Musculoskeletal MRI at 7 T: do we need more or is it more than enough?

Ultra-high field magnetic resonance imaging (UHF-MRI) provides important diagnostic improvements in musculoskeletal imaging. The higher signal-to-noise ratio leads to higher spatial and temporal resolution which results in improved anatomic detail and higher diagnostic confidence. Several methods, such as T2, T2*, T1rho mapping, delayed gadolinium-enhanced, diffusion, chemical exchange saturation transfer, and magnetisation transfer techniques, permit a better tissue characterisation. Furthermore, UHF-MRI enables in vivo measurements by low-γ nuclei (23Na, 31P, 13C, and 39K) and the evaluation of different tissue metabolic pathways. European Union and Food and Drug Administration approvals for clinical imaging at UHF have been the first step towards a more routinely use of this technology, but some drawbacks are still present limiting its widespread clinical application. This review aims to provide a clinically oriented overview about the application of UHF-MRI in the different anatomical districts and tissues of musculoskeletal system and its pros and cons. Further studies are needed to consolidate the added value of the use of UHF-MRI in the routine clinical practice and promising efforts in technology development are already in progress

Pseudo-monoenergetic x-ray diffraction measurements using balanced filters for coherent-scatter computed tomography

In the treatment of kidney stones, knowing stone composition has been established as an important aid to the understanding of stone formation and in preventing recurrences, particularly the composition of the initial “core” of the stone. Traditionally, stone composition has come from laboratory techniques such as infrared spectroscopy and x-ray diffraction. These methods require taking multiple samples of excised stone fragments and powdering them - losing structural information in the process, and therefore the specific core composition. Coherent-scatter computed tomography (CSCT) is a method of non-destructive “composition” imaging based on measurements of diffraction patterns from tissues. Use of an x-ray tube degrades scatter-pattern angular resolution due to the x-ray spectral width, making it difficult to uniquely identify some materials. The use of two transmission filters with similar atomic numbers (balanced “Ross filters”) to generate pseudo-monoenergetic scatter patterns of common kidney stone components is described as it applies to CSCT. We show that an analysis of angular-blur mechanisms reveals that focal spot size and beam width are the most important factors determining Bragg-peak width when erbium and thulium balanced filters are used. A Bragg-peak RMS angular width of approximately 0.14° (relative width of 3% at 5° scatter angle) can be achieved, reducing peak-overlap in the scatter functions of common kidney stone constituents. CSCT is capable of producing 3-D material-distribution maps. In previous studies, such maps were of relative material density. We describe a theoretical method to generate absolute (g/cm3) mass-density distributions. Balanced-filter CSCT improves scatter-function angular resolution and allows for the measurement of common kidney-stone constituents with non-overlapping peaks

REDUCING THE BURDEN OF CANCER WITH ARTIFICIAL INTELLIGENCE: IMAGE-BASED MODELS FOR BREAST CANCER DETECTION, ADVANCED STAGE RISK, AND CROSS-MODALITY VISUALIZATION

Ph.D

Advanced characterisation methods for the analysis of nanoformulations and extracellular vesicles

Nanomedicine represents a challenging and highly multidisciplinary research field, concerned with the development and study of nanoformulations for diagnostic and/or therapeutic purposes. The nano-sized particles of interest are increasingly complex. Their translational potential has been hampered by difficulties in their thorough characterisation. On the nano scale, small variations in size and composition can have large implications for their pharmacodynamic and pharmacokinetic behaviour. More precise techniques are therefore required to address these challenges. This thesis describes novel, advanced characterisation methods designed for the detailed study of single nanoparticles and their interaction and uptake behaviour with cells. A platform technology for Single Particle Automated Raman Trapping Analysis – SPARTA - was developed, capable of non-destructive, label-free and automated comprehensive single particle analysis. With the SPARTA system, the composition, functionalisation, size and dynamic reactions on the surface can be investigated in detail, of a wide variety of nanoparticles, through their Raman spectra. A further improved, custom designed SPARTA 2.0 platform was built, optimised for the analysis of complex biological particles, such as EVs. EVs represent a high potential as biomarkers, studied here in the context of breast cancer. The SPARTA 2.0 platform was able to resolve compositional differences between non-cancerous and cancer cell-derived EVs with excellent sensitivity and specificity. This highlights the possibility for development of new minimally invasive diagnostic approaches. In addition, a new imaging strategy for investigation of the EV-cellular interaction is presented, based on 3D Focused Ion Beam – Scanning Electron Microscopy (FIB-SEM). FIB-SEM allows the generation of 3D models of the subcellular structure and visualisation of the cellular trafficking of nanoparticles. This represents a powerful new approach for investigating EV uptake. The methods developed in this thesis allow for the single particle-based analysis of a wide variety of nanoformulations and EVs, to aid in understanding their composition, applicability and cellular interactions.Open Acces

