Caractérisation tridimensionnelle de l’amplitude articulaire de l’épaule

L’épaule est l’articulation la plus mobile et la plus instable du corps humain dû à la faible quantité de contraintes osseuses et au rôle des tissus mous qui lui confèrent au moins une dizaine de degrés de liberté. La mobilité de l’épaule est un facteur de performance dans plusieurs sports. Mais son instabilité engendre des troubles musculo-squelettiques, dont les déchirures de la coiffe des rotateurs sont fréquentes et les plus handicapantes. L’évaluation de l’amplitude articulaire est un indice commun de la fonction de l’épaule, toutefois elle est souvent limitée à quelques mesures planaires pour lesquelles les degrés de liberté varient indépendamment les uns des autres. Ces valeurs utilisées dans les modèles de simulation musculo-squelettiques peuvent amener à des solutions non physiologiques. L’objectif de cette thèse était de développer des outils pour la caractérisation de la mobilité articulaire tri-dimensionnelle de l’épaule, en passant par i) fournir une méthode et son approche expérimentale pour évaluer l’amplitude articulaire tridimensionnelle de l’épaule incluant des interactions entre les degrés de liberté ; ii) proposer une représentation permettant d’interpréter les données tri-dimensionnelles obtenues; iii) présenter des amplitudes articulaires normalisées, iv) implémenter une amplitude articulaire tridimensionnelle au sein d’un modèle de simulation numérique afin de générer des mouvements sportifs optimaux plus réalistes; v) prédire des amplitudes articulaires sécuritaires et vi) des exercices de rééducation sécuritaires pour des patients ayant subi une réparation de la coiffe des rotateurs. i) Seize sujets ont été réalisé séries de mouvements d’amplitudes maximales actifs avec des combinaisons entre les différents degrés de liberté de l’épaule. Un système d’analyse du mouvement couplé à un modèle cinématique du membre supérieur a été utilisé pour estimer les cinématiques articulaires tridimensionnelles. ii) L’ensemble des orientations définies par une séquence de trois angles a été inclus dans un polyèdre non convexe représentant l’espace de mobilité articulaire prenant en compte les interactions entre les degrés de liberté. La combinaison des séries d’élévation et de rotation est recommandée pour évaluer l’amplitude articulaire complète de l’épaule. iii) Un espace de mobilité normalisé a également été défini en englobant les positions atteintes par au moins 50% des sujets et de volume moyen. iv) Cet espace moyen, définissant la mobilité physiologiques, a été utilisé au sein d’un modèle de simulation cinématique utilisé pour optimiser la technique d’un élément acrobatique de lâcher de barres réalisée par des gymnastes. Avec l’utilisation régulière de limites articulaires planaires pour contraindre la mobilité de l’épaule, seulement 17% des solutions optimales sont physiologiques. En plus, d’assurer le réalisme des solutions, notre contrainte articulaire tridimensionnelle n’a pas affecté le coût de calculs de l’optimisation. v) et vi) Les seize participants ont également réalisé des séries d’amplitudes articulaires passives et des exercices de rééducation passifs. La contrainte dans l’ensemble des muscles de la coiffe des rotateurs au cours de ces mouvements a été estimée à l’aide d’un modèle musculo-squelettique reproduisant différents types et tailles de déchirures. Des seuils de contrainte sécuritaires ont été utilisés pour distinguer les amplitudes de mouvements risquées ou non pour l’intégrité de la réparation chirurgicale. Une taille de déchirure plus grande ainsi que les déchirures affectant plusieurs muscles ont contribué à réduire l’espace de mobilité articulaire sécuritaire. Principalement les élévations gléno-humérales inférieures à 38° et supérieures à 65°, ou réalisées avec le bras maintenu en rotation interne engendrent des contraintes excessives pour la plupart des types et des tailles de blessure lors de mouvements d’abduction, de scaption ou de flexion. Cette thèse a développé une représentation innovante de la mobilité de l’épaule, qui tient compte des interactions entre les degrés de liberté. Grâce à cette représentation, l’évaluation clinique pourra être plus exhaustive et donc élargir les possibilités de diagnostiquer les troubles de l’épaule. La simulation de mouvement peut maintenant être plus réaliste. Finalement, nous avons montré l’importance de personnaliser la rééducation des patients en termes d’amplitude articulaire, puisque des exercices passifs de rééducation précoces peuvent contribuer à une re-déchirure à cause d’une contrainte trop importante qu’ils imposent aux tendons.

