Magnetic Resonance Imaging Methods Research Articles

#444 Novel MRI filtration fraction method to assess glomerular hemodynamics in diabetic kidney disease

Abstract Background and Aims Filtration fraction (FF) is the ratio of the glomerular filtration rate (GFR) to renal plasma flow (RPF) and is therefore an important measure of glomerular hemodynamics. The gold standard method to assess effective RPF is renal clearance of para-aminohippuric acid (PAH) but technical and labour-intensive difficulties limit its application [1]. Quicker and simpler assays of FF are needed, particularly to assess the renal hemodynamic dysfunction (hyper- or hypofiltration) and effects/mode of action of therapeutic interventions in chronic kidney disease (CKD). We assessed a novel magnetic resonance imaging (MRI) technique to measure FF in patients with diabetic kidney disease (DKD) and healthy controls (HC) [2]. Method This cross-sectional sub-study included 32 DKD subjects with measured GFR (mGFR) ≤ 60 ml/ min/1.73 m2 and stratified into the following GFR stages as per the Kidney Disease Improving Global Outcomes (KDIGO) classification: stage G3a (mGFR 45-59 ml/ min/1.73 m2, n = 3), G3b (mGFR 30-44 ml/ min/1.73 m2, n = 8), G4 (mGFR 15-29 ml/ min/1.73 m2, n = 15), G5 (<15 ml/ min/1.73 m2, n = 6), and 18 age-, gender-matched HC with mGFR ≥ 60 ml/min/1.73 m2. All subjects were 18-79 years old. mGFR was assessed using iohexol clearance. Renal blood flow (RBF) (ml/min) was measured by a 5-minute add-on phase contrast MRI of the renal artery of each kidney and then summed together. RBF was corrected for Body Surface Area. RPF and FF were calculated as below: ${\rm{RPF }} = {\rm{ RBF}} \times \ ( {1\ -{\rm{ Hematocrit}}} )$ ${\rm{FF}} = {\rm{mGFR}}/{\rm{RPF}}$ Results RBF and mGFR were highly correlated (R2 = 0.70, Fig. 1). FF was 17.1% for HC and decreased with increasing degrees of renal impairment (Fig. 2). While the difference between HC and G3a DKD group was not significant, there was highly significant difference between HC and all other DKD groups (p < 0.001). The standard deviation in the G3a group was relatively large with only 3 subjects in this group. Conclusion The phase contrast MRI scan can provide a quick and simple measurement of glomerular hemodynamics and therewith further insights into the pathophysiology of DKD and its progression. Given the limitations of the existing method for assessing renal plasma flow, this MRI method can facilitate the inclusion of filtration fraction in DKD clinical trials. Further, the described method could be used to identify hyperfiltration, a compensatory mechanism that can influence results in clinical trials of DKD.

Changes in the visual areas of the cerebral cortex in children with left-sided anisometropic amblyopia according to structural MRI and resting-state fMRI

Thanks to the development of structural and functional magnetic resonance imaging (MRI) methods, in recent decades there has been a lot of research aimed at elucidating brain abnormalities caused by amblyopia. In the cases of this prevalent visual disorder, the anomalies causing decreased visual acuity and other visual disabilities cannot be determined by standard ophthalmologic examination. Since there are several types of this disorder that are fundamentally different in etiology, it is natural to suggest the presence of different types of corresponding brain abnormalities. In this regard, before obtaining a general picture of the pathogenesis of amblyopia, studies conducted on groups of specially selected similar patients are very important. This paper presents the results of a study of school-age children with left-sided anisometropic amblyopia. In the patients investigated, MRI data revealed interhemispheric differences in the thickness of the lateral occipital cortex, and resting-state fMRI revealed interhemispheric differences in the local coherence of the hemodynamic signal within 17 Brodmann area and in the functional connectivity between 17 and 18+19 Brodmann areas. The data obtained contribute to the creation of a general MRI database on the pathophysiology of amblyopia, help clarify some controversial issues and indicate the advisability of using resting-state fMRI in ophthalmology.

