Black and white images

High contrast

Narrow dynamic range

Poor contrast resolution

The screen on which images are shown

Usually cathode ray tube or a flat panel monitor

Many levels of brightness

Assignment of a different shade of gray for each echo amplitude

Different colors represent different signal strengths

Low contrast

Wide dynamic range

Improved contrast resolution 

Real world variable that attains a continuumof values

Actual weight, true length, etc

Changes the data format from ultrasound signals to that of a television; converts penetration pattern into a horizontal line pattern

Allows image to be manipulated/altered between storing and displaying

Originally made gray scale display possible

Divides pictures into 1000x1000 matrix with electrical storage element (silicon wafer)

Electrons from CRT gun strike these elements and the charge is stored

Stored charges are later read to retrieve information 

Advantages: excellent spatial resolution/image detail

Disadvantages: image fade/flicker, drift, deterioration

A computer memory and microprocessor used to digitize images

Converts image data into numbers that are stored in memory

Numbers are processed and re-translated for display as an image

Random Access Memory

Computer memory

Smallest element of a digital picture

Can display one color at a time

More pixels = better resolution

Spatial resolution determined by pixel density

Pixels per square inch

Higher = greater detail/spatial resolution

Smallest amount of digital storage

Bistable has value of 0 or 1

More = more shades of gray = better contrast resolution

Computer language

Group of bits -> series of 0's and 1's 

2ⁿ

n = number of bits

Manipulating the data before storage in the scan converter

Data is altered forever

Cannot be undone/reversed

Log compression -> lowers high level echoes and boosts lower level echoes; dynamic range is reduced

TGC changes

Write magnification

Fill-in interpolation

Persistence

Spatial compounding

Manipulating the data after it has been stored in the scan converter memory but prior to display

Increases versatility of display process

Can be undone

Similar to zooming in on a portion of a digital photo

Occurs after the image data is in a scan converter (post-processing)

New image has same number of scan lines and pixels as original image

Spatial resolution does not change, only enlarges pixels

Can be used on a frozen image

The enlargement of a portion of an image to improve detail

"Zoom"

Fills the screen; area magnified is called region of interest (ROI)

Applied during data acquisition to zoom in on an area

Discards old image when new image data is acquired

Number of scan lines or pixels in region of interest is greater than they were in the same region of the original image

Spatial resolution improves -> more pixels of the same size as original

Averages multiple frames obtained by steering the sound beams in different directions 

Multiple images are obtained from different imaging angles

Reduces shadowing artifacts

Divides a reflection into sub-bands of smaller frequency ranges; each sub-band creates an image

All images are averaged, improving signal-to-noise ratio

Speckle and clutter artifacts are reduced

Spatial resolution is improved

Makes the image look sharper by emphasizing sharp edge boundaries

Creates subtle bright and dark highlights on either side of boundaries

Temporal Compounding 

aka Persistence aka Frame Averaging

Imaging process technique that continues to display information from older images

A number of prior frames are superimposed onto the current frame

Produces a smoother image with reduced noise, higher signal-to-noise ratio, and improved image quality

Differs from spatial compounding in that all frames are from same view/angle

Dynamic technique that produces images from sound reflections using the following premise:

Images are related to the mechanical properties of tissue. Depending on how tissues respond to force, they will be displayed in different ways

Used to help distinguish between benign and malignant masses

Form of electronic receive focusing that listens to echoes returning from different depths with different numbers of elements

Few elements for shallow, more elements for increasing depth

Allows beam to be as narrow as possible at all depths

Optimizes lateral resolution at all depths

Digital ultrasound storage lab (computer hard drives)

Instant access

No degradation of information 

Store and forward technology