Advanced Techniques for Image Quality Assessment of Modern X-ray Computed Tomography Systems

X-ray computed tomography (CT) imaging constitutes one of the most widely used diagnostic tools in radiology today with nearly 85 million CT examinations performed in the U.S in 2011. CT imparts a relatively high amount of radiation dose to the patient compared to other x-ray imaging modalities and as a result of this fact, coupled with its popularity, CT is currently the single largest source of medical radiation exposure to the U.S. population. For this reason, there is a critical need to optimize CT examinations such that the dose is minimized while the quality of the CT images is not degraded. This optimization can be difficult to achieve due to the relationship between dose and image quality. All things being held equal, reducing the dose degrades image quality and can impact the diagnostic value of the CT examination.

A recent push from the medical and scientific community towards using lower doses has spawned new dose reduction technologies such as automatic exposure control (i.e., tube current modulation) and iterative reconstruction algorithms. In theory, these technologies could allow for scanning at reduced doses while maintaining the image quality of the exam at an acceptable level. Therefore, there is a scientific need to establish the dose reduction potential of these new technologies in an objective and rigorous manner. Establishing these dose reduction potentials requires precise and clinically relevant metrics of CT image quality, as well as practical and efficient methodologies to measure such metrics on real CT systems. The currently established methodologies for assessing CT image quality are not appropriate to assess modern CT scanners that have implemented those aforementioned dose reduction technologies.

Thus the purpose of this doctoral project was to develop, assess, and implement new phantoms, image quality metrics, analysis techniques, and modeling tools that are appropriate for image quality assessment of modern clinical CT systems. The project developed image quality assessment methods in the context of three distinct paradigms, (a) uniform phantoms, (b) textured phantoms, and (c) clinical images.

The work in this dissertation used the “task-based” definition of image quality. That is, image quality was broadly defined as the effectiveness by which an image can be used for its intended task. Under this definition, any assessment of image quality requires three components: (1) A well defined imaging task (e.g., detection of subtle lesions), (2) an “observer” to perform the task (e.g., a radiologists or a detection algorithm), and (3) a way to measure the observer’s performance in completing the task at hand (e.g., detection sensitivity/specificity).

First, this task-based image quality paradigm was implemented using a novel multi-sized phantom platform (with uniform background) developed specifically to assess modern CT systems (Mercury Phantom, v3.0, Duke University). A comprehensive evaluation was performed on a state-of-the-art CT system (SOMATOM Definition Force, Siemens Healthcare) in terms of noise, resolution, and detectability as a function of patient size, dose, tube energy (i.e., kVp), automatic exposure control, and reconstruction algorithm (i.e., Filtered Back-Projection– FPB vs Advanced Modeled Iterative Reconstruction– ADMIRE). A mathematical observer model (i.e., computer detection algorithm) was implemented and used as the basis of image quality comparisons. It was found that image quality increased with increasing dose and decreasing phantom size. The CT system exhibited nonlinear noise and resolution properties, especially at very low-doses, large phantom sizes, and for low-contrast objects. Objective image quality metrics generally increased with increasing dose and ADMIRE strength, and with decreasing phantom size. The ADMIRE algorithm could offer comparable image quality at reduced doses or improved image quality at the same dose (increase in detectability index by up to 163% depending on iterative strength). The use of automatic exposure control resulted in more consistent image quality with changing phantom size.

Based on those results, the dose reduction potential of ADMIRE was further assessed specifically for the task of detecting small (<=6 mm) low-contrast (<=20 HU) lesions. A new low-contrast detectability phantom (with uniform background) was designed and fabricated using a multi-material 3D printer. The phantom was imaged at multiple dose levels and images were reconstructed with FBP and ADMIRE. Human perception experiments were performed to measure the detection accuracy from FBP and ADMIRE images. It was found that ADMIRE had equivalent performance to FBP at 56% less dose.

Using the same image data as the previous study, a number of different mathematical observer models were implemented to assess which models would result in image quality metrics that best correlated with human detection performance. The models included naïve simple metrics of image quality such as contrast-to-noise ratio (CNR) and more sophisticated observer models such as the non-prewhitening matched filter observer model family and the channelized Hotelling observer model family. It was found that non-prewhitening matched filter observers and the channelized Hotelling observers both correlated strongly with human performance. Conversely, CNR was found to not correlate strongly with human performance, especially when comparing different reconstruction algorithms.

