Zeiss CIRRUS HD-OCT 500, Руководство пользователя

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Posterior Segment Scans
2660021169012 Rev. A 2017-12 CIRRUS HD-OCT User Manual
6-2
Posterior Segment Scans
CIRRUS OCT Angiography
CIRRUS OCT Angiography is a method that uses differences between B-scans to generate
contrast associated with motion, in particular the motion of blood through the vasculature.
CIRRUS OCT Angiography can be subject to several of the same artifacts seen in OCT
structural imaging, and may also have some artifacts particular to this type of imaging. To
minimize errors and artifacts, acquire Angiography Cube scans with FastTrac on.
The scans used for CIRRUS OCT Angiography are: Angiography scan, Montage Angio scan,
and ONH Angiography scan.
NOTE: CIRRUS OCT Angiography is not intended as a substitute for fluorescein
angiography.
NOTE: Vascular findings on fluorescein angiography may be absent, poorly defined, or
variably defined on CIRRUS OCT Angiography. Additionally, leakage, staining, and pooling
are not features of CIRRUS OCT Angiography.
Angiography Scan
Scanning results in either a 3x3 mm, 6x6 mm, or 8x8 mm square cube, and is similar to the
Macular 512x128/200x200 cubes but uses an intensity-based frequency filtering technique
to generate images with detailed vasculature. To image vascular flow, each B-scan in the
scan pattern is repeated several times consecutively. Comparisons of contrast on
consecutive B-scans in the same location reveal some areas with contrast change over time
and some areas with constant contrast. Temporal contrast change in a specific location is
thought to be due to erythrocyte motion and hence indicates a vessel location.
Montage Angio Scan
The 6 6x6 mm or 5 8x8 mm scans increase the Field of View (FOV) of Cirrus OCTA through
the use of a montage to 10x14 mm and 14x14 mm respectively. The FOV, which is now
fixed, is comparable to traditional imaging systems such as mydriatic and non-mydriatic
fundus cameras. Wide-field montage images enable high-resolution vascular imaging over
a larger region of the retina to further expand the applicability of OCT angiography.
The Montage Angio acquisition workflow is unique from the other Angiography scan
acquisitions because you can acquire all the Angiography scans consecutively without
going to the Quality Check screen each time. You review all of the scans at the end of the
last scan you acquired. This ability shortens the time for both the patient and the operator.
ONH Angiography Scan
The 4.5x4.5 mm ONH Angiography scan expands the capability of CIRRUS, which enables
the use of OCTA in the vascular assessment of the optic nerve.