A level set approach to segmenting a deforming myocardium from dynamically acquired SPECT projection data

Dynamic cardiac single photon emission computed tomography (SPECT) offers an effective way for observing fundamental physiological functions of organs and could aid in the early diagnosis of cardiovascular disease, in particular, for those patients with minimal disease. This would improve the chances of recovery by initiating appropriate therapy and an altered life style. To make dynamic cardiac SPECT viable with present clinical scanners methods need to be developed that reconstruct time activity curves from dynamically moving organs representing the change of tracer concentration as a function of time from projection data acquired from slowly rotating gamma cameras. This type of data analysis faces the challenge of modeling both rigid and non-rigid body deformation as well as modeling of a time varying tracer concentration. In the work presented here, we develop methods for segmenting the beating heart using an approach based upon level sets, which can deal naturally with topological changes. A variational formulation of the level set method was implemented. This allowed the inclusion of a priori information and was computationally efficient. The algorithm was first evaluated with simulated dynamic cardiac image data. The MCAT phantom was used to generate data containing 32 time frames over one cardiac cycle. Each frame had a matrix size of 64×64×32 voxels with a resolution of 6.25 mm. Starting with an initial estimate of the boundary, the algorithm then converged to an accurate segmentation of the deforming heart. The initial estimate was not important and we could segment simultaneously both interior and exterior boundaries. This algorithm forms the foundation for the segmentation of the boundary of the deforming myocardium directly from projection data

Detecting cells in time varying intensity images in confocal microscopy for gene expression studies in living cells

In this work we present a time-lapsed confocal microscopy image analysis technique for an automated gene expression study of multiple single living cells. Fluorescence Resonance Energy Transfer (FRET) is a technology by which molecule-to-molecule interactions are visualized. We analyzed a dynamic series of ~102 images obtained using confocal microscopy of fluorescence in yeast cells containing RNA reporters that give a FRET signal when the gene promoter is activated. For each time frame, separate images are available for three spectral channels and the integrated intensity snapshot of the system. A large number of time-lapsed frames must be analyzed to identify each cell individually across time and space, as it is moving in and out of the focal plane of the microscope. This makes it a difficult image processing problem. We have proposed an algorithm here, based on scale-space technique, which solves the problem satisfactorily. The algorithm has multiple directions for even further improvement. The ability to rapidly measure changes in gene expression simultaneously in many cells in a population will open the opportunity for real-time studies of the heterogeneity of genetic response in a living cell population and the interactions between cells that occur in a mixed population, such as the ones found in the organs and tissues of multicellular organisms

Longitudinal Evaluation of Fatty Acid Metabolism in Normal and Spontaneously Hypertensive Rat Hearts with Dynamic MicroSPECT Imaging

The goal of this project is to develop radionuclide molecular imaging technologies using a clinical pinhole SPECT/CT scanner to quantify changes in cardiac metabolism using the spontaneously hypertensive rat (SHR) as a model of hypertensive-related pathophysiology. This paper quantitatively compares fatty acid metabolism in hearts of SHR and Wistar-Kyoto normal rats as a function of age and thereby tracks physiological changes associated with the onset and progression of heart failure in the SHR model. The fatty acid analog, 123I-labeled BMIPP, was used in longitudinal metabolic pinhole SPECT imaging studies performed every seven months for 21 months. The uniqueness of this project is the development of techniques for estimating the blood input function from projection data acquired by a slowly rotating camera that is imaging fast circulation and the quantification of the kinetics of 123I-BMIPP by fitting compartmental models to the blood and tissue time-activity curves

Design and Implementation of a Facility for Discovering New Scintillator Materials

We describe the design and operation of a high-throughput facility for synthesizing thousands of inorganic crystalline samples per year and evaluating them as potential scintillation detector materials. This facility includes a robotic dispenser, arrays of automated furnaces, a dual-beam X-ray generator for diffractometery and luminescence spectroscopy, a pulsed X-ray generator for time response measurements, computer-controlled sample changers, an optical spectrometer, and a network-accessible database management system that captures all synthesis and measurement data