The uniform background phantoms used in the previous studies provided a good first-order approximation of image quality. However, due to their simplicity and due to the complexity of iterative reconstruction algorithms, it is possible that such phantoms are not fully adequate to assess the clinical impact of iterative algorithms because patient images obviously do not have smooth uniform backgrounds. To test this hypothesis, two textured phantoms (classified as gross texture and fine texture) and a uniform phantom of similar size were built and imaged on a SOMATOM Flash scanner (Siemens Healthcare). Images were reconstructed using FBP and a Sinogram Affirmed Iterative Reconstruction (SAFIRE). Using an image subtraction technique, quantum noise was measured in all images of each phantom. It was found that in FBP, the noise was independent of the background (textured vs uniform). However, for SAFIRE, noise increased by up to 44% in the textured phantoms compared to the uniform phantom. As a result, the noise reduction from SAFIRE was found to be up to 66% in the uniform phantom but as low as 29% in the textured phantoms. Based on this result, it clear that further investigation was needed into to understand the impact that background texture has on image quality when iterative reconstruction algorithms are used.

To further investigate this phenomenon with more realistic textures, two anthropomorphic textured phantoms were designed to mimic lung vasculature and fatty soft tissue texture. The phantoms (along with a corresponding uniform phantom) were fabricated with a multi-material 3D printer and imaged on the SOMATOM Flash scanner. Scans were repeated a total of 50 times in order to get ensemble statistics of the noise. A novel method of estimating the noise power spectrum (NPS) from irregularly shaped ROIs was developed. It was found that SAFIRE images had highly locally non-stationary noise patterns with pixels near edges having higher noise than pixels in more uniform regions. Compared to FBP, SAFIRE images had 60% less noise on average in uniform regions for edge pixels, noise was between 20% higher and 40% lower. The noise texture (i.e., NPS) was also highly dependent on the background texture for SAFIRE. Therefore, it was concluded that quantum noise properties in the uniform phantoms are not representative of those in patients for iterative reconstruction algorithms and texture should be considered when assessing image quality of iterative algorithms.

The move beyond just assessing noise properties in textured phantoms towards assessing detectability, a series of new phantoms were designed specifically to measure low-contrast detectability in the presence of background texture. The textures used were optimized to match the texture in the liver regions actual patient CT images using a genetic algorithm. The so called “Clustured Lumpy Background” texture synthesis framework was used to generate the modeled texture. Three textured phantoms and a corresponding uniform phantom were fabricated with a multi-material 3D printer and imaged on the SOMATOM Flash scanner. Images were reconstructed with FBP and SAFIRE and analyzed using a multi-slice channelized Hotelling observer to measure detectability and the dose reduction potential of SAFIRE based on the uniform and textured phantoms. It was found that at the same dose, the improvement in detectability from SAFIRE (compared to FBP) was higher when measured in a uniform phantom compared to textured phantoms.

The final trajectory of this project aimed at developing methods to mathematically model lesions, as a means to help assess image quality directly from patient images. The mathematical modeling framework is first presented. The models describe a lesion’s morphology in terms of size, shape, contrast, and edge profile as an analytical equation. The models can be voxelized and inserted into patient images to create so-called “hybrid” images. These hybrid images can then be used to assess detectability or estimability with the advantage that the ground truth of the lesion morphology and location is known exactly. Based on this framework, a series of liver lesions, lung nodules, and kidney stones were modeled based on images of real lesions. The lesion models were virtually inserted into patient images to create a database of hybrid images to go along with the original database of real lesion images. ROI images from each database were assessed by radiologists in a blinded fashion to determine the realism of the hybrid images. It was found that the radiologists could not readily distinguish between real and virtual lesion images (area under the ROC curve was 0.55). This study provided evidence that the proposed mathematical lesion modeling framework could produce reasonably realistic lesion images.

Based on that result, two studies were conducted which demonstrated the utility of the lesion models. The first study used the modeling framework as a measurement tool to determine how dose and reconstruction algorithm affected the quantitative analysis of liver lesions, lung nodules, and renal stones in terms of their size, shape, attenuation, edge profile, and texture features. The same database of real lesion images used in the previous study was used for this study. That database contained images of the same patient at 2 dose levels (50% and 100%) along with 3 reconstruction algorithms from a GE 750HD CT system (GE Healthcare). The algorithms in question were FBP, Adaptive Statistical Iterative Reconstruction (ASiR), and Model-Based Iterative Reconstruction (MBIR). A total of 23 quantitative features were extracted from the lesions under each condition. It was found that both dose and reconstruction algorithm had a statistically significant effect on the feature measurements. In particular, radiation dose affected five, three, and four of the 23 features (related to lesion size, conspicuity, and pixel-value distribution) for liver lesions, lung nodules, and renal stones, respectively. MBIR significantly affected 9, 11, and 15 of the 23 features (including size, attenuation, and texture features) for liver lesions, lung nodules, and renal stones, respectively. Lesion texture was not significantly affected by radiation dose.