The Use of Dixon Magnetic Resonance Imaging Methods for the Quantification of Rotator Cuff Fatty Infiltration: A Systematic Review

Fatty infiltration of the rotator cuff muscles is very common following rotator cuff tears and is one of the most important factors in determining treatment. Current clinical practice relies on subjective evaluation of fatty infiltration through categorical scoring based on the Goutallier classification system. The Dixon magnetic resonance imaging (MRI) sequence provides flexibility in selecting echo times for water–fat separation. The Dixon method, therefore, has the potential to provide robust and high-quality fat quantification that allows for more accurate calculation of fat fraction (%Fat) of the rotator cuff muscles than the Goutallier classification system. However, significant variance exists in sequencing and post-processing methodology within the recent application of Dixon sequences to quantify rotator cuff fatty infiltration. In this paper, we conducted a systematic review to synthesize the relevant literature utilizing Dixon sequencing for the quantification of rotator cuff fatty infiltration. The literature search was extracted from 1094 articles, with 12 studies included in the final review. Regardless of the varying sequencing pattern and post-processing techniques among studies, the findings suggest the Dixon method is reliable for quantitatively calculating the fat fraction of the rotator cuff muscles, even at very low levels of fatty infiltration. In addition, a quantitative difference in fat fraction was observed between participants with different degrees of tear vs. those without any shoulder pathologies. Multi-point Dixon imaging has the potential to be utilized clinically to objectively quantify fatty infiltration and may lead to improved clinical decision making for patients with rotator cuff tears.

Ultrahigh field diffusion magnetic resonance imaging uncovers intriguing microstructural changes in the adult zebrafish brain caused by Toll-like receptor 2 genomic deletion.

Toll-like receptor 2 (TLR2) belongs to the TLR protein family that plays an important role in the immune and inflammation response system. While TLR2 is predominantly expressed in immune cells, its expression has also been detected in the brain, specifically in microglia and astrocytes. Recent studies indicate that genomic deletion of TLR2 can result in impaired neurobehavioural function. It is currently not clear if the genomic deletion of TLR2 leads to any alterations in the microstructural features of the brain. In the current study, we noninvasively assess microstructural changes in the brain of TLR2-deficient (tlr2-/-) zebrafish using state-of-the art magnetic resonance imaging (MRI) methods at ultrahigh magnetic field strength (17.6 T). A significant increase in cortical thickness and an overall trend towards increased brain volumes were observed in young tlr2-/- zebrafish. An elevated T2 relaxation time and significantly reduced apparent diffusion coefficient (ADC) unveil brain-wide microstructural alterations, potentially indicative of cytotoxic oedema and astrogliosis in the tlr2-/- zebrafish. Multicomponent analysis of the ADC diffusivity signal by the phasor approach shows an increase in the slow ADC component associated with restricted diffusion. Diffusion tensor imaging and diffusion kurtosis imaging analysis revealed diminished diffusivity and enhanced kurtosis in various white matter tracks in tlr2-/- compared with control zebrafish, identifying the microstructural underpinnings associated with compromised white matter integrity and axonal degeneration. Taken together, our findings demonstrate that the genomic deletion of TLR2 results in severe alterations to the microstructural features of the zebrafish brain. This study also highlights the potential of ultrahigh field diffusion MRI techniques in discerning exceptionally fine microstructural details within the small zebrafish brain, offering potential for investigating microstructural changes in zebrafish models of various brain diseases.

Improved MRI methods to quantify retinal and choroidal blood flow applied to a model of glaucoma

PurposeBlood flow (BF) of the retinal and choroidal vasculatures can be quantitatively imaged using MRI. This study sought to improve methods of data acquisition and analysis for MRI of layer-specific retinal and choroidal BF and then applied this approach to detect reduced ocular BF in a well-established mouse model of glaucoma from both eyes.MethodsQuantitative BF magnetic resonance imaging (MRI) was performed on glaucomatous DBA/2J and normal C57BL/6J mice. Arterial spin labeling MRI was applied to image retinal and choroidal BF using custom-made dual eye coils that could image both eyes during the same scan. Statistics using data from a single eye or two eyes were compared. BF values were calculated using two approaches. The BF rate per quantity of tissue was calculated as commonly done, and the peak BF values of the retinal and choroidal vasculatures were taken. Additionally, the BF rate per retinal surface area was calculated using a new analysis approach to attempt to reduce partial volume and variability by integrating BF over the retinal and choroidal depths.ResultsOcular BF of both eyes could be imaged using the dual coil setup without effecting scan time. Intraocular pressure was significantly elevated in DBA/2J mice compared to C57BL/6J mice (P<0.01). Both retinal and choroidal BF were significantly decreased in DBA/2J mice in comparison to the age-matched normal C57BL/6J mice across all measurements (P < 0.01). From simulations, the values from the integrated BF analysis method had less partial volume effect, and from in vivo scans, this analysis approach also improved power.ConclusionThe dual eye coil setup allows bilateral eye data acquisition, increasing the amount of data acquired without increasing acquisition times in vivo. The reduced ocular BF found using the improved acquisition and analysis approaches replicated the results of previous studies on DBA/2J mice. The ocular hypertensive stress-induced BF reduction found within these mice may represent changes associated with glaucomatous progression.

