Whole-body imaging at 7T: preliminary results.

The objective of this study was to investigate the feasibility of whole-body imaging at 7T. To achieve this objective, new technology and methods were developed. Radio frequency (RF) field distribution and specific absorption rate (SAR) were first explored through numerical modeling.

Source of low-frequency fluctuations in functional MRI signal.

Purpose: To investigate the source of native low-frequency fluctuations (LFF) in functional MRI (fMRI) signal.

Materials And Methods: Phase analysis was performed on tissue-segmented fMRI data acquired at systematically varying sampling rates.

Results: LFF in fMRI signal were both native and aliased in origin.

Adaptive pacing of visual stimulation for fMRI studies involving overt speech.

We report the development of an interactive approach to single-word language production studies in fMRI. The approach, adaptive pacing, involves real-time adjustment of stimulus presentation times based on individual subject performance timing and content. At the same time, it maintains a stochastic distribution of interstimulus intervals to avoid confounding task covariates with speech-related signal variance.

Model assessment and model building in fMRI.

Model quality is rarely assessed in fMRI data analyses and less often reported. This may have contributed to several shortcomings in the current fMRI data analyses, including: (1) Model mis-specification, leading to incorrect inference about the activation-maps, SPM[t] and SPM[F]; (2) Improper model selection based on the number of activated voxels, rather than on model quality; (3) Under-utilization of systematic model building, resulting in the common but suboptimal practice of using only a single, pre-specified, usually over-simplified model; (4) Spatially homogenous modeling, neglecting the spatial heterogeneity of fMRI signal fluctuations; and (5) Lack of standards for formal model comparison, contributing to the high variability of fMRI results across studies and centers. To overcome these shortcomings, it is essential to assess and report the quality of the models used in the analysis.

Segmentation of wall and plaque in in vitro vascular MR images.

Atherosclerosis leads to heart attack and stroke, which are major killers in the western world. These cardiovascular events frequently result from local rupture of vulnerable atherosclerotic plaque. Non-invasive assessment of plaque vulnerability would dramatically change the way in which atherosclerotic disease is diagnosed, monitored, and treated.

Dynamic magnetic resonance imaging of the female pelvis: the relationship with the Pelvic Organ Prolapse quantification staging system.

Purpose: Magnetic resonance imaging (MRI) was performed to determine anatomical correlations with respect to physical examination using the Pelvic Organ Prolapse (POP) staging system. In addition, the standard POP staging system was analyzed to obtain normative data and determine any risk factors for prolapse.

Materials And Methods: A total of 52 continent women 19 to 67 years old participated in our study.