Ultrasonagraphy - B-scan Flashcards
imaging tests provide a
picture of the bodys internal structure. - can be used to diagnose a disorder, determine how severe a disorder is, and monitor people after dx
an imaging test that uses soundwaves is called
ultrasonography
ultrasonography uses what type of soundwaves and how is it transmitted?
uses HIGH frequency soundwaves and is transmitted from probe/transducer into the eye
how does an ultrasongraphy work?
- high Hz soundwaves hit intraocular structures, -echo is reflected back to the probe -echo converted to electrical system, -electrical signal is turned into a 2D IMAGE on a monitor
t/f the weaker the echo, the brighter the display
false. THE STRONGER
what is the most common frequency used in ophthalmic ultrasound? A. 15 MHZ, B. 25 hz c. 11 hz, d. 10MHz
D. 10MHZ, becaust it provides the best combo of tissue penetration AND image resolution
ultrasound information can be displayed on a monitor In various ways . What are the different ways an ultrasound can be displayed in ophthalmic ultrasound?
A- scan or B-scan
what is a A-Scan? Or how do you know you are viewing the A-scan?
it would be displayed as spikes on a graph
what is a B-scan? How do you know you are viewing a B-scan vs A-scan?
a B-scan is the actual 2D anatomical image. A-scan are the electical spikes
an A scan is most commonly used for ?
measuring axial length AND tumor differentiation
why would we need to know axial length and what scan are we going to use?
we need to know for determing DIOPTRIC power for an IOL, and get a Ascan done
which scan is the best scan to use for determining the difference between tumors inside the eye?
a scan
what do the spikes on a scan represent?
an ultrasonic echo from a SPECIFIC ocular structure
Figure 1: The five primary amplitude spikes in A-scan ultrasound
- cornea 2. ANTERIOR Lens 3. POSTERIOR lens, 4. retina, 5. sclera/orbital fat
what equipment piece is more reliable for IOL dioptric power?
lenstar
pic of normal healthy patient B SCAN. Label each
a cornea/probe b. iris c. anterior lens d. posterior lens e. viterous d. optic nerve
on the probe. There is an arrow/marker. The position of the marker is held
relative to the eye based on the TYPE OF CUT/SCAN desired.
the position of the probe in relation to the EYE GAZE!!! Tells you ___________
type of scan you are doing
what coupling agent is needed for trans-lid method ON B scan
ultrasound gel ONLY!!! No anesthetic or tear gel. The lid is closed for this method
what coupling agent is needed for TRANS-CONJUNCTIVA method on B SCAN
artificial tear gel (celluvisc, genteal gel) ….the more gel the better resolution. ANESTHETIC IS REQUIRED!!!!
define decibels
a measure of sound INTENSITY . 1/10 of bell
mHz is a
unit for frequency in ultrasonography
sound impedance ** EXAM QUESTION . Why is sound impedance crucial?
it gives us information on the difference in the echo reflectivity from one structure to another. This where get the information on data anaylsis and difference in pathology.
Homogeneous sound impedance structure is
means theres not much sound impedance.
if a sound impedance is heterogenous, what does this indicate?
it’s a difference between one echo reflectivity to another.
homogeneous sound impedance means sound passes
through with NO signal coming back. ESP. viterous and optic nerve. Sound traveling fast through optic nere
hetergenous sound impedences means sound passes through
but SENDS AN ECHO BACK (Echo reflectivity) . Represented by white.
