975 resultados para MR dampers
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Repàs de com ha estat representada la Costa Brava, com a escenari d’exteriors, al món del cinema amb diverses localitzacions tant des d’una perspectiva metodològica documental com des d’una perspectiva metodològica simbòlica
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BACKGROUND: The Contegra® is a conduit made from the bovine jugular vein and then interposed between the right ventricle and the pulmonary artery. It is used for cardiac malformations in the reconstruction of right ventricular outflow tract. OBJECTIVE: To describe both normal and pathological appearances of the Contegra® in radiological imaging, to describe imaging of complications and to define the role of CT and MRI in postoperative follow-up. MATERIALS AND METHODS: Forty-three examinations of 24 patients (17 boys and 7 girls; mean age: 10.8 years old) with Contegra® conduits were reviewed. Anatomical description and measurements of the conduits were performed. Pathological items examined included stenosis, dilatation, plicature or twist, thrombus or vegetations, calcifications and valvular regurgitation. Findings were correlated to the echographic gradient through the conduit when available. RESULTS: CT and MR work-up showed Contegra® stenosis (n = 12), dilatation (n = 9) and plicature or twist (n = 7). CT displayed thrombus or vegetations in the Contegra® in three clinically infected patients. Calcifications of the conduit were present at CT in 12 patients and valvular regurgitation in three patients. The comparison between CT and/or MR results showed a good correlation between the echographic gradient and the presence of stenosis in the Contegra®. CONCLUSION: CT and MR bring additional information about permeability and postoperative anatomy especially when echocardiography is inconclusive. Both techniques depict the normal appearance of the conduit, and allow comparison and precise evaluation of changes in the postoperative follow-up.
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Comprend : Historiettes d'un ermite
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Purpose: To report the diffusion-weighted MR imaging (DWI) findings in hepatic alveolar echinococcosis (AE). To evaluate the usefulness of apparent diffusion coefficients (ADCs) for differentiating the 5 types of AE lesions (as reported by Kodama, Radiology, 2003).Methods and Materials: We retrospectively included 17 patients (10 women, mean age 64.3years) with 48 AE liver lesions (>1cm2) that had been investigated by 3-Tesla MR imaging between March 2008 and August 2011 performing our standard protocol including DWI (b-values: 0, 300 and 600s/mm2). In consensus, two radiologists assessed lesion characteristics such as diameter, cystic and/or fibrotic components including Kodama classification, signal intensity, contrast enhancement, calcifications (on CT), and measured the ADC of each lesion. AE was confirmed by serology, biopsy and/or surgery in all patients.Results: Seventeen lesions of Kodama type 1, 10 of type 2, 19 of type 3, 1 of type 4 and 1 of type 5 were found. Mean(±SD) ADC of all AE lesions was 1.75±0.45 ×10-3mm2/s. Mean(±SD) ADCs of Kodama type 1, 2, 3, 4 and 5 lesions were 1.74±0.55, 1.71±0.49, 1.82±0.36, 1.46±0 and 1.43±0 ×10-3mm2/s, respectively. No significant difference was noted between the different Kodama types (p=0.89). Presence of fibrotic (p=0.24) and/or calcified (p=0.90) components, or contrast enhancement (p=0.84) of AE lesions were not correlated with significant differences in ADCs.Conclusion: ADCs of AE lesions are relatively low compared to other cystic liver lesions, which is helpful in suggesting the diagnosis. However, ADCs were not found to be useful for differentiating Kodama types of AE lesions.
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Référence bibliographique : Rol, 54219
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Référence bibliographique : Rol, 54783
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Référence bibliographique : Rol, 54782
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Référence bibliographique : Rol, 55433
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Our objective was a prospective comparison of MR enteroclysis (MRE) with multidetector spiral-CT enteroclysis (MSCTE). Fifty patients with various suspected small bowel diseases were investigated by MSCTE and MRE. The MSCTE was performed using slices of 2.5 mm, immediately followed by MRE, obtaining T1- and T2-weighted sequences, including gadolinium-enhanced acquisition with fat saturation. Three radiologists independently evaluated MSCTE and MRE searching for 12 pathological signs. Interobserver agreement was calculated. Sensitivities and specificities resulted from comparison with pathological results ( n=29) and patient's clinical evolution ( n=21). Most pathological signs, such as bowel wall thickening (BWT), bowel wall enhancement (BWE) and lymphadenopathy (ADP), showed better interobserver agreement on MSCTE than on MRE (BWT: 0.65 vs 0.48; BWE: 0.51 vs 0.37; ADP: 0.52 vs 0.15). Sensitivity of MSCTE was higher than that of MRE in detecting BWT (88.9 vs 60%), BWE (78.6 vs 55.5%) and ADP (63.8 vs 14.3%). Wilcoxon signed-rank test revealed significantly better sensitivity of MSCTE than that of MRE for each observer ( p=0.028, p=0.046, p=0.028, respectively). Taking the given study design into account, MSCTE provides better sensitivity in detecting lesions of the small bowel than MRE, with higher interobserver agreement.
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We advocate the use of a novel compressed sensing technique for accelerating the magnetic resonance image acquisition process, coined spread spectrum MR imaging or simply s2MRI. The method resides in pre-modulating the signal of interest by a linear chirp, resulting from the application of quadratic phase profiles, before random k-space under-sampling with uniform average density. The effectiveness of the procedure is theoretically underpinned by the optimization of the coherence between the sparsity and sensing bases. The application of the technique for single coil acquisitions is thoroughly studied by means of numerical simulations as well as phantom and in vivo experiments on a 7T scanner. The corresponding results suggest a favorable comparison with state-of-the-art variable density k-space under-sampling approaches.