C. A. Cuenod

New criteria for assessing fit quality in dynamic contrast-enhanced T1-weighted MRI for perfusion and permeability imaging

Contrast‐enhanced (CE) MRI provides in vivo physiological information that cannot be obtained by conventional imaging methods. This information is generally extracted by using models to represent the circulation of contrast agent in the body. However, the results depend on the quality of the fit obtained with the chosen model. Therefore, one must check the fit quality to avoid working on physiologically irrelevant parameters. In this study two dimensionless criteria—the fraction of modeling information (FMI) and the fraction of residual information (FRI)—are proposed to identify errors caused by poor fit. These are compared with more conventional criteria, namely the quadratic error and the correlation coefficient, both theoretically and with the use of simulated and real CE‐MRI data. The results indicate the superiority of the new criteria. It is also shown that these new criteria can be used to detect oversimplified models. Magn Reson Med, 2005.

Shear wave elastography of tumour growth in a human breast cancer model with pathological correlation

ObjectiveTo assess stiffness in a human breast cancer implanted in mice using shear wave elastography (SWE) during tumour growth and to correlate the results with pathology.MethodsLocal ethics committee for animal research approval was obtained. A human invasive ductal carcinoma was implanted subcutaneously in 24 athymic nude female mice. Ultrasound was longitudinally performed in 22 tumours, every 1–2xa0weeks. Maximum diameter and mean stiffness were collected. Seven tumours were measured both in vivo and ex vivo. Tumours of different sizes were removed for pathological analysis on which the percentages of viable cellular tissue, fibrosis and necrosis were measured.ResultsA total of 63 SWE measurements were performed. Stiffness increased during tumour growth with an excellent correlation with size (ru2009=u20090.94, Pu2009<u20090.0001). No differences were found between the values of stiffness in vivo and ex vivo (Pu2009=u20090.81). There was a significant correlation between elasticity and fibrosis (ru2009=u20090.83, Pu2009<u20090.0001), a negative correlation with necrosis (ru2009=u2009−0.76, pu2009=u20090.0004) but no significant correlation with cellular tissue (ru2009=u20090.40, pu2009=u20090.1).ConclusionFibrosis plays an important role in stiffness as measured by SWE, whereas necrosis is correlated with softness.Key Points• In a breast cancer model, ultrasound tumour stiffness is correlated with size.• Stiffness changes with tumour growth are correlated with pathological changes.• Stiffness is very well correlated with proportion of tumour fibrosis.• Stiffness is inversely correlated with proportion of tumour necrosis.• Tumour stiffness measurements are similar in vivo and ex vivo.

In vivo MRI assessment of placental and foetal oxygenation changes in a rat model of growth restriction using blood oxygen level-dependent (BOLD) magnetic resonance imaging

AbstractObjectivesTo evaluate whether changes in BOLD signal intensities following hyperoxygenation are related to intrauterine growth restriction (IUGR) in a rat model.MethodsIUGR was induced in pregnant rats by ligating the left vascular uterine pedicle at day 16 of gestation. BOLD MR imaging using a balanced steady-state free-precession (balanced-SSFP) sequence on a 1.5-T system was performed on day 19. Signal intensities (SI) before and after maternal hyperoxygenation were compared in the maternal liver and in control and growth-restricted foetoplacental units (FPUs).ResultsMaternal hyperoxygenation resulted in a significant increase in SI in all regions of interest (Pu2009<u20090.05) in the 18 rats. In the control group, the SI (mean ± SD) increased by 21xa0%u2009±u200915 in placentas (nu2009=u200974) and 13xa0%u2009±u20098.5 in foetuses (nu2009=u200953). In the IUGR group, the increase was significantly lower: 6.5xa0%u2009±u20094 in placentas (nu2009=u200936) and 7xa0%u2009±u20095.5 in foetuses (nu2009=u200934) (Pu2009<u20090.05).ConclusionBOLD MRI allows non-invasive assessment of the foetoplacental response to maternal hyperoxygenation in the rat and demonstrates its alteration in an IUGR model. This imaging method may provide a useful adjunct for the early diagnosis, evaluation, and management of human IUGR.Key Points• Intra-uterine growth restriction is an important cause of perinatal morbidity and mortality.n • Blood oxygen level-dependent MRI non-invasively assesses foetoplacental response to maternal hyperoxygenation.n • In the rat, foetoplacental response to maternal hyperoxygenation is altered in IUGR.n • Functional MRI may help to assess human IUGR.

Diffusion-weighted imaging for evaluation of uterine arterial embolization of fibroids.

To determine whether diffusion‐weighted imaging (DWI) characteristics could predict the effectiveness of uterine arterial embolization in treatment of fibroids.

New dynamic three-dimensional MRI technique for shoulder kinematic analysis.

To establish a new imaging technique using dynamic MRI three‐dimensional (3D) volumetric acquisition in real‐time, on six normal shoulders for the analysis of the 3D shoulder kinematics during continuous motion.

