Intravascular fluorescence is a catheter-based

molecular imaging Molecular imaging is a field of medical imaging that focuses on imaging molecules of medical interest within living patients. This is in contrast to conventional methods for obtaining molecular information from preserved tissue samples, such as h ...

technique that uses near-infrared

fluorescence Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with colore ...

to detect artery wall autofluorescence (NIRAF) or fluorescence generated by molecular agents injected intravenously (NIRF) . No commercial systems based on intravascular fluorescence are currently on the market, however, significant steps forwards in intravascular fluorescence imaging technology have been made between 2010-2016. It is typically used to detect functional state of artery wall including some known high-risk features of atherosclerosis (e.g., inflammation). It is usually combined with structural imaging modalities such as

Intravascular ultrasound Intravascular ultrasound (IVUS) or intravascular echocardiography 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 cathe ...

and/or Intracoronary optical coherence tomography, to provide functional information in a morphological context.

Methods

Intravascular fluorescence typically used

laser-induced fluorescence Laser-induced fluorescence (LIF) or laser-stimulated fluorescence (LSF) is a spectroscopic method in which an atom or molecule is excited to a higher energy level by the absorption of laser light followed by spontaneous emission of light. It was f ...

to stimulate fluorescence emission of particular vessel wall and plaque components or previously injected molecular agents (i.e.,

). Fluorescence detection can be obtained by integration over a short period of time of the emitted intensity, life-time (i.e.,

fluorescence-lifetime imaging microscopy Fluorescence-lifetime imaging microscopy or FLIM is an imaging technique based on the differences in the exponential decay rate of the photon emission of a fluorophore from a sample. It can be used as an imaging technique in confocal microscopy, ...

or FLIM), or by analyzing the spectral shape of emitted fluorescence (

fluorescence spectroscopy Fluorescence spectroscopy (also known as fluorimetry or spectrofluorometry) is a type of electromagnetic spectroscopy that analyzes fluorescence from a sample. It involves using a beam of light, usually ultraviolet light, that excites the electro ...

Near-infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those of ...

light is often used to stimulate fluorescence emission in the case of intravascular applications. Imaging

catheters In medicine, a catheter ( ) is a thin tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. Catheters are man ...

contain an

optical fiber An optical fiber, or optical fibre, is a flexible glass or plastic fiber that can transmit light from one end to the other. Such fibers find wide usage in fiber-optic communications, where they permit transmission over longer distances and at ...

to deliver and collect light to and from inner lumen of human body through semi-invasive interventions (e.g.,

percutaneous coronary intervention Percutaneous coronary intervention (PCI) is a minimally invasive non-surgical procedure used to treat stenosis, narrowing of the coronary artery, coronary arteries of the heart found in coronary artery disease. The procedure is used to place and ...

in case of coronary arteries).

Applications

Several research studies demonstrated the role of intravascular fluorescence for the diagnosis of vascular diseases. Plaque autofluorescence has been used in a first-in-man study in coronary arteries in combination with Intracoronary optical coherence tomography (OCT). Similarly, intravascular

has been used in combination with OCT in a clinical study using an

FDA The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

approved molecular target (i.e., indocyanine green) to detect high-risk features of carotid plaques at risk for

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

. Molecular agents has been also used to detect specific features, such as stent

fibrin Fibrin (also called Factor Ia) is a fibrous protein, fibrous, non-globular protein involved in the Coagulation, clotting of blood. It is formed by the action of the protease thrombin on fibrinogen, which causes it to polymerization, polymerize. ...

accumulation to detect unhealed intravascular stent ''in vivo'' at increased risk of

thrombosis Thrombosis () is the formation of a Thrombus, blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel (a vein or an artery) is injured, the body uses platelets (thrombocytes) and fib ...

and enzymatic activity related to artery inflammation.

References

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Methods

Applications

References

See also