957 resultados para Weighted MRI
Resumo:
Myelography is a nearly ninety-year-old method that has undergone a steady development from the introduction of water-soluble contrast agents to CT myelography. Since the introduction of magnetic resonance imaging into clinical routine in the mid-1980s, the role of myelography seemed to be constantly less important in spinal diagnostics, but it remains a method that is probably even superior to MRI for special clinical issues. This paper briefly summarizes the historical development of myelography, describes the technique, and discusses current indications like the detection of CSF leaks or cervical root avulsion.
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BCT is a benign entity, whose appearance on conventional MR imaging makes its differentiation from neoplastic, inflammatory, or subacute ischemic disease challenging. SWI is sensitive to susceptibility effects from deoxyhemoglobin with excellent spatial resolution. Only scarce case reports have described the utility of SWI in cases of BCT. Our aim was to show the diagnostic value of SWI applied to a larger series of cases.
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The objective of our study was to evaluate whether there is injury to the transverse ligament of the atlas in patients with acute whiplash.
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DWI and DTI of the brain have proved to be useful in many neurologic disorders and in traumatic brain injury. This prospective study aimed at the evaluation of the influence of the PMI and the cause of death on the ADC and FA for the application of DWI and DTI in forensic radiology.
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Semi-weak n-hyponormality is defined and studied using the notion of positive determinant partition. Several examples related to semi-weakly n-hyponormal weighted shifts are discussed. In particular, it is proved that there exists a semi-weakly three-hyponormal weighted shift W (alpha) with alpha (0) = alpha (1) < alpha (2) which is not two-hyponormal, which illustrates the gaps between various weak subnormalities.
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We characterize positive quadratic hyponormality of the weighted shift W-alpha(x) associated to the weight sequence alpha(x) : 1, 1, root x, (root u, root v, root w)(Lambda) with Stampfli recursive tail, and produce an interval in x with non-empty interior in the positive real line for quadratic hyponormality but not positive quadratic hyponormality for such a shift. (C) 2013 Elsevier Inc. All rights reserved.
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We describe a case of a fatal speed flying accident in which the victim was electrocuted, burned and fell from a great height. Post-mortem imaging revealed acute appearing fractures on CT, without bone marrow oedema on MRI. Based on the known clinical imaging findings of bone marrow oedema in acute fractures, we concluded that the speed flyer died from electrocution rather than the fall and that the fractures occurred post-mortem. Radiological imaging augmented the reconstruction of the peri-mortem events. Further research is needed to assess whether bone marrow oedema in acute fractures is a reliable vital sign.
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To assess the temperature dependency of tissue contrast on post mortem magnetic resonance (PMMR) images both objectively and subjectively; and to visually demonstrate the changes of image contrast at various temperatures.
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To retrospectively assess the diagnostic sensitivity of 45° Dunn view and cross-table lateral radiographs for the assessment of cam deformity by comparison with radial MRI.
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This study compares the performance and the reproducibility of quantitative T2, T2* and the magnetisation transfer ratio (MTR) of articular cartilage at 7T and 3T.
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To assess, compare and correlate quantitative T2 and T2* relaxation time measurements of intervertebral discs (IVDs) in patients suffering from low back pain, with respect to the IVD degeneration as assessed by the morphological Pfirrmann Score. Special focus was on the spatial variation of T2 and T2* between the annulus fibrosus (AF) and the nucleus pulposus (NP).
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To develop a semiquantitative MRI-based scoring system (HOAMS) of hip osteoarthritis (OA) and test its reliability and validity.
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Fast quantitative MRI has become an important tool for biochemical characterization of tissue beyond conventional T1, T2, and T2*-weighted imaging. As a result, steady-state free precession (SSFP) techniques have attracted increased interest, and several methods have been developed for rapid quantification of relaxation times using steady-state free precession. In this work, a new and fast approach for T2 mapping is introduced based on partial RF spoiling of nonbalanced steady-state free precession. The new T2 mapping technique is evaluated and optimized from simulations, and in vivo results are presented for human brain at 1.5 T and for human articular cartilage at 3.0 T. The range of T2 for gray and white matter was from 60 msec (for the corpus callosum) to 100 msec (for cortical gray matter). For cartilage, spatial variation in T2 was observed between deep (34 msec) and superficial (48 msec) layers, as well as between tibial (33 msec), femoral, (54 msec) and patellar (43 msec) cartilage. Excellent correspondence between T2 values derived from partially spoiled SSFP scans and the ones found with a reference multicontrast spin-echo technique is observed, corroborating the accuracy of the new method for proper T2 mapping. Finally, the feasibility of a fast high-resolution quantitative partially spoiled SSFP T2 scan is demonstrated at 7.0 T for human patellar cartilage.
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To define the feasibility of utilizing T2* mapping for assessment of early cartilage degeneration prior to surgery in patients with symptomatic femoroacetabular impingement (FAI), we compared cartilage of the hip joint in patients with FAI and healthy volunteers using T2* mapping at 3.0 Tesla over time.