4 T Z-spectra were almost identical to the experimental ground truth, showing low RMSE (0.11% ± 0.0013% for seven PCr tubes, 1.8% ± 0.2% for three egg white tubes, and 0.79% ± 0.54% for three rat slices) and high R2 (>0.99). The synthesized amide and NOE contrast maps, calculated using the Lorentzian difference, were also well matched with the experiments. Additionally, the synthesis model exhibited robustness to B0 inhomogeneities, noise, and other acquisition imperfections. In conclusion, the proposed framework enables synthesis of higher-B0 Z-spectra from lower-B0 ones, which may facilitate CEST MRI quantification and applications.

Improvement of MRS at ultra-high field using a wireless RF array.

We aim to assess a straightforward technique to enhance spectral quality in the brain, particularly in the cerebellum, during 7 T MRI scans. This is achieved through a wireless RF array insert designed to mitigate signal dropouts caused by the limited transmit field efficiency in the inferior part of the brain. We recently developed a wireless RF array to improve MRI and 1H-MRS at 7 T by augmenting signal via inductive coupling between the wireless RF array and the MRI coil. In vivo experiments on a Siemens 7 T whole-body human scanner with a Nova 1Tx/32Rx head coil quantified the impact of the dorsal cervical array in improving signal in the posterior fossa, including the cerebellum, where the transmit efficiency of the coil is inherently low. The 1H-MRS experimental protocol consisted of paired acquisition of data sets, both with and without the RF array, using the semi-LASER and SASSI sequences. The overall results indicate that the localized 1H-MRS is improved significantly in the presence of the array. Comparison of in vivo 1H-MRS plots in the presence versus absence of the array demonstrated an average SNR enhancement of a factor of 2.2. LCModel analysis reported reduced Cramér-Rao lower bounds, indicating more confident fits. This wireless RF array can significantly increase detection sensitivity. It may reduce the RF transmission power and data acquisition time for 1H-MRS and MRI applications, specifically at 7 T, where 1H-MRS requires a high-power RF pulse. The array could provide a cost-effective and efficient solution to improve detection sensitivity for human 1H-MRS and MRI in the regions with lower transmit efficiency.

Neurofunctional and microstructural features of the brain in patients with nutritional obesity according to special magnetic resonance imaging techniques (literature review)

Background. Obesity is a chronic disease characterized by excessive accumulation of adipose tissue in the body, manifested by an increase in body weight by 20 percent or more of the average values. Obesity is becoming an increasingly significant public health problem. Assessment of the functional pathology of the brain provides more information about the pathogenetic changes leading to metabolic disorders. Modern methods of neuroimaging make it possible to obtain information about the initial functional changes in the brain according to the data of intracerebral connectivity - functional connectivity between its individual structures.Objective. The study of modern literature data on functional disorders of brain connectivity in patients with obesity, including those with eating disorders.Materials and methods. A systematic review of studies published in foreign and domestic literature has been carried out. Articles were searched using the PubMed database and Elibrary.Results. The problem of functional and microstructural studies of the brain in obesity is covered in sufficient detail in Western English-language literature. Nevertheless, it must be stated that at the moment there are practically no articles on the subject under study in domestic scientific publications. However, it should be noted that in the foreign literature there are rare data on neuroimaging of the brain in the aspect of neural network connectivity, studies in obesity with concomitant somatic pathology, for example, in type II diabetes, and other disorders of the endocrine system. There are relatively few data where correlations would be made with the age and gender of patients, concomitant mental disorders, which emphasizes the relevance of the issue.At the subsequent stages of the joint development of endocrinology, psychiatry and radiation diagnostics, the use of modern MRI techniques will help with the choice of target structures for stereotaxic correction of the described pathology. The clinical application of functional MRI will help to reveal the pathogenesis of various types of obesity at the neurofunctional levels with further prediction and analysis of the development of the disease, while the inconsistency and inconsistency of the currently obtained results of studies of the pathogenesis of alimentary obesity in terms of the pathology of functional connectivity based on fMRI, the absence clinical application of special MRI techniques substantiate the need to continue scientific research in this direction

Fluorinated PAMAM-Arginine Carrier Prodrugs for pH-Sensitive Sustained Ibuprofen Delivery

ObjectiveThe development of an efficient, multifunctional drug delivery system overcoming different obstacles generally associated with drug formulations, including the poor accumulation of the active principle in the target site and its sustained release for prolonged time.MethodsOur study proposes the development of a fluorinated poly(amidoamine) (PAMAM) carrier prodrug combining drug release boosted in alkaline environments with a possible implementation in 19F MRI applications. In particular, we functionalized the terminal primary amines of PAMAM G2 and G4 through an ad hoc designed fluorinated ibuprofen-arginine Michael acceptor to obtain multifunctional ibuprofen-PAMAM-Arg conjugates.ResultsThese carriers demonstrated pH-dependent and sustained ibuprofen release for more than 5 days. This advantage was observed in both weak alkaline and physiological buffer solutions, allowing to overcome the limits associated to the burst release from similar fluorinated Arg-PAMAM dendrimers with ibuprofen physically encapsulated.ConclusionThese findings, coupled to the high biocompatibility of the system, suggest a potential synergistic biomedical application of our conjugates, serving as vehicles for drug delivery and as 19F magnetic resonance imaging contrast agents.

