Dynamic Three-Dimensional Shoulder Mri during Active Motion for Investigation of Rotator Cuff Diseases.

BACKGROUND: MRI is the standard methodology in diagnosis of rotator cuff diseases. However, many patients continue to have pain despite treatment, and MRI of a static unloaded shoulder seems insufficient for best diagnosis and treatment. This study evaluated if Dynamic MRI provides novel kinematic data that can be used to improve the understanding, diagnosis and best treatment of rotator cuff diseases. METHODS: Dynamic MRI provided real-time 3D image series and was used to measure changes in the width of subacromial space, superior-inferior translation and anterior-posterior translation of the humeral head relative to the glenoid during active abduction. These measures were investigated for consistency with the rotator cuff diseases classifications from standard MRI. RESULTS: The study included: 4 shoulders with massive rotator cuff tears, 5 shoulders with an isolated full-thickness supraspinatus tear, 5 shoulders with tendinopathy and 6 normal shoulders. A change in the width of subacromial space greater than 4mm differentiated between rotator cuff diseases with tendon tears (massive cuff tears and supraspinatus tear) and without tears (tendinopathy) (p = 0.012). The range of the superior-inferior translation was higher in the massive cuff tears group (6.4mm) than in normals (3.4mm) (p = 0.02). The range of the anterior-posterior translation was higher in the massive cuff tears (9.2 mm) and supraspinatus tear (9.3 mm) shoulders compared to normals (3.5mm) and tendinopathy (4.8mm) shoulders (p = 0.05). CONCLUSION: The Dynamic MRI enabled a novel measure; 'Looseness', i.e. the translation of the humeral head on the glenoid during an abduction cycle. Looseness was better able at differentiating different forms of rotator cuff disease than a simple static measure of relative glenohumeral position.The authors received no specific funding for this work

In Vivo Detection of Succinate by Magnetic Resonance Spectroscopy as a Hallmark of SDHx Mutations in Paraganglioma

International audiencePurpose: Germline mutations in genes encoding mitochon-drial succinate dehydrogenase (SDH) are found in patients with paragangliomas, pheochromocytomas, gastrointestinal stromal tumors, and renal cancers. SDH inactivation leads to a massive accumulation of succinate, acting as an oncometabolite and which levels, assessed on surgically resected tissue are a highly specific biomarker of SDHx-mutated tumors. The aim of this study was to address the feasibility of detecting succinate in vivo by magnetic resonance spectroscopy. Experimental Design: A pulsed proton magnetic resonance spectroscopy (1 H-MRS) sequence was developed, optimized, and applied to image nude mice grafted with Sdhb À/À or wild-type chromaffin cells. The method was then applied to patients with paraganglioma carrying (n ¼ 5) or not (n ¼ 4) an SDHx gene mutation. Following surgery, succinate was measured using gas chromatography/mass spectrometry, and SDH protein expression was assessed by immunohistochemistry in resected tumors. Results: A succinate peak was observed at 2.44 ppm by 1 H-MRS in all Sdhb À/À-derived tumors in mice and in all paragangliomas of patients carrying an SDHx gene mutation, but neither in wild-type mouse tumors nor in patients exempt of SDHx mutation. In one patient, 1 H-MRS results led to the identification of an unsus-pected SDHA gene mutation. In another case, it helped define the pathogenicity of a variant of unknown significance in the SDHB gene. Conclusions: Detection of succinate by 1 H-MRS is a highly specific and sensitive hallmark of SDHx mutations. This non-invasive approach is a simple and robust method allowing in vivo detection of the major biomarker of SDHx-mutated tumors. Clin Cancer Res; 22(5); 1120–9. Ó2015 AACR

Qualité de la modélisation en imagerie dynamique de la microcirculation avec injection d'un agent de contraste (nouveaux critères et applications en multimodalité)

