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Reliability of Ocular and Orbital Diagnosis with B-Scan Ultrasound
RELIABILITY O F OCULAR AND ORBITAL DIAGNOSIS W I T H B-SCAN ULTRASOUND 2. ORBITAL DIAGNOSIS D. JACKSON COLEMAN,
M.D.
New York, New York In order to determine the reliability of our ultrasonic diagnosis of orbital disease, 100 cases studied by orbital ultrasonography were analyzed by long term follow-up or pathologic correlation. The cases are as con secutive as possible, and deletions were made only when adequate diagnoses were not available. The distribution of pathology in this series of 100 cases is representative of that found in the cases referred for orbital ultra sonic examination at the Edward S. Harkness Eye Institute. This is a pre-selected group in that much exophthalmos, particularly of endocrine etiology, had already been diag nosed and did not require ultrasonic evalua tion. Patients with possible lacrimal gland tumors are not included in this series. Orbital diagnosis with ultrasound is dis tinctly different from ocular diagnosis. Ascan orbital tracings may be difficult to inter pret because the orbit, unlike the globe, has few discrete landmarks clearly separated by acoustically homogeneous tissue such as the vitreous or aqueous. We use primarily Bscan ultrasound because it provides two-di mensional sections of the orbit, facilitating orientation and permitting recognition of normal or pathologic retro-ocular ultrasonic tissue patterns. Patients are usually referred for orbital ultrasonograms because the ophthalmologist suspects orbital tumor, due to exophthalmos or retinal striae. Ultrasonic evaluation can From the Ultrasound Laboratory of the Edward S. Harkness Institute of Ophthalmology, New York. This study was supported by Public Health Service Grant EY-00275-06 from the National Eye Institute. Reprint requests to D. Jackson Coleman, M.D., Edward S. Harkness Institute of Ophthalmology, Columbia-Presbyterian Medical Center, 635 West 165th Street, New York, New York 10032.
determine the presence of tumors and can chart their position and extent. METHOD
Our A-, B-, and M-scan techniques for orbital diagnosis were developed during the past several years through experience with over 1000 patients. We have drawn freely from the experience of Purnell, 1 who pre sented a classic description and categoriza tion of retrobulbar B-scan ultrasound pat terns. Techniques of orbital compression, as described by Ossoinig,2 were not generally used in this series. B-scan procedure is in general the same as outlined for ocular diagnosis in Part 1 of this study.3 Scans are made horizontally in order to avoid overhanging orbital bone. The transducers used are ceramic (PZT) at 5 mHz and lithium sulfate at 10 and 15 mHz, focused at 50 mm. In cases of orbital diag nosis, almost all scans are performed at these lower frequencies of 5, 10, or 15 mHz to ob tain the penetration necessary to reach the orbital apex. Higher frequency ultrasound is readily absorbed in tissue, and penetrates poorly. With lower frequencies, resolution is sacrificed to obtain penetration. Conse quently, in the figures presented, the ocular structures appear less well resolved than in those figures shown in Part 1, the ocular sec tion. If evaluation of the globe is also de sired, the previously described ocular scan procedure is carried out first, and then lower frequency and increased gain are employed for the orbital scan. The use of differenti ated and non-differentiated pulse-triggering, as well as linear pulse-triggering techniques, are identical to those described in the ocular section.
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B-scan ultrasonograms of the orbit can be classified in four diagnostic categories: (1) normal, (2) tumor, (3) inflammatory change or vascular anomaly, and (4) foreign body. Further subdivision of the second and third categories can be made, as shown in a flow chart describing our diagnostic classification (Fig.l).
sound velocities of 1462 m/sec for fat com pared with 1615 m/sec for optic nerve and 1631 m/sec for muscle. This sharp difference in velocities causes the acoustic impedance mismatches which outline the transitions be tween tissue types. The relatively uniform tissue structures of muscles and nerve return only low amplitude echoes, thus often giving the appearance of dark or empty areas.
