نتایج جستجو برای: pulse sequence
تعداد نتایج: 491602 فیلتر نتایج به سال:
Spin echo imaging is often called the workhorse of MRI as it is frequently a large part of many clinical protocols. By definition, the “spin echo” is the occurrence of transverse magnetization that has been re-phased by a refocusing RF pulse. Note that transverse magnetization exists following an excitation RF pulse that tips the magnetization from the equilibrium, longitudinal direction into t...
Introduction The recognition of the role of trabecular bone (TB) architecture as an independent predictor of bone strength has spurred the development of noninvasive imaging methods. Recent advances in imaging technology now permit in vivo imaging of TB at a resolution adequate for analysis of the 3D architecture of the TB network [1]. Spin-echo imaging has proven to be advantageous since it is...
Proton chemical shift imaging yielding separate water and lipid images was performed in a multisection mode on a clinical 1.5-T whole-body magnetic resonance imaging unit. Imaging was performed with a minor modification of the standard multisection spin-warp technique: that is, the addition of a sinc pulse or a soft square pulse and a homospoil gradient at the beginning of the pulse sequence. P...
Intensity normalization is an important preprocessing step in magnetic resonance (MR) image analysis. In MR images (MRI), the observed intensities are primarily dependent on (1) intrinsic magnetic resonance properties of the tissues such as proton density (PD ), longitudinal and transverse relaxation times (T1 and T2 respectively), and (2) the scanner imaging parameters like echo time (TE), rep...
Radiotherapy plays an increasingly important role in cancer treatment, and medical imaging plays an increasingly important role in radiotherapy. Magnetic resonance imaging (MRI) is poised to be a major component in the development towards more e ective radiotherapy treatments with fewer side e ects. This thesis attempts to contribute in realizing this potential. Radiotherapy planning requires s...
PURPOSE To develop an arrhythmia-insensitive rapid (AIR) cardiac T1 mapping pulse sequence for quantification of diffuse fibrosis. METHODS An arrhythmia-insensitive cardiac T1 mapping pulse sequence was developed based on saturation recovery T1 weighting, which is inherently insensitive to heart rate and rhythm, and two single-shot balanced steady-state free precession image acquisitions with...
We propose a merit function for the expected contrast to noise ratio in tissue quantifications, and formulate a nonlinear, nonconvex semidefinite optimization problem to select locally-optimal balanced steady-state free precession (bSSFP) pulse-sequence design variables. The method could be applied to other pulse sequence types, arbitrary numbers of tissues, and numbers of images. To solve the ...
The percentage of people having a lower leg amputation is high, and the incidence unemployment among these amputees likewise rising. Hence, it requires intervention an innovative solution to serve function lost limb. Electromyogram (EMG) signals result potential generated by muscles during contraction. In this work, attempt has been made extract EMG from four set muscle groups acquired were pre...
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