Ординатура / Офтальмология / Английские материалы / Ophthalmic Ultrasound A Diagnostic Atlas 2nd edition_ DiBernardo, Greenberg_2006
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Figure 9–3 Normal muscles. Standardized A-scan measurements of normal extraocular muscles. Double-headed arrows show the diameter of each muscle. (A) Superior rectus. (B) Medial rectus. (C) Lateral rectus. (D) Inferior rectus.
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Figure 9–4 Thyroid eye disease. (A) and (B) Longitudinal scans showing the inserting tendons (arrows) that are normal in thickness and the large muscle bellies (M) from the medial recti in both orbits of a patient with thyroid eye disease. (C) and (D) A-scan showing the widening of the muscles and high internal reflectivity (M).
Note: Thyroid eye disease (TED) is generally a bilateral condition with enlargement of the extraocular muscles. The enlargement may be subtle or marked. Clinically, patients with TED present with diplopia, mild external irritation, and often lid retraction is present. Echographically, there is enlargement of the muscle bellies and asymmetry between the muscle pairs. The inserting tendon is not usually involved, and the reflectivity exhibited by the muscles is quite high, sometimes making it difficult to display the muscles on both B-scan and standardized A-scan.
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Figure 9–5 Myositis. (A) Transverse scan of the enlarged muscle belly (arrow). (B) Transverse scan showing the enlarged inserting tendon of the rectus muscle (arrow). (C) Longitudinal scan showing the low reflective enlargement from the tendon to the muscle belly (arrows). (D) Standardized A-scan showing massive, low reflective enlargement of the muscle belly (arrow).
Note: Generally, myositis is a unilateral process that involves one or two muscles in the affected orbit. In most cases the chief complaint is pain on eye movement; however, double vision may be present. Echographically, the involved muscles are markedly enlarged and very low reflective. The enlargement and decrease in reflectivity involve the entire muscle from the inserting tendon to the belly. Serial echographic examinations following the initiation treatment is an excellent way to document improvement.
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Figure 9–6 Metastatic carcinoma. (A) Longitudinal B-scan showing marked thickening of the right inferior rectus muscle (M) with the normal appearing inserting tendon (arrow). ON, optic nerve. (B) Horizontal transverse B-scan showing a cross section of the thickened muscle belly (M). (C) Standardized A-scan showing medium reflectivity of the thickened muscle belly (M). (From Byrne SF, Green RL. Ultrasound of the Eye and Orbit. St. Louis, MO: Mosby; 1992. Reprinted by permission.)
Figure 9–7 Melanoma. Peripheral longitudinal section through insertion of affected superior rectus muscle showing a normal inserting tendon of the muscle (arrow). (From DiBernardo C, Pacheco EM, Hughes JR, et al. Echographic evaluation and findings in metastatic melanoma to extraocular muscles. Ophthalmology. 1996;103(11):1794–1797. Reprinted by permission.)
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Figure 9–8 Melanoma. Cutaneous melanoma metastatic to the superior rectus muscle. (A) Transverse B-scan (cross section) showing a massively enlarged superior rectus muscle (M). (B) Longitudinal B-scan (radial section) showing marked posterior thickening and rounded appearance of the tumor within the muscle sheath (M) and the uninvolved inserting tendon anteriorly (arrow). (C) Standardized A-scan demonstrating massive enlargement of the muscle belly fibers with low internal reflectivity (M). (From DiBernardo C, Pacheco EM, Hughes JR, et al. Echographic evaluation and findings in metastatic melanoma to extraocular muscles. Ophthalmology. 1996;103(11):1794–1797. Reprinted by permission.)
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Evaluation of the Orbit
Over the last two decades in many practices, the role of ophthalmic ultrasound has advanced to include evaluation of the orbit. Aside from the retrobulbar optic nerves and extraocular muscles, which were discussed in previous chapters, evaluation of the orbital soft tissue, vasculature, and periorbital regions is now commonplace.
Because ultrasound is a non-invasive procedure it can be used as the initial imaging tool prior to ordering more invasive tests or it can be used as an adjunct to other imaging studies when findings are not straightforward. The same screening techniques that are used for evaluation of the globe can be employed for orbital screening; however, knowledge of the normal orbital anatomy is essential to obtain useful information.
