Ultrasound produces sound waves that are beamed into the body causing return echoes that are recorded to “visualize” structures beneath the skin. The ability to
measure different echoes reflected from a variety of tissues allows a shadow picture to be constructed. The technology is especially accurate at seeing the interface between solid and fluid filled spaces.
Ultrasonography or Medical Diagnostic sonography is an ultrasound-based diagnostic imaging technique used for visualizing subcutaneous body structures including internal organs, blood vessels, muscles, tendons and joints to detect the presence or not of pathology or lesions.
Different modes of ultrasound images are available. The most well-known type is a B-mode image, which displays a two-dimensional cross-section of the tissue being imaged. Other types of image can display blood flow, motion of tissue over time, the location of blood, the presence of specific molecules, the stiffness of tissue, or the anatomy of a three-dimensional region. Ultrasound can also be used therapeutically, to break up gallstones and kidney stones or to heat and destroy diseased or cancerous tissue.
In contrast to other medical imaging modalities, ultrasonography has several advantages which include acquisition of real-time images, its portability (can be brought to a sick patient’s bedside), it is cheaper, and it does not employ ionizing radiation. Disadvantages include limited field of view, difficulty imaging structures behind bone, and its relative dependence on a skilled sonographer.
A transducer, or probe, transmits the sound waves and receives the returning sound waves and signals. A gel is applied on the patient’s skin to prevent the distortion of the sound waves by air trapped between the probe and patient’s skin. By employing their knowledge in human anatomy, pathology and ultrasound technology, sonographers can evaluate specific structures and clinical conditions and make appropriate findings on the conditions of patients. To achieve good and expected results the sonographer must be knowledgeable and skilful.
The accuracy of the test is very much sonographer dependent. This means that the key to a good test is the sonographer.
Ultrasound can be enhanced by using Doppler technology which can measure whether an object is moving towards or away from the probe. This can allow the sonographer to measure blood flow in organs such as the heart or liver, or within specific blood vessels.
Ultrasound is not limited to diagnosis, but can also be used in screening for disease and to aid in treatment of diseases or conditions.
Sonographers routinely use ultrasonography to assess the progression of pregnancy. Pelvic ultrasounds can be obtained trans-abdominally where the probe is placed on the abdominal wall, or trans-vaginally, where the probe is placed in the vagina to diagnose growths or tumors of the ovary, uterus, Fallopian tubes.
Sonographers use echocardiography to evaluate the heart, the heart’s valve function, and blood flow through them. It can be employed to evaluate the heart wall motion and the amount of blood the heart pumps with each stroke
Ultrasound can be used to detect blood clots in veins (superficial or deep venous thrombosis) or artery blockage (stenosis) and dilatation (aneurysms).
Aside from In addition to its use in obstetrics, ultrasound can be used to evaluate most of the solid structures in the abdominal cavity. This includes the liver, gallbladder, pancreas, kidneys, bladder, prostate, testicles, uterus, and ovaries.
Sonographers evaluate the thyroid gland looking for nodules, growths, or tumours.
Ultrasound can be used to detect bulging of fluid from a swollen knee joint into the back of the knee, called a Baker’s cyst.
Sonographers use Ultrasound to screen for blood vessel diseases. They measure blood flow and blockage in the carotid arteries to predict potential risk for future stroke.