Fluorescence spectroscopy and imaging of myocardial infarction
Abstract
Fluorescence optical techniques use light in the UV-blue spectral range to measure tissue metabolism non-invasively. In this research, fluorescence optical techniques were utilized for ex vivo and in vivo myocardium spectroscopy and imaging in small animal models. ^ For in vivo heart studies optical methods are used to assess tissue structure and biochemistry associated with heart attack (myocardial infarction) that is the leading cause of death in United States. An experimental endeavor of this complexity was made possible through the collaboration of the ESE Department and the School of Medicine. Fluorescence-based techniques demonstrate the potential of online, in vivo and noninvasive diagnosis of tissue metabolism. Based upon small animal models, we have discovered an intrinsic tissue signal to open up a field of optical spectroscopy called in vivo "optical biopsy". ^ At present, the gold standard for detecting tissue abnormality is histopathalogy of excisional biopsies. This procedure requires physical removal of tissue, staining for better resolution and specimen handling. Although this gold standard provides spatial resolution, it suffers from sampling error and offline data analysis. We have investigated the tissue metabolic states in normal and abnormal cases by fluorescence spectroscopy and imaging of tissue intrinsic probes. We utilized fluorometery as the optical technique to acquire fluorescence signals of these fluorophores. We have also used fluorescence imaging to image the biochemical changes in the whole tissue surface and subsurface. One abnormal tissue state occurs when cells undergo programmed cell death or so-called "apoptosis". Apoptosis is an orchestrated process in which cells commit suicide. For instance, the therapeutic method of photodynamic therapy (PDT) of tumor cells can trigger the initiation of apoptosis. Another example is myocardial infarction that causes myocytes (heart cells) to become apoptotic. It is known that myocardial infarction produces a wave of apoptotic myocytes that will propagate around the infarction area and has been hypothesized to eventually cause heart failure. Fluorescence spectroscopy and imaging as diagnostic tools are able to monitor the biochemical changes during this disease process. ^ Keywords. Optical diagnostic tools, fluorescence spectroscopy, fluorescence imaging, apoptosis, ischemia, hypoxia, redox state, mitochondria, perfused heart, infracted heart, phosphorescence, Nicotinamide adenine dinucleotide (NADH), flavoprotein (FP), cryo-imaging. ^
Subject Area
Engineering, Biomedical|Engineering, Electronics and Electrical
Recommended Citation
Mahsa Ranji,
"Fluorescence spectroscopy and imaging of myocardial infarction"
(January 1, 2007).
Dissertations available from ProQuest.
Paper AAI3292067.
http://repository.upenn.edu/dissertations/AAI3292067