Comparative Analysis of Costing Methods for Magnetic Resonance Imaging in a Tertiary Care Teaching Hospital: An Observational Study

Abstract Background: Health-care costs, often determined through outdated methods, fail to capture the true costs of care delivery. Traditional costing methods in the health-care sector have proven insufficient, leading to potential revenue losses and increased patient out-of-pocket expenses. Activity-based costing (ABC) and time-driven ABC (TDABC) offer alternative approaches to cost calculation, aiming for a more accurate reflection of resource consumption. Methodology: This descriptive observational study was conducted in the magnetic resonance imaging (MRI) center of a tertiary care teaching hospital, focusing on a single noncontrast MRI scan costing. Direct observations and record reviews, including standard operating procedures, policy letters, financial documents, and miscellaneous records, were employed. Results: Using traditional costing, the unit cost of an MRI scan was calculated at INR 1291.51. ABC yielded a unit cost of INR 3613.77, while TDABC resulted in a unit cost of INR 2764.39. A comparison between the three costing methods revealed potential revenue losses with traditional costing. In contrast, TDABC appeared to strike a balance between financial prudence and reduced patient out-of-pocket expenses. Conclusion: The study emphasizes the significance of understanding true costs in health-care delivery. The results advocate for the adoption of TDABC as a favorable compromise, enabling the hospital to retain revenue without burdening patients with additional costs. Notably, the study highlights the necessity for a granular understanding of true costs for successful transitions from volume to value in health care.

Comparing two MRI methods to assess fundamental sex differences in resting cerebral blood flow

Background: Cerebral blood flow (CBF) is a critical measurement for understanding healthy brain physiology prior to aging or neurologic diseases. Patterns of stroke and neurologic pathologies are often sex-specific. Therefore, it is important to understand basic sex differences in CBF, which are often associated with poor brain outcomes. Furthermore, prior literature examining sex differences in CBF is confounded by age, comorbidities, medications, lack of control of menstrual cycle and/or hormonal contraceptive use, and methodological discrepancies. The objective of this study was to compare two different magnetic resonance imaging (MRI) methods of quantifying CBF in young adults while controlling for the aforementioned confounding factors. We hypothesized that females would display higher CBF than males, and that there would be a high reliability between Arterial Spin Labeling (ASL) and 4D Flow MRI. Methods: 30 males and 26 females (23 ± 4yr) were studied on a single MRI (3T) visit. Subjects were fasted 8 hours and withheld caffeine, exercise, and NSAIDs for at least 24 hours. Females were not taking hormonal contraception and were studied on days 1-7 of the menstrual cycle. Microvascular CBF (mL/100g/min) was assessed via pseudo-continuous ASL (pcASL) while 4D Flow MRI acquired with Phase Contrast Vastly undersampled Isotropic Projection Reconstruction (PC VIPR) yielded macrovascular flow via the larger cerebral arteries, summing the internal carotid arteries and basilar artery for total CBF (mL/min). A T1-weighted MRI scan was used to provide brain volumes, allowing CBF from PC VIPR to be normalized and compared to ASL (mL/100g/min). The scans were taken consecutively, with subjects breathing normoxic gas while hemodynamics and end tidal CO2 were monitored. Regression analysis was used to determine reliability of two measures to test a sex difference in CBF. Results: Linear regression analysis demonstrated reliability between measurements of resting CBF via ASL and PC VIPR (p<0.001, R2=0.621). However, ASL measured significantly higher blood flows than PC VIPR in females (63.40 ± 8.55 vs. 56.47 ± 8.48 mL/100g/min, p<0.001) while male subjects had similar flows measured by both methods (45.75 ± 9.39 vs. 46.69 ± 8.19 mL/100g/min, p=0.464). Females displayed an increase in resting CBF compared to males, being 27.8% and 17.3% higher in the ASL and PC VIPR flow measurements (both p<0.001), respectively. Conclusions: These results demonstrate that ASL and PC VIPR CBF display a strong correlation, and that females have greater resting CBF compared to males that is detected by both MRI methods of quantification. However, ASL resulted in greater flow measurements in females, resulting in larger differences being observed (27.8% versus 17.3%). This discrepancy in CBF quantification warrants further investigation to determine the optimal mode of CBF measurement and comparison. Funding by NIH (HL150361). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Human brain 7Li-MRI following low-dose lithium dietary supplementation in healthy participants

