Magnetic resonance stress tagging in ischemic heart disease.

High-dose dobutamine magnetic resonance stress testing has been shown to be superior to dobutamine stress echocardiography for diagnosis of coronary artery disease (CAD). We determined the feasibility of quantitative myocardial tagging during low- and high-dose dobutamine stress and tested the ability of global systolic and diastolic quantitative parameters to identify patients with significant CAD. Twenty-five patients suspected of having significant CAD were examined with a standard high-dose dobutamine/atropine stress magnetic resonance protocol (1.5-T scanner, Philips). All patients underwent invasive coronary angiography as the standard of reference for the presence (n = 13) or absence (n = 12) of significant CAD. During low-dose dobutamine stress, systolic (circumferential shortening, systolic rotation, and systolic rotation velocity) and diastolic (velocity of circumferential lengthening and diastolic rotation velocity) parameters changed significantly in patients without CAD (all P < 0.05 vs. rest) but not in patients with CAD. Identification of patients without and with CAD during low-dose stress was possible using the diastolic parameter of "time to peak untwist." At high-dose stress, none of the global systolic or diastolic parameters showed the potential to identify the presence of significant CAD. With myocardial tagging, a quantitative analysis of systolic and diastolic function was feasible during low- and high-dose dobutamine stress. In our study, the diastolic parameter of time to peak untwist as assessed during low-dose dobutamine stress was the most promising global parameter for identification of patients with significant CAD. Thus quantitative myocardial tagging may become a tool that reduces the need for high-dose dobutamine stress.

Selective three-dimensional visualization of the coronary arterial lumen using arterial spin tagging.

Conventional coronary magnetic resonance angiography (MRA) techniques display the coronary blood-pool along with the surrounding structures, including the myocardium, the ventricular and atrial blood-pool, and the great vessels. This representation of the coronary lumen is not directly analogous to the information provided by x-ray coronary angiography, in which the coronary lumen displayed by iodinated contrast agent is seen. Analogous "luminographic" data may be obtained using MR arterial spin tagging (projection coronary MRA) techniques. Such an approach was implemented using a 2D selective "pencil" excitation for aortic spin tagging in concert with a 3D interleaved segmented spiral imaging sequence with free-breathing, and real-time navigator technology. This technique allows for selective 3D visualization of the coronary lumen blood-pool, while signal from the surrounding structures is suppressed.

Spiral MR myocardial tagging.

In the present study, complementary spatial modulation of magnetization (CSPAMM) myocardial tagging was extended with an interleaved spiral imaging sequence. The use of a spiral sequence enables the acquisition of grid-tagged images with a tagline distance as low as 4 mm in a single breath-hold. Alternatively, a high temporal resolution of 77 frames per second was obtained with 8-mm grid spacing. Ten healthy adult subjects were studied. With this new approach, high-quality images can be obtained and the tags persist throughout the entire cardiac cycle.

Discourse Type Clustering using POS n-gram Profiles and High-Dimensional Embeddings

Abstract: To cluster textual sequence types (discourse types/modes) in French texts, K-means algorithm with high-dimensional embeddings and fuzzy clustering algorithm were applied on clauses whose POS (part-ofspeech) n-gram profiles were previously extracted. Uni-, bi- and trigrams were used on four 19th century French short stories by Maupassant. For high-dimensional embeddings, power transformations on the chi-squared distances between clauses were explored. Preliminary results show that highdimensional embeddings improve the quality of clustering, contrasting the use of bi and trigrams whose performance is disappointing, possibly because of feature space sparsity.

Single breath-hold slice-following CSPAMM myocardial tagging.

Myocardial tagging has shown to be a useful magnetic resonance modality for the assessment and quantification of local myocardial function. Many myocardial tagging techniques suffer from a rapid fading of the tags, restricting their application mainly to systolic phases of the cardiac cycle. However, left ventricular diastolic dysfunction has been increasingly appreciated as a major cause of heart failure. Subtraction based slice-following CSPAMM myocardial tagging has shown to overcome limitations such as fading of the tags. Remaining impediments to this technique, however, are extensive scanning times (approximately 10 min), the requirement of repeated breath-holds using a coached breathing pattern, and the enhanced sensitivity to artifacts related to poor patient compliance or inconsistent depths of end-expiratory breath-holds. We therefore propose a combination of slice-following CSPAMM myocardial tagging with a segmented EPI imaging sequence. Together with an optimized RF excitation scheme, this enables to acquire as many as 20 systolic and diastolic grid-tagged images per cardiac cycle with a high tagging contrast during a short period of sustained respiration.