T H E NORMAL ORBIT
T H E ABNORMAL ORBIT
RESULTS
The normal retrobulbar echo pattern (Fig. Acoustically abnormal orbits show vary 2) is an inverted pyramid shaped, acousti ing degrees of deviation from this normal cally opaque (white) area bounded by the orbital pattern. Most of these abnormalities globe anteriorly and indented posteriorly by may be classified into three groups: tumors, an acoustically empty (black) triangle that inflammatory change or vascular anomaly, or widens towards the orbital apex. This trian foreign body (Fig. 1). Some orbits were ab gle is formed by the optic nerve. Scans above normal, but showed only minimal changes. and below the nerve produce echo patterns These were reported as "abnormal scan with that appear as acoustically opaque (white) non-specific changes." crescents. Scans are made horizontally in or In general, the characteristic shape of the der to avoid overhanging orbital bone. normal orbital ultrasonic pattern is so consis The source of the echoes producing the tent that comparison of an abnormal orbit relatively uniform orbital patterns is not ab with the same patient's normal orbit is not re solutely known, but most observers agree quired. In cases of cavernous sinus throm with Purnell, 1 who postulated that orbital fat bosis, optic neuritis, arachnoid cysts, and globules provide the major source of these other conditions where only very subtle ultraechoes. M-scans of the orbit have demon sonically detectable changes occur, compari strated marked vascular pulsatile activity so son with the other, normal, orbit is obtained. a vascular contribution to these echoes must Tumors—When definite tumors were also be considered. found with B-scan ultrasound, they pre The optic nerve pattern uniformly appears sented four general diagnostic patterns: as an area of little or no reflectance, forming solid, cystic, angiomatous, or infiltrative (Fig. 1). The most characteristic tumor pat the triangular notch. The anterior angle of the triangle is relatively acute (40°) nor tern is that of a mass with a sharply defined mally, and rounding of this area can be a acoustic boundary impinging on the normal retrobulbar echo pattern. The globe may be clue to an enlarged optic nerve. compressed in the adjacent area. This wellThe outer wall of the retrobulbar pattern defined edge may precede either an acousti is formed by the orbital wall and/or the reccally solid or an acoustically cystic mass. Se tus muscles. In scans made through the globe rial sectioning of the orbit can determine the center, the rectus muscle outline can often be extent of the tumor and its position in the seen and the shadows traced forward to the orbit. globe at the region of muscle attachment. The orbital apex is not easily seen but can be Solid tumors (rounded outline, poor approximated by the confluence of the optic sound transmission). Solidity of a tumor is nerve and the rectus muscle shadows. indicated ultrasonically by: (1) high sound Buschmann4 has measured acoustic char absorption (marked acoustic attenuation) acteristics of orbital tissues and reported resulting in the inability to penetrate to the
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Unknown orbit I (B-scan)
i
Acoustically abnormal orbit
Acoustically normal orbit
I
Foreign body
Mass lesion
i—
Rounded
Γ
l_ 1
Good transmission Poor transmission cystic tumor solid tumor (for (for example: example: meningioma, mucocoele, glioma, dermoid) neurofibroma) Fig. 1 (Coleman). Ultrasonic
Irregular
L_ —
Good transmission angiomatous tumor (for example: hemangioma, lymphangioma)
i
1
Inflammatory change Diffuse (for example : cellulitis)
I
Localized (for 1 example: endocrine abscess granuloma)
Poor transmission infiltrative tumor (for example: lymphoma, metastatic cancer) characterization of cases referred for orbital evaluation.
orbital wall ; (2) the presence of low-ampli tude "internal reflections" which indicate a homogeneous tissue with only a few acoustic discontinuities (or more precisely, acoustic impedance mismatches). The presence of
high-amplitude echoes usually indicates such discontinuities as large blood vessels or con nective tissue septae. Tumors that are usually rounded in ultra sonic appearance and exhibit high sound ab-
Opiic Nerve
Fig. 2 (Coleman). A normal retrobulbar fat pattern is shown in a horizontal section through the optic nerve. The optic nerve appears as an acoustically empty triangle. The globe shows less resolution of anterior segment structures at the lower frequencies (5 and 10 mHz) used to study the orbit when com pared with 15 and 20 mHz resolution used to study the globe.