BackgroundLithium is an effective mood stabiliser, but its mechanism of action is incompletely defined. Even at very low doses, lithium may have neuroprotective effects, but it is not clear if these relate to brain lithium concentration in vivo. We have developed magnetic resonance imaging (7Li-MRI) methods to detect lithium in the brain following supplementation at a very low dose. MethodsLithium orotate supplements were taken by nine healthy adult male subjects (5 mg daily) for up to 28 days, providing 2–7 % of the lithium content of a typical therapeutic lithium carbonate dose. One-dimensional 7Li-images were acquired on a 3.0 T MRI scanner. All subjects were scanned on day 14 or 28; seven were scanned on both, one at baseline and one after 7-days washout. Results7Li-MR signal amplitude was broadly stable between days 14 and 28. Two subjects had notably higher 7Li-signal intensities (approximately 2–4×) compared to other study participants. LimitationsLithium adherence was self-reported by all participants without formal validation. The coarse spatial resolution necessary for detection of low concentrations of 7Li exhibits imperfect spatial separation of signal from adjacent pixels. Conclusions7Li-MRI performed using a clinical 3T scanner demonstrated detection of lithium in the brain at very low concentration, in the range of approximately 10–60 mM. The methods are suited to studies assessing low dose lithium administration in psychiatric and neurodegenerative disorders, and permit the comparison of different lithium salt preparations at a time of emerging interest in the field.

Harmonizing three-dimensional MRI using pseudo-warping field guided GAN

In pursuit of cultivating automated models for magnetic resonance imaging (MRI) to aid in diagnostics, an escalating demand for extensive, multisite, and heterogeneous brain imaging datasets has emerged. This potentially introduces biased outcomes when directly applied for subsequent analysis. Researchers have endeavored to address this issue by pursuing the harmonization of MRIs. However, most existing image-based harmonization methods for MRI are tailored for 2D slices, which may introduce inter-slice variations when they are combined into a 3D volume. In this study, we aim to resolve inconsistencies between slices by introducing a pseudo-warping field. This field is created randomly and utilized to transform a slice into an artificially warped subsequent slice. The objective of this pseudo-warping field is to ensure that generators can consistently harmonize adjacent slices to another domain, without being affected by the varying content present in different slices. Furthermore, we construct unsupervised spatial and recycle loss to enhance the spatial accuracy and slice-wise consistency across the 3D images. The results demonstrate that our model effectively mitigates inter-slice variations and successfully preserves the anatomical details of the images during the harmonization process. Compared to generative harmonization models that employ 3D operators, our model exhibits greater computational efficiency and flexibility.

Differentiation of the Intradural Extramedullary Spinal Tumors, Schwannomas and Meningiomas, Utilizing the Contrast Ratio as a Quantitative Magnetic Resonance Imaging Method