Application of high-resolution MRI in evaluating statin efficacy on symptomatic intracranial atherosclerosis.

To investigate the efficacy of statins on symptomatic intracranial atherosclerotic plaques using high-resolution 3.0 T MR vessel wall imaging (HR-MRI). Patients with symptomatic intracranial atherosclerotic plaques (cerebral ischemic events within the last three months) confirmed by HR-MRI from July 2017 to August 2022 were retrospectively included in this study. The enrolled patients started statin therapy at baseline. All the patients underwent the follow-up HR-MRI examination after statin therapy for at least 3 months. A paired sample t-test and Wilcoxon rank sum test were used to evaluate the changes in plaque characteristics after statin therapy. Multivariate linear regression was further used to investigate the clinical factors associated with statin efficacy. A total of 48 patients (37 males; overall mean age = 60.2 ± 11.7 years) were included in this study. The follow-up time was 7.0 (5.6-12.0) months. In patients treated with statins for > 6 months (n = 31), plaque length, wall thickness, plaque burden, luminal stenosis and plaque enhancement were significantly reduced. Similar results were found in patients with good lipid control (n = 21). Younger age, lower BMI and hypertension were associated with decreased plaque burden. Lower BMI, hypertension and longer duration of statin therapy were associated with decreased plaque enhancement. Younger age and hypertension were associated with decreased luminal stenosis (all p < 0.05). HR-MRI can effectively evaluate plaques changes after statin therapy. Statins can reduce plaque burden and stabilize plaques. The effect of statin may have a relationship with age, BMI, hypertension, and duration of statin therapy. High-resolution MRI can be applied to evaluate the efficacy of statins on symptomatic intracranial atherosclerotic plaques. Long-term statin use and well-controlled blood lipid levels can help reduce plaque burden and stabilize plaques. High-resolution MRI provides great help evaluating the changes of plaque characteristics after statin therapy. Efficacy of statins is associated with duration of use, controlled lipid levels, and clinical factors. High-resolution MRI can serve as an effective method for following-up symptomatic intracranial atherosclerosis.

Cartilage compositional MRI-a narrative review of technical development and clinical applications over the past three decades.

Articular cartilage damage and degeneration are among hallmark manifestations of joint injuries and arthritis, classically osteoarthritis. Cartilage compositional MRI (Cart-C MRI), a quantitative technique, which aims to detect early-stage cartilage matrix changes that precede macroscopic alterations, began development in the 1990s. However, despite the significant advancements over the past three decades, Cart-C MRI remains predominantly a research tool, hindered by various technical and clinical hurdles. This paper will review the technical evolution of Cart-C MRI, delve into its clinical applications, and conclude by identifying the existing gaps and challenges that need to be addressed to enable even broader clinical application of Cart-C MRI.

Nanostructured gadolinium(III) micelles: Synthesis, characterization, cytotoxic activities, and MRI applications in vivo

Gadolinium-based contrast agents (GBCAs) are used in around 40 % of MRI procedures. Despite initial perceptions of minimal risk, their long-term use has emphasized the need to reduce toxicity and develop more efficient GBCAs with extended blood retention. Advancements in nanomaterials have led to improved GBCAs, enhancing MRI diagnostics. This study synthesizes and characterizes nanostructured gadolinium(III) micelles as superior MRI contrast agents. The complexes, [Gd(L)2], where L is a ligand of the N-alkyl-N-methylglucamine surfactant series (L8, L10 or L12, L10), form nanostructured micelles in aqueous solution. Gd(L8)2 and Gd(L10)2 relaxivities remained stable across concentrations. Compared to Gd-DTPA, Gd(III) micelles showed enhanced T1-weighted MRI contrast. Gd(L12)2 micelles exhibited cytotoxicity against B16F10 melanoma cells (IC50 42.5 ± 2.2 μM) and L292L929 fibroblasts (IC50 52.0 ± 2.5 μM), with a selectivity index of 1.2. In vivo application in mice brain T2-weighted images suggests nanostructured Gd(III) micelles are promising MRI contrast agents for targeting healthy organs or tumors.