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Fig. 3 (Coleman). Meningioma of the orbit demonstrating typical rounded anterior border and evi dence of acoustic absorption by the mass. The posterior edge of the mass is relatively well outlined here, but often is absent or poorly seen, as in Figures 4 and 5. sorption are the neurogenic tumors such as meningioma (Figs. 3 and 4 ) , glioma (Fig. 5), neurofibroma, or neurilemmoma. Cystic tumors (rounded outline, good sound transmission). In the cystic tumor pattern, a sharp leading edge of a mass is also seen. However, no acoustic reflections are noted from within the tumor. A marked reflection from the orbital wall posterior to these masses can usually be seen. This ability to transmit sound well is characteristic of fluid filled masses or cysts. These character istics have been noted in those cases of mucoceles (Figs. 6 and 7), orbital cysts, and dermoids (Fig. 8) which have been exam ined. Angiomatous tumors (irregular outline, good sound transmission). These tumors show finger-like acoustically "empty" pro trusions extending anteriorly into the retrobulbar fat pattern much in the manner of the optic nerve shadow. These indentations show relatively good sound transmission, but do not have a sharply defined posterior bound
ary, as do the orbital cysts. These patterns are usually associated with hemangioma or lymphangioma and often extend along the rectus muscles. Occasionally,' an "end" of one of these fingers can be transected, giving the appearance of a small cyst in the orbit (Figs. 9 and 10). Other hemangiomas and lymphangiomas may appear as relatively well-outlined tumor masses (Figs. 11 and 12). They are intermediate in transmission between the solid and cystic categories but may resemble the typical cystic pattern. Infiltrative tumors (irregular outline, poor sound transmission). The final tumor type presents a jaggedly indented retrobulbar pat tern. Acoustic transmission is poor, as in solid tumors. The outlines differ from those produced by inflammatory changes (de scribed below) in that they are sharp walled and discrete, and good transmission to out line the orbital wall is missing. This tumor pattern was termed "invasive" by Purnell. In our experience it is the most difficult to identify, as inflammatory changes often pro-
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Fig. 4 (Coleman). Meningioma of the orbit showing rounded anterior border and displacement of the optic nerve.
Fig. S (Coleman). Glioma of the orbit showing rounded mass surrounding the optic nerve shadow. Compression of the globe is evident in the region of the optic disk.
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\
709
Transducer artifact
I
ft
Fig. 6 (Coleman). Mucocele of the orbit extending from region of the ethmoid. The mass appears rounded and internal reflections are minimal, The well-defined outlining of the orbital wall at the apex is characteristic of fluid filled masses.
Fig. 7 (Coleman). Mucocele of orbit showing absence of internal reflections. Comparison of echo amplitude at the back of the mass with echoes from adjacent orbital walls demonstrates good transmission and probable cystic structure.
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Fig. 8 (Coleman). Dermoid of the orbit with poorly outlined mass in the region temporal to the nerve. The posterior margin is partially outlined at low gain (i.e., with limited amplification) indicating moderately good transmission. This tumor was not seen by radiographie techniques.
y
"s
Fig. 9 (Coleman). Hemangioendothelioma of orbit showing finger-like extension of tumor along tem poral orbital wall and evidence of good sound transmission.
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ßilobed
TUMOR
Fig. 10 (Coleman). Lymphangioma of orbit demonstrating irregular outline and apparent cystic area produced by transecting an extension of the tumor.
(
Transducer artifaci Speculum
\
L·.
\ No**
TUMOR;
Fig. 11 (Coleman). Lymphangioma of orbit showing rounded outline and moderate acoustic transmis sion. The interior of the mass is prominent but transmission of sound was moderately good.
