Specifics of cardiac magnetic resonance imaging in children

SummaryThis review points out three specific features of cardiac magnetic resonance imaging (MRI) in children: the small size of the heart modifies the usual balance between signal-to-noise ratio and spatial resolution; the higher and more variable heart rate limits tissue characterization and temporal resolution; and motion artefacts (notably respiratory motions) must be dealt with. In the second part of this review, we present the current and future practices of cardiac magnetic resonance (CMR) in children, based on the experience of all French paediatric cardiac MRI centres

The effectiveness of policy evaluation: insights from the health care sector in Mexico and Chile

Over time, the predominant tendency of many governments’ agencies has been to evaluate a programme or policy investing large amount of resources in supporting policy evaluation. However, recommendations suggested by policy evaluators are not always taken up. Moreover, there is relatively little evidence of the extent of policy evaluation effectiveness (i.e. the influence of evaluation on the programme evaluated) and the factors which have significant impact on it. This dissertation aims to shed light on this issue by focusing on the Mexican and Chilean experiences of policy evaluation in the health care sector. It provides a detailed analysis of the extent to which evaluations have led to changes in policies and programmes and reveals a rather limited effectiveness of policy evaluation in these countries. I argue that shortcomings in the effectiveness of policy evaluation can be explained by institutional and political factors, primarily the nature of Intra Governmental Relations (IGR), but also the quality of bureaucracy, the level of democracy, the autonomy of policy evaluators, and the type of policy evaluation framework. While all of these factors seem to have some influence, the relationship between the executive and legislature is clearly the key determinant of the take up of recommendations. Thus, the findings of this thesis suggest that strengthening coordination between the different parts of government is needed to enhance the effectiveness of policy evaluation. In addition, the analysis also suggests that policy evaluation is likely to be more effective when it incorporates budgetary incentives

El sistema de monitoreo y evaluación del estado de Chihuahua: el mercado y los costos de las evaluaciones de programas públicos

Este artículo tiene como propósito describir el Sistema de Monitoreo y Evaluación (m&e) en el estado de Chihuahua y analizar sus lo-gros y desafíos, especialmente en torno a las características del mercado de evaluaciones, los procedimientos y costos de contratación. Para su realización se emplea una metodología mixta que incluye el análisis cuantitativo rela-cionado con la información estadística sobre las contrataciones y evaluaciones realizadas y una metodología cualitativa, sobre el diseño y or-ganización del Sistema de m&e y el proceso de evaluación. A partir de este estudio de caso, se concluye que el Sistema de m&e muestra avances importantes, pero también requiere la revisión de su diseño institucional, la relevancia de las políticas y los programas que se seleccionan para ser evaluados, aumentar la transparencia de los procesos de contratación y definir criterios para determinar los precios pagados en cada caso. Su valor radica en la importancia del análisis del diseño institucional de estos sistemas. Aunque dicho análisis se desarrolla a nivel local, permite entender la operación de otros sistemas a nivel nacional y las propuestas son válidas en cual-quier contexto.This paper aims to describe the Monitoring and Evaluation (m&e) System in the state of Chihuahua and to analyze its achievements and challenges, particularly regarding the market, procedures and costs of evaluations. For this purpose, mixed methodology is used, including quantitative analysis of statistical data on evaluations performed, as well as qualitative analysis of the m&e design, organization and the evaluation process. The case study shows relevant progress of the m&e System. However, its institutional design, the relevance of policies and programs selected for evaluation and the insufficient transparency of hiring processes need to be revised, as well as the criteria for determining the prices for each case. Its value lies in the importance of analyzing the institutional design of these systems and even though it is on a local level it allows for understanding the operation of other systems on a national level, and proposals are valid in any context

Real time flow with fast GPU reconstruction for continuous assessment of cardiac output

A novel approach for continuous cardiac output quantification during an exercise was developed and implemented on a heterogeneous image reconstruction system. Combination of spiral real-time PCMR sequence with parallel imaging allowed on high-temporal acquisition. Application of a GPU for image processing resulted in almost instantaneous reconstruction. An external computer equipped with the GPU was networked using CORBA technology. This let on seamless processing from a clinician point of view. The implementation was tested and validated against our multi -core CP

Colon wall motility: comparison of novel quantitative semi-automatic measurements using cine MRI

Background Recently, cine magnetic resonance imaging (MRI) has shown promise for visualizing movement of the colonic wall, although assessment of data has been subjective and observer dependent. This study aimed to develop an objective and semi-automatic imaging metric of ascending colonic wall movement, using image registration techniques. Methods Cine balanced turbo field echo MRI images of ascending colonic motility were acquired over 2 min from 23 healthy volunteers (HVs) at baseline and following two different macrogol stimulus drinks (11 HVs drank 1 L and 12 HVs drank 2 L). Motility metrics derived from large scale geometric and small scale pixel movement parameters following image registration were developed using the post ingestion data and compared to observer grading of wall motion. Inter and intra-observer variability in the highest correlating metric was assessed using Bland–Altman analysis calculated from two separate observations on a subset of data. Key Results All the metrics tested showed significant correlation with the observer rating scores. Line analysis (LA) produced the highest correlation coefficient of 0.74 (95% CI: 0.55–0.86), p < 0.001 (Spearman Rho). Bland–Altman analysis of the inter- and intra-observer variability for the LA metric, showed almost zero bias and small limits of agreement between observations (−0.039 to 0.052 intra-observer and −0.051 to 0.054 inter-observer, range of measurement 0–0.353). Conclusions & Inferences The LA index of colonic motility derived from cine MRI registered data provides a quick, accurate and non-invasive method to detect wall motion within the ascending colon following a colonic stimulus in the form of a macrogol drink