Accurate memory for object location by individuals with intellectual disability: Absolute spatial tagging instead of configural processing?

Using head-mounted eye tracker material, we assessed spatial recognition abilities (e.g., reaction to object permutation, removal or replacement with a new object) in participants with intellectual disabilities. The "Intellectual Disabilities (ID)" group (n=40) obtained a score totalling a 93.7% success rate, whereas the "Normal Control" group (n=40) scored 55.6% and took longer to fix their attention on the displaced object. The participants with an intellectual disability thus had a more accurate perception of spatial changes than controls. Interestingly, the ID participants were more reactive to object displacement than to removal of the object. In the specific test of novelty detection, however, the scores were similar, the two groups approaching 100% detection. Analysis of the strategies expressed by the ID group revealed that they engaged in more systematic object checking and were more sensitive than the control group to changes in the structure of the environment. Indeed, during the familiarisation phase, the "ID" group explored the collection of objects more slowly, and fixed their gaze for a longer time upon a significantly lower number of fixation points during visual sweeping.

Semantic domains and supersens tagging for domain-specific ontology learning

In this paper we propose a novel unsupervised approach to learning domain-specific ontologies from large open-domain text collections. The method is based on the joint exploitation of Semantic Domains and Super Sense Tagging for Information Retrieval tasks. Our approach is able to retrieve domain specific terms and concepts while associating them with a set of high level ontological types, named supersenses, providing flat ontologies characterized by very high accuracy and pertinence to the domain.

[112-POS] : Increased post-partum prevalence of hypertension and renal dysfunction after preeclampsia

OBJECTIVES: Women with a history of preeclampsia (PE) are at increased risk of long term cardiovascular and end-stage renal diseases. However, follow up of preeclamptic women is often omitted, mainly due to a weakness of knowledge of maternal caregivers and lack of comprehensive guidelines. The aim of this study was to define the prevalence of albuminuria, high blood pressure, and renal dysfunction 6 weeks after a preeclampsia. METHODS: This is a prospective case-control study comparing women presenting with preeclampsia to an unmatched control group of women with no hypertensive disorders of pregnancy. A complete medical assessment was performed at 6 weeks post-partum. Recruitment started in June 2010. RESULTS: 324 women were included in the PE group and 50 in the control one. Characteristics of both groups and results of the medical work-up at 6 weeks post-partum are presented in Table 1. Women with preeclampsia presented with a higher BMI, higher prevalence of office high blood pressure, pathological albuminuria and renal hyper-filtration than women in the control group. CONCLUSIONS: Prevalence of post-partum hypertension, and renal dysfunction is higher in women with PE than in uncomplicated pregnancies. Systematic assessment of renal risk factors 6 weeks after preeclampsia allows identification of high-risk women and early implementation of preventive and therapeutic strategies. DISCLOSURES: A. Ditisheim: None. B. Ponte: None. G. Wuerzner: None. M. Burnier: None. M. Boulvain: None. A. Pechère-Bertschi: None.

Quantification of the local heartwall motion by magnetic resonance myocardial tagging.

Sophisticated magnetic resonance tagging techniques provide powerful tools for the non-invasive assessment of the local heartwall motion towards a deeper fundamental understanding of local heart function. For the extraction of motion data from the time series of magnetic resonance tagged images and for the visualization of the local heartwall motion a new image analysis procedure has been developed. New parameters have been derived which allows quantification of the motion patterns and are highly sensitive to any changes in these patterns. The new procedure has been applied for heart motion analysis in healthy volunteers and in patient collectives with different heart diseases. The achieved results are summarized and discussed.

Combining protein identification and quantification: C-terminal isotope-coded tagging using sulfanilic acid.

Two methods of differential isotopic coding of carboxylic groups have been developed to date. The first approach uses d0- or d3-methanol to convert carboxyl groups into the corresponding methyl esters. The second relies on the incorporation of two 18O atoms into the C-terminal carboxylic group during tryptic digestion of proteins in H(2)18O. However, both methods have limitations such as chromatographic separation of 1H and 2H derivatives or overlap of isotopic distributions of light and heavy forms due to small mass shifts. Here we present a new tagging approach based on the specific incorporation of sulfanilic acid into carboxylic groups. The reagent was synthesized in a heavy form (13C phenyl ring), showing no chromatographic shift and an optimal isotopic separation with a 6 Da mass shift. Moreover, sulfanilic acid allows for simplified fragmentation in matrix-assisted laser desorption/ionization (MALDI) due the charge fixation of the sulfonate group at the C-terminus of the peptide. The derivatization is simple, specific and minimizes the number of sample treatment steps that can strongly alter the sample composition. The quantification is reproducible within an order of magnitude and can be analyzed either by electrospray ionization (ESI) or MALDI. Finally, the method is able to specifically identify the C-terminal peptide of a protein by using GluC as the proteolytic enzyme.

