strongly echoic
usually with acoustic shadows
calcified echoes
mixed echogenicity
with or without shadowing
Complex
Device that converts energy from one form to another
Transducers
Crystal
matching layers
Damping material
Transducer case
electronic cable
Transducer components
diameter determines beam shape
like beam of flashlight
shape is region in the patient which sound travels
Crystal
provide an acoustic connection between crystals and skin
reduces amount of reflection from large acoustic mismatch
allows wave to travel into the body
gel
matching layers
decrease secondary reverberations of crystal with returning signals
reduces the ring time and results in an increase in depth resolution (axial)
Damping material
provides housing for all internal components
Trasducer Case
caontains bundle wires to cary electrical signals to and from the crytals
Electronic cable
uses series of B-mode images to biuld a 2 d image of tissue
transducer attached to articulated arm to provide system with position and orientation
no longer used due to numerous drawbacks
B-scan (Static scan)
provides cinematic view of the area being evaluated by displaying a rapid series of images sequentially
Real Time B-Mode
all modern systems use real time approach
signals integrated into a scan converter for 2d image display
Real time movie
Real Time Imaging
Hz
images per second
2 factors Sound speed in medium
depth of imaging
higher frame rate better temporal resolution and image quality
Frame Rate
ability to precisely position a moving structure
important in adult and fetal echo
high rate yields better movies but worse photographs
Temporal resolution
shallow depth incrases frame rate and resolution
deeper decreases frame rate and degrades resolution
depth and frame rate inversely related
operator controlled
imaging depth
Single Focus
Multi Focus
Focus
only 1 sound pulse is transmitted down the scan line
high frame rate
superior resolution
inferior lateral resolution
Single Focus
Adj number of focus Pulses
longer time
decreases frame rate
inferior temporal resolution
superior lateral resolution
Multi Focus
ability to distinguish between structures that are side by side
lateral resolution
operator controlled
size increases number of pulses increases
sector size
field of view
