Diagnòstic precoç de l'esclerosi múltiple

L'esclerosi múltiple afecta predominantment a dones joves, no es coneix el seu origen ni té tractament curatiu, però pot seguir-se el seu desenvolupament amb tècniques de diagnòstic per imatges, com la ressonància magnètica. El Dr. Rovira de la Unitat de Ressonància Magnètica de l'Hospital Universitari de la Vall d'Hebron ha demostrat l'eficiència del diagnòstic de l'esclerosi múltiple per a aquesta tècnica si es realitza dins les primeres setmanes del primer episodi neurològic. Això facilitaria el tractament dels pacients i, encara que no són teràpies curatives, produirien un efecte beneficiós disminuint la freqüència de posteriors episodis neurològics.La esclerosis múltiple afecta predominantemente a mujeres jóvenes, no se conoce su origen ni tiene tratamiento curativo, pero puede seguirse su desarrollo con técnicas de diagnosis por imágenes, como la resonancia magnética. El Dr. Rovira de la Unidad de Resonancia Magnética del Hospital Universitario Vall d'Hebron ha demostrado la eficiencia del diagnóstico de la esclerosis múltiple mediante esta técnica si se realiza dentro de las primeras semanas del primer episodio neurológico, lo que facilitaría el tratamiento de los pacientes y, aunque no sean terapias curativas, produciría un efecto beneficioso disminuyendo la frecuencia de posteriores episodios neurológicos

Application of a Mamdani-type fuzzy rule-based system to segment periventricular cerebral veins in susceptibility-weighted images

This paper presents an algorithm designed to segment veins in the periventricular region of the brain in susceptibility-weighted magnetic resonance images. The proposed algorithm is based on a Mamdani-type fuzzy rule-based system that enables enhancement of veins within periventricular regions of interest as the first step. Segmentation is achieved after determining the cut-off value providing the best trade-off between sensitivity and specificity to establish the suitability of each pixel to belong to a cerebral vein. Performance of the algorithm in susceptibility-weighted images acquired in healthy volunteers showed very good segmentation, with a small number of false positives. The results were not affected by small changes in the size and location of the regions of interest. The algorithm also enabled detection of differences in the visibility of periventricular veins between healthy subjects and multiple sclerosis patients. © Springer International Publishing Switzerland 2016.Postprint (author's final draft

Theta-modulation drives the emergence of connectivity patterns underlying replay in a network model of place cells

Place cells of the rodent hippocampus fire action potentials when the animal traverses a particular spatial location in any environment. Therefore for any given trajectory one observes a repeatable sequence of place cell activations. When the animal is quiescent or sleeping, one can observe similar sequences of activation known as replay, which underlie the process of memory consolidation. However, it remains unclear how replay is generated. Here we show how a temporally asymmetric plasticity rule during spatial exploration gives rise to spontaneous replay in a model network by shaping the recurrent connectivity to reflect the topology of the learned environment. Crucially, the rate of this encoding is strongly modulated by ongoing rhythms. Oscillations in the theta range optimize learning by generating repeated pre-post pairings on a time-scale commensurate with the window for plasticity, while lower and higher frequencies generate learning rates which are lower by orders of magnitude

Measuring iron deposits within focal lesions in patients presenting clinically isolated syndrome

Postprint (author's final draft

Theta-modulation drives the emergence of connectivity patterns underlying replay in a network model of place cells

Place cells of the rodent hippocampus fire action potentials when the animal traverses a particular spatial location in any environment. Therefore for any given trajectory one observes a repeatable sequence of place cell activations. When the animal is quiescent or sleeping, one can observe similar sequences of activation known as replay, which underlie the process of memory consolidation. However, it remains unclear how replay is generated. Here we show how a temporally asymmetric plasticity rule during spatial exploration gives rise to spontaneous replay in a model network by shaping the recurrent connectivity to reflect the topology of the learned environment. Crucially, the rate of this encoding is strongly modulated by ongoing rhythms. Oscillations in the theta range optimize learning by generating repeated pre-post pairings on a time-scale commensurate with the window for plasticity, while lower and higher frequencies generate learning rates which are lower by orders of magnitude

Measuring cervical cord atrophy in multiple sclerosis patients. A longitudinal MRI study

Postprint (author's final draft

Correlation between brain volume change and T2 relaxation time in patients with clinically isolated syndrome

Postprint (published version

Calculation of the variance in surveys of the economic climate

Public opinion surveys have become progressively incorporated into systems of official statistics. Surveys of the economic climate are usually qualitative because they collect opinions of businesspeople and/or experts about the long-term indicators described by a number of variables. In such cases the responses are expressed in ordinal numbers, that is, the respondents verbally report, for example, whether during a given trimester the sales or the new orders have increased, decreased or remained the same as in the previous trimester. These data allow to calculate the percent of respondents in the total population (results are extrapolated), who select every one of the three options. Data are often presented in the form of an index calculated as the difference between the percent of those who claim that a given variable has improved in value and of those who claim that it has deteriorated

Comparison between gadolinium-enhanced 2D T1-weighted gradient-echo and spin-echo sequences in the detection of active multiple sclerosis lesions on 3.0T MRI

Objectives To compare the sensitivity of enhancing multiple sclerosis (MS) lesions in gadolinium-enhanced 2D T1-weighted gradient-echo (GRE) and spin-echo (SE) sequences, and to assess the influence of visual conspicuity and laterality on detection of these lesions. Methods One hundred MS patients underwent 3.0T brain MRI including gadolinium-enhanced 2D T1-weighted GRE and SE sequences. The two sets of contrast-enhanced scans were evaluated in random fashion by three experienced readers. Lesion conspicuity was assessed by the image contrast ratio (CR) and contrast-to-noise ratio (CNR). The intracranial region was divided into four quadrants and the impact of lesion location on detection was assessed in each slice. Results Six hundred and seven gadolinium-enhancing MS lesions were identified. GRE images were more sensitive for lesion detection (0.828) than SE images (0.767). Lesions showed a higher CR in SE than in GRE images, whereas the CNR was higher in GRE than SE. Most misclassifications occurred in the right posterior quadrant. Conclusions The gadolinium-enhanced 2D T1-weighted GRE sequence at 3.0T MRI enables detection of enhancing MS lesions with higher sensitivity and better lesion conspicuity than 2D T1-weighted SE. Hence, we propose the use of gadolinium-enhanced GRE sequences rather than SE sequences for routine scanning of MS patients at 3.0T. Key Points • 2D SE and GRE sequences are useful for detecting active MS lesions. • Which of these sequences is more sensitive at high field remains uncertain. • GRE sequence showed better sensitivity for detecting active MS lesions than SE. • We propose GRE sequence for detecting active MS lesions at 3.0T.Postprint (author's final draft

Depósitos de Fe en lesiones focales de pacientes diagnosticados de síndrome clínicamente aislado

Postprint (author's final draft