Doctor of Philosophy, The Ohio State University, 2015, Electrical and Computer Engineering

In vivo imaging provides a venue for studying and understanding the biological mechanism of a living system noninvasively. High resolution scanning for MR imaging is practically limited by the length of the scan for in vivo applications. In vivo small animal MRI suffers from subject motion which can degrade image quality with blurring and artifacts. In many small animal imaging studies, multiple imaging views are already obtained as part of the normal workflow but the information taken from one view is not generally combined with that from another view. The main objective of this dissertation is to study the use of multiple imaging views for improving image quality in small animal MR imaging studies. The goal of the study is to evaluate post-processing techniques that could make use of multiple low resolution image acquisitions for increasing resolution in through-plane 3D images and to reduce motion artifacts in in-plane 2D images. Both qualitative and quantitative comparisons are carried out to evaluate the performance of the algorithms and they are demonstrated in in vivo settings.

Committee: Bradley Clymer PhD (Advisor); Kimerly Powell PhD (Advisor); Can Koksal PhD (Committee Member) Subjects: Electrical Engineering

Master of Science in Biomedical Engineering (MSBME), Wright State University, 2015, Biomedical Engineering

Non-contact imaging photoplethysmography is an exciting new field based on the principles of traditional photoplethysmography where viable signals can now be acquired without the use of contact equipment. Recent advances regarding non-contact imaging photoplethysmography have permitted a wide range of new possibilities focused on sensing the cardiopulmonary system. Physiological metrics such as pulse rate, respiration rate, and pulse rate variability can be obtained by current photoplethysmographic imaging methods. Although previous systems were challenged by head-motion artifacts, the mitigation of rigid head-motion artifacts has been demonstrated with a multi-imager design. This study investigated the feasibility and accuracy of pulse rate variability utilizing a multi-imager recording system. Parameters such as sampling rate, image resolution, and number of imagers utilized were examined in an attempt to minimize overall system data bandwidth. Accurate pulse rate variability metrics where found within the frequency and temporal domains, along with promising results regarding the aforementioned input parameters.

Committee: Mary Fendley Ph.D. (Advisor); Nasser Kashou Ph.D. (Committee Member); Phani Kidambi Ph.D. (Committee Member) Subjects: Biomedical Engineering; Biomedical Research

Master of Science in Engineering (MSEgr), Wright State University, 2012, Biomedical Engineering

In computed tomography (CT) systems, many different artifacts may be present in the reconstructed image. These artifacts can greatly reduce image quality. For our laboratory prototype CT system, a fan-beam/cone-beam focal high-resolution computed tomography (fHRCT) scanner, the major artifacts that affect image quality are distortions due to errors in the reconstruction algorithm's geometric parameters, ring artifacts caused by uncalibrated detectors, cupping and streaking created by beam hardening, and patient-based motion artifacts. Optimization of the system was required to reduce the effects of the first three artifact types, and an algorithm for correction of translational motion was developed for the last. System optimization of the system occurred in three parts. First, a multi-step process was developed to determine the geometric parameters of the scanner. The ability of the source-detector gantry to translate allowed a precise method to be created for calculating these parameters. Second, a general flat-field correction was used to linearize the detectors and reduce the ring artifacts. Lastly, beam hardening artifacts were decreased by a preprocessing technique. This technique assumes linear proportionality between the thickness of the calibration material, aluminum, and the experimental measurement of ln(No/N), where No is the total number of photons entering the material and N is the number of photons exiting the material. In addition to system optimization to minimize artifacts, an algorithm for correction of translational motion was developed and implemented. In this method, the integral mass and center of mass at each projection angle was seen to follow a sinusoidal or sinusoidal-like curve. Fits were used on the motion-encoded sinograms to determine both of these curves and, consequently, the amount and direction of motion that occurred. Each projection was individually adjusted to compensate for this motion by widening or narrowing the projection bas (open full item for complete abstract)

Committee: Thomas Hangartner PhD (Advisor); David Short MS (Committee Member); Julie Skipper PhD (Committee Member) Subjects: Biomedical Engineering