MRI Contrast Agents: Developments, Challenges, and Future Trends

Contrast agents in medicine are chemical materials used to improve tissue and fluid contrast in the body during medical imaging. It is mainly used in improving the visibility of blood vessels and the gastrointestinal tract. Some types of contrast materials are used in a medical imaging examination and can be classified according to the imaging technique used. The first contract agent dates back to 1988 which is called gadopentetate dimeglumine (Magnevist®) and was allocated for Magnetic Resonance Imaging (MRI). Then, I has become available in clinical use. Afterwards, many studies have examined the capability of MRI contrast agents to be used in diagnostic imaging in all parts of the body including the skin, the central nervous system, heart and circulation, breast, lungs, musculoskeletal and lymphatic systems, and even the gastrointestinal tract. Nowadays, MRI contrast agents are widely used in clinical practice and have expanded beyond the imitational expectations to be a key tool in disease diagnosis around the world. Contrast-Enhanced (CE) MRI keeps in development and new technologies have emerged and new agents were introduced, with great opportunity being provided to ensure better imaging and patient management practices. Also, new clinical challenges were associated with the progress in CE-MRI. This paper aims to overview the historical development of MRI and contrast materials in order to shed light on the clinical development of CE-MRI. Also, the paper overviews the contemporary perspectives and clinical challenges associated with CE-MRI with the provision of significant future trends

A Representation of the Exact Solution of Generalized Lane-Emden Equations Using a New Analytical Method

A new analytic method is applied to singular initial-value Lane-Emden-type problems, and the effectiveness and performance of the method is studied. The proposed method obtains a Taylor expansion of the solution, and when the solution is polynomial, our method reproduces the exact solution. It is observed that the method is easy to implement, valuable for handling singular phenomena, yields excellent results at a minimum computational cost, and requires less time. Computational results of several test problems are presented to demonstrate the viability and practical usefulness of the method. The results reveal that the method is very effective, straightforward, and simple

Role of Stem Cells in Orthopaedic Surgery: Theoretical Survey

This study aims at analyzing the Stem cell application is a burgeoning field of medicine that is likely to influence the future of orthopaedic surgery. Stem cells are associated with great promise and great controversy. For the orthopaedic surgeon, stem cells may change the way that orthopaedic surgery is practiced and the overall approach of the treatment of musculoskeletal disease. Stem cells may change the field of orthopaedics from a field dominated by surgical replacements and reconstructions to a field of regeneration and prevention. This review will introduce the basic concepts of stem cells pertinent to the orthopaedic surgeon and proceed with a more in depth discussion of current developments in the study of stem cells in orthopaedic surgery. Keywords: Stem cell, orthopaedic, surgery

Tracking Control of Redundant Manipulators with Singularity-Free Orientation Representation and Null-Space Compliant Behaviour

This paper presents a suitable solution to control the pose of the end-effector of a redundant robot along a pre-planned trajectory, while addressing an active compliant behaviour in the null-space. The orientation of the robot is expressed through a singularity-free representation form. To accomplish the task, no exteroceptive sensor is needed. While a rigorous stability proof confirms the developed theory, experimental results bolster the performance of the proposed approach

RP2-associated X-linked Retinopathy: Clinical Findings, Molecular Genetics, and Natural History

PURPOSE: To review and describe in detail the clinical course, functional and anatomical characteristics of RP2-associated retinal degeneration. DESIGN: Retrospective case series. PARTICIPANTS: Males with disease-causing variants in the RP2 gene. METHODS: Review of all case notes and results of molecular genetic testing, retinal imaging (fundus autofluorescence (FAF) imaging, optical coherence tomography (OCT)) and electrophysiology assessment. MAIN OUTCOME MEASURES: Molecular genetic testing, clinical findings including best-corrected visual acuity (BCVA), qualitative and quantitative retinal imaging analysis, and electrophysiology parameters. RESULTS: Fifty-four molecularly confirmed patients were identified, from 38 pedigrees. Twenty-eight disease-causing variants were identified; with 20 not previously clinically characterized. Fifty-three patients (98.1%) presented with retinitis pigmentosa. The mean age of onset (range, ±SD) was 9.6 years of age (1-57 years, ± 9.2 years). Forty-four patients (91.7%) had childhood-onset disease, with mean age of onset of 7.6 years. The commonest first symptom was night blindness (68.8%). Mean BCVA (range, ±SD) was 0.91 LogMAR (0-2.7, ±0.80) and 0.94 LogMAR (0-2.7, ±0.78) for right and left eyes respectively. Based on the WHO visual impairment criteria, 18 patients (34%) had low vision. The majority (17/22) showed ERG evidence of a rod-cone dystrophy. Pattern ERG P50 was undetectable in all but 2 patients. A range of FAF findings was observed, from normal to advanced atrophy. There were no statistically significant differences between right and left eyes for ellipsoid zone (EZ) width and outer nuclear layer (ONL) thickness. The mean annual rate of EZ width loss was 219 μm/year and the mean annual decrease in ONL thickness was 4.93 μm/year. No patient with childhood-onset disease had identifiable EZ after the age of 26 years at baseline or follow-up. Four patients had adulthood-onset disease and a less severe phenotype. CONCLUSIONS: This study details the clinical phenotype of RP2 retinopathy in a large cohort. The majority presented with early-onset severe retinal degeneration, with early macular involvement and complete loss of the foveal photoreceptor layer by the third decade of life. Full-field ERGs revealed rod-cone dystrophy in the vast majority, but with generalised (peripheral) cone system involvement of widely varying severity in the first two decades of life

RBP3-retinopathy - inherited high myopia and retinal dystrophy: Genetic Characterization, Natural History, and Deep Phenotyping

