PURPOSE Changes in human body composition can affect the accuracy of spine bone mineral density (BMD) measurements. The purpose of this study was to evaluate whether fat and water in the soft tissue of the abdomen influence lumbar spine BMD measurements obtained using dual energy X-ray absorptiometry (DXA). MATERIALS AND METHODS Duplicate BMD measurements were carried out on healthy volunteer...

PURPOSE The conventional spectrally selective fat saturation pulse may perform poorly with inhomogeneous amplitude of static (polarizing) field (B0 ) and/or amplitude of (excitation) radiofrequency field (B1 ) fields. We propose a four dimensional spectral-spatial fat saturation pulse that is more robust to B0/B1 inhomogeneity and also shorter than the conventional fat saturation pulse. THEOR...

OBJECTIVE Patients who have a greater distribution of intraabdominal adipose tissue as compared with subcutaneous adipose tissue and an increased ratio of intraabdominal adipose tissue to subcutaneous adipose tissue are at greater risk for developing cardiovascular disease and type 2 diabetes mellitus. In previous MR investigations, researchers have used conventional T1-weighted spin-echo image...

Uniform suppression of fat signal is desired in clinical applications. Based on phase differences introduced by different chemical shift frequencies, Dixon method and its variations are used as alternatives of fat saturation methods, which are sensitive to B0 inhomogeneities. Iterative Decomposition of water and fat with Echo Asymmetry and Least squares estimation (IDEAL) separates water and fa...

is more subtle, more deeply intertwined and more strangely integrated than any of our pictures of her. It is not merely that our pictures are not full enough; each of our pictures in the end turns out to be so basically mistaken that the marvel is that it worked at all. List of Papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals. Dixon ...

Introduction: In cardiac imaging, it is essential to consider the homogeneity of the active B1 field (B1+) [1]. We present a realtime implementation of Transmit In-Plane Compensation (TIP-COMP) RF pulse [2], which can compensate different B1+ variations. Methods: Experiments were performed on a GE Signa EXCITE 3.0T system using a custom real-time imaging system [3]. To validate the accuracy of ...

Quantitative ultrasound features such as the attenuation slope, sound speed and scatterer size, have been utilized to evaluate pathological variations in soft tissues such as the liver and breast. However, the impact of variations in the sound speed and backscatter due to underlying fat content or fibrotic changes, on the attenuation slope has not been addressed. Both numerical and acoustically...

Introduction-Quantitative computed tomography (QCT) has been commonly used to acquire subject-specific, volumetric bone densities in vivo. With QCT, bone is modeled as a specimen composed of water and mineral, and the x-ray attenuation coefficients (i.e., Hounsfield number) after being corrected with scan phantoms, is used to calculate the mineral density of each voxel.[1] With QCT, a heterogen...

INTRODUCTION Although fatty infiltration of liver is a benign process that generally results from chronic alcohol uptake or obesity, such lifestyle factors may lead to chronic disease. Measuring the fat concentration in liver may therefore prove useful in assessing disease status. In this study, we report the usefulness of line scan echo planar spectroscopic imaging (LSEPSI) for this problem. ...

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 echoes cause artifacts that degrade image...