Ultrasound Glossary

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.

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.

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.

Mitral stenosis is a narrowing of the mitral valve that restricts blood flow from the left atrium to the left ventricle, evaluated by echocardiography.

A modality refers to a particular imaging technique or method, such as ultrasound, CT, or MRI.

A moiré artifact is a wavy or linear striping pattern that can appear on ultrasound when the transducer is held at certain angles.

A molar pregnancy is an abnormal pregnancy caused by a genetic error during fertilization, appearing on ultrasound as a characteristic heterogeneous mass with small cysts.

A monoamniotic pregnancy occurs when twins share both a placenta and an amniotic sac, the highest-risk type of multiple gestation.

A monochorionic pregnancy is one in which twins share a single placenta but may have separate or shared amniotic sacs.

Motion artifact occurs when patient movement or breathing disrupts the ultrasound image, making it blurry or distorted.

Mucinous adenocarcinoma is a type of cancer that produces mucin, often occurring in the gastrointestinal tract, detectable on ultrasound as a mass.

A multicystic dysplastic kidney is an abnormal kidney consisting of non-communicating cysts, typically non-functional and not requiring treatment.

A multinodular goiter is an enlarged thyroid gland containing multiple nodules, commonly evaluated with ultrasound.

Multiple gestations refer to pregnancies with more than one fetus, requiring careful ultrasound assessment to determine chorionicity and amnionicity.

Sonographic Murphy sign — focal tenderness directly over the gallbladder during ultrasound examination, indicating acute cholecystitis.

Muscle tissue, visible on ultrasound as hypoechoic linear bundles, is a fundamental structure of the musculoskeletal system.

Ultrasound imaging of tendons, muscles, ligaments, nerves, and joints for diagnosis of soft tissue injuries and guidance of injections.

Myasthenia gravis is an autoimmune neuromuscular disease that can be associated with thymic abnormalities visible on ultrasound.

A mycotic aneurysm is an infected aneurysm, typically resulting from bacterial seeding during bacteremia or endocarditis.

A myelencephalocele is a severe form of neural tube defect in which brain tissue herniates through an opening in the skull.

A myelomeningocele is a neural tube defect in which the spinal cord and meninges herniate through an opening in the vertebral column.

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

Myopia, or nearsightedness, causes high optical power in the eye, which can lead to unusual findings when eyes are scanned with ultrasound.

Myxedema is severe hypothyroidism characterized by accumulation of mucopolysaccharides in the skin and soft tissues.