Free-breathing myocardial T2 measurements at 1.5T

POSTER PRESENTATIONInternational audienc

A multimodal real-time MRI articulatory corpus of French for speech research

In this work we describe the creation of ArtSpeechMRIfr: a real-time as well as static magnetic resonance imaging (rtMRI, 3D MRI) database of the vocal tract. The database contains also processed data: denoised audio, its phonetically aligned annotation, articulatory contours, and vocal tract volume information , which provides a rich resource for speech research. The database is built on data from two male speakers of French. It covers a number of phonetic contexts in the controlled part, as well as spontaneous speech, 3D MRI scans of sustained vocalic articulations, and of the dental casts of the subjects. The corpus for rtMRI consists of 79 synthetic sentences constructed from a phonetized dictionary that makes possible to shorten the duration of acquisitions while keeping a very good coverage of the phonetic contexts which exist in French. The 3D MRI includes acquisitions for 12 French vowels and 10 consonants, each of which was pronounced in several vocalic contexts. Ar-ticulatory contours (tongue, jaw, epiglottis, larynx, velum, lips) as well as 3D volumes were manually drawn for a part of the images

Real time magnetic resonance assessment of septal curvature accurately tracks acute hemodynamic changes in pediatric pulmonary hypertension

International audienceBACKGROUND:This study assesses the relationship between septal curvature and mean pulmonary artery pressure and indexed pulmonary vascular resistance in children with pulmonary hypertension. We hypothesized that septal curvature could be used to estimate right ventricular afterload and track acute changes in pulmonary hemodynamics.METHODS AND RESULTS:Fifty patients with a median age of 6.7 years (range, 0.45-16.5 years) underwent combined cardiac catheterization and cardiovascular magnetic resonance. The majority had idiopathic pulmonary arterial hypertension (n=30); the remaining patients had pulmonary hypertension associated with repaired congenital heart disease (n=17) or lung disease (n=3). Mean pulmonary artery pressure and pulmonary vascular resistance were acquired at baseline and during vasodilation. Septal curvature was measured using real-time cardiovascular magnetic resonance. There was a strong correlation between mean pulmonary artery pressure and SCmin at baseline and during vasodilator testing (r=-0.81 and -0.85, respectively; P<0.01). A strong linear relationship also existed between pulmonary vascular resistance and minimum septal curvature indexed to cardiac output both at baseline and during vasodilator testing (r=-0.88 and -0.87, respectively; P<0.01). Change in septal curvature metrics moderately correlated with absolute change in mean pulmonary artery pressure and pulmonary vascular resistance, respectively (r=0.58 and -0.74; P<0.01). Septal curvature metrics were able to identify vasoresponders with a sensitivity of 83% (95% confidence interval, 0.36-0.99) and a specificity of 91% (95% confidence interval, 0.77-0.97), using the Sitbon criteria. Idiopathic pulmonary arterial hypertension subgroup analysis revealed 3 responders with ΔSCmin values of 0.523, 0.551, and 0.568. If the middle value of 0.551 is taken as a cutoff, the approximate sensitivity would be 67% and the specificity would be 93%.CONCLUSIONS:Septal curvature metrics are able to estimate right ventricular afterload and track acute changes in pulmonary hemodynamics during vasodilator testing. This suggests that septal curvature could be used for continuing assessment of load in pulmonary hypertension

Synchronisation vocale et mouvement compensé en reconstruction pour une ciné IRM de la parole

National audienceL’imagerie dynamique du conduit vocal permet d’étudier et de modéliser la production de laparole. La durée moyenne de chaque son est d’environ 80 ms. Lemouvement de chaque articulateur, en particulier la langue, doit être mesuréavec suffisamment de précision. Actuellement la fluoroscopie à rayon X estutilisée cliniquement. L’IRM temps réel permet la visualisation directe desmouvements articulatoires [1] mais reste limitée en résolution. Lasynchronisation de l’IRM par un système acoustique est possible [2] maisnécessite l’exécution de mouvements articulatoires avec une parfaitereproductibilité. Dans ce travail nous proposons un dispositif optimisé pour laréalisation d’une imagerie dynamique IRM de la parole avec une hauterésolution spatiale et temporelle. Il s’appuie sur l’utilisation conjointe d’unmicrophone compatible IRM enregistrant la parole pendant l’acquisition IRMet d’une reconstruction d’images synchronisées a posteriori incluant unecompensation du mouvement. Cette reconstruction permet une prise encompte de la variabilité de répétition de la phrase lors de l’acquisition