Echo boards

Question 1

What is the frequency of US waves?

Answer 1

20,000 Hz

Question 2

Return of US signal to transducer when it encounters a strong reflector

Answer 2

Reflection

Question 3

Radiation of US beams in multiple directs from a small structure i.e. blood cell

Answer 3

Scattering

Question 4

Deflection of US beams from straight line caused by difference in acoustic impedance of tissues

Answer 4

Deflection

Question 5

Loss of signal strength as US energy is absorbed in tissue

Answer 5

Attenuation

Question 6

Wavelength formula

Answer 6

Wavelength (mm) = 1.54/frequency (MHz)

Question 7

Speed of US waves in soft tissue

Answer 7

1,540 m/s

Question 8

CSA formula

Answer 8

Area = πr² = 0.785D²

Question 9

SV formula

Answer 9

SV = VTI x CSA

Question 10

CO formula

Answer 10

CO = SV x HR

Question 11

AVA by continuity formula

Answer 11

AVA = [(0.785 LVOT-D²) x LVOT-VTI]/AV-VTI

Question 12

EROA formula

Answer 12

EROA = (2πr² x Alias-V)/MR-V

Question 13

Regurgitant volume formula

Answer 13

R Vol = EROA x MR-V

Question 14

PHT from DT

Answer 14

PHT = 0.29 x DT

Question 15

MVA from PHT

Answer 15

MVA = 220/PHT

Question 16

MVA from DT

Answer 16

MVA = 759/PHT

Question 17

MVA by PISA

Answer 17

MVA = [(2πr² x Alias-V)/MR-V] (Θ/180)

Question 18

RIMP formula

Normal cut offs

Answer 18

RIMP = (IVCT + IVRT)/ET - abnormal > 0.43
OR
RIMP = (TCO - ET)/ET - abnormal > 0.56

Question 19

LAP in MR

Answer 19

LAP = SBP - 4MR-V²

Question 20

LVEDP in AR

Answer 20

LVEDP = DBP - 4AR-V²

Question 21

RVSP/PASP in TR

Answer 21

RVSP/PASP = 4TR-V² + RAP

Question 22

PVR formula

Answer 22

PVR = (TR-V/RVOT-VTI) x 10 + 0.16

Question 23

Nyquist limit formula

Answer 23

Nyquist limit = PRF/2

Question 24

Qp:Qs formula

Significance cut off

Answer 24

Qp:Qs = RV SV/LV SV = [(0.785 RVOT-D²) x RVOT VTI]/[(0.785 LVOT-D²) x LVOT VTI]

Significant if > 1.5

Question 25

Pulse repetition period

Answer 25

TIME from the start of one pulse to the start of the next pulse - includes when pulse is "on" and listening period Affected by depth of view

Question 26

Pulse repetition frequency Definition Formula

Answer 26

Number of pulses that occur in 1 second PRF = 77,000 cm/s / depth of view cm Affected by depth of view

Question 27

Duty factor Definition Formula

Answer 27

Percentage of time that the system transmits a pulse Duty factor (%) = pulse duration/PRP x 100

Question 28

Temporal resolution

Answer 28

Ability to distinguish two events close in time Accurate locate moving structures in a particular instant of time Higher frame rate, better temporal resolution M-MODE

Question 29

Axial resolution

Answer 29

Type of spatial resolution. ability to differentiate 2 objects PARALLEL to US beam Higher frequency, higher axial resolution axial resolution (mm) = (0.77 x # cycles in pulse)/frequency

Question 30

Lateral resolution

Answer 30

Ability to differentiate 2 objects PERPENDICULAR to US beam Dependent on width of beam

Question 31

"Go-return time"/"Time of flight" formula

Answer 31

distance to boundary (mm) = time (microsec) x 0.77 mm/microsec 13 microsec rule - total distance traveled = 2 times reflector depth - 1 cm reflector = 13 microsec - 2 cm reflector = 26 microsec - 3 cm reflector = 39 microsec - 4 cm reflector = 52 microsec

Question 32

Doppler shift formula

Answer 32

Doppler shift = (2 x reflector speed x incident frequency x cos (angle))/propagation speed 0 degree --> 1 cosine 60 degree --> 0.5 cos 90 degree --> 0