21. echocardiography Flashcards
what is the importance of ultrasonography
- Examine parenchymal and fluid filled organs
- With physical examination and other diagnostic methods.
- Results should be evaluated with findings of other examinations
Echocardiography
name the different parts of the US machine
transducer (the probe)
signal-processing equipment
monitor
what is ultrasound
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
what is the normal frequency of typical sonographic scanners
1-18 megahertz (MHz)
low frequency produce less resolution, but goes deeper into the body
ultrasonography
what normally produces the sound wave
a piezoelectric transducer, elicited form elecrical impulses from the US system
ultrasonography
what produce the different structures we can see in a picture
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
ultrasonography
what produces black spots on the image
if sound travels fully through a material, no echo is reflected
eg fluid
ultrasonography
what is acustic impedance
- 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.
ultrasonography
how do we calculate the acustic impedance
acustic impedance:Z
density: P
acustic velocity: V
Z=PxV
ultrasonography
how do we know the depth of the material we see in the image?
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
ultrasonography
what causes some material on the image to be brighter?
the greater difference between the aucustic impedances of the neighbouring materials, the larger the echo (brightness) on the screen
ultrasonography
what happens if the US hit gas or solid material
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
ultrasonography
what is acustic shadowing
when US hit gas or solid material, the black field remains black
list the techniques of ultrasonography
- 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
ultrasonography
what are the two main types of transducers
linear transducer
sector transducer
echocardiography
what is special about echocardiography compared to normal US
- only sector transducers can be used
- numbers of echocardiographic windows are limited
- examination planes, transducer orientations and nomenclature differ from those of abdominal US
echocardiography
what can we do/ find
- 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
echocardiography
what are the main types of ecg
- M-mode (undirectional) ecg
- two dimentional (B mode) ecg
- doppler ecg
echocardiography
how does M mode look like
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
echocardiography
what types of doppler ecg techniques do we have
- color flow doppler technique (CF)
- pulsed wave doppler tech (PW)
- continous wave dopler tech (CW)
(the two last ones are spectral doppler methods)
echocardiography
what organs are on the left side of the thorax
- left lung
- heart - auricular side
- aorta
echocardiography
what organs are on the right side of the thorax
- vena cava
- atrial side of heart
- right lung
echocardiography
what do we see with a right parasternal transducer position
- long axis plane: four chamber view
- short axis plane: we can see many segments/ slices of the heart at different levels
echocardiography
what are the short axis planes
- papillary muscle level
- chorda tendinea level
- mitral valve level
- aorta level
