Échographie

Ultrasonography emits high-frequency sound waves, typically between 2 to 18 megahertz, into the body using a handheld transducer. These waves reflect off internal structures and tissues. The transducer receives the echoes, and the time taken for reflected waves to return helps determine the distance to tissue boundaries, allowing a computer to construct a detailed anatomical image called a sonogram.

Gel is applied to the transducer before it contacts the skin. This gel creates an acoustic seal that enables better transmission of sound waves between the transducer and the skin surface. Without this acoustic coupling, sound waves would be poorly transmitted, resulting in degraded image quality and reduced diagnostic accuracy.

Ultrasonography is used to examine body structures like the shoulder and knee, monitor fetal development during pregnancy, and diagnose tumor progression. It also evaluates organ function, assesses blood flow in vessels, identifies gallstones and kidney stones, and guides interventions such as joint injections. Additionally, it examines the musculoskeletal system, including tendons, ligaments, and soft tissues.

Ultrasonography is non-invasive and does not use ionizing radiation, making it a safe imaging method for patients of all ages, including pregnant women. Unlike x ray imaging that exposes patients to harmful radiation, ultrasonography relies on sound waves to visualize internal structures, eliminating radiation-related health risks while providing valuable diagnostic information.

Image quality is heavily operator-dependent and cannot penetrate bone or gas-filled structures. Excess subcutaneous fat in obese individuals attenuates the echo signal, limiting clear visualization of deeper structures. These limitations can affect diagnostic accuracy and may require alternative imaging methods in certain clinical situations.

Doppler ultrasound is a specialized form of ultrasonography used to evaluate blood flow in vessels. While standard ultrasonography creates static images of anatomical structures, Doppler ultrasound measures the direction and velocity of blood flow, helping detect blockages, narrowing, or abnormalities such as deep vein thrombosis or carotid artery disease.

A transducer is a handheld device placed on the skin surface that both emits and receives high-frequency sound waves. It sends sound waves into the body and captures echoes that bounce back from internal structures. The transducer converts these echoes into real-time images displayed on a computer monitor, providing diagnostic information about organs and tissues.