Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. The most striking example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, while the emitted light is in the visible region, which gives the fluorescent substance a distinct color that can be seen only when exposed to UV light. Fluorescent materials cease to glow nearly immediately when the radiation source stops, unlike phosphorescent materials, which continue to emit light for some time after.
Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. This is traditionally done by injecting a radio-opaque contrast agent into the blood vessel and imaging using X-ray based techniques such as fluoroscopy.
Optical coherence tomography (OCT) is an imaging technique that uses low-coherence light to capture micrometer-resolution, two- and three-dimensional images from within optical scattering media. It is used for medical imaging and industrial nondestructive testing (NDT). Optical coherence tomography is based on low-coherence interferometry, typically employing near-infrared light. The use of relatively long wavelength light allows it to penetrate into the scattering medium. Confocal microscopy, another optical technique, typically penetrates less deeply into the sample but with higher resolution.
Restenosis is the recurrence of stenosis, a narrowing of a blood vessel, leading to restricted blood flow. Restenosis usually pertains to an artery or other large blood vessel that has become narrowed, received treatment to clear the blockage and subsequently become renarrowed. This is usually restenosis of an artery, or other blood vessel, or possibly a vessel within an organ.
Coronary thrombosis is defined as the formation of a blood clot inside a blood vessel of the heart. This blood clot may then restrict blood flow within the heart, leading to heart tissue damage, or a myocardial infarction, also known as a heart attack.
An atheroma, or atheromatous plaque ("plaque"), is an abnormal accumulation of material in the inner layer of the wall of an artery.
Intravascular ultrasound (IVUS) is a medical imaging methodology using a specially designed catheter with a miniaturized ultrasound probe attached to the distal end of the catheter. The proximal end of the catheter is attached to computerized ultrasound equipment. It allows the application of ultrasound technology, such as piezoelectric transducer or CMUT, to see from inside blood vessels out through the surrounding blood column, visualizing the endothelium of blood vessels in living individuals.
The history of invasive and interventional cardiology is complex, with multiple groups working independently on similar technologies. Invasive and interventional cardiology is currently closely associated with cardiologists, though the development and most of its early research and procedures were performed by diagnostic and interventional radiologists.
Fractional flow reserve (FFR) is a technique used in coronary catheterization to measure pressure differences across a coronary artery stenosis to determine the likelihood that the stenosis impedes oxygen delivery to the heart muscle.
Intima–media thickness (IMT), also called intimal medial thickness, is a measurement of the thickness of tunica intima and tunica media, the innermost two layers of the wall of an artery. The measurement is usually made by external ultrasound and occasionally by internal, invasive ultrasound catheters. Measurements of the total wall thickness of blood vessels can also be done using other imaging modalities.
Spontaneous coronary artery dissection (SCAD) is an uncommon but dangerous condition in which one of the arteries that supply the heart spontaneously develops a blood collection, or hematoma, within the artery wall. This leads to a separation and weakening of the walls of the artery.
Coronary CT angiography is the use of computed tomography (CT) angiography to assess the coronary arteries of the heart. The subject receives an intravenous injection of radiocontrast and then the heart is scanned using a high speed CT scanner, allowing physicians to assess the extent of occlusion in the coronary arteries, usually in order to diagnose coronary artery disease.
Cardiac imaging refers to non-invasive imaging of the heart using ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), or nuclear medicine (NM) imaging with PET or SPECT. These cardiac techniques are otherwise referred to as echocardiography, Cardiac MRI, Cardiac CT, Cardiac PET and Cardiac SPECT including myocardial perfusion imaging.
Multi-spectral optoacoustic tomography (MSOT), also known as functional photoacoustic tomography (fPAT), is an imaging technology that generates high-resolution optical images in scattering media, including biological tissues. MSOT illuminates tissue with light of transient energy, typically light pulses lasting 1-100 nanoseconds. The tissue absorbs the light pulses, and as a result undergoes thermo-elastic expansion, a phenomenon known as the optoacoustic or photoacoustic effect. This expansion gives rise to ultrasound waves (photoechoes) that are detected and formed into an image. Image formation can be done by means of hardware or computed tomography. Unlike other types of optoacoustic imaging, MSOT involves illuminating the sample with multiple wavelengths, allowing it to detect ultrasound waves emitted by different photoabsorbing molecules in the tissue, whether endogenous or exogenous. Computational techniques such as spectral unmixing deconvolute the ultrasound waves emitted by these different absorbers, allowing each emitter to be visualized separately in the target tissue. In this way, MSOT can allow visualization of hemoglobin concentration and tissue oxygenation or hypoxia. Unlike other optical imaging methods, MSOT is unaffected by photon scattering and thus can provide high-resolution optical images deep inside biological tissues.
Lumivascular refers to a minimally invasive procedure in which an interventional catheter with real time intravascular light (lumi) imaging capabilities is inserted percutaneously into a vascular blood vessel for the treatment of vascular disease.
Giovanni J. Ughi, engineer and scientist, is one of the inventors of multimodality Optical Coherence Tomography (OCT) and Laser-induced fluorescence molecular imaging, pioneering a first-in-man study of coronary arteries during his work at Massachusetts General Hospital. The results of his work, combining two imaging technologies, may better identify dangerous coronary plaques, responsible for coronary artery disease and myocardial infarction. He also was one of the pioneers of targeted molecular imaging of human atherosclerosis, determining the use of a FDA approved molecular agent that can illuminate high-risk features of human carotid atherosclerotic plaques and other molecular agents for the identification of unhealed stents that are at higher risk of stent thrombosis.
Guillermo J. Tearney is a professor of pathology at Harvard Medical School, a physicist in the department of dermatology at the Massachusetts General Hospital, a pathologist in the department of pathology at the Massachusetts General Hospital and runs a research laboratory at the Wellman Center for Photomedicine at the Massachusetts General Hospital in Boston Massachusetts. Tearney received his BA in applied mathematics, graduating cum laude (1988), his MD graduating magna cum laude (1998) from Harvard Medical School, and received his PhD in electrical engineering (1997) from the Massachusetts Institute of Technology. He is a well-known name in the field of biomedical optics, castroenterology, and interventional cardiology for his prominent role on the development of endoscopic optical coherence tomography, in particular intracoronary optical coherence tomography, its translation to the clinic and commercialization. He is recognized as one of the inventors of Intracoronary optical coherence tomography. He is also recognized as co-inventor of optical coherence tomography for endoscopic imaging and diagnosis of esophagus disorders, a clinical technology currently commercialized by NinePoint Medical.
Intracoronary optical coherence tomography (OCT), is an endoscopic-based application of optical coherence tomography. Analogous to intravascular ultrasound, intracoronary OCT uses a catheter to deliver and collect near infrared light to create cross-sectional images of the artery lumen and wall. Intracoronary OCT creates images at a resolution of approximately 15 micro-meters, an order of magnitude improved resolution with respect to intravascular ultrasound and X-ray coronary angiogram.
Intravascular imaging is a catheter based system that allows physicians such as interventional cardiologists to acquire images of diseased vessels from inside the artery. Intravascular imaging provides detailed and accurate measurements of vessel lumen morphology, vessel size, extension of diseased artery segments, vessel size and plaque characteristics. Examples of intravascular imaging modalities are intravascular ultrasound (IVUS) and Intracoronary Optical Coherence Tomography.
Vasilis Ntziachristos is a Greek American biomedical engineer, scientist, and inventor, best known for his development of fundamental and translational research tools for imaging tissues based on fluorescence and optoacoustics.
