Explore the vast range of titles available.

Characterization of porous media is essential in a wide range of biomedical and industrial applications. Microstructural features can be probed non-invasively by diffusion magnetic resonance imaging (dMRI). However, diffusion encoding in conventional dMRI may yield similar signatures for very different microstructures, which represents a significant limitation for disentangling individual microstructural features in heterogeneous materials. To solve this problem, we propose an augmented multidimensional diffusion encoding (MDE) framework, which unlocks a novel encoding dimension to assess time-dependent diffusion specific to structures with different microscopic anisotropies. Our approach relies on spectral analysis of complex but experimentally efficient MDE waveforms. Two independent contrasts to differentiate features such as cell shape and size can be generated directly by signal subtraction from only three types of measurements. Analytical calculations and simulations support our experimental observations. Proof-of-concept experiments were applied on samples with known and distinctly different microstructures. We further demonstrate substantially different contrasts in different tissue types of a post mortem brain. Our simultaneous assessment of restriction size and shape may be instrumental in studies of a wide range of porous materials, enable new insights into the microstructure of biological tissues or be of great value in diagnostics.

In rheumatoid arthritis (RA), chronic inflammation is thought to drive increased cardiovascular risk through accelerated atherosclerosis. It may also lead to a more high-risk plaque phenotype. We sought to investigate carotid plaque phenotype in RA patients using Dynamic Contrast-Enhanced MRI (DCE-MRI) and Fludeoxyglucose Positron Emission Tomography(FDG-PET). In this pilot study, RA patients and age/sex-matched controls were evaluated for cardiovascular risk factors and carotid plaque on ultrasound. Subjects with plaque >2 mm thick underwent DCE-MRI, and a subgroup of patients had FDG-PET. Comparison of MRI findings between groups and correlation between clinical, serological markers and imaging findings was undertaken. 130 patients and 62 controls were recruited. Plaque was more prevalent in the RA group (53.1% vs 37.0%, p = 0.038) and was independently associated with IL6 levels (HR[95%CI]: 2.03 [1.26, 3.26] per quartile). DCE-MRI data were available in 15 patients and 5 controls. Higher prevalence of plaque calcification was noted in RA, despite similar plaque size (73.3% vs 20%, p = 0.04). FDG-PET detected plaque inflammation in 12/13 patients scanned and degree of inflammation correlated with hs-CRP (r = 0.58, p = 0.04). This study confirms increased prevalence of atherosclerosis in RA and provides data to support the hypothesis that patients have a high-risk plaque phenotype.

Background The clinical translation of positron emission tomography (PET) radiotracers for cancer management presents complex challenges. We have developed consensus-based recommendations for preclinical and clinical assessment of novel and established radiotracers, applied to image different cancer types, to improve the standardisation of translational methodologies and accelerate clinical implementation. Methods A consensus process was developed using the RAND/UCLA Appropriateness Method (RAM) to gather insights from a multidisciplinary panel of 38 key stakeholders on the appropriateness of preclinical and clinical methodologies and stakeholder engagement for PET radiotracer translation. Panellists independently completed a consensus survey of 57 questions, rating each on a 9-point Likert scale. Subsequently, panellists attended a consensus meeting to discuss survey outcomes and readjust scores independently if desired. Survey items with median scores ≥ 7 were considered ‘required/appropriate’, ≤ 3 ‘not required/inappropriate’, and 4–6 indicated ‘uncertainty remained’. Consensus was determined as ~ 70% participant agreement on whether the item was ‘required/appropriate’ or ‘not required/not appropriate’. Results Consensus was achieved for 38 of 57 (67%) survey questions related to preclinical and clinical methodologies, and stakeholder engagement. For evaluating established radiotracers in new cancer types, in vitro and preclinical studies were considered unnecessary, clinical pharmacokinetic studies were considered appropriate, and clinical dosimetry and biodistribution studies were considered unnecessary, if sufficient previous data existed. There was ‘agreement without consensus’ that clinical repeatability and reproducibility studies are required while ‘uncertainty remained’ regarding the need for comparison studies. For novel radiotracers, in vitro and preclinical studies, such as dosimetry and/or biodistribution studies and tumour histological assessment were considered appropriate, as well as comprehensive clinical validation. Conversely, preclinical reproducibility studies were considered unnecessary and ‘uncertainties remained’ regarding preclinical pharmacokinetic and repeatability evaluation. Other consensus areas included standardisation of clinical study protocols, streamlined regulatory frameworks and patient and public involvement. While a centralised UK clinical imaging research infrastructure and open access federated data repository were considered necessary, there was ‘agreement without consensus’ regarding the requirement for a centralised UK preclinical imaging infrastructure. Conclusions We provide consensus-based recommendations, emphasising streamlined methodologies and regulatory frameworks, together with active stakeholder engagement, for improving PET radiotracer standardisation, reproducibility and clinical implementation in oncology.

Background The clinical translation of positron emission tomography (PET) radiotracers for cancer management presents complex challenges. We have developed consensus-based recommendations for preclinical and clinical assessment of novel and established radiotracers, applied to image different cancer types, to improve the standardisation of translational methodologies and accelerate clinical implementation. Methods A consensus process was developed using the RAND/UCLA Appropriateness Method (RAM) to gather insights from a multidisciplinary panel of 38 key stakeholders on the appropriateness of preclinical and clinical methodologies and stakeholder engagement for PET radiotracer translation. Panellists independently completed a consensus survey of 57 questions, rating each on a 9-point Likert scale. Subsequently, panellists attended a consensus meeting to discuss survey outcomes and readjust scores independently if desired. Survey items with median scores [greater than or equal to] 7 were considered 'required/appropriate', [less than or equal to] 3 'not required/inappropriate', and 4-6 indicated 'uncertainty remained'. Consensus was determined as ~ 70% participant agreement on whether the item was 'required/appropriate' or 'not required/not appropriate'. Results Consensus was achieved for 38 of 57 (67%) survey questions related to preclinical and clinical methodologies, and stakeholder engagement. For evaluating established radiotracers in new cancer types, in vitro and preclinical studies were considered unnecessary, clinical pharmacokinetic studies were considered appropriate, and clinical dosimetry and biodistribution studies were considered unnecessary, if sufficient previous data existed. There was 'agreement without consensus' that clinical repeatability and reproducibility studies are required while 'uncertainty remained' regarding the need for comparison studies. For novel radiotracers, in vitro and preclinical studies, such as dosimetry and/or biodistribution studies and tumour histological assessment were considered appropriate, as well as comprehensive clinical validation. Conversely, preclinical reproducibility studies were considered unnecessary and 'uncertainties remained' regarding preclinical pharmacokinetic and repeatability evaluation. Other consensus areas included standardisation of clinical study protocols, streamlined regulatory frameworks and patient and public involvement. While a centralised UK clinical imaging research infrastructure and open access federated data repository were considered necessary, there was 'agreement without consensus' regarding the requirement for a centralised UK preclinical imaging infrastructure. Conclusions We provide consensus-based recommendations, emphasising streamlined methodologies and regulatory frameworks, together with active stakeholder engagement, for improving PET radiotracer standardisation, reproducibility and clinical implementation in oncology. Keywords: Consensus guidelines, Positron emission tomography, Cancer imaging, Preclinical evaluation, Clinical validation, Translational methods, Radiotracers, Diagnostic imaging, Imaging biomarker, RAND/UCLA Appropriateness Method