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Chemical shift based methods are often used to achieve uniform water-fat separation that is insensitive to Bo inhomogeneities. Many spin-echo (SE) or fast SE (FSE) approaches acquire three echoes shifted symmetrically about the SE, creating time-dependent phase shifts caused by water-fat chemical shift. This work demonstrates that symmetrically acquired(More)
Hepatic steatosis is characterized by abnormal and excessive accumulation of lipids within hepatocytes. It is an important feature of diffuse liver disease, and the histological hallmark of non-alcoholic fatty liver disease (NAFLD). Other conditions associated with steatosis include alcoholic liver disease, viral hepatitis, HIV and genetic lipodystrophies,(More)
This work describes a new approach to multipoint Dixon fat-water separation that is amenable to pulse sequences that require short echo time (TE) increments, such as steady-state free precession (SSFP) and fast spin-echo (FSE) imaging. Using an iterative linear least-squares method that decomposes water and fat images from source images acquired at short TE(More)
PURPOSE To evaluate the validity of different approaches to determine the signal-to-noise ratio (SNR) in MRI experiments with multi-element surface coils, parallel imaging, and different reconstruction filters. MATERIALS AND METHODS Four different approaches of SNR calculation were compared in phantom measurements and in vivo based on: 1) the(More)
The statistical properties of background noise such as its standard deviation and mean value are frequently used to estimate the original noise level of the acquired data. This requires the knowledge of the statistical intensity distribution of the background signal, that is, the probability density of the occurrence of a certain signal intensity. The(More)
Cardiac echo-planar imaging suffers invariably from regions of severe distortion and T*2 decay in the myocardium. The purpose of this work was to perform local measurements of T*2 and field inhomogeneities in the myocardium and to identify the sources of focal signal loss and distortion. Field inhomogeneity maps and T*2 were measured in five normal(More)
Robust fat suppression techniques are required for many clinical applications. Multi-echo water-fat separation methods are relatively insensitive to B(0) field inhomogeneity compared to the fat saturation method. Estimation of this field inhomogeneity, or field map, is an essential and important step, which is well known to have ambiguity. For an iterative(More)
Multiecho chemical shift-based water-fat separation methods are seeing increasing clinical use due to their ability to estimate and correct for field inhomogeneities. Previous chemical shift-based water-fat separation methods used a relatively simple signal model that assumes both water and fat have a single resonant frequency. However, it is well known(More)
Time-resolved cardiac imaging is particularly interesting in the interventional setting since it would provide both image guidance for accurate procedural planning and cardiac functional evaluations directly in the operating room. Imaging the heart in vivo using a slowly rotating C-arm system is extremely challenging due to the limitations of the data(More)
An MR line scan protocol has been used to measure relaxation parameters (T1 and T2) in isolated, blood perfused rabbit hearts at various blood oxygenations. Hearts were retrogradely perfused at 37 degrees C with a cardioplegic solution (modified St. Thomas' solution) containing sheep red blood cells and adenosine (1 mM) to maximally vasodilate the coronary(More)