Schwannomas and meningiomas are the most common intradural extramedullary spinal tumors; however, differentiating between them using magnetic resonance imaging (MRI) is a frequent challenge. In this study, we aimed to investigate using the contrast ratio (CR) as a quantitative MRI method in the differentiation of schwannomas and meningiomas. We analyzed the data of patients with intradural extramedullary spinal tumors who underwent surgery and were diagnosed with either schwannomas or meningiomas by histopathological analysis. Regions of interest were set for the entire spinal tumor on T2-weighted sagittal MRI. To obtain the CR values of spinal tumors (CRtumor), we used the signal intensity (SI) values of the tumor (SItumor) and spinal cord (SIcord) according to the following formula: [CRtumor= (SItumor-SIcord)/(SItumor+SIcord)]. The study included 50 patients (23 males and 27 females) with a mean age of 61.5-years-old (11-85-years-old). Histopathological analysis revealed that 33 and 17 patients were diagnosed with schwannomas and meningiomas, respectively. The mean CR values of the schwannomas and meningiomas were 0.3040 ± 0.1386 and 0.0173 ± 0.1929, respectively. The CR value of the schwannomas was statistically significantly higher than that of meningiomas (P < 0.01). The cutoff CR value obtained from the receiver operating characteristic curve was 0.143, with a specificity and sensitivity of 90.9% and 88.2%, respectively. Furthermore, the value for the area under the receiver operating characteristic curve was 0.925 (95% confidence interval: 0.852-0.998). The evaluation of CRs by using MRI in distinguishing between schwannomas and meningiomas is a beneficial quantitative tool.

Visualization of Reissner's membrane in the mouse inner ear using highly sensitive magnetic resonance imaging analysis

Although research on hearing loss, including the identification of causative genes, has become increasingly active, the pathogenic mechanism of hearing loss remains unclear. One of the reasons for this is that the structure of the inner ear of mice, which is commonly used as a genetically modified animal model, is too small and complex, making it difficult to accurately capture abnormalities and dynamic changes in vivo. Especially, Reissner's membrane is a very important structure that separates the perilymph and endolymph of the inner ear. This malformation or damage induces abnormalities in hearing and balance. Until now, imaging analyses, such as magnetic resonance imaging (MRI) and computed tomography, are performed to investigate the inner ear structure in vivo; however, it has been difficult to analyze the small inner ear structure of mice owing to resolution. Therefore, there is an urgent need to develop an image analysis method that can accurately capture the structure of the inner ear of mice including Reissner's membrane, both dynamically and statically.This study aimed to investigate whether it is possible to accurately capture the structure (e.g., Reissner's membrane) and abnormalities of the inner ear of mice using an 11.7T MRI. By combining two types of MRI methods, in vivo and ex vivo, we succeeded for the first time in capturing the fine structure of the normal mouse inner ear, such as the Reissner’s membrane, and inflammatory lesions of otitis media mouse models in detail and accurately. In the future, we believe that understanding the state of Reissner's membrane during living conditions will greatly contribute to the development of research on inner ear issues, such as hearing loss.

ВИЗУАЛИЗАЦИЯ ПЕРИТОНЕАЛЬНОГО МЕТАСТАЗИРОВАНИЯ: ОБЗОР ЛИТЕРАТУРЫ И СОБСТВЕННЫЙ ОПЫТ

Peritoneal metastasis is typical for malignant neoplasms of the ovary, stomach, intestines and other localizations. Metastases can mimic other pathological changes. Ambiguous conclusions about the effectiveness of certain methods of visualization and differentiation of peritoneal metastasis given in the scientific literature explain the lack of a unified approach in its diagnosis. Imaging of the peritoneum directly impacts tumor burden assessment, prognosis, and treatment planning. Purpose of the study: to analyze the information content of modern methods of visualizing peritoneal metastasis, based on literature data and our own experience. Materials and methods. The study was carried out on the basis of a literature analysis of publications of the electronic search system PubMed. We also conducted our own research on the comparative effectiveness of visualization methods implemented in the conditions of the Republican Clinical Oncologic Dispensary of Ministry of Health of the Republic of Bashkortostan. Results: analysis of the literature showed that all visualization methods have certain capabilities and limitations. Diagnosis of metastases located in the small intestine and lesions less than 5 mm in size is significantly difficult. Adhesive processes in the abdominal cavity, difficult to differentiate confluent tumor masses and inflammatory changes also affect the examination results. Our own experience demonstrates the admissibility of using a combination of pelvic magnetic resonance imaging and abdominal computed tomography for preoperative visualization of peritoneal metastases. Imaging results using instrumental methods were comparable to surgical assessment. In addition to the diagnostic limitations stated in the scientific literature, we identified difficulties in interpreting the results due to the lack of criteria for assessing peritoneal pathology by radiologists. Conclusion. Thus, according to the literature, the standard for diagnosing peritoneal metastases has not been defined. Computed tomography and magnetic resonance imaging methods are relatively accessible methods for visualizing peritoneal metastasis and complement each other, taking into account the diagnostic limitations and capabilities of each. To improve the assessment of the tumor burden at the preoperative stage, it is worth considering the possibility of creating uniform protocols for describing peritoneal metastases by abdominal region by radiologists, which will significantly facilitate the assessment and treatment planning in the future.

