Intervertebral disc characterisation by elastography: a preliminary study.

BiomecAM chai

Lectures on graded differential algebras and noncommutative geometry

These notes contain a survey of some aspects of the theory of graded differential algebras and of noncommutative differential calculi as well as of some applications connected with physics. They also give a description of several new developments.Comment: 71 pages; minor typo correction

Non-invasive biomechanical characterization of intervertebral discs by shear wave ultrasound elastography: a feasibility study.

PublishedJournal ArticleThe final publication is available at Springer via http://dx.doi.org/10.1007/s00330-014-3382-8OBJECTIVES: Although magnetic resonance is widely spread to assess qualitatively disc morphology, a simple method to determine reliably intervertebral disc status is still lacking. Shear wave elastography is a novel technique that allows quantitative evaluation of soft-tissues' mechanical properties. The aim of this study was to assess preliminary the feasibility and reliability of mechanical characterization of cervical intervertebral discs by elastography and to provide first reference values for asymptomatic subjects. METHODS: Elastographic measurements were performed to determine shear wave speed (SWS) in C6-C7 or C7-T1 disc of 47 subjects; repeatability and inter-operator reproducibility were assessed. RESULTS: Global average shear wave speed (SWS) was 3.0 ± 0.4 m/s; measurement repeatability and inter-user reproducibility were 7 and 10%, respectively. SWS was correlated with both subject's age (p = 1.3 × 10(-5)) and body mass index (p = 0.008). CONCLUSIONS: Shear wave elastography in intervertebral discs proved reliable and allowed stratification of subjects according to age and BMI. Applications could be relevant, for instance, in early detection of disc degeneration or in follow-up after trauma; these results open the way to larger cohort studies to define the place of this technique in routine intervertebral disc assessment. KEY POINTS: A simple method to obtain objectively intervertebral disc status is still lacking. Shear wave elastography was applied in vivo to assess intervertebral discs. Elastography showed promising results in biomechanical disc evaluation. Elastography could be relevant in clinical routine for intervertebral disc assessment.ParisTech BiomecAM chair programParisTechYves Cotrel FoundationsSociété GénéraleProteorCove

Intervertebral disc characterization by shear wave elastography: An in vitro preliminary study.

Published onlineJOURNAL ARTICLEAuthor's accepted (post-print) manuscriptThe final version of record is available at http://dx.doi.org/10.1177/0954411914540279Patient-specific numerical simulation of the spine is a useful tool both in clinic and research. While geometrical personalization of the spine is no more an issue, thanks to recent technological advances, non-invasive personalization of soft tissue's mechanical properties remains a challenge. Ultrasound elastography is a relatively recent measurement technique allowing the evaluation of soft tissue's elastic modulus through the measurement of shear wave speed. The aim of this study was to determine the feasibility of elastographic measurements in intervertebral disc. An in vitro approach was chosen to test the hypothesis that shear wave speed can be used to evaluate intervertebral disc mechanical properties and to assess measurement repeatability. In total, 11 oxtail intervertebral discs were tested in compression to determine their stiffness and apparent elastic modulus at rest and at 400 N. Elastographic measurements were performed in these two conditions and compared to these mechanical parameters. The protocol was repeated six times to determine elastographic measurement repeatability. Average shear wave speed over all samples was 5.3 ± 1.0 m/s, with a repeatability of 7% at rest and 4.6% at 400 N; stiffness and apparent elastic modulus were 266.3 ± 70.5 N/mm and 5.4 ± 1.1 MPa at rest, respectively, while at 400 N they were 781.0 ± 153.8 N/mm and 13.2 ± 2.4 MPa, respectively. Correlations were found between elastographic measurements and intervertebral disc mechanical properties; these preliminary results are promising for further in vivo application.ParisTech BiomecAM chair programProteorParisTechYves Cotrel Foundation

In vivo cervical intervertebral disc characterisation by elastography.