Transocular B-scan probe positions (vertical, horizontal, and oblique), longitudinal scans, and even axial scans can be used to evaluate the intraconal regions and the more posterior portions of the orbit. Paraocular B-scan probe positions (transverse, horizontal, and oblique)
that by-pass the globe completely can be used to evaluate the more anterior regions of the orbits. All B-scan images provide the topographic features (location, size, shape, borders, and condition of the orbital bone) of the normal and abnormal orbital structures. Standardized A-scan provides the quantitative information (size, structure, reflectivity, consistency, vascularity, mobility, and sound attenuation) necessary to confirm the diagnosis.
The normal orbital soft tissue is echogenic and highly reflective on both B-scan and standardized A-scan. Orbital disorders have highly variable echographic characteristics, so having a good understanding of any given patient’s medical history as well as knowing the histopathology of the various orbital lesions will improve the diagnostic ability of most echographers.
The following images are a collection of some of the more commonly seen orbital lesions. We have included a few rare cases as well.
Suggested Readings
Byrne SF, Green RL. Second Edition: Ultrasound of the |
Dutton JJ, Byrne SF, Proia AD. Diagnostic Atlas of Orbital |
Eye and Orbit. St. Louis: CV Mosby Yearbook; 2002 |
Diseases. Philadelphia: WB Saunders Company; 2000 |
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Figure 10–1 Normal orbital scans. (A) Transocular transverse cross-section scan showing the normally high reflective orbital tissue. (B) Transocular longitudinal radial scan showing the normally high reflective orbital tissue and the slightly lower reflective extraocular muscle (arrows). (C) Paraocular transverse scan showing the normally high reflective tissue in the anterior aspect of the orbit. (D) Paraocular longitudinal scan showing no infiltration in the anterior portion of the orbit. The globe is in the lower portion of the echogram (G).
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Figure 10–2 Normal orbital A-scan (transocular/transverse). (A) Standardized A-scan with the sound beam directed through the globe (G) showing the highly reflective pattern from the normal orbital tissue (arrow). (B) Normal orbital A-scan (paraocular). Standardized A-scan with the sound beam bypassing the globe to show the highly reflective pattern from the normal orbital tissue (arrows). The probe (P) is placed directly over the tissue.
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Figure 10–3 Posterior scleritis. (A) Transverse B-scan showing thickening of the ocular coats and low reflective infiltration in Tenon’s capsule (arrows). (B) Longitudinal scan showing the infiltration in Tenon’s capsule (arrow). (C) Longitudinal scan directed at the temporal posterior pole showing focal, shallow elevation of the retina (arrow). (D) Standardized A-scan showing the thickened sclera (S) and the low reflective infiltration behind the sclera (arrow).
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Figure 10–4 Posterior scleritis (nodular). (A) Transverse B- scan showing the localized area of marked fundus thickening (left arrow) and the low reflective infiltration in Tenon’s capsule (right arrow). (B) Longitudinal scan showing the same area of fundus thickening and the close proximity to the optic nerve (ON). (C) Standardized A-scan showing the marked thickening of the sclera
(S) and the low reflective infiltration in Tenon’s capsule (arrow).
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Figure 10–5 Dilated vertical vein. (A) Transverse B-scan showing long section of dilated vein (arrows) in a patient with carotidcavernous sinus fistula. (B) Longitudinal B-scan showing cross section of dilated vein (arrow); M, muscle.
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Figure 10–6 Lacrimal gland. (A) Transverse paraocular B-scan of the normal lacrimal gland. The orbital soft tissue and the normal lacrimal gland have similar reflectivities, therefore the two structures normally cannot be delineated from each other. (B) Paraocular view of the normal lacrimal gland (L); V, vitreous. (C) Paraocular A-scan showing the highly reflectivity of the normal lacrimal gland (arrow).
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Figure 10–7 Dacryoadenitis. (A) Transverse paraocular scan showing diffuse enlargement of the lacrimal gland (L) and surrounding orbital soft tissue with low reflective areas of infiltration (arrow). (B) Corresponding paraocular A-scan displays the medium to high reflectivity of the inflamed lacrimal gland (L) and the area of lower reflectivity from the surrounding infiltration (arrow).