Image Optimization & Instumentation

probe; preset

probe; preset

the 1st thing you should do when you sit down to a machine is select the correct ___________ and ______________ for the exam

presets

• pre-programmed settings for each exam or anatomy

• set up by machine manufacturer

• settings can be changed by applications specialist to customize per facility

starting point

presets are a _____________ and do not replace proper image optimization during every exam

automatic image optimization techniques

• spatial compounding

• persistence

• frequency compounding

• edge enhancement

• harmonics

spatial compounding

• multiple frames are formed at varying angles which are averaged together to create one image

• scan lines are directed in multiple directions using phasing so anatomy is scanned more than once

phasing

with spatial compounding, scan lines are directed in multiple directions using _____________ so anatomy is scanned more than once

frame rate

since oldest frame is replaced with the newest frame, spatial compounding does not affect ________________

signal to noise

spatial compounding allows for improved image quality by reducing speckle and improving __________________ ratio

clutter; reverberation

spatial compounding improves image quality by reducing __________ artifacts and _____________ artifacts

specular reflections

spatial compounding improves presentation of __________________ because the multiple angles increase the likelihood of 90 degree incidence

shadowing

spatial compounding allows for visualization of structures behind strongly attenuating structures, which reduces ____________

compound imaging

spatial compounding is also known as _______________

Sono CT

Philips uses the term _______________ for spatial compounding

crossbeam

GE uses the term _______________ for spatial compounding

spatial compound imaging

Siemens uses the term _______________ for spatial compounding

frame averaging

persistence is also known as ________________

signal to noise

the main goal of persistence is to reduce noise by improving the ______________ ratio

angle

unlike with spatial compounding, with persistence the ____________ is not changed between frames

weighted average

unlike with spatial compounding, with persistence frames have a ________________ so that newer frames count more than older frames

reduced

with persistence, random echoes are averaged, allowing for random content (and noise) to be ___________

dynamic range; contrast resolution

reducing speckle improves _______________ and _________________

allows for increased sensitivity to weak signals

why is persistence useful in color Doppler?

movement

with persistence, ______________ of anatomy must be minimal

low

rapidly moving structures like the heart have ____________ persistence

high

slower moving structures have ____________ persistence

frequency compounding

averages 2 or more frames created at different frequencies to form an image

separately; simultaneously

for frequency compounding, frames are processed _______________ but ________________

sequentially

unlike spatial compounding and persistence, with frequency compounding, frames are not processed _______________

frequency compounding

_______________ can be used with moving structures

temporal resolution

frequency compounding does not degrade ______________

frequency averaging; frequency fusion

frequency compounding can also be known as ________________ or _________________

texture

frequency compounding improves ____________ because it combines multiple frequencies

parallel processing

with frequency compounding, the receiver uses _____________ to receive 2 or more narrower bandwidths

edge enhancement

sharpens boundaries to make them more detectable and allow for more precise measurements

preprocessing

edge enhancement is a _____________ technique

fundamental

harmonics transmit at a lower frequency, which is the _______________

2nd harmonic

harmonics receive at a higher frequency, which is the ________________

penetration; resolution

harmonics allow for better ______________ when transmitting and better ______________ when receiving

pressure changes

harmonics are generated within the tissue during wave propagation due to _______________

grating lobe

harmonics reduce reverberation, clutter, and ________________ artifacts

grating lobe

extra beams like side lobes but from arrays instead of single elements

depth

___________ should be adjusted to include the anatomy without useless information in the far field

axial resolution

depth and ________________ are not related

lateral resolution

__________________ varies with depth because of the beam width

speckle

with contrast resolution, less tissue interrogated means less ________________ and less chance of artifacts like refraction

PRF; FR

depth is inversely related to _____________ and ______________

divergence

______________ occurs after the focus

lateral resolution

___________________ will be degraded deeper in the far zone

greater; smaller

_____________ intensity at the focus because the area is _______________

decibels

gain setting is displayed in ________________

transmit

when changing the gain, _________________ signal remains the same

intensity

changing the gain does not change ___________ in the patient

overall gain; receiver gain; amplification

gain is also known as _____________, _________________, and ______________

time gain compensation

TCG stands for:

depth gain compensation

time gain compensation is also known as _________________

TGCs

allows for extra amplification to compensate for attenuation with depth

attenuation

____________ increases with depth

depth zones

TGC sliders represent ________________

profile; curve; slope

positions of the TCGs are referred to as the TGC __________, ___________, or ______________

frame rate

having a narrow sector width increases ____________

improves

using a narrow sector width ____________ image quality

dynamic range

the ratio of the maximum to minimum amplitude a system can handle

decibels

dynamic range is expressed in ____________

compression

technique that decreases dynamic range

compression

some ______________ is operator controlled whereas some occurs during echo reception

inversely

compression and dynamic range are _____________ related

colorized B-mode

since the human eye has a limited dynamic range when it comes to shades of gray, adding hues of color through _______________ can assist with visualization of slight differences

color maps; tint maps

colorized B-mode is also known as ____________ and _____________

preprocessing

processing of the signal occurs in real time and cannot be adjusted after image is stored (before freeze)

post processing

changes that can be made after the data is stored (after freeze)

write zoom

• preprocessing

• live zoom

• rescans area of interest

• acquires new data

• increases # of pixels or scan lines

• improves spatial resolution

read zoom

• post processing

• frozen zoom

• displays original data

• # of pixels or scan lines is same as original image

panoramic imaging

• an extended image display beyond the normal limits of the transducer

• physically move transducer across the patient to build an image over time

uniformity

with panoramic imaging, quality of sweep is dependent on _____________ of sweep speed

trapezoid scanning

• changes rectangular shaped image into a trapezoidal shape

• using linear array as if it were 2 transducers

phasing

trapezoid scanning is controlled by ___________