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Fig. 12 (Coleman). Hemangiopericytoma of the orbit showing rounded outline and moderately good sound transmission.
duce similar appearances, especially when edema is present around the optic nerve. Metastatic tumors and lymphomas (Figs. 13 and 14) are represented in this category, as are orbits that have had prior surgery. It is not always possible to classify orbital tumors in the four categories noted above, since tumors do not always appear the same anatomically. In general, however, the pat tern and absorption characteristics outlined have been highly consistent for the tumor types noted. Other ultrasonic techniques can augment the available information. M-scan ultrasound offers a technique for evaluating differences between solid or tissue-filled as against fluid-filled tumors. It provides a means of studying vascular effects as well as the effect of pressure on the globe and com pression of orbital contents. This technique will be described separately as it was not used during most of the present series. Inflammatory changes of the orbit— Scans of these patients, referred with a question of possible tumor of the orbit, showed characteristic changes not noted in
the tumor group. In endocrine disease, a dis tinct orbital wall outline can be seen along the major portion or the entire area adjacent to the rectus muscles. An acoustically clear space corresponding to the thickness of the rectus muscles is noted anterior to the orbital wall (Fig. 15). In all of these cases, there is little or no incursion on the retrobulbar echo pattern, and there is a normal optic nerve shadow. In some patients, a small rounded "mass" is noted directly adjacent to the optic nerve at the orbital apex. These "masses" are considered to represent sections of su perior and inferior rectus muscles. The group of patients whose scans were categorized as inflammatory disease on follow-up proved to have thyroid exophthalmopathy, pseudotumor, myositis, or reactive lymphoid hyperplasia. The inflammatory changes can be diffuse, as in cellulitis (Fig. 16), or localized, as in abcess or granuloma (Fig. 17). Areas of localized inflammation can also be detected in optic nerve disease, or inflammation of Tenon's capsule (Figs. 18 and 19). Also, inflammatory tissue can form
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Fig. 13 (Coleman). Lymphosarcoma of orbit demonstrating irregular outline and poor sound trans mission.
Fig. 14 (Coleman). Lymphoma of orbit with irregular outline of tumor mass and evidence of poor acoustic transmission.
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Fig. IS (Coleman). Enlarged rectus muscles seen in thyroid exophthalmos. Exceptionally good out lining of the orbital wall adjacent to the rectus muscles is characteristic of this disease.
Fig. 16 (Coleman). Cellulitis of the orbit showing diffuse sponge-like character. No mass outline is seen.
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Nerv f\,upticOptic nerw Inflammatory Focus
j
Fig. 17 (Coleman). Granuloma of the orbital apex presenting as a definite mass with moderate trans missions. Such tumors are often acoustically indistinguishable from orbital tumors of neoplastic origin. a discrete mass which may appear acousti cally as a tumor (Fig. 17). These masses may have ultrasonic characteristics resem bling any of the true mass lesions. The granulomatous "tumor" appearance is most diffi cult to distinguish from the tumor of neo plastic origin. Foreign bodies—Only one orbital foreign body was seen in this series. This was a piece of wood not seen by x-ray, but ultrasonically localized. In general, small metallic foreign bodies are not easily detectable with ultra sound, but by using special amplitude orien tation techniques (or M-scan in the case of magnetic foreign bodies) they can often be outlined. A storage scope photograph of the wood splinter encountered in this series is shown in Figure 20. STATISTICAL RESULTS
In this series of 100 cases, the ultrasonograms in 59 were considered to exhibit evi dence of orbital tumor. In 11 cases, findings were considered normal, and in one case an orbital foreign body was localized. In the re
maining 29 cases, ultrasonograms were clas sified as showing inflammatory changes, or simply as being abnormal (possible tumor). In regard to the reliability of these diag noses (Table 1), no case classified as normal, or as showing inflammatory change, was later found to have tumor. Two cases classi fied as abnormal (possible tumor) were later found to have orbital tumors. Of the 59 cases thought to exhibit evidence of orbital tumor, seven were found by biopsy not to have tumor, or showed remission following corticosteroid treatment. Of the remaining 52, there were 12 found to have tumorous masses of an inflammatory nature (classified as granulomas), and in 40 the presence of a neoplastic orbital lesion was confirmed. This series thus presents a false-positive rate of 12%. There were no false negatives in detection of orbital tumors in this series, but in two cases of tumor, the scans were classed only as abnormal or suspicious. The false positive diagnoses are presumed to be caused by inflammatory tissue, such as granuloma, pseudotumor or myositis which
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N
'
Optic Nerve
Fig. 18 (Coleman). Inflammation surrounding optic nerve and extending temporally in the region of Tenon's capsule.