PublishedJournal ArticleThis is an Accepted Manuscript of an article published by Taylor & Francis in Computer Methods in Biomechanics and Biomedical Engineering on 30/07/2014, available online: http://www.tandfonline.com/10.1080/10255842.2014.931515Not availableParisTech BiomecAM chair programProteorSociété GénéraleCoveaParisTechYves Cotrel Foundation

Non-invasive scoring of cellular atypia in keratinocyte cancers in 3D LC-OCT images using Deep Learning

Diagnosis based on histopathology for skin cancer detection is today's gold standard and relies on the presence or absence of biomarkers and cellular atypia. However it suffers drawbacks: it requires a strong expertise and is time-consuming. Moreover the notion of atypia or dysplasia of the visible cells used for diagnosis is very subjective, with poor inter-rater agreement reported in the literature. Lastly, histology requires a biopsy which is an invasive procedure and only captures a small sample of the lesion, which is insufficient in the context of large fields of cancerization. Here we demonstrate that the notion of cellular atypia can be objectively defined and quantified with a non-invasive in-vivo approach in three dimensions (3D). A Deep Learning (DL) algorithm is trained to segment keratinocyte (KC) nuclei from Line-field Confocal Optical Coherence Tomography (LC-OCT) 3D images. Based on these segmentations, a series of quantitative, reproducible and biologically relevant metrics is derived to describe KC nuclei individually. We show that, using those metrics, simple and more complex definitions of atypia can be derived to discriminate between healthy and pathological skins, achieving Area Under the ROC Curve (AUC) scores superior than 0.965, largely outperforming medical experts on the same task with an AUC of 0.766. All together, our approach and findings open the door to a precise quantitative monitoring of skin lesions and treatments, offering a promising non-invasive tool for clinical studies to demonstrate the effects of a treatment and for clinicians to assess the severity of a lesion and follow the evolution of pre-cancerous lesions over time.© 2022. The Author(s)

Multilocal field trials to test alternative products to reduce copper applications to control potato late blight in organic systems

The main objective of those trials was to determine alternatives to massive copper utilization to control potato late blight (Phytophthora infestans (Mont.) de Bary) in organic systems. To reach such a target, we first performed a screening of candidates products and additives under controlled conditions in the laboratory. Thereafter, the most promising products were tested in the field in 2006. Those trials were set up in three different sites, two sites in Belgium and one site in France. Herseaux (B) and Loos-en-Gohelle (F) are situated near by see level in an important potato culture basin with silty soil. Libramont is located at 500 m of altitude, far from any potato culture basin, with a sandy-loamy and stony soil. The cultivar Ditta was used in Belgium while the cultivar Juliette was planted in France. Their resistance to foliage late blight is, respectively, medium and medium-high. In total 8 modalities were compared. The products were applied in accordance to the advice of the local late blight warning system. The control was sprayed, at each advice, with 3 kg/ha of copper sulphate (Bordeaux mixture). We tested two additives to Bordeaux mixture, used at the 3 kg/ha rate as well, the first one is a short chain amino-acid extract, used to enhance rainfastness, while the other one is an hydrogen peroxide stabilised with an organic molecule. This second product was used for its disinfectant effect added to the protection effect of copper sulphate. We also tested the efficiency of a formulation presenting a low copper concentration (Glutex CU 90 with 10% copper) and of an association between a potassium phosphite and a copper tallate (Solucuivre with 5% copper). Those two components were also evaluated separately. Finally, we tested a product containing rhamnolipid biosurfactant (Zonix) supposed to physically destroy the zoospore's membrane. The 2006 climatic conditions were very particular. June and July were very dry while August was very wet with optimum late blight development conditions. The disease development was very slow during July and radically increased during August

Longitudinal grey and white matter changes in frontotemporal dementia and Alzheimer's disease

Behavioural variant frontotemporal dementia (bvFTD) and Alzheimer's disease (AD) dementia are characterised by progressive brain atrophy. Longitudinal MRI volumetry may help to characterise ongoing structural degeneration and support the differential diagnosis of dementia subtypes. Automated, observer-independent atlas-based MRI volumetry was applied to analyse 102 MRI data sets from 15 bvFTD, 14 AD, and 10 healthy elderly control participants with consecutive scans over at least 12 months. Anatomically defined targets were chosen a priori as brain structures of interest. Groups were compared regarding volumes at clinic presentation and annual change rates. Baseline volumes, especially of grey matter compartments, were significantly reduced in bvFTD and AD patients. Grey matter volumes of the caudate and the gyrus rectus were significantly smaller in bvFTD than AD. The bvFTD group could be separated from AD on the basis of caudate volume with high accuracy (79% cases correct). Annual volume decline was markedly larger in bvFTD and AD than controls, predominantly in white matter of temporal structures. Decline in grey matter volume of the lateral orbitofrontal gyrus separated bvFTD from AD and controls. Automated longitudinal MRI volumetry discriminates bvFTD from AD. In particular, greater reduction of orbitofrontal grey matter and temporal white matter structures after 12 months is indicative of bvFTD