(TEE) Transesophageal echocardiography provides a superior view of cardiac anatomy compared with transthoracic echocardiography. TEE is performed by the introduction of a probe attached to a fiberoptic endoscope into the esophagus. Caused by the position close to the heart e.g., clot finding and the view of the mitral valve are improved.

Indications:
The piezoelectric crystal creating the acoustic power is mounted on the gastroscope that must be swallowed by the patient. This endoscopic transducer is miniaturized to approximately the size of a fingernail. Usually the probe is in place for an average of 15 minutes, to numb the surface a topical anesthetic is sprayed into the throat, in addition a conscious sedation is recommended.

See also Myocardial Contrast Echocardiography, Stress Echocardiogram, M-Mode Echocardiography, Contrast Enhanced Ultrasound and Vascular Ultrasound Contrast Agents.

(HVL) The attenuation of ultrasound waves in human tissue is characterized as the half value layer, or the half power distance. Half value layer means the distance the sound beam will travel in a tissue before its amplitude or energy is attenuated to half its original value. Air and lung tissue have extremely short half-power distances and represent severe obstacles to the transmission of acoustic energy.

(LIPU / LIUS) Low intensity pulsed ultrasound is a form of mechanical power that is transmitted through and into tissues as an acoustic pressure wave. Low intensity pulsed ultrasound is often used in musculoskeletal and joint ultrasound and has therapeutic benefits for healing of (fresh) fractures, those that demonstrate either a delayed union or nonunion, and soft tissue repair.

A projector (transmitter) converts the energy from the power amplifier (generator) into an acoustic pressure output. Projectors are usually driven near their resonance frequencies where they provide the highest acoustic output.

Conventional, CT and MR imaging technologies are limited in their availability, to depict soft tissue, or to show dynamic activity, like cardiac muscle contractility and blood flow. Easy applicability, real-time sonography and biopsy facilitation are important advantages in veterinarian medicine. Veterinary ultrasound has a very high sensitivity to show the composition of soft tissues, but the low specificity is a disadvantage. High ultrasound system performance includes Doppler techniques, contrast enhanced ultrasound, 3D ultrasound, and tissue harmonic imaging to improve resolution.
Technical and physical requirements of veterinary ultrasound are the same as in human ultrasonography. The higher the sound frequency, the better the possible resolution, but the poorer the tissue penetration. Image quality is depended of the ultrasound equipment. For example, a 10 MHz transducer is excellent for imaging of superficial structures; a 3.5 or 5.0 megahertz transducer allows sufficient penetration to see inner structures like the liver or the heart. In addition, the preparation and performing of the examination is similar to that of humans. The sound beam penetrates soft tissue and fat well, but gas and bone impede the ultrasonic power. Fluid filled organs like the bladder are often used as an acoustic window, and an ultrasound gel is used to conduct the sound beam.