Objective: To examine the genetic and clinical features and the natural history of RBP3-associated retinopathy. // Design: Multi-center international, retrospective, case series. // Setting: Three tertiary referral centers. // Participants: Adults and children, with molecularly confirmed RBP3-associated retinopathy. // Main Outcomes and Measures: Multi-center, international, retrospective, consecutive observational study in three tertiary referral centers of adults and children, with molecularly confirmed RBP3-retinopathy. The genetic, clinical and retinal imaging findings, including optical coherence tomography (OCT) and fundus autofluorescence (FAF), were investigated both cross-sectionally and longitudinally. The results of International standard full-field and pattern electroretinography (ERG; PERG) were reviewed. // Results: We ascertained 12 patients (5 females), from 10 families, with four patients previously reported. Eight novel disease-causing RBP3 variants were identified. Ten patients were homozygous. The mean age (±SD, range) of the group was 21.4 years (±19.1, 2.9-60.5 years) at baseline evaluation. All 12 patients were highly myopic with a mean spherical equivalent of -16.0D (range; -7.0D to -33.0D). Visual acuity was not significantly different between eyes and no significant anisometropia was observed. Mean best corrected visual acuity (BCVA) was 0.48 LogMAR (range; 0.2-1.35, SD; ± 0.29 LogMAR) at baseline. Eleven patients had longitudinal BCVA assessment, with a mean BCVA of 0.46 LogMAR after a mean follow-up of 12.6 years. All patients were symptomatic with reduced VA and myopia by the age of 7 years. All patients had myopic fundi and features in keeping with high myopia on OCT, including choroidal thinning. The 4 youngest patients had no fundus pigmentary changes, with the rest presenting with a variable degree of mid-peripheral pigmentation and macular changes. FAF showed variable phenotypes, ranging from areas of increased signal to advanced atrophy in older patients. OCT showed cystoid macular edema at presentation in three patients, which persisted during follow-up in two patients and resolved to atrophy for the third patient. The ERGs were abnormal in 9 of 9 cases, revealing variable relative involvement of rod and cone photoreceptors with additional milder dysfunction post-phototransduction in some. All but one had PERG evidence of macular dysfunction, severe in most. // Conclusions: This study details the clinical and functional phenotype of RBP3-retinopathy in the largest cohort reported to date. RBP3-retinopathy is a disease characterized by early onset, slow progression over decades, and high myopia. The phenotypic spectrum and natural history as described herein has prognostic and counselling implications. RBP3-related disease should be considered in children with high myopia and retinal dystrophy

Metal-THINGS: On the metallicity and ionization of ULX sources in NGC 925

We present an analysis of the optical properties of three Ultra Luminous X-ray (ULX) sources identified in NGC 925. We use Integral field unit data from the George Mitchel spectrograph in the context of the Metal-THINGS survey. The optical properties for ULX-1 and ULX-3 are presented, while the spaxel associated with ULX-2 had a low S/N, which prevented its analysis. We also report the kinematics and dimensions of the optical nebula associated with each ULX using ancillary data from the PUMA Fabry-Perot spectrograph. A BPT analysis demonstrates that most spaxels in NGC 925 are dominated by star-forming regions, including those associated with ULX-1 and ULX-3. Using the resolved gas-phase metallicities, a negative metallicity gradient is found, consistent with previous results for spiral galaxies, while the ionization parameter tends to increase radially throughout the galaxy. Interestingly, ULX-1 shows a very low gas metallicity for its galactocentric distance, identified by two independent methods, while exhibiting a typical ionization. We find that such low gas metallicity is best explained in the context of the high-mass X-ray binary population, where the low-metallicity environment favours active Roche lobe overflows that can drive much higher accretion rates. An alternative scenario invoking accretion of a low-mass galaxy is not supported by the data in this region. Finally, ULX-3 shows both a high metallicity and ionization parameter, which is consistent with the progenitor being a highly-accreting neutron star within an evolved stellar population region.Comment: Accepted by Ap

Using Machine Learning Algorithms to Develop a Clinical Decision-Making Tool for COVID-19 Inpatients.

BACKGROUND: Within the UK, COVID-19 has contributed towards over 103,000 deaths. Although multiple risk factors for COVID-19 have been identified, using this data to improve clinical care has proven challenging. The main aim of this study is to develop a reliable, multivariable predictive model for COVID-19 in-patient outcomes, thus enabling risk-stratification and earlier clinical decision-making. METHODS: Anonymised data consisting of 44 independent predictor variables from 355 adults diagnosed with COVID-19, at a UK hospital, was manually extracted from electronic patient records for retrospective, case-control analysis. Primary outcomes included inpatient mortality, required ventilatory support, and duration of inpatient treatment. Pulmonary embolism sequala was the only secondary outcome. After balancing data, key variables were feature selected for each outcome using random forests. Predictive models were then learned and constructed using Bayesian networks. RESULTS: The proposed probabilistic models were able to predict, using feature selected risk factors, the probability of the mentioned outcomes. Overall, our findings demonstrate reliable, multivariable, quantitative predictive models for four outcomes, which utilise readily available clinical information for COVID-19 adult inpatients. Further research is required to externally validate our models and demonstrate their utility as risk stratification and clinical decision-making tools

High Prevalence of Respiratory Ciliary Dysfunction in Congenital Heart Disease Patients With Heterotaxy

Patients with congenital heart disease (CHD) and heterotaxy show high postsurgical morbidity/mortality, with some developing respiratory complications. Although this finding is often attributed to the CHD, airway clearance and left-right patterning both require motile cilia function. Thus, airway ciliary dysfunction (CD) similar to that of primary ciliary dyskinesia (PCD) may contribute to increased respiratory complications in heterotaxy patients