L'imagerie dynamique de microcirculation dispose d'un potentiel important pour l'étude de nombreuses pathologies in vivo, en complément à l'imagerie conventionnelle. Or pour obtenir des cartes de paramètres microcirculatoires à partir des données dynamiques, une modélisation doit être effectuée. Les méthodes actuelles pour vérifier la qualité de cette modélisation n'étant pas satisfaisantes, le potentiel de l'imagerie dynamique en est fortement réduit. Nous montrons ici que pour étudier la modélisation, tant qualitativement que quantitativement, il est nécessaire de traiter séparément les questions de qualité d'ajustement et de robustesse,. Nous avons mis au point une nouvelle méthode, basée sur l'autocorrélation, pour estimer les amplitudes des composantes corrélées et non corrélées des signaux. Cette méthode nous a permis de corriger le coefficient de corrélation R et la matrice de covariance, et ainsi de définir de nouveaux critères de fiabilité et une matrice de covariance corrigée pour les remplacer. L'amélioration apportée par les nouveaux critères est démontrée sur simulations et sur données IRM dynamiques réelles. La matrice de covariance corrigée estime la robustesse et la redondance locale des paramètres. Elle peut être calculée conjointement pour compléter les nouveaux critères de fiabilité. Les améliorations apportées par les nouveaux indicateurs doivent faciliter le développement de l'imagerie de la microcirculation. L'intérêt des nouveaux indicateurs est illustré sur un grand panel de données d'imagerie. Ils constituent plus généralement de nouveaux outils de traitement du signal.The microcirculation dynamic imaging could be a relevant imaging when used in addition with more conventional medical imaging. The dynamic data are modeled, pixel by pixel, to provide microcirculation parameters maps. However there is no efficient tool to assess the modeling quality. The relevance of the parametric maps provided by the dynamic imaging is then limited. Here, we show that a qualitative and quantitative study of the modeling quality needs first to distinguish two questions : the quality of the data fits and the robusness for the random noise. To separate the questions, we designed a new autocorrelation based method which is able to estimate the amplitude of both the correlated and not correlated component of a signal. This method allowed us to correct the correlation coefficient R and the covariance matrix estimation. It allowed us to define new reliability criteria and a corrected covariance matrix to replace the more conventional indicators. It was shown, on simulated data and in MR data, that new reliabily criteria are obviously better than the R to assess fit quality. The corrected covariance matrix which assess the robustness and the redoundancy can be calculated in addition to the reliability criteria unlike conventional one which is limited to good data fits. Thus the modeling quality is obviously improved by the new indicators. It should improve the clinical use of microcirculation dynamic imaging where guaranties are needed against artefact. The interest of the new criteria is showed on many different dynamic data. More generaly the new indicators appear as new efficient tools for signal analysis.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Effets d'un traitement antiangiogénique sur la microcirculation tumorale (mise en évidence par IRMf chez la souris à l'aide d'un agent de contraste macromoléculaire)

PARIS6-Bibl.Pitié-Salpêtrie (751132101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Etude des tumeurs annexielles du pelvis féminin en IRM fonctionnelle (mise au point des techniques et applications cliniques.)

La caractérisation préopératoire des tumeurs annexielles est déterminante pour la prise en charge chirurgicale. L IRM fonctionnelle dynamique avec injection (DCE-MRI) permet une optimisation de la caractérisation des tissus. Les tumeurs annexielles se distinguent selon leur courbe dynamique de rehaussement qui reflètent l immaturité de la paroi vasculaire et l expression du VEGFR-2 sur les cellules endothéliales. En vue d une analyse quantitative du rehaussement, il est souhaitable de réaliser une séquence turbo-FLASH avec des angles élevés pour obtenir une dynamique de rehaussement optimale associée à une quasi linéarité de la relation entre le signal et la concentration de gadolinium. L initialisation par un modèle de Kéty étendu stabilise la modélisation compartimentale à 4 paramètres qui permet la description la plus complète des échanges entre les compartiments vasculaire et interstitiel. L optimisation de l acquisition et du post traitement des datas ont permis la réalisation d une analyse quantitative de la prise de contraste, analyse reproductible et pertinente pour comprendre les phénomènes physiopathologiques au sein des tissus. Dans le domaine des tumeurs annexielles, la perfusion tissulaire et la fraction volumique sanguine sont plus élevées dans les tumeurs malignes que dans les tumeurs bénignes. Enfin, l analyse quqntitative du rehaussement a permis la mise en évidence de données pertinentes sur la perfusion du myométre et tout particulièrement du myomètre interne qui pourrait avoir une rôle majeur dans l avenir dans le cadre des programmes de procréation médicalement assistéeThe preoperative characterization of adnexal tumors is crucial for surgical care. Dynamic contrast enhanced MR imaging (DCE-MRI) allows an optimization of the tissue characterization. Adnexal tumors differ according to their dynamic curve enhancement, which reflect the immaturity of the vascular wall and the expression of VEGFR-2 on endothelial cells. For a quantitative analysis of enhancement, a turbo-FLASH sequence with high angles is better to get both optimal dynamic enhancement range and an almost linear relationship between the signal and the concentration of gadolinium. Initialization by a extended Kéty model stabilizes our two-compartmental model which allows the best description of exchanges between the capillary and the interstitial spaces.Using quantitative DCE MRI, malignant adnexal tumors display higher tissue perfusion and blood volume fraction than benign tumors. Finally, quantitative DCE-MRI is a suitable, non-invasive tool to assess physiological microvascular states and variations in normal myometrium, and could potentially be used to assess the role of the inner myometrium in assisted reproductive therapy.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Méthodes d'analyse de la microcirculation tumorale en IRM

