Ultrasound Glossary

A myxoma is a cardiac tumor, most commonly arising from the left atrium, visible on echocardiography.

The nasal bones are small bones in the nose that can be measured on prenatal ultrasound as a marker for chromosomal abnormalities.

The region immediately adjacent to the transducer face where the ultrasound beam is relatively uniform before spreading.

Neovascularization is the formation of new blood vessels, which can be detected on color Doppler ultrasound as a sign of inflammation or malignancy.

A nephroblastoma is a malignant kidney tumor in children, also known as Wilms tumor, visible as a renal mass on ultrasound.

Nephrolithiasis is the medical term for kidney stone disease, with stone appearance and location best shown on ultrasound.

Nephroptosis is abnormal mobility or descent of the kidney, potentially visible on ultrasound when the patient changes position.

Nephrotic syndrome is characterized by severe proteinuria and reduced serum proteins, with ultrasound used to evaluate kidney size and echogenicity.

Nerves are bundles of nerve fibers visible on high-resolution ultrasound, particularly during musculoskeletal and peripheral nerve examination.

Compression of a peripheral nerve within an anatomic tunnel, evaluated on ultrasound by increased nerve cross-sectional area.

Neural tube defects are congenital malformations of the brain or spinal cord resulting from failure of the neural tube to close during fetal development.

A neuroblastoma is a malignant tumor of neural crest origin, most commonly arising in the adrenal gland, visible as a renal or suprarenal mass on ultrasound.

Neurofibromatosis is a genetic disorder characterized by the development of neurofibromas (tumors of nerve tissue), visible as soft tissue masses on ultrasound.

A neuroma is a benign tumor of nerve tissue that can occur in various locations, including common sites like the interdigital space of the foot.

Newborn screening refers to the use of ultrasound in newborn infants to detect congenital abnormalities and disease.

Nodal metastasis refers to cancer spread to lymph nodes, visible on ultrasound as enlarged or abnormal-appearing lymph nodes.

A nodule is a small, discrete lesion or abnormality, typically less than 10 millimeters in diameter, visible on ultrasound.

Nonalcoholic fatty liver disease is the accumulation of excess fat in the liver in patients without significant alcohol consumption.

Nonechogenic is a term describing structures that do not produce ultrasound echoes, appearing completely dark on ultrasound images.

Nonimmune hydrops fetalis is severe fluid accumulation in the fetus not caused by Rh incompatibility, detectable on prenatal ultrasound.

Nuchal cord occurs when the umbilical cord wraps around the fetal neck, readily detected on prenatal ultrasound.

The nuchal fold is a measurement of skin thickening at the back of the fetal neck, used as a prenatal screening marker for chromosomal abnormalities.

A sonographic measurement of fluid at the back of the fetal neck at 11–14 weeks, used to screen for chromosomal abnormalities.

Nucleation is the process by which gallstones or kidney stones begin to form, with factors affecting nucleation studied in stone disease research.

Ultrasound imaging of the pregnant uterus to evaluate fetal development, anatomy, growth, and well-being.

A fluid-filled sac within the ovary containing an oocyte, visualized on ultrasound during ovulation monitoring.

Twisting of the ovary on its pedicle causing ischemia — a gynecologic emergency evaluated with Doppler ultrasound.

Enlargement of the main pancreatic duct on ultrasound, normally less than 3 mm — a key finding in pancreatitis and pancreatic ductal adenocarcinoma.

A standard echocardiographic view showing the left ventricle, mitral valve, aortic valve, and aortic root in a long-axis plane.

The parotid gland is the largest salivary gland, located in front of the ear, and can be evaluated by ultrasound for masses, stones, and inflammation.

Patent ductus arteriosus is a congenital heart condition in which a fetal blood vessel fails to close after birth, diagnosed by echocardiography.

The maximum blood flow velocity measured during systole using spectral Doppler — a key parameter for grading vascular stenosis.

Pelvic inflammatory disease (PID) is an infection of the female reproductive organs, evaluated by ultrasound for complications like abscess.

Excess fluid in the pericardial sac surrounding the heart, detected on echocardiography.

Pericarditis is inflammation of the pericardium (the sac around the heart), which may produce an effusion detectable on echocardiography.

The pericardium is the protective sac surrounding the heart, visible on echocardiography as a bright, thin line.

Peripheral artery disease is narrowing of the arteries supplying the limbs, assessed by Doppler ultrasound for stenosis and blood flow abnormalities.

Periportal fibrosis is scarring around the portal tracts of the liver, which appears as increased echogenicity along the portal vein branches on ultrasound.

The peritoneum is the membrane lining the abdominal cavity, assessed by ultrasound for fluid, thickening, or masses.

A phased array is a type of ultrasound transducer with a small footprint that produces a fan-shaped image, commonly used in cardiac imaging.

A small-footprint transducer that steers the beam electronically, producing a sector image — the standard probe for echocardiography.

Piezoelectric refers to the property of certain materials to convert electrical energy into sound waves and vice versa, forming the basis of ultrasound transducers.

The property of certain crystals to generate an electric charge when mechanically stressed, and to deform when an electric current is applied — the physical basis of ultrasound transducers.

The placenta is a temporary organ that connects the fetus to the uterine wall, routinely assessed on prenatal ultrasound for location, maturity, and abnormalities.

Placenta accreta is a serious pregnancy condition in which the placenta grows too deeply into the uterine wall, detectable on prenatal ultrasound.

Abnormal placental attachment to the uterine wall — accreta, increta, or percreta — evaluated on ultrasound in high-risk pregnancies.

A condition in which the placenta partially or completely covers the internal cervical os, identified on ultrasound.

Placental abruption is premature separation of the placenta from the uterine wall, which may show as a blood collection on ultrasound.

Placental grading is an ultrasound classification system that describes the maturity of the placenta based on its appearance and calcification.

Plantar fasciitis is inflammation of the thick tissue on the bottom of the foot, diagnosed and evaluated by ultrasound.