The second study demonstrating the utility of the lesion modeling framework focused on assessing detectability of very low-contrast liver lesions in abdominal imaging. Specifically, detectability was assessed as a function of dose and reconstruction algorithm. As part of a parallel clinical trial, images from 21 patients were collected at 6 dose levels per patient on a SOMATOM Flash scanner. Subtle liver lesion models (contrast = -15 HU) were inserted into the raw projection data from the patient scans. The projections were then reconstructed with FBP and SAFIRE (strength 5). Also, lesion-less images were reconstructed. Noise, contrast, CNR, and detectability index of an observer model (non-prewhitening matched filter) were assessed. It was found that SAFIRE reduced noise by 52%, reduced contrast by 12%, increased CNR by 87%. and increased detectability index by 65% compared to FBP. Further, a 2AFC human perception experiment was performed to assess the dose reduction potential of SAFIRE, which was found to be 22% compared to the standard of care dose.

In conclusion, this dissertation provides to the scientific community a series of new methodologies, phantoms, analysis techniques, and modeling tools that can be used to rigorously assess image quality from modern CT systems. Specifically, methods to properly evaluate iterative reconstruction have been developed and are expected to aid in the safe clinical implementation of dose reduction technologies.

Effective Dose Estimation in Fast-kV Switch Dual Energy Computed Tomography

Purpose

The objective of our study was to test a new approach to approximating organ dose by using the effective energy of the combined 80kV/140kV beam used in fast kV switch dual-energy (DE) computed tomography (CT). The two primary focuses of the study were to first validate experimentally the dose equivalency between MOSFET and ion chamber (as a gold standard) in a fast kV switch DE environment, and secondly to estimate effective dose (ED) of DECT scans using MOSFET detectors and an anthropomorphic phantom.

Materials and Methods

A GE Discovery 750 CT scanner was employed using a fast-kV switch abdomen/pelvis protocol alternating between 80 kV and 140 kV. The specific aims of our study were to (1) Characterize the effective energy of the dual energy environment; (2) Estimate the f-factor for soft tissue; (3) Calibrate the MOSFET detectors using a beam with effective energy equal to the combined DE environment; (4) Validate our calibration by using MOSFET detectors and ion chamber to measure dose at the center of a CTDI body phantom; (5) Measure ED for an abdomen/pelvis scan using an anthropomorphic phantom and applying ICRP 103 tissue weighting factors; and (6) Estimate ED using AAPM Dose Length Product (DLP) method. The effective energy of the combined beam was calculated by measuring dose with an ion chamber under varying thicknesses of aluminum to determine half-value layer (HVL).

Results

The effective energy of the combined dual-energy beams was found to be 42.8 kV. After calibration, tissue dose in the center of the CTDI body phantom was measured at 1.71 ± 0.01 cGy using an ion chamber, and 1.73±0.04 and 1.69±0.09 using two separate MOSFET detectors. This result showed a -0.93% and 1.40 % difference, respectively, between ion chamber and MOSFET. ED from the dual-energy scan was calculated as 16.49 ± 0.04 mSv by the MOSFET method and 14.62 mSv by the DLP method.

Three-dimensional outcomes of twin-block appliance treatment and the influence of the postured wax bite

Aims 1 To identify the 3D soft tissue volumetric and linear landmark changes following treatment with the Twin-Block Appliance TBA. 2 To estimate the TBA treatment outcome on the soft tissue facial profile volumetric and linear landmark changes from the Postured Wax Bite (PWB). 3 To identify if there is any association between certain soft tissue landmark variables and successful treatment outcome of the TBA as measured by the reduction in overjet. 4 To assess the effects of TBA treatment on facial expressions. Materials and Methods Forty-seven Caucasian subjects with Class II division 1 were recruited. 3D images captured of each subject, pre-treatment (T1), with the PWB (T2) and at the end of treatment (T3). Soft tissue volumetric and linear changes as well as the correlation between facial parameters and successful treatment were calculated. Results The mean soft tissue volumetric change from T1 to T3 was 22.24 ± 16.73 cm³. Soft tissue profile linear changes from T1-T3 for lower facial landmarks were 4-5 mm. From T1-T3, the mean soft tissue volumetric change of the total sample was 60% of the change produced by the PWB (T1 to T2). Correlations were weak for all 3D facial parameters and successful overjet reduction. Facial expression changes were only significant for the lower landmarks. Conclusions 1 TBA treatment, in growing subjects, increased the lower facial soft tissue volume and caused forward movement of the lower soft tissue facial profile landmarks.2 The PWB can be used to estimate the treatment outcome of the TBA on soft tissue profile changes.3 No association was found between soft tissue landmark variables and successful overjet reduction.4 TBA treatment had no effect on the upper facial landmarks for each facial expression but it changed the lower facial expressions significantly except for maximal smile in males.