Європейські рекомендації 2023 року щодо лікування кардіоміопатій та впровадження їх у практику в Україні

In this article we analyzed the main positions of the recommendations of the European Society of Cardiology regarding the treatment of cardiomyopathies and presented the actual issues of implementing recommendations into clinical practice in Ukraine. The diagnostic flowchat of a patient with suspected cardiomyopathy is presented. Five phenotypes of cardiomyopathies are presented with current definition. New fenotype of non-dilated left ventricular cardiomyopathy is presented. The role of various imaging methods in diagnosis of cardiomyopathy phenotype is considered. The role of methods of genetic testing and magnetic resonance imaging of the heart with contrast is determined. The attention is focused on the need to differentiate the etiology of phenotypes and phenocopies of cardiomyopathies for pathogenetic treatment. Methods of assessing the risk of sudden cardiac death in cardiomyopathies and methods of secondary and primary prevention are discussed. Calculators for the risk of sudden death in cardiomyopathies and indications for implantation of a cardioverter-defibrillator are given. The management of patients with atrial fibrillation in various cardiomyopathies is determined. The issue of treatment of heart failure in patients with different phenotypes and ethiology of cardiomyopathies is discussed. Attention is focused on the role of «cardiomyopathy teams» in cardiological centers. An experience of echocardiographic diagnostics of cardiomyopathies, genetic testing, usage of magnetic resonance imaging in cardiomyopathies is presented.

Association between homotopic connectivity and clinical symptoms in first-episode schizophrenia

BackgroundAbnormal functional connectivity (FC) in the brain has been observed in schizophrenia patients. However, studies on FC between homotopic brain regions are limited, and the results of these studies are inconsistent. The aim of this study was to compare homotopic connectivity between first-episode schizophrenia (FES) patients and healthy subjects and assess its correlation with clinical symptoms. MethodsThirty-one FES patients and thirty-three healthy controls (HC) were included in the study. The voxel-mirrored homotopic connectivity (VMHC) method of resting-state functional magnetic resonance imaging (rs-fMRI) was used to analyse the changes in homotopic connectivity between the two groups. The 5-factor PANSS model was used to quantitatively evaluate the severity of symptoms in FES patients. Partial correlation analysis was used to assess the correlation between homotopic connectivity changes and clinical symptoms. ResultsCompared to those in the HC group, VMHC values were decreased in the paracentral lobule (PL), thalamus, and superior temporal gyrus (STG) in the FES group (P < 0.05, FDR correction). No significant differences in white matter volume (WMV) within the subregion of the corpus callosum or in brain regions associated with reduced VMHC were observed between the two groups. Partial correlation analyses revealed that VMHC in the bilateral STG of FES patients was positively correlated with negative symptoms (rleft = 0.46, p < 0.05; rright = 0.47, p < 0.05), and VMHC in the right thalamus was negatively correlated with disorganized/concrete symptoms (rright = 0.45, p < 0.05). ConclusionOur study revealed that homotopic connectivity is altered in the resting-state brain of FES patients and correlates with the severity of negative symptoms; this change may be independent of structural changes in white matter. These findings may contribute to the development of the abnormal connectivity hypothesis in schizophrenia patients.

Efficacy of fat quantification methods used in MRI to distinguish between normal, benign, and malignant bone marrow pathologies in children.

