Ultrasonography – It is a radiologic method in which the deep structures of the human body parts are visualized by recording (echoes) of ultrasonic waves directed into the tissues.

Principle of Ultrasonography – The theory of the sonography is similar as that of depth-sounding in oceanographic studies of the ocean floor.  The ultrasonic waves are restricted to a narrow beam, which can transmit through reflected by the medium toward, which they are directed. It depends on the nature of the surface when they strike.

In the examination of the diagnostic ultrasonography, the ultrasonic waves, which are produced by electrically stimulate crystal known as a transducer. When the beam strikes an interface or boundary between tissues of varying density (e.g. muscle and blood), some of the sound waves are reflected back to the transducer as echoes. The echoes are then changed into electrical impulses are displayed on an oscilloscope, which save an image of the tissues.

Ultrasonography can also be used in the examination of the heart (echocardiography), which is placed in the aneurysms of the aorta and other abnormalities of the major blood vessels. It identifies the size and structural changes in organs in the abdominopelvic cavity and also identifying and distinguishing cancers and benign cysts. This method can also be used to evaluate tumors and foreign bodies of the eye, and to demonstrate retinal detachment.

Types of Ultrasonography – There are several types of Ultrasonography, which are discussed below

1. A-mode Ultrasonography – It is the technique that an ultrasonography modality provides simple displays, which are plotted as a series of peaks and the height of which represents the depth of the echoing structure from the transducer.
2. B-Mode Ultrasonography – It is also called as Brightness-Modulated display, and is the method in which a wide range of applications including imaging of a kidneys, liver, fetus, uterus, prostate, gallbladder, cardiovascular structures, breast, early ovarian cancer and many more. It is also used to assess various complications such as infection, rejection, patency, and thrombosis of biliary tracts and identifying gallbladder calculi. It retardation and major congential anomalies including hydtocephaly, congenital heart disease, anencephaly, fetal tumors, meningocele, dextrocardia, polycystic kidneys, diaphragmatic hernia, omphalocele, gastroschisis, hydrops fetalis, and many more.
3. Gray-Scale Ultrasonography – It is the technique in which B-mode Ultrasonography scanning the strength of the echoes, which can be displayed in shades of gray according to their amplitude.
4. Doppler Ultrasonography – It is that type of ultrasonography in which the measurement and a visual record are made of the shift in frequency of a continuous ultrasonic wave proportional to the blood-flow velocity in underlying  vessels. It is also used in diagnosis of extra cranial occlusive vascular disease and in the detection of the fetal heart beat or of the velocity of the movement of a structure, such as the beating heart.
5. Real-Time Ultrasonography – It is that type of Ultrasonography in which B-mode ultrasonography using an array of detectors so that scans can be used made electronically at a rate of 30 frames a second.