Ординатура / Офтальмология / Английские материалы / Ophthalmic Ultrasound A Diagnostic Atlas 2nd edition_ DiBernardo, Greenberg_2006
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Figure 11–5 Gancyclovir mplant. Recently, patients with ocular manifestations of acquired immune deficiency syndrome began to be treated with intraocular gancyclovir, which is delivered through a small capsule that is sutured into the peripheral scleral wall, protruding into the vitreous. The medication is time-released over a period of months and can be replaced periodically. Knowing this information prior to performing ultrasound is vital for the echographer because the implant behaves like a foreign body echographically. (A) Transverse scan showing the implant (arrow) and the associated shadow (S). (B) Longitudinal scan showing the peripheral location of the implant (arrow) and shadow (S). (C) A-scan at a greatly reduced gain showing the highly reflective signal produced by the implant. All of the sound is being attenuated by the implant, leaving no signals behind it.
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Figure 11–6 Artifacts/multiple signals. (A) and (B) This patient had undergone vitrectomy with fluid-gas exchange. Over time, most of the gas dissipated; however, a small bubble was present anteriorly and produced these multiple signals.
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Figure 11–7 Artifacts/silicone. The velocity (speed) of sound is determined by the medium through which it travels. Most diagnostic ultrasound equipment in ophthalmology is programmed to read scans based on the average velocity of sound in soft tissue (1548 m/s). The velocity through silicone oil is 980 m/s. Consequently, the image appears disproportionately bigger and it is almost impossible to get an accurate echogram. Clinically, this patient had an extensive retinal detachment that was not detected echographically.
Figure 11–8 Residual silicone. Transverse B-scan following removal of silicone oil. B-scan image shows multiple, highly reflective signals that persist and represent silicone oil bubbles. Clinically, no hemorrhage was noted within the globe.
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Figure 11–9 Artifacts/perfluorocarbon (PFC). Liquid PFC is a substance used during retinal detachment surgery to act as a temporary tamponade to keep the retina flattened against the globe wall. When introduced into the eye, it disperses much like mercury and scatters into small bubbles. PFC is removed at the end of the procedure; however, some small bubbles may remain and appear as small foreign body signals with shadowing (S) on echographic examination.
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Figure 11–10 Artifacts/gas. Asking the patient to turn the head opposite the area being examined but having him or her maintain the gaze in the area to be examined is often useful to manipulate a large intraocular gas-air bubble and thereby obtain useful echographic images.
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Figure 11–11 Artifacts/gas. Sound does not travel through air or gas. When a patient has had fluid-gas exchange, it can be difficult to image the eye. However, if the gas bubble does not fill the vitreous cavity, it may be possible to image the posterior pole by repositioning the bubbles so they do not interfere with the transmission of sound. This can be done by moving the patient’s head opposite the area to be examined while the patient continues to gaze in the area being examined. (A) Transverse echogram showing the interface of a large bubble (arrows) and distortion of the image beneath the bubble. (B) The patient has been repositioned to allow the bubble to float out of the path of sound, allowing better imaging.
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Figure 11–12 Sclerochoroidal calcification. Sclerochoroidal calcifications are generally noted bilaterally and are multifocal. Clinically they can be flat or elevated. They can be idiopathic or present as a result of abnormal calcium and phosphorous metabolism.
(A) and (B) Sclerochoroidal calcification appears very similar to the echographic findings in osteoma, with plaque-like appearance and shadowing. (C) and (D) A-scan at reduced gain. The sound is absorbed by the areas of calcification.
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Figure 11–13 Anophthalmos. (A) and (B) Echograms taken from a 1-day-old infant. No globes could be identified.
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Figure 11–14 Microphthalmos with cyst. (A) Transverse scan showing a very small globe (G) and a huge cystic cavity (C). (B) Longitudinal scan showing the small globe (G) and irregular borders (arrow) of the cystic cavity (C).
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Figure 11–15 Phthisis. (A) Transverse scan at high gain showing a small globe filled with opacities. (B) Transverse scan at decreased gain showing marked calcification of the globe wall.
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Figure 11–16 Phthisis. Transverse scan of a disorganized, calcified globe. Frequently it is impossible to differentiate the intraocular structures.
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Figure 11–17 Ampulla of vortex vein. Dilatation of a vortex vein can present as a dome-shaped elevation of the fundus, near the equator, when the patient is fixating in extreme gaze. Slight pressure to the globe wall may collapse the dilatation of the vessel.
(A) Transverse scan showing a focal, dome-shaped elevation of the fundus (arrow). (B) Slight pressure to the globe causes the collapse of the vein and flattening of the fundus elevation (arrow).
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Figure 11–18 Marfan’s syndrome. Axial echogram showing the typical findings of a patient with Marfan’s syndrome: dislocated, cataractous lens (L), and total retinal detachment (arrows).