Fat quantification methods in magnetic resonance imaging (MRI) have been studied to differentiate bone marrow pathologies in adult patients; however, scarce literature is available in pediatric patients. To evaluate the efficacy of the T1 signal intensity value (T1-SIV), out-of-phase/in-phase signal ratio (OP/IP SR), and fat fraction (FF) to differentiate between normal, benign, and malignant pathological processes. A total of 48 pediatric patients with lumbar and pelvic MRI were classified into three groups according to bone marrow pathology (group 1, normal; group 2, benign pathology/reconversion; group 3, malignant). The efficacy of T1-SIV, OP/IP SR, and FF values in differentiating these pathologies was evaluated using Kruskal-Wallis or analysis of variance and followed by Bonferroni or Dunn-Bonferroni tests. Cutoff values for malignant infiltration were defined using ROC analysis. Although these values were significantly different in all three groups (P = 0.001-0.008), this difference was not sufficient to discriminate between all groups. Subgroup analyses showed significant differences in T1-SIV between groups 1-3, in OP/IP SR between groups 1-3, 2-3, and 1-2, in FF between groups 1-2 and 1-3 in various regions (P = 0.001-0.049). Cutoff values had a sensitivity and specificity of 90%-100% for OP/IP SR and FF. T1-SIV, OP/IP SR, and FF may potentially distinguish normal from pathological bone marrow. OP/IP SR and FF values detected malignant infiltration with high sensitivity and specificity in this study. However, only OP/IP SR may significantly differentiate benign and malignant bone marrow pathologies which needs to be confirmed in the future study with a larger patient population.

A genetic optimisation and iterative reconstruction framework for sparse multi-dimensional diffusion–relaxation correlation MRI

Multi-dimensional diffusion–relaxation correlation (DRC) magnetic resonance imaging (MRI) techniques have recently been developed to investigate tissue microstructures. Sub-voxel tissue heterogeneity is resolved from the local correlation distributions of relaxation time and molecular diffusivity. However, the implementation of these techniques considerably increases the total acquisition time, and simply reducing the scan time may be at the expense of detailed structural resolution. To overcome these limitations, an optimised framework was proposed for acquiring microstructural maps of the human brain on a clinically feasible timescale. First, the acquisition parameters of the multi-dimensional DRC MRI method were sparsely optimised using a genetic algorithm with a fitness function according to the spectral resolution of the correlation map, hardware requirements, and total scan time. Next, the acquired DRC MRI data were processed using a proposed numerical algorithm based on the dynamic inverse Laplace transform (ILT). Prior knowledge from one-dimensional data was then utilised in the iterative procedure to improve the spectral resolution. Finally, the proposed framework was validated using Monte Carlo simulations and experimental data acquired from healthy participants on an MRI scanner. The results demonstrated that the suggested approach is feasible for offering high-resolution DRC maps that correspond to distinct microstructures with a limited amount of optimised acquisition data from two-dimensional DRC sampling space. By significantly reducing scan time while retaining structural resolution, this approach may enable multi-dimensional DRC MRI to be more widely used for quantitative evaluation in biological and medical settings.

Engineering water exchange is a safe and effective method for magnetic resonance imaging in diverse cell types

Aquaporin-1 (Aqp1), a water channel, has garnered significant interest for cell-based medicine and in vivo synthetic biology due to its ability to be genetically encoded to produce magnetic resonance signals by increasing the rate of water diffusion in cells. However, concerns regarding the effects of Aqp1 overexpression and increased membrane diffusivity on cell physiology have limited its widespread use as a deep-tissue reporter. In this study, we present evidence that Aqp1 generates strong diffusion-based magnetic resonance signals without adversely affecting cell viability or morphology in diverse cell lines derived from mice and humans. Our findings indicate that Aqp1 overexpression does not induce ER stress, which is frequently associated with heterologous expression of membrane proteins. Furthermore, we observed that Aqp1 expression had no detrimental effects on native biological activities, such as phagocytosis, immune response, insulin secretion, and tumor cell migration in the analyzed cell lines. These findings should serve to alleviate any lingering safety concerns regarding the utilization of Aqp1 as a genetic reporter and should foster its broader application as a noninvasive reporter for in vivo studies.

Magnetic resonance metrics for identification of cuprizone-induced demyelination in the mouse model of neurodegeneration: a review.

