Ultrasound Glossary

Abnormal fluid accumulation within a joint capsule, readily detected by ultrasound and important for diagnosing infection, arthritis, and injury.

One of the large veins in the neck that drains blood from the head, frequently evaluated during vascular ultrasound and used for central venous access.

One of two bean-shaped organs that filter blood and produce urine, among the most frequently evaluated structures in abdominal ultrasound.

A fluid-filled sac within the kidney that is usually simple and benign, classified by the Bosniak system when complex features are present.

A hard mineral deposit that forms within the kidney, appearing on ultrasound as a bright structure with a dark shadow behind it.

A surgical procedure in which a healthy kidney from a donor is placed in a patient with kidney failure, with ultrasound used for monitoring before and after the operation.

The informal term for understanding and operating the various controls, settings, and adjustments on an ultrasound machine.

A specialized immune cell that lines the blood vessels inside the liver and plays a role in how the liver interacts with contrast agents on ultrasound.

The labrum is a ring of cartilage that surrounds a joint socket, commonly examined by ultrasound in the shoulder and hip.

A laceration is a tear or irregular wound in soft tissue, sometimes identified on ultrasound as a disruption in the normal organ architecture.

Large bowel obstruction is a blockage of the large intestine that can sometimes be evaluated with ultrasound.

Lateral resolution is the ability of an ultrasound system to distinguish two objects side by side at the same depth.

The left atrium is the upper-left chamber of the heart that receives oxygenated blood from the lungs.

The left ventricle is the heart’s main pumping chamber, responsible for sending oxygenated blood to the body.

Left ventricular ejection fraction (LVEF) is a percentage that measures how much blood the left ventricle pumps out with each heartbeat.

The left ventricular outflow tract (LVOT) is the pathway through which blood exits the left ventricle into the aorta.

A leiomyoma is a benign smooth muscle tumor, most commonly found in the uterus, where it is also called a fibroid.

Leiomyosarcoma is a rare malignant tumor of smooth muscle that can occur in the uterus or other soft tissue locations.

The lesser saphenous vein is a superficial vein running along the back of the lower leg, commonly evaluated with venous ultrasound.

A linear array is a type of ultrasound transducer with a flat surface that produces a rectangular image, commonly used for superficial structures.

A transducer with crystals arranged in a straight line, producing a rectangular image — used for superficial and vascular imaging.

A linear transducer is a high-frequency ultrasound probe with a flat footprint, used primarily for imaging near the skin surface.

A lipoma is a common benign tumor made of fat tissue that appears on ultrasound as a soft, well-defined, echogenic mass.

A liposarcoma is a malignant tumor of fat tissue that may appear as a large, heterogeneous mass on ultrasound.

The liver is the largest solid organ in the abdomen, routinely evaluated by ultrasound for size, texture, and disease.

A liver biopsy is a procedure in which a small sample of liver tissue is removed for testing, often guided by ultrasound.

A liver transplant is the surgical replacement of a diseased liver with a healthy donor liver, monitored closely by ultrasound afterward.

The longitudinal plane is a scanning orientation that divides the body or an organ into left and right halves along its long axis.

An ultrasound scan taken along the length of a structure, showing how long it is. Most longitudinal scans are sagittal views that show the body from head to toe.

A low-resistance waveform on Doppler ultrasound shows continuous forward blood flow throughout the cardiac cycle, typical of organs needing constant blood supply.

Ultrasound assessment of the lungs and pleura, used to detect pneumothorax, pleural effusion, and pulmonary edema.

A lymph node is a small, bean-shaped immune structure that can be evaluated by ultrasound for size, shape, and signs of disease.

Lymphedema is chronic swelling caused by a buildup of lymphatic fluid, which can be assessed with ultrasound to evaluate tissue changes.

Lymphoma is a cancer of the lymphatic system that can cause enlarged lymph nodes and organ involvement visible on ultrasound.

A single-line ultrasound display showing motion over time, used primarily in cardiac and fetal heart imaging.

M-Mode is an ultrasound technique that shows motion over time. Learn how M-Mode works and its applications in cardiac imaging.

A special ultrasound mode that shows motion over time, like a recording of how a structure moves. It displays a line graph that tracks movement in one direction, useful for measuring heart valve movements.

Mastitis is an infection or inflammation of breast tissue that can be evaluated with ultrasound to rule out abscess formation.

MCA-PSV (Middle Cerebral Artery Peak Systolic Velocity): Peak systolic velocity in the fetal middle cerebral artery; values >1.5 MoM indicate fetal anemia and trigger further evaluation. Middle cerebral artery peak systolic velocity (MCA-PSV) is a Doppler measurement used to screen for fetal anemia. Elevated MCA-PSV (>1.5 MoM for gestational age) indicates increased cardiac output from…

A real-time display estimating the potential for mechanical bioeffects such as cavitation from the ultrasound beam.

Meckel diverticulum is a congenital pouch in the small intestine that can occasionally be visualized or suggested by ultrasound findings.

The median arcuate ligament is a fibrous arch of the diaphragm that can compress the celiac artery, detectable on Doppler ultrasound.

The mediastinum is the central compartment of the chest containing the heart, great vessels, and other structures, partially accessible to ultrasound.

Medullary carcinoma is a type of cancer that can occur in the thyroid or breast, appearing as a solid mass on ultrasound.

A meniscus is a crescent-shaped cartilage pad in the knee joint that can be partially evaluated with ultrasound.

The mesentery is a fold of tissue that attaches the intestines to the abdominal wall, sometimes visible on ultrasound when inflamed or diseased.

Mesothelioma is a cancer of the mesothelial lining, most often affecting the pleura, that may present with effusions visible on ultrasound.

A false duplicate image of a structure appearing on the opposite side of a strong reflective surface such as the diaphragm.

The mitral annulus is the fibrous ring surrounding the mitral valve, measured during echocardiography to assess valve and heart function.

Mitral regurgitation is the backward leaking of blood through the mitral valve, detected and graded by Doppler echocardiography.