Indoleacetic acid

Indocyanine Green (ICG) is a cyanine dye used in medical diagnostics. It is used in certain types of eye examination, including angiography, and in cardiology for determining cardiac output. Its fluorescence properties make it useful in certain surgical procedures.

History

Indocyanine Green was first synthesized in the 1950s and has been used in medical diagnostics since the 1960s. It was initially used in cardiology to measure cardiac output, hepatic function, and blood flow.

Properties

ICG is a tricarbocyanine dye that is water soluble and binds tightly to plasma proteins in the blood. It has a peak spectral absorption at about 800 nm. These properties make it ideal for medical imaging.

Medical uses

Ophthalmology

In ophthalmology, ICG is used in angiography to examine the choroid, a layer of blood vessels in the eye. This can help diagnose conditions such as age-related macular degeneration and polypoidal choroidal vasculopathy.

Cardiology

ICG can be used in cardiology to measure cardiac output, the volume of blood being pumped by the heart. The dye is injected into the blood stream and its concentration over time is measured with a photodetector.

Surgery

The fluorescence properties of ICG can be used in surgery to highlight certain tissues. For example, it can be used in neurosurgery to highlight brain tumors, in plastic surgery to assess tissue perfusion, and in oncology to highlight cancerous tumors.

Safety

ICG is generally considered safe for use in humans. However, it can cause side effects in some people, including nausea, headache, and hypotension. It is contraindicated in people with iodine allergy as it contains iodine.

See also

• Fluorescein angiography
• Optical coherence tomography
• Near-infrared spectroscopy