Neurodegenerative disorders, including Multiple Sclerosis (MS), are heterogenous disorders which affect the myelin sheath of the central nervous system (CNS). Magnetic Resonance Imaging (MRI) provides a non-invasive method for studying, diagnosing, and monitoring disease progression. As an emerging research area, many studies have attempted to connect MR metrics to underlying pathophysiological presentations of heterogenous neurodegeneration. Most commonly, small animal models are used, including Experimental Autoimmune Encephalomyelitis (EAE), Theiler's Murine Encephalomyelitis (TMEV), and toxin models including cuprizone (CPZ), lysolecithin, and ethidium bromide (EtBr). A contrast and comparison of these models is presented, with focus on the cuprizone model, followed by a review of literature studying neurodegeneration using MRI and the cuprizone model. Conventional MRI methods including T1 Weighted (T1W) and T2 Weighted (T2W) Imaging are mentioned. Quantitative MRI methods which are sensitive to diffusion, magnetization transfer, susceptibility, relaxation, and chemical composition are discussed in relation to studying the CPZ model. Overall, additional studies are needed to improve both the sensitivity and specificity of MRI metrics for underlying pathophysiology of neurodegeneration and the relationships in attempts to clear the clinico-radiological paradox. We therefore propose a multiparametric approach for the investigation of MR metrics for underlying pathophysiology.

Exploration of anatomical distribution of brain metastasis from breast cancer at first diagnosis assisted by artificial intelligence

ObjectivesThis study aimed to explore the spatial distribution of brain metastases (BMs) from breast cancer (BC) and to identify the high-risk sub-structures in BMs that are involved at first diagnosis. MethodsMagnetic resonance imaging (MRI) scans were retrospectively reviewed at our centre. The brain was divided into eight regions according to its anatomy and function, and the volume of each region was calculated. The identification and volume calculation of metastatic brain lesions were accomplished using an automatically segmented 3D BUC-Net model. The observed and expected rates of BMs were compared using 2-tailed proportional hypothesis testing. ResultsA total of 250 patients with BC who presented with 1694 BMs were retrospectively identified. The overall observed incidences of the substructures were as follows: cerebellum, 42.1 %; frontal lobe, 20.1 %; occipital lobe, 9.7 %; temporal lobe, 8.0 %; parietal lobe, 13.1 %; thalamus, 4.7 %; brainstem, 0.9 %; and hippocampus, 1.3 %. Compared with the expected rate based on the volume of different brain regions, the cerebellum, occipital lobe, and thalamus were identified as higher risk regions for BMs (P value ≤ 5.6*10−3). Sub-group analysis according to the type of BC indicated that patients with triple-negative BC had a high risk of involvement of the hippocampus and brainstem. ConclusionsAmong patients with BC, the cerebellum, occipital lobe and thalamus were identified as higher-risk regions than expected for BMs. The brainstem and hippocampus were high-risk areas of the BMs in triple negative breast cancer. However, further validation of this conclusion requires a larger sample size.

Clinical Application of MRI in Coronavirus Disease 2019: A Bibliometric Analysis.

Currently, coronavirus disease 2019 (COVID-19) continues to remain in the pandemic stage, leading to severe challenges in the global public healthcare system. Magnetic resonance imaging (MRI) methods have played an important role in the diagnosis of COVID-19 and the structural evaluation of the affected organs. Reviewing and summarizing the application of MRI has significant clinical implications for COVID-19. The study aimed to analyze literature related to the application of MRI in COVID-19 using bibliometric tools, to explore the research status, hotspots, and developmental trends in this field, and to provide a reference for the application of MRI in the clinical diagnosis and evaluation of COVID-19. We used the Web of Science Core Collection database to search and collect relevant literature on the use of MRI in COVID-19. The authors, institutes, countries, journals, and keyword modules of the bibliometric analysis software CiteSpace and VOSviewer were used to analyze and plot the network map. A total of 1506 relevant articles were shortlisted through the search; the earliest study was published in 2019, showing an overall upward trend every year. The research was mainly presented as published articles. Clinical neurology was found to be the primary discipline. The United States had the highest publication volume and influence in this field. Countries around the world cooperated more closely. The Cureus Journal of Medical Science was the main periodical to publish articles. Institutes, such as Harvard Medical School, Mayo Clinic, and Massachusetts General Hospital, have published a large number of papers. Some of the high-frequency keywords were "COVID-19", "SARS-CoV-2", "magnetic resonance", "myocarditis", and "cardiac magnetic resonance imaging". The keyword clustering study showed that the current research mainly focuses on five "hot" directions. There is a need to strengthen cross-teamwork and multidisciplinary collaboration in the future to completely explore the positive role of MRI in COVID-19 and to discover breakthroughs for the challenges in the clinical diagnosis and treatment of COVID-19.