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Figure 11–19 Marfan’s syndrome, dislocated lens, and retinal detachment. (A) Transverse scan showing vitreous opacities (V), dislocated lens (L), and total retinal detachment (arrows). (B) Longitudinal scan showing the same vitreous opacities (V), dislocated lens (L), and retinal detachment (arrow). A large shadow is produced by the lens (S). The optic nerve (ON) is below.
Figure 11–20 Scleral infolding. (A, B) Transverse and longitudinal scans showing irregularity of the globe wall (arrows) with adjacent shadowing in the orbit (S).
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Figure 11–21 Normal axial length measurements. Axial length measurement using the contact method. The probe is placed directly on the cornea, and the sound beam is aimed perpendicular to the intraocular structures along the visual axis. AL, anterior lens; P, probe on the cornea; PL, posterior lens; R, retina.
Figure 11–22 Phakia/immersion. Performing the immersion technique to obtain axial length measurements may be the most accurate way of measuring the eye, simply because the probe does not touch the cornea, thus preventing corneal compression and shortening of the globe. This method can be used for phakic, aphakic, and pseudophakic patients; AL, anterior lens surface; C, cornea; F, fluid in immersion shell; PL, posterior lens surface; R, retina.
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Figure 11–23 Aphakia/immersion. Sometimes the posterior lens capsule can be very dense and produce a significant spike; it is important for the echographer to recognize this; arrow, posterior lens capsule; C, cornea; F, fluid in immersion shell; R, retina.
Figure 11–24 Pseudophakia. Axial length measurement in a patient with an intraocular lens. It is important to compare the measurements of both eyes even when the patient has had previous cataract extraction and intraocular lens placement; arrows, multiple signals from the intraocular lens; L, lens implant; P, probe on cornea; R, retina.
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Figure 11–25 Interferometry. Multiple axial length measurements can and should be obtained on both eyes. A good scan includes a steeply rising high spike from the RPE (circles), reproducible measurements, and a signal-to-noise ratio 2.
Index
Page numbers followed by an italic f or t indicate the entry on that page is in a figure or table.
A
A-constant, 133
Acquired immune deficiency syndrome, gancyclovir implant for, 136f
Adenoid cystic carcinoma, 129f Adhesion, focal vitreoretinal, 44f
traction retinal detachment with, 40, 45f, 46f Aftermovement, 3
AIDS, gancyclovir implant for, 136f
Amplitude modulation, 1. See also Standardized A-scan Ampulla of vortex vein, 141f
Angle closure, in UBM image, 21f
Angle displacement, mild, in UBM image, 24f Anophthalmos, 139f
Anterior chamber (segment) evaluation of, 11–12, 12f–26f immersion scan of, 11, 12f–18f off-axis scan of, 16f
UBM scans of, 11, 18f–26f Anterior chamber cyst
immersion scan of, 14f UBM image of, 21f, 22f
Anterior chamber depth constant (ACD), 133 Anterior chamber hyphema
immersion scan of, 14f traumatic, 70, 72f
vitreous abnormalities with, 28, 29 Anterior synechia, UBM image of, 21f Anteroposterior scan. See Axial scan Aphakia, 133, 143f
Artifacts
gas, 136f, 137f, 138f multiple signals, 136f perfluorocarbon, 137f silicone, 137f
A-scan, standardized, 1, 2–3. See also specific disorders and findings
of asteroid hyalosis, 28
basic screening techniques of, 3, 5f
of choroidal detachment, 62 clock hours evaluation in, 2
comparison with fluorescein angiography, 1 at decreased gain, 5f
differentiation of tissue in, 1
of extraocular muscles, 114, 115f, 116f gain in, 2
immersion technique in, 11, 12f, 13f of intraocular tumors, 79
kinetic properties of, 3 of mass-like lesions, 3
one-dimensional imaging in, 1 of optic disc drusen, 105
of optic nerve, 104, 106f of orbit, 121, 122f probe in, 2, 4f
reflectivity in (height of spikes), 1, 2, 3 of retinal detachment, 40, 45f
of retinal pigment epithelial detachment, 41 of retinal tears, 41, 42f
of retinoschisis, 41
structure (distribution of spikes) in, 1, 3 tissue sensitivity in, 2, 5f
vascularity in, 3 of vitreous, 28–29
Asteroid hyalosis, 28, 31f Atrophy of optic nerve, 112f Avulsion of optic nerve, 113f Axial length measurements
immersion scan for, 143f interferometry for, 134, 144f normal, 143f
traditional biometry for, 133–134
Axial scan, 2, 10f. See also specific disorders and findings
of anterior segment, 11 of macula, 40
of optic nerve, 104 of orbit, 121
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