An ultrasound scan is a medical test that uses high-frequency sound waves to capture live images from the inside of your body. It’s also known as sonography. The technology is similar to that used by sonar and radar, which help the military detect planes and ships. Types of Ultrasound allows your doctor to see problems with organs, vessels, and tissues without needing to make an incision. Unlike other imaging techniques, ultrasound uses no radiation. For this reason, it’s the preferred method for viewing a developing fetus during pregnancy. Also Ultrasound or ultrasonography is a medical imaging technique that uses high frequency sound waves and their echoes. The technique is similar to the echolocation used by bats, whales and dolphins, as well as SONAR used by submarines. Ultrasound was originally developed during World War I to track submarines as SONAR technology (Sound, Navigation And Ranging). Ultrasound was first used medically in the 1950s, with very early applications in fetal biometry; nowadays, it is used in just about every field of medicine. Furthermore, it is also now practiced by a wide variety of professionals, in a multidisciplinary setting. The Types of Ultrasound listed below is a high frequency sound beyond the hearing of the human ear. The frequencies of ultrasound required for diagnostic medical imaging are in the range 1–20 MHz. These frequencies can be obtained by using piezoelectric materials (particularly crystals). When an electric current is applied and reversed across a slice of one of these materials, the material contracts or expands. So a rapidly alternating electric field can cause a crystal to vibrate. These vibrations are then passed through any adjacent materials, or into the air as a longitudinal wave is produced – a sound wave
Types of Ultrasounds
Abdominal Ultrasound
An abdominal ultrasound is a useful way of examining internal organs, including the liver, gallbladder, spleen, pancreas, kidneys, and bladder. This can help to diagnose a variety of conditions and to assess the damage caused by illness. Because it provides real-time images, ultrasound can also be used to:
- Guide procedures such as needle biopsies, in which needles are used to sample cells from organs for laboratory testing.
- Help a physician determine the source of many abdominal pains, such as stones in the gallbladder or kidney.
- Help identify the cause for enlargement of an abdominal organ.
- Doppler ultrasound is a special type of ultrasound study that examines major blood vessels. These images can help the physician to see and evaluate:
- Blockages to blood flow, such as clots.
- Build-up of plaque inside the vessel.
- Congenital malformation.
Pelvic Ultrasound Imaging
Pelvic ultrasounds are one of the most well-known forms of ultrasound, being one of the imaging tests used to monitor the health of the embryo or fetus during pregnancy. Aside from maternity medicine, these ultrasounds are also used to examine the uterus, ovaries, bladder, and prostate gland. Pelvic ultrasound is often used to diagnose conditions or the cause of conditions such as:
- Pelvic pain
- Abnormal bleeding
- Menstrual problems
- Ovarian cysts
- Uterine fibroids
- Ovarian and uterine cancers
- Kidney and bladder stones
Transabdominal
Patients receiving a transabdominal ultrasound need to have a full urinary bladder. Like other ultrasound procedures, patients lie on their back as a gel is applied to the abdomen. The transducer is then rubbed over the examination area and releases sound waves. This is a fairly straightforward ultrasound exam.
Transvaginal Ultrasound
For a transvaginal ultrasound, a woman needs to empty her bladder the same way she would for a gynecological exam. She also lies face up on her back with feet in stirrups. The transducer of the ultrasound needs to be inserted for this test. The transducer is smaller than the standard speculum used in Pap tests. A protective cover and gel for lubrication is placed on the transducer before it is inserted in the vagina.
Only the first two to three inches of the transducer is inserted in the vagina. The doctor may move it around to obtain images from different angles. The most common reason for transvaginal pelvic ultrasounds is to look for the cause of pelvic pain. Most patients report that this exam is more comfortable than a manual gynecologic examination.
Transrectal
In order to perform an ultrasound on the prostate gland, the transducer must be inserted through the rectum so that the sound waves can travel to the prostate. As with other inserted ultrasound procedures, the transducer is covered with a protective cover and lubrication before insertion. The transducer will need to be moved around in order to obtain images from different angles. These exams are typically performed with the patient lying down on their left side and knees bent up towards the chest.
