8 Operation
Instructions for Use
2660021169042 Rev. A 2018-03
8.6 Check Scan Quality
104 / 246
2660021169042 Rev. A 2018-03
8.6.4.3 Decorrelation Tails Acceptance Criteria
Test
Pass
Fail
Explanation
Bright
No Decorrelation
Tails; signal
detected shows
accurate motion.
•
DRL
has a
different
characteristic
appearance
than the
SRL
.
• RPE not
showing vascu-
lature
Decorrelation Tails
Appear
•
DRL
has the
same character-
istic appearance
as the
SRL
.
• Vessels appear
exactly the
same shape as
a layer superior
to it.
• RPE shows
vasculature
(exactly the
same shape as
a superior layer)
Bright shadows of more superficial vessels that
appear in posterior layers are decorrelation tails.
Decorrelation tails result from light that passes
through moving blood cells and returns to be
detected.
Inaccurately detected motion causes a weaker signal
to appear below the original signal.
Because the effect is correlated with the brightness
of the reflecting layer, decorrelation tails may seem
to disappear within the outer nuclear layer, but
appear strongly in the brightly-reflecting RPE.
Table 16:
Decorrelation Tails Acceptance
Layer
Enface
B-Scan
Explanation
SRL
• The larger vessels that appear
similar in SRL and DRL are decor-
relation tails and not present in
the DRL.
• DRL en face does not include the
larger vessels; they appear due
to the decorrelation tails.
• RPE enface does not normally
have vessels; vasculature
appears due to decorrelation
tails.
DRL
Decorrelation Tails
Above RPE
Decorrelation Tails
Table 17:
Decorrelation Tails Example: Normal Eye
8.6.4.4 Segmentation Acceptance Criteria
Test
Pass
Fail
Explanation
Flow
Detection
Appropriate presence or
absence of flow in the
layers of interest.
Unexpected presence or
absence of flow in the
layers of interest.
Segmentation errors can result in
incorrect visualization of flow.
Boundary lines that determine a
particular enface image appear as
pink dotted lines overlying the B-
scan.
Table 18:
Segmentation Acceptance
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