(Table A1) Diatom isotope measurements from ODP Hole 145-882A

In comparison to other sectors of the marine system, the palaeoceanography of the subarctic North Pacific Ocean is poorly constrained. New diatom isotope records of d13C, d18O, d30Si (d13Cdiatom, d18Odiatom, and d30Sidiatom) are presented alongside existing geochemical and isotope records to document changes in photic zone conditions, including nutrient supply and the efficiency of the soft-tissue biological pump, between Marine Isotope Stage (MIS) 4 and MIS 5e. Peaks in opal productivity in MIS 5b/c and MIS 5e are both associated with the breakdown of the regional halocline stratification and increased nutrient supply to the photic zone. Whereas the MIS 5e peak is associated with low rates of nutrient utilisation, the MIS 5b/c peak is associated with significantly higher rates of nutrient utilisation. Both peaks, together with other smaller increases in productivity in MIS 4 and 5a, culminate with a significant increase in freshwater input which strengthens/re-establishes the halocline and limits further upwelling of sub-surface waters to the photic zone. Whilst d30Sidiatom and previously published records of diatom d15N (d15Ndiatom) (Brunelle et al., 2007, 2010) show similar trends until the latter half of MIS 5a, the records become anti-correlated after this juncture and into MIS 4, suggesting a possible change in photic zone state such as may occur with a shift to iron or silicon limitation.

Structural and functional vulnerability to elevated pCO2 in marine benthic communities

The effect of elevated pCO2/low pH on marine invertebrate benthic biodiversity, community structure and selected functional responses which underpin ecosystem services (such as community production and calcification) was tested in a medium-term (30 days) mesocosm experiment in June 2010. Standardised intertidal macrobenthic communities, collected (50.3567°N, 4.1277°W) using artificial substrate units (ASUs), were exposed to one of seven pH treatments (8.05, 7.8. 7.6, 7.4, 7.2, 6.8 and 6.0). Community net calcification/dissolution rates, as well as changes in biomass, community structure and diversity, were measured at the end of the experimental period. Communities showed significant changes in structure and reduced diversity in response to reduced pH: shifting from a community dominated by calcareous organisms to one dominated by non-calcareous organisms around either pH 7.2 (number of individuals and species) or pH 7.8 (biomass). These results were supported by a reduced total weight of CaCO3 structures in all major taxa at lowered pH and a switch from net calcification to net dissolution around pH 7.4 (Omega calc = 0.78, Omega ara = 0.5). Overall community soft tissue biomass did not change with pH and high mortality was observed only at pH 6.0, although molluscs and arthropods showed significant decreases in soft tissue. This study supports and refines previous findings on how elevated pCO2 can induce changes in marine biodiversity, underlined by differential vulnerability of different phyla. In addition, it shows significant elevated pCO2-/low pH-dependent changes in fundamental community functional responses underpinning changes in ecosystem services.

Seawater carbonate chemistry and biological processes of Sepia officinalis during experiments, 2010

Acidification of ocean surface waters by anthropogenic carbon dioxide (CO2) emissions is a currently developing scenario that warrants a broadening of research foci in the study of acid-base physiology. Recent studies working with environmentally relevant CO2 levels, indicate that some echinoderms and molluscs reduce metabolic rates, soft tissue growth and calcification during hypercapnic exposure. In contrast to all prior invertebrate species studied so far, growth trials with the cuttlefish Sepia officinalis found no indication of reduced growth or calcification performance during long-term exposure to 0.6 kPa CO2. It is hypothesized that the differing sensitivities to elevated seawater pCO2 could be explained by taxa specific differences in acid-base regulatory capacity. In this study, we examined the acid-base regulatory ability of S. officinalis in vivo, using a specially modified cannulation technique as well as 31P NMR spectroscopy. During acute exposure to 0.6 kPa CO2, S. officinalis rapidly increased its blood [HCO3] to 10.4 mM through active ion-transport processes, and partially compensated the hypercapnia induced respiratory acidosis. A minor decrease in intracellular pH (pHi) and stable intracellular phosphagen levels indicated efficient pHi regulation. We conclude that S. officinalis is not only an efficient acid-base regulator, but is also able to do so without disturbing metabolic equilibria in characteristic tissues or compromising aerobic capacities. The cuttlefish did not exhibit acute intolerance to hypercapnia that has been hypothesized for more active cephalopod species (squid). Even though blood pH (pHe) remained 0.18 pH units below control values, arterial O2 saturation was not compromised in S. officinalis because of the comparatively lower pH sensitivity of oxygen binding to its blood pigment. This raises questions concerning the potentially broad range of sensitivity to changes in acid-base status amongst invertebrates, as well as to the underlying mechanistic origins. Further studies are needed to better characterize the connection between acid-base status and animal fitness in various marine species.

