3Q03 Physics

Question 1

Another term for grating lobe artifact?

Answer 1

Haze

Question 2

Do we want a high or low SNR?

Answer 2

high SNR = improves contrast res

Question 3

What is the cost of frame/signal averaging?

Answer 3

FR and temporal res are decreased

Question 4

Can we control the amount of SC?

Answer 4

Yes we can add more angle (RES) or less with (SPD)

Question 5

What is Aberration?

Answer 5

when the sound beam gets distorted through fat resulting in a decrease intensity of the main beam and an increase in grating lobes

Question 6

How can we fix abberation?

Answer 6

Same way as we fix grating lobes - with harmonics (therefore harmonics is good in obese people)

Question 7

Which type of harmonics is better for axial res?

Answer 7

Pulse inversion

Question 8

Panoramic imaging is also known as:

Answer 8

EFOV (wide scan is not the same thing)

Question 9

How does axial strain elastography show malignancies?

Answer 9

darker areas = more stiff = more malignant

Question 10

How is tissue stiffness measured?

Answer 10

With young’s Modules where BM = stress/strain = change in pressure / (change in volume/volume)

Question 11

How can we determine stifness/malignancy by the E number?

Answer 11

higher E value = stiffer = more malignant

Question 12

How does shear wave elastogrophy work?

Answer 12

By produces shear waves into the body which are slow but travel faster the stiffer the area is aka malignant

In colour or shades of grey
it is quantifiable - E value

Question 13

How to determine the E value

Answer 13

E =3 x p x c^2

Question 14

What is the difference in shear waves compared to longitudinal sound eaves?

Answer 14

they are transverse, travel perpendicular to sound waves, and are a lot weaker

Question 15

What can lead to inaccurate results in axial strain elastogrpahy?

Answer 15

In axil you are making your own compressions and if you press to high it can create non linear changes in the strain = inaccurate results

Question 16

Blue tissue means

Answer 16

harder

Question 17

What is B-flow?

Answer 17

displays blood flow echoes on B-mode

Question 18

What are the main differences of B-flow and Doppler?

Answer 18

• not angle dependent
• no aliasing
• much better temporal and spatial res

Question 19

What is a transducer that provides real time volume imaging?

Answer 19

matrix

Question 20

In 3D oimagign which has the worst resolution

Answer 20

Z/coronal plane

Question 21

What is Multiplanar resolution

Answer 21

shows all 3 planes at the same time and you can chose how you want to slice through

Question 22

What type of scan has the WORST thermal risk?

Answer 22

PW SD because high PRF and large DF - not scanned across a FOV

Question 23

What is the order from most risk to least of thermal bioeffect?

Answer 23

1. CW
 PW SD
2. CD/PD
3. M mode
4 Least risk if 2D B mode

Question 24

What causes an icnrease in thermal effects?

Answer 24

increased out put power AND time

Question 25

What is the max SPTA?

Answer 25

720 mW/cm2

Question 26

What is mechanical bioeffects from?

Answer 26

transient cavitation - non thermal

Question 27

What is the recommended MI?

Answer 27

if gas bodies and obstetrics and neonates <0.3

but an MI <1.9 has no confirmed bioeffects

Question 28

When should each type of TI be used?

Answer 28

TIS - first triemster - 10 weeks
TIB - late first trimester, 2nd and 3rd
TIC - neonatal, pediatric, adult cranial, or spinal

Question 29

What are the recommended TI Values?

Answer 29

<2.0 in adulta

less than 0.7 in fetus

Question 30

What are common results of those scanned in utero?

Answer 30

• low birth weight
• delayed speech
• dyslexia
  non right handedness in boys