Introduction to Ultrasound Technology

What is Ultrasound?

• Ultrasound is a device that uses high-frequency sound waves.
• It is used to view tissues and organs.
• Ultrasound is commonly used on pregnant women to view and identify problems with the baby.

Definition of Ultrasound

• Ultrasound is a diagnostic technique where high-frequency sound waves penetrate the body and produce multiple echoes.
• These echo patterns can be viewed as an image on a computer screen.
• Frequency ranges used in medical ultrasound imaging are 2-15 MHz.
• Diagnostic medical applications have been in use since the late 1950s.

Ultrasound Language

• Hyper-echoic appears white.
• Hypo-echoic appears light grey.
• An-echoic appears black.

Advantages of Ultrasound

• Ultrasound is relatively inexpensive.
• It is easily accessible and available.
• It is considered safe and does not involve radiation.
• Ultrasound can be used to treat heart problems.
• It is a quick and painless procedure.
• Ultrasound can identify lesions and detect blood flow.
• It provides pregnant women with information about their child's growth.
• There are no known harms to people from ultrasound.

Disadvantages of Ultrasound

• Ultrasound has an inability to penetrate gas or bone.
• The quality of the ultrasound is operator-dependent.
• It tends to be less sensitive in some situations.
• Ultrasound is not available everywhere.
• Not all insurance companies cover the costs.
• Ultrasound can't detect many cancers.
• It may not be able to determine if a mass is malignant.
• The procedure can be expensive.
• Ultrasound is not 100% accurate.

Benefits to Society

• Ultrasound detects diseases before they progress.
• Doctors can pinpoint trouble spots and help people avoid life-threatening heart conditions.
• Doctors can predict the development of artery disease and offer early treatment.

Uses of Ultrasound

• In cardiology, echocardiography is an essential tool for valvular heart disease.
• In emergency medicine, it is used for trauma patients and acute abdomen issues.
• In gastroenterology, it is used in abdominal sonography for solid organs like the pancreas, liver, kidneys, etc.
• In gynecology, it is used to assess female pelvic organs like the uterus and ovaries.
• In neonatology, it is used for basic assessment of intracerebral structural abnormalities, bleeds, ventriculomegaly, or hydrocephalus.
• In neurology, it is used for assessing blood flow and stenoses in the carotid arteries (Carotid ultrasonography).
• In obstetrics, sonography is commonly used during pregnancy to check on the development of the fetus.
• In urology, it is used to study a patient's bladder, prostate, or testes.
• In musculoskeletal assessment, it is used for assessing tendons, muscles, nerves, ligaments, soft tissue masses, and bone surfaces.
• In the vascular system, it is used to assess patency and possible obstruction of arteries, diagnose DVT, and determine the extent and severity of venous insufficiency.

Emergency Medicine: The FAST Examination

• The Focused Assessment with Sonography for Trauma (FAST) is a rapid, bedside ultrasound examination.
• It is performed to identify intra-peritoneal hemorrhage or pericardial tamponade.
• FAST examines four areas for free fluid: Perihepatic & hepato-renal space, perisplenic, pelvis, and pericardium.
• Perihepatic scanning examines the hepatorenal space which is the most dependent part of the upper peritoneal cavity where small amounts of fluid collect.
• Blood shows as a hypoechoic black stripe between the capsule liver and the kidney’s fatty fascia.
• The probe is placed in the right mid- to posterior axillary line at the level of the 11th and 12th ribs.
• Perisplenic scanning examines the spleen and perisplenic areas in the left upper quadrant.
• The transducer is placed on the left posterior axillary line region between the 10th and 11th ribs.
• Pelvic scanning visualizes the cul-de-sac i.e. the Pouch of Douglas in females and the rectovesical pouch in males, where fluid will collect.
• The transducer is placed midline just superior to the symphysis pubis.
• Pericardial scanning screens for fluid between the fibrous pericardium and the heart, looking for possible cardiac tamponade.
• The transducer is placed just to the left of the xiphisternum and angled upwards under the costal margin.

Parts of the Ultrasound Machine

• The transducer probe is the main part of the machine.
• The CPU is the computer that performs calculations and tells the transducer to work.
• Transducer pulse control manages the settings for the probe.
• The display shows the image.
• A disk storage device stores the image.
• A printer is sometimes included.

Ultrasound Transducer Probe

• The transducer probe is the main part of the machine.
• It must be placed in contact with the skin.
• It makes and receives sound waves and echoes.
• It uses a quartz crystal in the probe.
• Quartz is a piezoelectric crystal which will vibrate and create sound waves when receiving electrical current.
• A quartz crystal is also used to listen for ultrasound waves when the waves return.

Ultrasound Examination Method

• An ultrasounographer applies jelly-like substance to the skin to improve transmission of sound waves.
• The jelly is used to eliminate air bubbles.
• The probe is covered with a plastic cover.
• The probe is moved over the skin to get images.

Science Behind Ultrasound

• Ultrasound is a medical imaging technique that uses high-frequency sound waves and their echoes.
• It uses 1-5 megahertz sound pulses into your body.
• Sound waves hit a boundary or air between tissues and then bounce back to the probe.
• The CPU calculates the distance from the probe to the boundary using the speed of sound in the tissue, and the echoes return to display an image.

B-Mode

• B stands for Brightness.
• B scans provide two-dimensional information about the cross-section.
• These are generally used to measure cardiac chamber dimensions, assess valvular structure and function.

Color Doppler

• Color Doppler is a diagnostic test using color doppler ultrasound.
• It provides a noninvasive assessment of anatomy and determination of the presence or absence of blood flow.
• Color Doppler is 88.9% sensitive and 98.8% specific.
• It is operator-dependent.

Duplex

• Duplex is an imaging test that uses ultrasound to examine the carotid arteries located in the neck.
• This test can show blocked or narrowed carotid arteries due to coronary artery disease, which can increase the risk of stroke.