Imaging techniques for the assessment of the bone osteoporosis-induced variations with particular focus on micro-ct potential

For long time, osteoporosis (OP) was exclusively associated with an overall bone mass reduction, leading to lower bone strength and to a higher fracture risk. For this reason, the measurement of bone mineral density through dual X-ray absorptiometry was considered the gold standard method for its diagnosis. However, recent findings suggest that OP causes a more complex set of bone alterations, involving both its microstructure and composition. This review aims to provide an overview of the most evident osteoporosis-induced alterations of bone quality and a résumé of the most common imaging techniques used for their assessment, at both the clinical and the laboratory scale. A particular focus is dedicated to the micro-computed tomography (micro-CT) due to its superior image resolution, allowing the execution of more accurate morphometric analyses, better highlighting the architectural alterations of the osteoporotic bone. In addition, micro-CT has the potential to perform densitometric measurements and finite element method analyses at the microscale, representing potential tools for OP diagnosis and for fracture risk prediction. Unfortunately, technological improvements are still necessary to reduce the radiation dose and the scanning duration, parameters that currently limit the application of micro-CT in clinics for OP diagnosis, despite its revolutionary potential

Imaging technologies to study the composition of live pigs: A review

Image techniques are increasingly being applied to livestock animals. This paper overviews recent advances in image processing analysis for live pigs, including ultrasound, visual image analysis by monitoring, dual-energy X-ray absorptiometry, magnetic resonance imaging and computed tomography. The methodology for live pigs evaluation, advantages and disadvantages of different devices, the variables and measurements analysed, the predictions obtained using these measurements and their accuracy are discussed in the present paper. Utilities of these technologies for livestock purposes are also reviewed. Computed tomography and magnetic resonance imaging yield useful results for the estimation of the amount of fat and lean mass either in live pigs or in carcasses. Ultrasound is not sufficiently accurate when high precision in estimating pig body composition is necessary but can provide useful information in agriculture to classify pigs for breeding purposes or before slaughter. Improvements in factors, such as the speed of scanning, cost and image accuracy and processing, would advance the application of image processing technologies in livestock animals

A general perspective of the characterization and quantification of nanoparticles: Imaging, spectroscopic, and separation techniques

This article gives an overview of the different techniques used to identify, characterize, and quantify engineered nanoparticles (ENPs). The state-of-the-art of the field is summarized, and the different characterization techniques have been grouped according to the information they can provide. In addition, some selected applications are highlighted for each technique. The classification of the techniques has been carried out according to the main physical and chemical properties of the nanoparticles such as morphology, size, polydispersity characteristics, structural information, and elemental composition. Microscopy techniques including optical, electron and X-ray microscopy, and separation techniques with and without hyphenated detection systems are discussed. For each of these groups, a brief description of the techniques, specific features, and concepts, as well as several examples, are described.Junta de Andalucía FQM-5974CEI-Biotic Granada CEI2013- MP-1

Imaging Cultural Heritage at Different Scales: Part I, the Micro-Scale (Manufacts)

Applications of non-invasive sensing techniques to investigate the internal structure and surface of precious and delicate objects represent a very important and consolidated research field in the scientific domain of cultural heritage knowledge and conservation. The present article is the first of three reviews focused on contact and non-contact imaging techniques applied to surveying cultural heritage at micro- (i.e., manufacts), meso- (sites) and macro-scales (landscapes). The capability to infer variations in geometrical and physical properties across the inspected surfaces or volumes is the unifying factor of these techniques, allowing scientists to discover new historical sites or to image their spatial extent and material features at different scales, from landscape to artifact. This first part concentrates on the micro-scale, i.e., inspection, study and characterization of small objects (ancient papers, paintings, statues, archaeological findings, architectural elements, etc.) from surface to internal properties

Periprosthetic bone loss: diagnostic and therapeutic approaches.

Total joint replacement surgery is being performed on an increasingly large part of the population. Clinical longevity of implants depends on their osseointegration, which is influenced by the load, the characteristics of the implant and the bone-implant interface, as well as by the quality and quantity of the surrounding bone. Aseptic loosening due to periprosthetic osteolysis is the most frequent known cause of implant failure. Wear of prosthetic materials results in the formation of numerous particles of debris that cause a complex biological response. Dual-energy X-ray Absorptiometry (DXA) is regarded as an accurate method to evaluate Bone Mineral Density (BMD) around hip or knee prostheses. Further data may be provided by a new device, the Bone Microarchitecture Analysis (BMA), which combines bone microarchitecture quantification and ultra high resolution osteo-articular imaging. Pharmacological strategies have been developed to prevent bone mass loss and to extend implant survival. Numerous trials with bisphosphonates show a protective effect on periprosthetic bone mass, up to 72 months after arthroplasty. Strontium ranelate has been demonstrated to increase the osseointegration of titanium implants in treated animals with improvement of bone microarchitecture and bone biomaterial properties