Projects in the Center for NMR Research include:
Brain Imaging Initiative
The unique ability to provide in vivo biological information and excellent visualization of human soft tissues has led to widespread clinical and research application of Magnetic Resonance Imaging (MRI). Recent technological improvement in high field MRI, defined as static magnetic fields greater then 2.0 Tesla, provides potential for significant advances in biomedical imaging and in vivo biological research. Unfortunately, interaction of biological tissues with high static (B0) and radio frequency (B1) magnetic fields result in severe image artifacts that restrict applications of high field MRI technology.
The long-term objective of this research is to understand and develop bioengineering solutions to limitations of MRI at high magnetic field strength. As recommended in NIH PA #PAR-02-010, this project will use a partnership of both academic institutions and private industry to develop a design-directed bioengineering approach to this problem. Specifically, we will draw expertise and partnership from the Center for Magnetic Resonance Research at the University of Minnesota (a premiere 7.0 Tesla whole-body MRI research facility), REMCOM (a magnetic field modeling software company), and the National High Magnetic Field Laboratory ( a National Research Laboratory incorporating 750 MHz MRI microscopy and a 11.7 Tesla, 40 cm bore animal system). Information and technology obtained through this Bioengineering Research Partnership will have wide-reaching benefit to a growing number of high field MRI centers developing worldwide. Through a better understanding of tissue interactions with high B0 and high frequency B1 fields, methods can be developed to overcome current obstacles that limit application of high field MRI to important biomedical problems.
Memory and Aging Study
The Memory and Aging Study is a longitudinal study of the relationship between aging and memory loss. Our main goal is to identify early indicators of problems with memory. Secondary goals include:
- Developing novel and non-invasive approaches to study changes in memory function.
- Identifying genetic factors that affect rate of progression in patients with mild cognitive impairment or mild Alzheimer’s disease.
- Validating an MRI technique for diagnosis of mild cognitive impairment and/or Alzheimer’s disease.
The study will involve genetic, imaging, psychiatric and neuropsychological investigation of memory loss during aging. We will do this with pencil-and-paper questionnaires of memory, mood and health history; a blood sample for genetic analysis; and various MRI scans.
Additionally, the MRI scans and a smell identification test will be used to investigate problems with sense of smell in early Alzheimer’s disease.
Magnetic Susceptibility Effect
A technique for reducing B0 field inhomogeneity and magnetic susceptibility artifacts in gradient-recalled-echo (GRE) images is presented. The artifacts are mainly produced by intravoxel phase dispersion due to local gradients in the slice direction and can be very large at high field strengths.
This 3D technique uses incremental phase encoding in the slice refocusing gradient to sample k-space over the full range of spatial frequencies of the excitation profile. A third Fourier transform of the resultant 2D set of images, generates an image set in which the artifacts produced by the low-order field gradients are separated from the high-order field gradients responsible for T2* contrast.
Application to high field brain imaging at 3.0 T for human and at 9.4 T for young rats illustrate the significant improvement in quality of the T2*-weighted contrast images.