Ultrasonagraphy Flashcards
- What is ultrasound?
Sound waves with frequencies higher than the human audible range
- What is the upper limit of Human sound wave freq considered to be?
Approx. 20kHz
- What are the sound wave frequencies of :
-Elephants
-Whistle
-Dolphins
?
Elephants = 15-30Hz Whistle = 18-22kHz Dolphins = 160kHz
- What are the two main functions of the ultrasound probe?
- Emit a sound wave
2. Receive echoes from the original sound wave
- What are the two results that could happen whenever an ultrasound wave passes through a tissue boundary?
-> It can be reflected
OR
-> Will pass through and continue propagating (moving )
- If an ultrasound wave is passing a tissue, which will reflect MORE of the sound
-Adjacent tissues with varying densities
OR
-Adjacent tissues with similar densities
Adjacent tissues with varying densities will reflect more of the sound wave, adjacent tissues with similar densities will reflect less..
- What do the pixels of the ultrasound image represent?
The intensity of the sound and the depth that it has been reflected from
- Knowing that an ultrasound image depends on depth , what creates a poor image and what creates a good image in ultrasound?
Poor image = Air in lungs and fluid (urine,bile,cysts)
Good image = Bone
- Out of bone and fluid, which ones are low amplitude and high amplitude
Bone = High Amplitude = Strong Reflection = Good Picture
Fluid = Low Amplitude = Poor Reflections = Poor Image
- What are some clinical Applications of ultrasound?
-Abdominal
-Gynaecology
-Obstetrics
-Urinary
-Breast
-Lungs
and many more…
- What are 6 advantages of using Ultrasound?
- No radiation
- No documented side effects in human
- Usually non-invasive
- Well tolerated
- “Real time” imaging
- Results immediate
- Widely Accessible
- What are 4 disadvantages of using ultrasound?
- Quality of picture dependant on patient habitus ( physique)
- Training is more resource intensive for departments compared to other modalities
- Effectiveness and accuracy are highly operator dependant
- May be side effects we don’t know off yet
- In what two parts of the body can ultrasound be invasive?
- Transvaginal
- Endoanal
- When is ultrasound painful?
In gallbladder stone
- Ultrasound is dependant on patient habitus. Does resolution increase or decrease with increased BMI?
Decreases
- Why do we have a selection of different types of transducers?
Increased choice of technical variables = Optimisation of image
- What can you have choice over in different transducers?
- Sector Width
- Scan depth (resolution)
- Patient Habitus
- Field of view
- What does Obstetric mean?
Relating to Childbirth
- What is major advantage of using obstetric ultrasound over X-ray/CT?
No Ionising Radiation
- How far into pregnancy are all Women in the UK offered an ultrasound?
12/20 weeks
- Approx. how many mm’s is the foetus at 12 weeks?
45-48mm
- What does the 12 week scan detect?
- Foetal Viability (ability to survive outside uterus)
- Number of foetus’s
- Gross Anatomy
- Major Abnormalities
- Morphology of ovaries
- Accurate gestational age
- What is Anencephaly?
skull isn’t fully formed so brain soft tissue is exposed to the acidic amniotic fluid
- What is Omphalocele/Exomphalos ??
herniation of abdominal organs due to the skin not fusing properly
- What is Blighted Ovum/Missed Miscarriage?
empty sack with no baby that causes the same symptoms as pregnancy
- What is Molar Pregnancy?
non-viable fertilised egg that won’t come to full term implants in the uterus
- What is Cystic Hygroma?
fluid-filled sac that results from a blockage in the lymphatic system
- In the 12 week scan we can test for chromosomal abnormalities, which syndrome would we test for?
Down Syndrome
- How is down syndrome caused?
Random mutations in the egg before fertilisation
- Is down syndrome common for babies with older or younger mums
Older mums
- Throughout the world what is the frequency of Down Syndrome?
3 per 2000 births
- How do we test for down syndrome in the 12 week ultrasound?
Foetal nuchal translucency (NT) screening uses ultrasound to measure the size of the nuchal pad (skin containing fluid) at the nape of the foetal neck This is often larger in babies with Down syndrome.It should be performed between 11 weeks and 13 weeks + 6 days.