Microfabricated dual sprayer for on-line mass tagging of phosphopeptides.

Phosphopeptides tagging reactions by dinuclear zinc(II) complexes (1,3-bis[bis(2-pyridylmethyl)amino]-propan-2-olato dizinc(II)3+, called tag) were performed with a dual-channel microsprayer in electrospray ionization mass spectrometry. The reaction is first studied ex situ and analyzed with a commercial electrospray source. In situ reactions (i.e., inside the Taylor cone) were achieved with a dual-channel microsprayer both with the tag synthesized chemically before the experiments and with the tag electrogenerated by in situ oxidation of a zinc electrode, also used to apply the electrospray current. The device consists of a polyimide microchip with two microchannels (20 microm x 50 microm x 1 cm) etched on each side of the structure and connecting only at the tip of the microchip. We demonstrate here that mixing two solutions with different physicochemical properties inside the Taylor cone can be used to selectively tag target molecules.

Toward high-resolution myocardial tagging.

Magnetic resonance imaging with preceding tissue tagging is a robust method for assessing cardiac motion of the entire heartbeat cycle with a high degree of accuracy. One limitation of this technique, however, is the low resolution of the obtained displacement map of the labeled points within the myocardium. By a new tagging technique, which is based on the combination of two or more measurements of the same slice but with different grid positions, a highly improved resolution of cardiac motion data can be achieved. In combination with a multi-heart-phase echo-planar imaging sequence, such images with doubled grid frequency can be acquired in two short breath-hold periods.

Improved myocardial tagging contrast in cine balanced SSFP images.

PURPOSE: To improve the tag persistence throughout the whole cardiac cycle by providing a constant tag-contrast throughout all the cardiac phases when using balanced steady-state free precession (bSSFP) imaging. MATERIALS AND METHODS: The flip angles of the imaging radiofrequency pulses were optimized to compensate for the tagging contrast-to-noise ratio (Tag-CNR) fading at later cardiac phases in bSSFP imaging. Complementary spatial modulation of magnetization (CSPAMM) tagging was implemented to improve the Tag-CNR. Numerical simulations were performed to examine the behavior of the Tag-CNR with the proposed method, and to compare the resulting Tag-CNR with that obtained from the more commonly used spoiled gradient echo (SPGR) imaging. A gel phantom, as well as five healthy human volunteers, were scanned on a 1.5T scanner using bSSFP imaging with and without the proposed technique. The phantom was also scanned with SPGR imaging. RESULTS: With the proposed technique, the Tag-CNR remained almost constant during the whole cardiac cycle. Using bSSFP imaging, the Tag-CNR was about double that of SPGR. CONCLUSION: The tag persistence was significantly improved when the proposed method was applied, with better Tag-CNR during the diastolic cardiac phase. The improved Tag-CNR will support automated tagging analysis and quantification methods.

Assessment of systolic and diastolic LV function by MR myocardial tagging.

Heart failure has been divided into several different forms depending on etiology, clinical course and pathophysiology of left ventricular (LV) dysfunction. Systolic and diastolic dysfunction are characterized by a reduced cardiac output with normal (= diastolic dysfunction) or depressed (= systolic dysfunction) LV pump function. New diagnostic techniques such as magnetic resonance imaging (MRI) allow to determine noninvasively LV 3D motion by labelling specific myocardial regions (= myocardial "tagging") with a rectangular or radial grid. From the deformation of this grid rotational and translational motion of the heart can be derived. A "wringing" motion of the left ventricle has been described during systole which includes a clockwise rotation at the base and a counterclockwise rotation at the apex. During diastole, an "untwisting" motion has been demonstrated. In the normal heart, diastolic "untwisting" occurs primarily during isovolumic relaxation, analogous to the systolic "wringing" which takes place mainly during isovolumic contraction. A prolongation of the "untwisting" motion was found in the hypertrophied (aortic stenosis) and hibernating myocardium. Thus, heart failure is associated with profound alterations in the mechanical function of the heart which are manifested by changes in systolic "wringing" and diastolic "untwisting" motion.