Faculty at Marquette and the Medical College of Wisconsin are engaged in research related to functional imaging of organ physiology. Functional imaging is an interdisciplinary activity that allows scientists, engineers and physicians to simultaneously quantify the structural and functional aspects of a biological system. Advances in imaging technology are making available an unprecedented amount of data from intact organs. Biomedical engineers use this data to study organ structure-function relationships with increasingly high levels of resolution and quantification. Modern functional imaging modalities thereby provide the experimental tools to address significant physiological questions in a relatively noninvasive manner.
In the past decade, faculty at Marquette and MCW have worked to make technological advancement of functional magnetic resonance imaging and use the technique to understand brain systems activated when healthy individuals perform sensory, motor and cognitive tasks in the scanner.
Functional neuroimaging is becoming an area of increasing importance in systems (or integrative) neuroscience. More recently, MCW and Marquette fMRI investigators have begun to apply the technique to diagnose and monitor patients with a variety of neurological and psychiatric disorders, including brain tumors, stroke, epilepsy, Alzheimer's disease, Parkinson's disease, multiple sclerosis, head injury, visual disorders and spinal cord injury. The results have led to earlier disease detection, closer monitoring of brain conditions and the effectiveness of investigational therapies.
fMRI and visual field mapping
Research focuses on using fMRI and signal and image processing to understand processing of visual function in the visual cortex. These methods are being introduced to the clinical environment to diagnose and predict visual field defect, known as scotomata. Scotomata, regions of blindness in the visual field, can be caused by injury at any location in the visual system, severely impacting various activities of daily living. In clinical practice, it is acknowledged that invasive surgical procedures involving cortical visual pathways can sometimes cause partial vision loss. To date, there are no widely accepted procedures for predicting such side effects for patients who must make critical decisions about the desirability of surgery or surgical extent. fMRI can be used to map the topography and function of visual cortex in and near a potential site of surgery. Using this information, it is possible to predict what portions of the visual field are likely to be affected by a particular surgical approach. A visual defect simulator that can provide the patient with a first-hand simulated experience of the predicted scotoma has recently been developed.
fMRI, EEG, and auditory and speech function
Research focuses on the neurophysiological basis of phonetic and auditory perception in humans. This research relies on the integration of event-related potentials and fMRI to achieve both high-temporal and high-spatial resolution of brain activation patterns. Innovative methods in simultaneous ERP/fMRI acquisition and fMRI-constrained ERP source modeling to investigate neurocognitive problems requires extensive collaboration between biomedical engineering and neurocognitive disciplines.
Diffusion tensor imaging of spinal cord pathology
The purpose of this project is to develop techniques for imaging the spinal cord to determine which connections have been lost and which are intact after spinal cord injury. This research is important to both neurosurgeons and clinicians involved in rehabilitation. The development involves a technique called diffusion tensor imaging, which produces measurements of the diffusion properties of the spinal cord. Preliminary data suggest that there are dimensional changes in the spinal cord, even at locations distant from the injury site. In addition, there appear to be changes in diffusion in the spinal cord following injury.
Tools for use in fMRI studies of sensory-motor performance
A number of faculty have been using a variety of technology to assess sensory-motor learning and performance in populations such as stroke and spinal cord injury. The technologies involve motors, accuators and computer control to manipulate the movement of ankles, wrists, legs, arms, hips and knees. Recently, these faculty have been interested in performing these same sensory-motor control experiments in the MR scanner to image brain function and spinal cord function during manipulation and response. The strong magnetic fields posed by the MR scanner require the development of a whole line of new devices that are MR compatible and can mimic the instrumentation typically used outside of the MR scanner. Recently, faculty and graduate students have developed instruments for manipulating wrist and ankle movement in the MR scanner to be used in studying patients after stroke or spinal cord injury. MR-compatible equipment for monitoring physiologic function, such as ECG, EEG and respiration, are also aspects of the fMRI research.
The Medical Imaging Systems Laboratory focuses on the design and optimization of medical imaging technologies. Current research projects include investigating dose reduction, scatter reduction and energy-weighting techniques for CT; designing a dynamic multipinhole micro-SPECT system; and investigating a dedicated breast CT system with an inverse geometry. Systems-level research is performed using computer simulation methods and experiments in collaboration with radiologists, physicists and engineers at the Zablocki VA Medical Center, the Medical College of Wisconsin and Froedtert Memorial Lutheran Hospital.