Showing papers by "Alex Rovira published in 2001"

Isolated demyelinating syndromes: comparison of CSF oligoclonal bands and different MR imaging criteria to predict conversion to CDMS

Abstract: Aim of the study: To evaluate and compare the capacity of oligoclonal bands (OB) and three sets of MR imaging criteria to predict the conversion of clinically isolated syndromes (CIS) to clinically definite multiple sclerosis (CDMS). Patients and methods: One hundred and twelve patients with CIS were prospectively studied with MR imaging and determination of OB. Based on the clinical follow-up (conversion or not conversion to CDMS), we calculated the sensitivity, specificity accuracy, positive and negative predictive value of the OB, and MR imaging criteria proposed by Paty et al, Fazekas et al and Barkhof et al. Results: CDMS developed in 26 (23.2%) patients after a mean follow-up of 31 months (range 12-62). OB were positive in 70 (62.5%) patients and were associated with a higher risk of developing CDMS. OB showed a sensitivity of 81%, specificity of 43%, accuracy of 52%, positive predictive value (PPV) of 30% and negative predictive value (NPV) of 88%. Paty and Fazekas criteria showed the same results ...

Magnetization transfer ratio values and proton MR spectroscopy of normal-appearing cerebral white matter in patients with liver cirrhosis.

Abstract: BACKGROUND AND PURPOSE: Hepatic encephalopathy in cirrhotic patients may be the clinical manifestation of disturbed cerebral cell volume homeostasis. The aim of this study was to investigate the presence of significant changes in magnetization transfer ratio (MTR) values, which could reflect an increase in free water within the brain of patients with liver cirrhosis, and to correlate these findings with minimal hepatic encephalopathy and proton MR spectroscopy (1 H-MRS) abnormalities. METHODS: Twenty-four patients with liver cirrhosis and eight healthy control volunteers were included in the study. MR imaging studies included conventional T1- and T2-weighted imaging, 1 H-MRS, and magnetization transfer imaging. MTR and 1 H-MRS values were obtained from normal-appearing white matter and were correlated with each other and with the presence of minimal hepatic encephalopathy. RESULTS: 1 H-MRS showed a decrease in choline and myo-inositol and an increase in glutamine 1 glutamate with respect to creatine 1 phosphocreatine. MTR values were significantly decreased in cirrhotic patients when compared with healthy control volunteers, although this decrease was not significantly higher in the patients with minimal hepatic encephalopathy. The decreases in MTR values correlated with increases in glutamine 1 glutamate. CONCLUSION: The MTR decrease in patients with liver cirrhosis may be caused by lowgrade astrocytic swelling produced as a response to the osmotic stress occurring in these patients. However, in this cross-sectional study, we did not find a correlation between MTR decrease and the presence of minimal hepatic encephalopathy, probably because of limitations in MTR quantification techniques.

Usefulness of magnetic resonance spectroscopy for diagnosis of hepatic encephalopathy in a patient with relapsing confusional syndrome.

Abstract: Magnetic resonance spectroscopy allows the assessment of several metabolites in brain tissue. In patients with hepatic encephalopathy, this technique shows a rise in glutamine and a decrease in myoinositol in brain tissue. However, the role of magnetic resonance spectroscopy in the diagnosis of hepatic encephalopathy is not known. We report the case of a patient with a relapsing confusional syndrome who underwent magnetic resonance spectroscopy. Previously, hepatic encephalopathy was ruled out because of the negative results of a transjugular liver biopsy and normal hepatic venous pressure gradient. The results of magnetic resonance were characteristic of hepatic encephalopathy. Abdominal computed tomography demonstrated large portosystemic shunts associated with cirrhosis of the liver. This case shows that magnetic resonance spectroscopy is an useful technique for the diagnosis of hepatic encephalopathy in selected cases, such as those without clinical signs of cirrhosis and/or large portosystemic shunts.

Conversión a esclerosis múltiple clínicamente definida tras un síndrome medular aislado: valor de la resonancia magnética craneal y medular

Abstract: Fundamento Los sindromes medulares aislados (SMA) pueden ser el primer brote de esclerosis multiple. El objetivo del presente estudio fue evaluar las caracteristicas clinicas, paraclinicas y la utilidad de la resonancia magnetica (RM) medular y craneal para predecir la conversion a esclerosis multiple clinicamente definida (EMCD) en pacientes con un SMA. Pacientes y metodo Evaluamos a 38 pacientes con un SMA. Se practico un protocolo clinico, asi como pruebas paraclinicas y RM craneal y medular. Resultados El 42,8% de los pacientes que cumplian los criterios diagnosticos de la RM craneal de Paty (p Conclusiones La RM craneal permite detectar a pacientes con un alto riesgo de desarrollar una EMCD y la RM medular aumenta la sensibilidad de conversion a EMCD.

Automatic segmentation of the encephalic parenchyma using fuzzy techniques

Abstract: This work shows an automatic, fast and reproducible algorithm to segment the encephalic parenchyma in magnetic resonance (MR) images. The algorithm has been implemented following a rule-based schema in which a fuzzy analysis of MR images information has been introduced to deal with the vagueness associated to the images. The obtention of a fuzzy result helps to determine the accuracy of the classification. The evaluation of the results is based on the use of quality indexes, which allow the comparison with previous works.