La néoangiogénèse est impliquée dans le développement des tumeurs. Certains facteurs stimulant l angiogénèse ont été isolés et peuvent être inhibés. La surveillance de l activité de ces thérapies inhibitrices, souvent cytostatiques, ne peut se baser sur une observation morphologique. L étude fonctionnelle de la microcirculation est possible en IRM grâce à l analyse de la pharmacocinétique de traceurs dans la tumeur.L activité d une thérapie antiangiogénique a été surveillée en IRM grâce au Spin Labeling (ASL) couplé à une suppression du bruit de fond. Cette technique permet de quantifier la perfusion tissulaire, grâce à un marquage électromagnétique des protons du sang. L ASL a permis de distinguer dès le 1er mois les patients répondeurs des patients en progression, ce que les mesures morphologiques ne révélaient qu à 3 mois. L analyse de la perméabilité capillaire par l analyse dynamique des rehaussements (ADR) tissulaires et artériels après injection de produit de contraste a été optimisée grâce à une séquence double écho dont la pondération était adaptée aux concentrations mesurées : T2* pour les concentrations élevées et T1 pour les basses. Cette technique a permis de réduire de 58% l erreur d estimation de la perméabilité capillaire. Le développement d une technique de mesure des temps de relaxation en une apnée a permis d améliorer les estimations de perfusion (ASL) et de perméabilité (ADR) en évitant d utiliser des valeurs de T1 tumorales approximatives lors de la quantification.En mesurant la perfusion et la perméabilité tumorale, cibles des traitements antiangiogéniques, l ASL et l ADR se présentent comme des méthodes attractives pour le suivi de ces thérapies.Angiogenesis plays a key role in tumor growth. New approaches to treat cancer by interfering with angiogenesis stimulating factors are now available. However, clinicians need new surrogates of antiangiogenic activity. Tumor size changes occure 2 or 3 month after the beginning of the treatment, which is to late. Functional analysis of tracer kinetic in tissue in MRI may be an attractive alternative.Antiangiogenic activity of a VEGF receptor inhibitor, was evaluated by tumor blood flow, assessed by arterial spin labeling (ASL) with background suppression. Preliminary results reveal a significant correlation (Spearman r = 0.90, p = .0002) between the change in blood flow at 1 month and change in tumor size measured at 4 months or the time of disease progression. A capillary permeability assessment in dynamic contrast enhancement (DCE) was optimized using a dual gradient echo sequence. This dual sequence was sensitive to high concentration thanks to T2* weighted images and to low concentrations with T1 weighted slices. The use of this sequence leads to reduce by 58% the permeability measurements.The development of a new technique to assess to relaxation time in the body within a single breath hold may improve perfusion and permeability measurements. Real relaxation time can be used for quantification instead of theoretical values, reducing systematic error.ASL and DCE have promise as early predictors of clinical response to antiangiogenic therapies and may help to identify non-responding patients.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Multivariate mathematical morphology for DCE-MRI image analysis in angiogenesis studies

International audienceWe propose a new computer aided detection framework for tumours acquired on DCE-MRI (Dynamic Contrast Enhanced Magnetic Resonance Imaging) series on small animals. In this approach we consider DCE-MRI series as multivariate images. A full multivariate segmentation method based on dimensionality reduction, noise filtering, supervised classification and stochastic watershed is explained and tested on several data sets. The two main key-points introduced in this paper are noise reduction preserving contours and spatio temporal segmentation by stochastic watershed. Noise reduction is performed in a special way that selects factorial axes of Factor Correspondence Analysis in order to preserves contours. Then a spatio-temporal approach based on stochastic watershed is used to segment tumours. The results obtained are in accordance with the diagnosis of the medical doctors

A free time point model for dynamic contrast enhanced exploration

International audienc