Endoscopic Management of Post-bariatric Surgery Fistula: a Tertiary Care Center Experience

Background and Study AimsPost-laparoscopic sleeve gastrectomy (LSG) fistula is a major complication, responsible for high morbidity. Endoscopic treatment represents an alternative to surgical management, with variable approaches and success rates. In this study, we aimed to evaluate the efficacy of endoscopic treatment in a tertiary care center.Patients and MethodsBetween March 2010 and March 2015, all patients referred to our center for endoscopic treatment of fistula related to laparoscopic sleeve gastrectomy were included. The primary endpoint was defined as a complete closure of the fistula without recurrence within the 2xa0months.ResultsA total of 26 patients were retrospectively included (73% female). The mean time between fistula diagnosis and first endoscopy was 27.4xa0days (±xa022). Twenty-three (88.4%) patients had a complete fistula closure after endoscopic treatment. The healing delay was 76.4xa0days (±u200942.8), and an average of 3.5 (±xa01.4) endoscopic procedures were required. Clinical efficacy was 100% when the endoscopic treatment was performed within the first 3xa0weeks, or 70% afterwards (pu2009=u20090.046). The fistula closure rate was similar between patients with endoscopic drainage (with or without other endoscopic techniques) and patient with closing techniques alone (85.7% vs. 89.5%, respectively).ConclusionEndoscopic treatment of fistula after LSG is efficient but requires early procedures within the first 3xa0weeks. Endoscopic strategies involving closing procedure or drainage procedure seem to be similar, but these data must be confirmed in large prospective clinical studies.

Nouvelle technique d’IRM dynamique en 3 dimensions pour l’analyse de la cinématique de l’épaule

Introduction De meilleures connaissances de la cinematique normale et pathologique de l’epaule pourraient ameliorer notre prise en charge diagnostique et therapeutique de la pathologie de la coiffe des rotateurs. Il n’existe, a ce jour, aucune technique d’imagerie permettant l’analyse de la cinematique en 3 dimensions (3-D) durant un mouvement continu pour cette articulation. L’objectif de notre travail est de mettre au point une nouvelle technique d’imagerie dynamique par IRM en realisant une acquisition volumetrique en temps reel. Materiel d’etude La serie comporte 6 epaules saines issues de 4 sujets, 1 homme et 3 femmes, d’âge moyen de 34,2xa0ans. Methodes Une acquisition standard statique etait d’abord realisee et servait de reference. Puis, une acquisition en 3D en temps reel durant la premiere phase d’abduction (FIESTA sequence) etait realisee. Les images obtenues etaient reconstruites en 3D. Le modele obtenu etait recale sur le modele 3D de reference. La position du centre de la tete humerale par rapport a la glene et la taille de l’espace sous-acromial etaient alors mesurees durant les differentes positions d’abduction. Une etude de reproductibilite intra-observateur a ete realisee. Resultats Pour les six epaules etudiees, il a ete possible, dans tous les cas, de realiser une acquisition en 3D durant un mouvement continu d’abduction de l’epaule et d’en etudier sa cinematique. L’abduction maximale etait en moyenne de 43° (de 30° a 60°) et la largeur de l’espace sous-acromial etait en moyenne de 7,7xa0mm (SDxa0±xa01,2). La tete humerale restait centree sur le centre de la glenexa0–xa0la variation maximale du centre de la tete humerale par rapport a la glene etait au maximum de 5,4xa0mm et la variation maximale de l’espace sous-acromial etait de 3,3xa0mm au cours de cette premiere phase d’abduction. Conclusion Cette etude a permis de mettre au point, pour la premiere fois, une technique d’IRM en 3D, durant un mouvement continu de l’epaule et d’en valider sa faisabilite. Les resultats suggerent que la position de la tete humerale par rapport a la glene reste stable lors de la premiere phase d’abduction chez un sujet sain. Une amelioration du protocole pourrait permettre une utilisation en pratique courante et peut etre ameliorer notre prise en charge diagnostique et therapeutique.

OP03.06: Fetomaternal pharmacokinetics of gadolinium chelate contrast agent after intravenous maternal application in mice

Objective: To investigate the intra-cardiac distribution of blood from central veins in a fetal lamb model using contrast-enhanced ultrasound imaging. Methods: Eighteen lambs at 135–138 days of gestation were studied using an acute intrauterine fetal lamb model. In 10 lambs contrast agent (CA) (Levovist 400 mg/ml) was injected through the tibial vein into the inferior vena cava (IVC), in 6 lambs into one of the umbilical veins (UV), and in 2 lambs through the right jugular vein into the superior vena cava (SVC). Continuous real-time ultrasound recordings were obtained of the fetal heart at the level of 4-chamber view and at the level of great vessels. Sequences of at least 50–60 images for each plane were analyzed off-line. Distribution of CA was estimated using the brightness intensity scale. Results: Almost 60% of the blood flow from the lower part of fetal body was directed to the left heart. About 40% of the UV blood reached the IVC through the ductus venosus, and 60% of the ductus venosus blood was directed to the left heart. Of the SVC blood flow, more than 90% was directed to the right atrium. Conclusion: Using CA we found that, in the near term fetal lamb, the left heart handles 60% of the oxygenated blood from ductus venosus, 60% of the blood from the lower part of fetal body and 10% of the SVC blood.

OC47: Placental functional MRI: a comprehensive mouse model

of third ventricle (Group 2). Abnormal cerebral findings in group 2 were always identified at the first neurosonogram, usually within midgestation, and were subsequently confirmed by magnetic resonance. In group 1, ventriculomegaly improved during pregnancy and eventually disappeared at birth in 11/16. In one case ventriculomegaly worsened and the infant albeit developing normally is now under consideration for neurosurgery. In all the other cases, diagnostic imaging and neurodevelopment appeared normal after birth. Of the 4 fetuses in group 2, 2 were terminated and autopsy confirmed the postnatal findings, 1 is affected by cortical maldevelopment and cerebral palsy, one with dilatation of third ventricle is developing normally at 14 months. Conclusions: Expert neurosonography and/or MR allow to identify subtle cerebral findings that have prognostic value in seemingly isolated mild cerebral ventriculomegaly. In this group of fetuses, there was no overt advantage of MR over ultrasound. Abnormal findings were usually detected prior to fetal viability.