The doctor may recommend a biopsy be performed if a lesion is found during the exam. In a biopsy, the radiologist uses the ultrasound images to guide a needle towards the prostate gland and extract a sample of the abnormal tissue. Ultrasound-guided biopsies are minimally invasive and only require a small incision.
Obstetric Ultrasound Imaging
Obstetric ultrasound (OB ultrasound) refers to the specialized use of sound waves to visualize and thus determine the condition of a pregnant woman and her embryo or fetus. Obstetric ultrasound should be performed only when clinically indicated. Some indications may be:
- To establish the presence of a living embryo/fetus
- To estimate the age of the pregnancy
- To diagnose congenital abnormalities
- To evaluate the position of the fetus
- To evaluate the position of the placenta
- To determine if there are multiple pregnancies
You will be asked to lie on your back or side. You will also be asked to expose your lower abdominal area. The obstetric ultrasound examination takes about 30-45 minutes.
This is a painless procedure. There may be varying degrees of discomfort from pressure as the sonographer guides the transducer over your abdomen, especially if you are required to have a full bladder. At times the sonographer may have to press more firmly to get closer to the embryo or fetus to better visualize the structure. This discomfort is temporary. Also, you may dislike the feeling of the water-soluble gel applied to your abdomen. With transvaginal scanning, there may be minimal discomfort as the transducer is moved in the vagina.
Carotid & Abdominal Aorta Ultrasound Imaging
Ultrasound of the carotid arterial system provides a fast, noninvasive means of identifying blockages of blood flow in the neck arteries to the brain that might produce a stroke or mini-stroke. Ultrasound of the abdominal aorta is primarily used to evaluate for an aneurysm which is an abnormal enlargement of the aorta usually from atherosclerotic disease.
The patient is positioned on an examination table that can tilt and move. A clear gel is applied to the area that will be examined. The gel helps the transducer make a secure contact and eliminates air pockets between the transducer and the skin, since the sound waves cannot penetrate air. The sonographer or radiologist then presses the transducer firmly against the skin and sweeps along the area of interest, reviewing the images on the monitor and capturing “snapshots” as required.
Liver Ultrasound
Liver Ultrasound determines the size, shape, and function of the liver, and can be used to detect tumors.
Renal Ultrasound
Renal ultrasound determines the size, shape, and function of the kidneys, and can be useful in the detection of kidney stones, cysts, and tumors.
Vascular Ultrasound
Vascular ultrasounds are used to analyze the flow of blood through the arteries and veins.
Thyroid Ultrasound
Thyroid Ultrasound checks for underactive and overactive thyroid glands, nodules, and cysts
Importance of ultrasound
There are multiple diagnostic uses of ultrasound. Until ultrasound came along, doctors could only listen to the foetal heart, on which presence was assumed to be an indicator of foetal well-being. With the advent of ultrasound, the information available to the pregnant patients’ attending doctors has increased markedly. Doctors are able measure the size of the foetus, which helps in determining when delivery of the baby would be expected; monitor growth of the developing foetus; check for structural abnormalities of foetus, e.g. head, and spine between 18 and 20 weeks of pregnancy; locate the site of the placenta; check for evidence of foetal well being or compromise with examinations of the foetal heart and even perform procedures on the foetus. The detection and assessment of growths in the female reproductive tract like fibroids, tubal or ovarian masses, cancers etc is another use of ultrasound. Ultrasound is used in the detection and assessment of conditions in the heart. It is used to examine the size, shape, and movement of the heart, including its valves and chambers as well as the blood flow through the heart. This type of ultrasound is called an echocardiogram, which can even be used to diagnose cardiac abnormalities in foetuses prior to their birth (foetal echocardiography). Ultrasound is used in the diagnosis of deep vein thrombosis (DVT), which is a condition in which there is blood clot formation (thrombi) in the deep veins. The thrombi can break loose and travel to the lungs, causing pulmonary embolism, which is a life threatening condition. Abnormal conditions in other organs that can be detected and assessed by ultrasound include the liver, gallbladder, pancreas, kidneys, bladder, prostate, testes, breasts, thyroid, lymph nodes, skin, joints, and eyes. Procedures like biopsies, in which tissue samples are taken for analysis, can be carried out under ultrasound guidance. The types of ultrasound listed below are used as a guide to the correct location of the site for the biopsy to be carried out. Examples include breast and prostate biopsies.