(Table 3, Page 417) Table 3. The concentrations of Zn, Cu, Pb, Cd, Ni, Co, Ag, Mn and Fe in a soluble in 1M HCl fraction of ferromanganese nodules of Slupsk Furrow in the southern Baltic sea

The concentration of Zn, Cu, Pb, Cd, Ni, Co, Ag, Mn, Fe, Ca, Mg, K and Na in molluscs Macoma balthica, Mya arenaria, Cardium glaucum, Mytilus edulis and Astarte borealis from the southern Baltic was determined. The surface sediments and ferromanganese concretions associated with the molluscs were also analysed for concentration of these metals. Species- and region-dependent differences in the metal levels of the organisms were observed. The properties of molluscs analysed which have a tendency toward elevated biological tolerance of selected trace metals were specified. The interelement relationship between metal concentrations in the soft tissue and the shell was estimated and was discussed.

Utility of sarcoma-specific fusion gene analysis in paraffin-embedded material for routine diagnosis at a specialist centre.

AIMS: Diagnosis of soft tissue sarcomas can be difficult. It can be aided by detection of specific genetic aberrations in many cases. This study assessed the utility of a molecular genetics/cytogenetics service as part of the routine diagnostic service at the Royal Marsden Hospital. METHODS: A retrospective audit was performed over a 15-month period to evaluate the diagnostic usefulness for soft tissue sarcomas with translocations of fluorescence in situ hybridisation (FISH) and reverse-transcriptase PCR (RT-PCR) in paraffin-embedded (PE) material. Results were compared with histology, and evaluated. RESULTS: Molecular investigations were performed on PE material in 158 samples (total 194 RT-PCR and 174 FISH tests), of which 85 were referral cases. Synovial sarcoma, Ewing sarcoma and low-grade fibromyxoid sarcoma were the most commonly tested tumours. Myxoid liposarcoma showed the best histological and molecular concordance, and alveolar rhabdomyosarcoma showed the best agreement between methods. FISH had a higher sensitivity for detecting tumours (73%, compared with 59% for RT-PCR) with a better success rate than RT-PCR, although the latter was specific in identifying the partner gene for each fusion. In particular, referral blocks in which methods of tissue fixation and processing were not certain resulted in higher RT-PCR failure rates. CONCLUSIONS: FISH and RT-PCR on PE tissue are practical and effective ancillary tools in the diagnosis of soft tissue sarcomas. They are useful in confirming doubtful histological diagnoses and excluding malignant diagnoses. PCR is less sensitive than FISH, and the use of both techniques is optimal for maximising the detection rate of translocation-positive sarcomas.

Fiducial Marker Guided Prostate Radiotherapy: A Review

Image guided radiotherapy (IGRT) is an essential tool in the accurate delivery of modern radiotherapy techniques. Prostate radiotherapy positioned using skin marks or bony anatomy may be adequate for delivering a relatively homogenous whole pelvic radiotherapy dose but these are not reliable when using reduced margins, dose escalation or hypo-fractionated stereotactic radiotherapy. Fiducial markers (FMs) for prostate IGRT have been in use since the 1990's. They require surgical implantation and provide a surrogate for the position of the prostate gland. A variety of FMs are available and they can be used in a number of ways. This review aims to establish the evidence for using prostate FMs in terms of feasibility, implantation procedures, types of FMs used, FM migration, imaging modalities used and the clinical impact of FMs. A search strategy was defined and a literature search was carried out in Medline. Inclusion and exclusion criteria were applied which resulted in 50 papers being included in this review. The evidence demonstrates that FMs provide a more accurate surrogate for the position of the prostate than either external skin marks or bony anatomy. A combination of FM alignment and soft tissue analysis is currently the most effective and widely available approach to ensuring accuracy in prostate IGRT. FM implantation is safe and well tolerated. FM migration is possible but minimal. Standardisation of all techniques and procedures in relation to the use of prostate FMs is required. Finally a clinical trial investigating a non-surgical alternative to prostate FMS is introduced.

