17-11-21 - Clinical Application of Ultrasound Flashcards
What is Lithotripsy?
What then happens to these particles?
Litho: L Stone and Tripsy: crushing.
Stones present in Urinary system are crushed into small sand like particles, by the vibratory impulses generated by biphasic, ultrasound shock waves.
These small particles are then excreted in the urine.
What is thermal index (TI)?
What is mechanical index (MI)?
Why were they introduced?
What are measures that can be taken to minimise the risk of ultrasound?
What principle does this refer to?
The Thermal Index (TI) and Mechanical Index (MI) were introduced to provide the operator with an indication of the potential for ultrasound induced bio-effects.
- Thermal index (TI) provides an onscreen indication of the relative potential for a tissue temperature rise during ultrasound
- Mechanical index (MI) provides an onscreen indication of the relative potential for ultrasound to induce an adverse bio effect by a non-thermal mechanism, such as cavitation
Cavitation in ultrasound refers to the formation, growth, and collapse of tiny gas bubbles in a liquid due to the pressure changes caused by ultrasound waves. It is an important phenomenon in medical and industrial applications of ultrasound.
- Perform DUS only when medically indicated, using the lowest acoustic output compatible with diagnosis, and for the shortest exposure possible
- This refers to the ALARA principle (As Low As Reasonable Achievable)
= means making every reasonable effort to maintain exposures to ionizing radiation as far below the dose limits as practical.
What is the definition of Point-of-care Ultrasound (POCUS)?
- Point of care ultrasound (POCUS) is defined as a goal-directed bedside ultrasound examination performed by a healthcare provider
- This is in order to answer a specific diagnostic question or to guide performance of an invasive procedure
It allows you to actually see what can only be inferred through palpation or auscultation
What is the angle of incidence in ultrasound?
What happens if the angle of incidence is perpendicular to the structure?
What happens if the angle of incidence is more parallel to the structure?
- Th angle of incidence in ultrasound is the angle at which US waves encounter the surface of the structure, which affects the way it is presented on the screen
- If the angle is perpendicular, or close to perpendicular (90 degrees), more US waves will be reflected back to the transducer, and fewer will be scattered away as a result, resulting in better image quality
- If the US waves are more parallel to the surface of the object (more than 45 degree of incidence), the image will have less definition
Central venous catheter insertion
Cranial ultrasound
What is Echocardiography? LVEF
The use of ultrasound to examine the heart
Estimation of heart function by the left ventricular ejection fraction (LVEF)
Measuring chamber and wall sizes
Valvular pathologies
Pericardiac effusion
Septal defects
This image explains the process of an ultrasound-guided core biopsy, which is used to obtain a tissue sample from a suspicious area (e.g., a breast mass) for histology (microscopic examination).
Steps:
1. Core Biopsy Needle: A special needle (Tru-cut) is used.
2. Needle Inserted into the Mass: Using ultrasound guidance, the needle is carefully positioned within the target area (e.g., breast mass).
3. Outer Sheath Fired: The needle mechanism is activated, taking a small core of tissue from the mass.
4. Needle Removed: The needle is withdrawn, carrying the tissue sample with it.
This procedure is minimally invasive and helps diagnose conditions like cancer by analyzing the tissue sample under a microscope.
What is Power Doppler sensitive to? What is it good at detecting?
- Power Doppler is sensitive to low blood flow in small vessels
- It is good at detecting synovitis, which is a swelling of a synovial membrane (can be caused by types of arthritis and other diseases)
Ultrasound guided joint aspiration (removal of fluid around a joint using a needle/syringe)
Ultrasound guided steroid injection
What is important during ophthalmic Ultrasound?
• The eye is a very vulnerable organ, so MI, TI and duration of US need to be kept down
This timeline highlights key ultrasound scans during pregnancy:
-
Dating Scan (Around 8–14 weeks):
- Confirms pregnancy, determines gestational age, and checks for multiples.
-
Nuchal Translucency Scan (11–14 weeks):
- Measures fluid at the back of the baby’s neck to screen for Down’s syndrome and other conditions.
-
Fetal Anomaly Scan (18–21 weeks):
- Detailed scan to check for structural abnormalities in the baby (e.g., heart, brain, limbs).
Ultrasound plays a critical role in monitoring fetal health and guiding further testing if necessary.
What is Focuses Assessment with Sonography in Trauma (FAST) and extended fast?
What is it normally used to identify?
Part of initial evaluation in the A&E of the patients admitted with blunt abdominal trauma
Aim is to identify the presence of free fluid in the peritoneal cavity
There is no attempt to visualise specific organ injuries, as ultrasound is not accurate in the early assessment of solid or hollow organ injury
eFAST incorporates the evaluation of the lungs and heartto diagnose pneumothorax, hemothorax and pericardial effusions within the emergency department
risks of US
Ultrasound waves can heat the tissues slightly.
It can produce small pockets of gas in body fluids or tissues (cavitation).
Use of ultrasound solely for Souvenir scanning – guidance from Health Protection Agency that parents should decide for themselves and weigh up risks vs benefit.
