Neuroimaging of Brain Activation Using Diffuse Optical Tomography

Abstract

This research has two parts. The first part focuses on the use of non-invasive imaging technique, diffuse optical tomography (DOT), to study the brain activation during the stimulation in the clinical room. It further extends the application of DOT by using it to monitor the hemodynamic response during the TMS stimulation in different parameters. Diffuse optical tomography (DOT) is based on NIR light that exploits the relative transparency of biological tissue. The part two and three extends the application in the hospital for delirium patient study and arm muscle dystrophy by adding the sources and detectors to monitor the brain and arm simultaneously.

Diffuse optical tomography provides three-dimensional tissue and functional information with high spatial resolution and excellent contrast. With the application on brain combined with repetitive transcranial magnetic stimulation (rTMS), we detect the different hemodynamic response with different resting motor threshold (rMT) stimulation parameters for healthy subjects. In a functional imaging approach, we study the hemodynamic changes and volumetric location of hemodynamic response. By doing so, we hope to project the tomography imaging as a cost effective and less harmful alternative imaging modality for the brain stimulation imaging. We propose a 100% rMT TMS stimulation for both healthy subjects and depressed patients.

In the first part, by using diffuse optical tomography, we guide its application and monitor the hemodynamic response successfully. With the comparison of hemodynamic response between healthy subjects and depressed patients in different views, it is useful for studying the mechanism of TMS and the pathophysiology of the disorders in which it is applied.

After the application for the brain detection during the TMS stimulation, we developed a novel and portable diffuse optical tomography imaging system for brain imaging in the hospital for delirium study. We scanned the delirium patient before and after treatment. Results from the treatments using our system can find different brain activation before and after treatment for the delirium patient. We found the significant difference of brain activation between before and after treatment of delirium patient. By analyzing the brain hemoglobin response for the delirium patient, our DOT system can help the doctor evaluate how delirious the patients are.