The Yale MRI groups mission is to develop novel MR imaging methods with both clinical and basic science applications. Research is underway to address basic science questions -- from stem cell migration and mechanisms of recovery, to understanding tissue damage and remodeling, to fundamental questions regarding brain function. The MRI group is highly interdisciplinary, and scientists within the group come from backgrounds of physics, engineering, chemistry, mathematics, and neuroscience.
R. Todd Constable: My lab has efforts underway examining the relationship between the increment in the functional MR signal measured during a task (cognitive or sensory/motor) and the influence of baseline brain activity on this increment. We have research projects aimed at understanding negative blood oxygenation level dependent signal changes observed in certain cognitive tasks and the relationship between simultaneously recorded surface EEG signals and fMRI, in order to better understand the relationship between the fMRI signal changes measured and brain function. Clinical applications include localization of inter-ictal electrical discharges in the brains of epilepsy patients, assessing normal vs. abnormal cortical connectivity, and functional mapping for neurosurgical treatment planning. In more fundamental MR engineering projects we are focused on developing novel MR imaging strategies for faster and more efficient parallel imaging. Some examples of current research projects in my laboratory include:
- Development of an approach to highly efficient parallel imaging.
- Understanding the influence of baseline activity on brain function.
- Understanding the relationship between EEG and fMRI.
- Studying functional connectivity and what it tells us about how the brain is wired.
Gigi Galiana: The main focus of my lab is developing imaging techniques based on new contrast mechanisms. One underexplored mode of contrast generation is that of iMQC signals (intermolecular multiple quantum coherence), unique two spin signals that can be generated even in pure water. These signals can produce highly resolved spectra in vivo or reflect subvoxel structure on a tunable distance scale, and many of our projects revolve around applying them to solve outstanding problems in biomedical MRI.
- For example, one major project in my lab is developing spectroscopic sequences to improve breast mammography. MRI breast mammography has exquisite sensitivity, but its specificity is quite low. Using iMQCs, we can acquire high resolution spectra of the lipid composition in lesions identified as suspicious on MR mammography, and we are testing whether these spectra can be used to predict which lesions actually merit biopsy.
- In addition to unique spectroscopic properties, iMQC signals also give different and nonlinear structural contrast. They are sensitive to gradients in oxygenation across a voxel, anisotropy, and magnetization changes, which may have applications in cancer imaging, fMRI, or the detection of various neurological diseases.
- One of the greatest challenges of these sequences is the long scan times they can require, and so I am also very interested in parallel imaging and other scan acceleration techniques. The iMQC fid is typically collected point by point (because it evolves in the indirect dimension), and adding two or three spatial dimensions to the encoding, or averages to boost the low SNR, can result in very long scan times. However, multichannel coils can boost SNR while also providing spatial localization that allows some of the spatial encoding steps to be skipped. Still greater acceleration gains may be possible with the nonlinear gradient encoding proposed by Dr. Constable, which is experimentally realizable at the MRRC, and I am also very active in this work.
Michelle Hampson: My lab is focused on the development and application of new functional imaging paradigms. These include resting state functional connectivity analyses and biofeedback via real-time fMRI (rt-fMRI). Rt-fMRI biofeedback has great potential as a clinical treatment for mental and neurological disorders. When used in conjunction with resting state functional connectivity assessments (collected before and after the biofeedback), it provides a powerful perturb-and-measure approach for studying human brain function. We have several ongoing projects:
- A study using rt-fMRI biofeedback to train patients with Tourette Syndrome to control their supplementary motor area. We are interested in whether gaining control over this brain region translates into an improvement in tic symptoms, and alterations in corticostriatal connectivity patterns.
- A study using rt-fMRI biofeedback to train people to control a region of their orbitofrontal cortex involved in anxiety. Our data from healthy subjects indicate that rt-fMRI biofeedback can induce a reorganization of limbic-prefrontal circuitry that enables people to control contamination-related anxiety. Future studies in obsessive-compulsive patients are needed to determine the clinical utility of this protocol.
- We are developing a rt-fMRI biofeedback protocol for use in PTSD patients.
- We are interested in the correlates of video game playing in the brain connectivity patterns of children.
Dana Peters: My research group focuses on development and application of new methods for cardiac MR. We have developed new late gadolinium enhancement (LGE) methods for visualizing fibrosis and scar in the myocardium, with 4 fold increased spatial resolution. High resolution LGE has several clinical applications to electrophysiology (EP). These include visualization of scar/remodeling in the left atrium, to demonstrate the pattern of remodeling, or to visualize ablation lesions. Another application is improved depiction of left ventricular myocardial scar, for more clearly delineating the scar, as a substrate of arrhythmias, and for comparison with EP data. Finally, we are researching undersampled radial imaging for cardiac applications. Some examples of current research projects in my laboratory include:
- Imaging of atrial fibrillation patients acutely after pulmonary vein isolation procedure.
- Correlation of scar in the left atrium due to remodeling with electrophysiology voltage maps.
- T1 mapping of the grey zone in left ventricular myocardial scar.
- Parallel imaging radial reconstruction methods.