21. echocardiography

Question 1

what is the importance of ultrasonography

Answer 1

• Examine parenchymal and fluid filled organs
• With physical examination and other diagnostic methods.
• Results should be evaluated with findings of other examinations

Question 2

Echocardiography

name the different parts of the US machine

Answer 2

transducer (the probe)
signal-processing equipment
monitor

Question 3

what is ultrasound

Answer 3

Sound waves with a frequency too high for humans to hear.
Images are made by sending a pulse of US into the tissue using the transducer
The sound will reflect echoes from the tissue and back to the probe.
the echoes are recorded and displayed on the US monitor

Question 4

what is the normal frequency of typical sonographic scanners

Answer 4

1-18 megahertz (MHz)

low frequency produce less resolution, but goes deeper into the body

Question 5

ultrasonography

what normally produces the sound wave

Answer 5

a piezoelectric transducer, elicited form elecrical impulses from the US system

Question 6

ultrasonography

what produce the different structures we can see in a picture

Answer 6

when the sound hits the border of two neighbouring materials with different densities, part of the sound is reflected back to the probe.
some of the sound will be absorbed or scattered further through the tissues

Question 7

ultrasonography

what produces black spots on the image

Answer 7

if sound travels fully through a material, no echo is reflected
eg fluid

Question 8

ultrasonography

what is acustic impedance

Answer 8

• A constant value characteristic for the given material.

- It is calculated as the density of the given material and the acustic speed of US within it.

Question 9

ultrasonography

how do we calculate the acustic impedance

Answer 9

acustic impedance:Z
density: P
acustic velocity: V
Z=PxV

Question 10

ultrasonography

how do we know the depth of the material we see in the image?

Answer 10

the time it takes for the echo to travel back to the probe is measured and used to calculate the depth of the tissue causing the echo

Question 11

ultrasonography

what causes some material on the image to be brighter?

Answer 11

the greater difference between the aucustic impedances of the neighbouring materials, the larger the echo (brightness) on the screen

Question 12

ultrasonography

what happens if the US hit gas or solid material

Answer 12

the density difference is so great that most of the aucustic energy is reflected and it becoes impossible to see deeper.
no US can pass through the objects
bone, stone, gases

Question 13

ultrasonography

what is acustic shadowing

Answer 13

when US hit gas or solid material, the black field remains black

Question 14

list the techniques of ultrasonography

Answer 14

• linear or sector transducers with the nessecary frequency
• proper contact between transducer and skin (hair clipping or shaving, US gel)
• ultrasound window
• transducer planes and directions

Question 15

ultrasonography

what are the two main types of transducers

Answer 15

linear transducer

sector transducer

Question 16

echocardiography

what is special about echocardiography compared to normal US

Answer 16

• only sector transducers can be used
• numbers of echocardiographic windows are limited
• examination planes, transducer orientations and nomenclature differ from those of abdominal US

Question 17

echocardiography

what can we do/ find

Answer 17

• examine cardiac chambers - wall+cavity
• recognize valvular disorders
• detect shunts with contrast ecg - septal defects, PDA
• quantitaive and functional exams - fractional shortening
• detection of blood flow disorders - doppler ecg

Question 18

echocardiography

what are the main types of ecg

Answer 18

• M-mode (undirectional) ecg
• two dimentional (B mode) ecg
• doppler ecg

Question 19

echocardiography

how does M mode look like

Answer 19

we choose an axis from the heart using the two dimentional ECG and the M mode shows us the movement of the heart as a continous wave

Question 20

echocardiography

what types of doppler ecg techniques do we have

Answer 20

• color flow doppler technique (CF)
• pulsed wave doppler tech (PW)
• continous wave dopler tech (CW)
  (the two last ones are spectral doppler methods)

Question 21

echocardiography

what organs are on the left side of the thorax

Answer 21

• left lung
• heart - auricular side
• aorta

Question 22

echocardiography

what organs are on the right side of the thorax

Answer 22

• vena cava
• atrial side of heart
• right lung

Question 23

echocardiography

what do we see with a right parasternal transducer position

Answer 23

• long axis plane: four chamber view

- short axis plane: we can see many segments/ slices of the heart at different levels

Question 24

echocardiography

what are the short axis planes

Answer 24

• papillary muscle level
• chorda tendinea level
• mitral valve level
• aorta level

Question 25

echocardiography

what is the LA/Ao ratio

Answer 25

• left atrial to aortic ratio
• we measure the diameters of the two and compare them
• normal LA/Ao is 1,5:1
• in cats we can measure in mm

Question 26

echocardiography

what is diolated cariomyopathy

Answer 26

the walls of the left ventricle are thinner, makng the cavity in the LV larger/dilated

Question 27

echocardiography

what is hypertrophic cardiomyopathy

Answer 27

the walls of the heart is so thick that during systole we can not se the lumen of the left ventricle

Question 28

echocardiography

what can we see when there is fluid around the heart

Answer 28

the wall of the right ventricle will be wavy/ jiggeling when it contracts, due to the flud pushing on it

Question 29

echocardiography

what is the principle of color doppler

Answer 29

doppler shift frequency is in direct proportion to the flow velocity of the red blood cells

Question 30

echocardiography

what is the regnestykke of color doppler

Answer 30

V=fc/(2F cos(a) )
V: velocity o target m/sec
f: doppler shift frequency Hz
c: velocity of sound in tissues m/sec
F: original US frequency Hz
a: beam and target direction angle