Limitations
The limitations to the use of ultrasound are due to its properties, viz: ultrasound waves cannot pass through bone, air, or gas. Therefore, it is not possible to produce detailed images of some parts of the body like the brain, which is surrounded by bone. Doctors utilise other imaging methods like CT scans and magnetic resonance imaging (MRI) scans to examine parts of the body that are not suitable for ultrasound examination.
Mechanism of an ultrasound scan
- The ultrasound machine transmits high-frequency (1 to 5 megahertz) sound pulses into your body using a probe.
- The sound waves travel into your body and hit a boundary between tissues (e.g. between fluid and soft tissue, soft tissue and bone).
- Some of the sound waves get reflected back to the probe, while some travel on further until they reach another boundary and get reflected.
- The reflected waves are picked up by the probe and relayed to the machine.
- The machine calculates the distance from the probe to the tissue or organ (boundaries) using the speed of sound in tissue (5,005 ft/s or1,540 m/s) and the time of each echo’s return (usually on the order of millionths of a second).
- The machine displays the distances and intensities of the echoes on the screen, forming a two dimensional image like the one shown below.
Frequently ask question on Types of Ultrasound
What happens after the test?
A radiologist will interpret your ultrasound images. Your doctor will discuss the results with you at a follow-up appointment. Your doctor may ask for another follow-up scan or other tests and set up an appointment to check on any issues that were found.
The difference between sonogram and types of Ultrasound
Often, the terms sonogram and ultrasound are used interchangeably. However, there’s a difference between the two:
- An ultrasound is a tool used to take a picture.
- A sonogram is the picture that the ultrasound generates.
- Sonography is the use of an ultrasound tool for diagnostic purposes.
NOTE : an ultrasound is the process, while a sonogram is the end result.
Types of Ultrasound
Sonography is a noninvasive, painless procedure. It uses high-frequency sound waves — called ultrasound waves —to produce images of organs, soft tissues, blood vessels, and blood flow, from inside the body. These images are used for medical analysis.
After x-ray exams, ultrasound is the most commonly used form of diagnostic imaging. It helps doctors gain insights into the inner workings of the body, and is known for being:
- safe
- radiation free
- noninvasive
- portable
- widely accessible
- affordable
Sonogram
A sonogram (also called an ultrasonogram) is the visual image produced during an ultrasound examination.
What is these Types of Ultrasound used for?
Probably best known for confirming and monitoring pregnancy, ultrasound is also commonly used by doctors for:
Diagnostics
Doctors use ultrasound imaging to help diagnose conditions affecting the organs and soft tissues of the body, including:
- abdomen
- liver
- kidneys
- heart
- blood vessels
- gallbladder
- spleen
- pancreas
- thyroid
- bladder
- breast
- ovaries
- testicles
- eyes
There are some diagnostic limitations for ultrasounds. For example, sound waves do not transmit well through areas that might hold gas or air (such as intestines), or areas blocked by dense bone.
Medical procedures
When a doctor needs to remove tissue from a very precise area in the body — such as in a needle biopsy — ultrasound imaging can help with visual direction.
Conclusion of Types of Ultrasound
Historically, the diagnosis of appendicitis has been made based on clinical findings. Diagnostic imaging has been used primarily to evaluate patients who have an atypical clinical presentation. Over the past several years, improvements in imaging technology have contributed to an increase in diagnostic accuracy in these patients.
These Types of Ultrasound has been suggested and used as the primary diagnostic imaging modality to evaluate for appendicitis. However, sonography is known to be highly operator dependent; large patient habitus and atypical appendiceal location are additional factors that may reduce the reliability of a negative sonographic examination for appendicitis.
CT is more accurate than ultrasound in the diagnosis of acute appendicitis. When dedicated CT examination of the appendix is performed to evaluate all patients with clinically suspected appendicitis, the diagnostic accuracy is 98%. Early and accurate diagnosis of appendicitis can decrease patient morbidity and hospital costs by reducing the delay in diagnosis of appendicitis and its associated complications, as well as by avoiding inpatient observation prior to surgery in patients who present with atypical symptoms. Furthermore, both CT and ultrasound may rapidly provide alternative diagnoses which can be treated on an outpatient basis.
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