Développement de matériaux à base de protéines extraites du byssus de la moule bleue Mytilus edulis

Le byssus est un amas de fibres que les moules produisent afin de s’ancrer aux surfaces immergées sous l’eau. Ces fibres sont pourvues de propriétés mécaniques impressionnantes combinant rigidité, élasticité et ténacité élevées. De plus, elles possèdent un comportement d’auto-guérison de leurs propriétés mécaniques en fonction du temps lorsque la contrainte initialement appliquée est retirée. Les propriétés mécaniques de ces fibres sont le résultat de l’agencement hiérarchique de protéines de type copolymère blocs riches en collagène et de la présence de métaux formant des liens sacrificiels réversibles avec certains acides aminés comme les DOPA et les histidines. Bien que cette fibre soit très intéressante pour la production de matériaux grâce à son contenu élevé en collagène potentiellement biocompatible, cette ressource naturelle est traitée comme un déchet par les mytiliculteurs. L’objectif de cette thèse était de valoriser cette fibre en extrayant les protéines pour générer une nouvelle classe de matériaux biomimétiques. Un hydrolysat de protéines de byssus (BPH) riche en acides aminés chargés, i.e. ~30 % mol, et permettant de former des films a pu être généré. Lorsque solubilisé à pH 10.5, le BPH forme un hydrogel contenant des structures en triple hélice de collagène et des feuillets β anti-parallèles intra- et inter-moléculaires. Suite à l’évaporation de l’eau, le film de BPH résultant est insoluble en milieu aqueux à cause des structures secondaires très stables agissant comme points de réticulation effectifs. Les propriétés mécaniques des films de BPH sont modulables en fonction du pH. Au point isoélectrique (pI = 4.5), les interactions électrostatiques entre les charges opposées agissent comme points de réticulation et augmentent la rigidité des films et leur contrainte à la rupture sans affecter la déformation à la rupture. À pH plus élevé ou plus bas que le pI, les performances mécaniques des films sont plus faibles à cause de la répulsion entre les groupements fonctionnels de même charge qui interagissent plutôt avec les molécules d’eau et causent le gonflement de la matrice protéique des films. Le BPH contenant un nombre élevé d’acides aminés chargés et réactifs, nous avons pu réticuler les films de manière covalente à l’aide d’EDC ou de glutaraldéhyde. Les propriétés mécaniques des films sont modulables en fonction de la concentration d’EDC utilisée lors de la réticulation ou en employant du glutaraldéhyde comme agent réticulant. Les films sont à la fois plus rigides et plus forts avec un degré de réticulation élevé, mais perdent leur extensibilité à mesure que les segments libres de s’étirer lors d’une traction deviennent entravés par les points de réticulation. La réticulation augmente également la résistance à la dégradation enzymatique par la collagénase, les films les plus fortement réticulés lui étant pratiquement insensibles. La spectroscopie infrarouge montre enfin que la réticulation entraîne une transition de feuillets β anti-parallèles inter-moléculaires vers des structures de type hélices de collagène/PPII hydratées. Des liens sacrificiels ont été formés dans les films de BPH par traitement au pI et/ou avec différents métaux, i.e. Na+, Ca2+, Fe3+, afin de moduler les propriétés mécaniques statiques et d’évaluer le rôle de ces traitements sur le comportement d’auto-guérison lors de tests mécaniques cycliques avec différents temps de repos. Plus la valence des ions métalliques ajoutés augmente, plus les propriétés mécaniques statiques affichent un module, une contrainte à la rupture et une ténacité élevés sans toutefois affecter la déformation à la rupture, confirmant la formation de liens sacrificiels. Les tests mécaniques cycliques montrent que les traitements au pI ou avec Ca2+ créent des liens sacrificiels ioniques réversibles qui mènent à un processus d’auto-guérison des performances mécaniques dépendant du pH. L’ajout de Fe3+ à différentes concentrations module les performances mécaniques sur un plus large intervalle et la nature plus covalente de son interaction avec les acides aminés permet d’atteindre des valeurs nettement plus élevées que les autres traitements étudiés. Le Fe3+ permet aussi la formation de liens sacrificiels réversibles menant à l’auto-guérison des propriétés mécaniques. Les spectroscopies Raman et infrarouge confirment que le fer crée des liaisons avec plusieurs acides aminés, dont les histidines et les DOPA. Les résultats dans leur ensemble démontrent que les films de BPH sont des hydrogels biomimétiques du byssus qui peuvent être traités ou réticulés de différentes façons afin de moduler leurs performances mécaniques. Ils pourraient ainsi servir de matrices pour des applications potentielles dans le domaine pharmaceutique ou en ingénierie tissulaire.

Hallux rigidus: Arthroplasty or arthrodesis. What technique produces better results?

