Microangiography ( ) is a type of

angiography 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. Modern angiography is perfor ...

that consists of the

radiography Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeu ...

of small blood or lymphatic vessels of an organ. While most other types of angiography cannot produce images of vessels smaller than 200 µm in diameter, microangiography does just that. A microangiographic image is the result of injection of a

contrast medium A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radio ...

into either the blood or the lymphatic system and, then, enlargement of the resulting radiograph. Thus, an image is obtained in which there is contrast between vessel and surrounding tissue. It is often used in order to detect microvascular lesions in organs. But, it has been suggested that microangiography can also be used to detect

tumors A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

through visualization of tumor-induced small blood vessels. This is because tumor growths require

vascularization Angiogenesis is the physiological process through which new blood vessels form from pre-existing vessels, formed in the earlier stage of vasculogenesis. Angiogenesis continues the growth of the vasculature by processes of sprouting and splitting ...

before they can develop more rapidly. A few of the commonly used types are fluorescent, silicone rubber, and synchrotron radiation microangiography.

Common types

Fluorescent microangiography

Also known as FMA, fluorescent microangiography is used to visualize and quantify changes in

microvasculature The microcirculation is the circulation of the blood in the smallest blood vessels, the microvessels of the microvasculature present within organ tissues. The microvessels include terminal arterioles, metarterioles, capillaries, and venules. ...

. It is different from other types of microangiography in that a fluorescent marker or

is used instead of something else.

Fluorescein Fluorescein is an organic compound and dye based on the xanthene tricyclic structural motif, formally belonging to triarylmethine dyes family. It is available as a dark orange/red powder slightly soluble in water and alcohol. It is widely used ...

and indocyanine green are often used for this purpose.

Laser Doppler holography

Computational imaging with lasers, ultrahigh-speed cameras, commodity graphics cards, and state-of-the-art statistical filtering algorithms, emerges as a competitive alternative to dye angiographies. This class of non-invasive microangiography techniques can be advantageously applied to the eye fundus to reveal endoluminal blood flow profiles in the

retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

and choroid.Puyo, L., M. Paques, M. Fink, J-A. Sahel, and M. Atlan. "In vivo laser Doppler holography of the human retina." Biomedical optics express 9, no. 9 (2018): 4113-4129.

Laser Doppler imaging Laser Doppler imaging (LDI) is an imaging method that uses a laser beam to scan live tissue. When the laser light reaches the tissue, the moving blood cells generate doppler components in the reflected ( backscattered) light. The light that comes ...

by holography provides high-contrast visualization of local blood flow in choroidal vessels in humans, with a spatial resolution comparable to state-of-the-art

indocyanine green angiography Indocyanine green angiography (ICGA) is a diagnostic procedure used to examine choroidal blood flow and associated pathology. Indocyanine green (ICG) is a water soluble cyanine dye which shows fluorescence in near-infrared (790–805 nm) range, wit ...

Silicone rubber microangiography

This type of microangiography produces a three-dimensional image that depicts the distribution of vasculature in a tissue. It is commonly used to determine changes in microvasculature.

Synchrotron radiation microangiography

This type of microangiography uses monochromatic synchrotron radiation and a high-definition video system to provide an image of small collateral arteries with a diameter less than 100 µm.

References