نتایج جستجو برای: inversion recovery
تعداد نتایج: 241145 فیلتر نتایج به سال:
Introduction: Fluid-attenuated inversion recovery (FLAIR) is widely used for its improved conspicuity of long T2 lesions by suppressing cerebrospinal fluid (CSF). Concerns remain, however, that the IR imparts T1 weighting that can decrease detectability and lead to mischaracterization of some lesions. Frequently both T2 and FLAIR images are acquired in clinical protocols to guard against these ...
Introduction: Look-Locker inversion recovery produces images at multiple inversion times (TI) after a 180° inversion pulse (1). In non-cardiac and phantom experiments, the sequence timing can be carefully controlled. This allows the user to exactly specify both the TIs and the magnetization recovery time between inversions. In cardiac imaging, however, these timing variables are measured in uni...
The aim of the present study is to develop a submillimeter volumetric (three-dimensional) fluid-attenuated inversion recovery sequence at 7T. Implementation of the fluid-attenuated inversion recovery sequence is difficult as increased T(1) weighting from prolonged T(1) constants at 7T dominate the desired T(2) contrast and yield suboptimal signal-to-noise ratio. Magnetization preparation was us...
FRIESEN (1936) induced crossing over in Drosophila males by X rays and found that most of the exchanges were in a preferred region, the complementary crossover classes were very unequal, and the percent recombination varied greatly from individual to individual. According to him, the data 'were sufficient to demonstrate the occurrence of spermatogonial crossing over. WHITTINGHILL (1937) found t...
OBJECTIVE This study focuses on the diverse effects of MRI parameters on image quality using widely available imaging pulse sequences. METHODS A tissue equivalent gel system has been used for Magnetic Resonance Imaging by using Xylenol orange dye with Fricke-Benzoic solution which was formulated by Kelly R.G (1998). The gel system was radiated while using 6MV photons from Varian Clinic Linear...
BACKGROUND AND PURPOSE FLAIR and double inversion recovery are important MR imaging scans for MS. The suppression of signal from CSF in FLAIR and the additional suppression of WM signal in double inversion recovery improve contrast between lesions, WM and GM, albeit at a reduced SNR. However, whether the acquisition of double inversion recovery is necessary is still debated. Here, we present an...
The relevance of cortical grey matter pathology in multiple sclerosis has become increasingly recognized over the past decade. Unfortunately, a large part of cortical lesions remain undetected on magnetic resonance imaging using standard field strength. In vivo studies have shown improved detection by using higher magnetic field strengths up to 7 T. So far, a systematic histopathological verifi...
Contrast optimization of a three-dimensional (3D) Fluid-attenuated inversion recovery (FLAIR) sequence is examined in the context of multiple sclerosis. In order to develop 3D FLAIR for enhanced detection of lesions, an iterative approach based on theoretical considerations was used. The 3D FLAIR sequence was systematically acquired with incremental parameter changes on a single subject with mu...
Objective. To compare periventricular lesions in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOsd). Materials and Methods. Sagittal and axial fluid attenuated inversion recovery (FLAIR) sequences of 20 NMOsd and 40 group frequency-matched MS patients were evaluated by two neuroradiologists. On axial FLAIR, periventricular area was characterized as free of lesions/smoot...
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