Hallux rígidus (HR) affects the first metatarsophalangeal joint (MTPJ) between 35% and 60% of the population over 65 years and there are multiple ways of treatment. Depending on the radiological stage where you find the deformity determines the procedure to be performed; in the early stages cheilectomy techniques and corrective osteotomy is performed while the more advanced ratings, the surgeon chooses destructive techniques considered as arthrodesis and arthroplasty. This final of degree project aims to focus on 1 MTPJ destructive techniques to clarify which of the procedures generates better results by a number of parameters; outcomes of the American Orthopaedic Foot scale and Ankle Society Hallux metatarsophalangeal Interphalangeal-scale (AOFAS), range of motion (ROM) of the 1ºAMTF, radiological classification. As for the implant arthroplasty technique, this article offers information on material and design that generates better relating to patient characteristics such as age, inflammatory joint diseases, viability and durability of the implant results. The conclusion from this review is that the values obtained in the arthrodesis according AOFAS decrease due to loss of mobility, but both techniques have similar values of effectiveness and concludes with the decision that the technique used is determined taking into account various factors and patient characteristics. Keywords: Hallux rígidus; (Hallux Rígidus) and surgery treatment; Hallux Rígidus arthrodesis; Hallux Rígidus arthroplasty; Hallux Rígidus (arthroplasty and arthrodesis).

Socket-shield and immediate implantation

Introduction - After tooth extraction, the alveolar bone undergoes a remodeling process, wich leads to horizontal and vertical bone loss. These resorption processes complicate dental rehabilitation, particularly in connection with implants. Various methods of guided bone regeneration have been described to retain the original dimension of the bone after extraction. Most procedures use filler materials and membranes to support the buccal plate and soft tissue, to stabilize the coagulum and to prevent epithelial ingrowth. It has also been suggested that resorption of the buccal bundle bone can be avoided by leaving a buccal root segment (socket-shield technique) in place, because the biological integrity of the buccal periodontum remains untouched. This method has also been decribed in connection with immediate implant placement. Objective - This literature review aim enumerate and describe the different treatments and tissue reactions after tooth extraction, immediate and delayed implantation. The socketshield technique, the evolution in tooth extraction and immediate implantation with high esthetic results due to the preservation of hard and soft tissues by leaving a buccal root segment in place. Materials and methods - For this purpose a research has been done and data was obtained from on-line resources: Medline, Pubmed, Scielo, Bireme, Bon, books and specialized magazines which was conducted between January 2016 and May 2016. A number of articles have been obtained in English and French ,published between 1997 and 2015 . The key words used were implantology, dental implant, hard/soft tissue, tooth extraction, immediate implantation, delayed implantation, socket-shield. Conclusion - In socket-shield technique, there were neither functional nor aesthetic changes in soft and hard tissues. It’s already a routine practice in the arsenal of highaesthetic immediate implantology and should be used when indicated. Although this technique is quiet promising, we should be aware of the incoming publications about a larger follow up and the predictability of leaving a fragment inside the socket after an extraction.

Evaluation of negative pressure vacuum-assisted system in acute and chronic wounds closure. Our experience

Negative-pressure therapy or vacuum-assisted closure (VAC) has been used in clinical applications since the 1940’s and has increased in popularity over the past decade. This dressing technique consists of an open cell foam dressing put into the wound cavity, a vacuum pump produces a negative pressure and an adhesive drape. A controlled sub atmospheric pressure from 75 to 150 mmHg is applied. The vacuum-assisted closure has been applied by many clinicians to chronic wounds in humans; however it cannot be used as a replacement for surgical debridement. The initial treatment for every contaminated wound should be the necrosectomy. The VAC therapy has a complementary function and the range of its indications includes pressure sores, stasis ulcers, chronic wounds such as diabetic foot ulcers, post traumatic and post operative wounds, infected wounds such as necrotizing fasciitis or sternal wounds, soft-tissue injuries, bone exposed injuries, abdominal open wounds and for securing a skin graft. We describe our experience with the VAC dressing used to manage acute and chronic wounds in a series of 135 patients, with excellent results together with satisfaction of the patients.

The bovine pericardial patch in breast reconstruction: a case report

In the last years there has been a growing demand of plastic surgery for soft tissue reconstruction. In response to this, many biological and synthetic devices have been produced, aiming to allow wide and complex body reshapings. Acellular dermal matrices are one of these devices, and are made of human or animal tissues made acellular after their sampling. They are used for cervical, breast and abdominal wall reconstruction. Tutopatch®, generally used for face reconstruction or neurosurgery, is made of acellular bovine pericardium, and its high amount of collagen allows a fast tissue healing and a scaffold for the surrounding tissue rigeneration. In our case report Tutopatch® has been used in immediate breast reconstruction after mastectomy. This device has been used to close laterally the subpectoral pocket, allowing a bigger volume prosthesis to be placed We have not experienced particular postoperatory complications, and after 12 months of follow up we have found a valid functional and aesthetic result. We consider Tutopatch® as a valid alternative to other acellular dermal matrices specifically designed for breast reconstruction.