Specific Aim 1: Develop and validate methodology to analyze, quantify and ultimately eliminate static magnetic field distortion artifacts produced in high field MR images by regional differences in magnetic susceptibility. This information will be used to develop artifact- correction techniques for high-speed functional MRI and distortion-free high field MRI of human, animal, and cellular anatomy. This Specific Aim will address the following goals:
- Develop and apply computer models of susceptibility induced artifacts, and T2* contrast in tissue.
- Develop, optimize, and apply methods for obtaining rapid, artifacts free, T2-weighted MR images of the head, for application to high field functional MRI (fMRI) studies.
- Develop, optimize, and apply methods for obtaining rapid, artifacts free, T2*-weighted images. This unique tissue contrast resulting from these techniques will be applied to the study of tissue magnetic susceptibility in normal and pathologic states in humans, and ultra-high field MR microscopy.
- Define the effects of small spatial domain susceptibility induced field gradients on image spatial resolution, and develop methods for improving contrast resolution at high magnetic field.
Specific Aim 2: Develop and validate models and methodology to analyze and quantify radio frequency (RF) magnetic field distortions occurring in the human head and body of men, women, children, and fetuses in uteri. These analyses will be used to evaluate regional RF power deposition from specific pulse sequences for patient safety and to develop methods to improve RF field homogeneity. This Specific Aim will address the following goals:
- Develop and optimize mathematical human models for using in Finite Difference (FD) calculations of B1 and B0 field interactions in the human body at high field MRI.
- Evaluate safety of high field MRI by understanding regional RF power deposition in the human body at high frequency B1 field strength and develop methodology for accurate Specific energy Absorption Rate (SAR) and temperature calculations based on human simulations.
- Improve understanding of B1 field distortion in the human body at frequencies used in high field MRI, and identify potential methods for reducing image artifacts produced by B1 field distortion.