\
Inflammation
y.
Optic Nierve
Fig. 19 (Coleman). Inflammation of Tenon's capsule showing an acoustically clear area surrounding the posterior of the globe and contiguous with the optic nerve shadow.
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^
Foreign Body (wood)
Fig. 20 (Coleman). Orbital foreign body. Wood splinter photographed from the storage or monitor oscilloscope. This foreign body was not radiopaque. Generally, small foreign bodies are difficult to see in the orbit unless they are well oriented to the beam or have exceptional acoustic reflectance.
did not appear as discrete tumor-like masses at the time of surgical examination. Usually additional ultrasonic inflammatory signs are present to place these patients in the inflam matory category but our tendency to over-di agnose must be recognized by the referring physician. This does not mean that the ultra sonic diagnosis should be discounted when it alone shows the presence of a tumor, for in the group of 40 neoplastic tumors, seven tu mors were detected only by ultrasound al though a battery of other diagnostic tests was employed.
CONCLUSION
Ultrasonography of the orbit is a rapid, safe and atraumatic clinical test. In the preoperative evaluation of exophthalmos, ultra sonography should be added to the armamen tarium of diagnostic techniques such as con ventional x-rays, tomography, radioactive isotope scanning, and angiography. Orbital ultrasonography offers better than 85% reliability in diagnosing the presence of an orbital tumor. Rare false-negatives, and approximately 12% false-positives occur in our hands.
TABLE 1 RELIABILITY OF ULTRASONIC DIAGNOSIS
Ultrasonic Diagnosis
Normal Tumor Abnormal (suspicious) or inflammatory changes Foreign body
Total Cases
Verification of Ultrasonic Diagnosis
Reliability of Diagnosis
By Pathology
By Long-term Follow-up
FalseFalsepositive negative
Percent Correct
11 59
7 58
4 1
0 7
0 0
100 88
29 1
18 1
11 0
0 0
2 0
93 100
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AMERICAN JOURNAL OF OPHTHALMOLOGY
Those cases found to have inflammatory change on ultrasonic evaluation fall in the thyroid or orbital pseudotumor group. In these cases, the use of corticosteroids to re duce inflammation and repeated ultrasonic evaluation over a period of time has been effective in reaching the proper diagnosis. SUMMARY
One hundred orbital ultrasonograms were assessed to determine the diagnostic reliabil ity of ultrasound. Ultrasonic diagnoses were made using B-scan, A-scan, and M-scan. In 59 cases, ultrasonograms were thought to show the presence of a tumor, and in seven these findings proved to be false-positives, a rate of 12%. Of the 11 scans classified as normal there were no false-negatives. One orbital foreign body was seen. In 29 cases, ul trasonograms were classified as suspicious or indicative of inflammatory change. In this series, B-scan ultrasonography proved a reli able, safe, and atraumatic method of examin ing the orbit for tumor or inflammatory change. Often these changes can be evalu ated in no other way. In this series, seven tu mors were detected only by ultrasound al
OCTOBER, 1972
though a battery of other diagnostic tests was employed. Ultrasonic evaluation provides the surgeon with the maximum information available prior to surgical exploration as to the size and position of an orbital tumor, en abling optimal patient management. ACKNOWLEDGMENTS
I thank Louise Franzen for assisting in all phases of preparing this report, Dr. Robert Jack for re viewing the manuscript, and Diana Scott for typing the manuscript. Mr. E. G. Bethke prepared the il lustrations. Margaret Cubberly prepared the photo graphs. REFERENCES
1. Purnell, E. W. : Ultrasonic interpretation of orbital disease. In Gitter, K. A., Keeney, A. H., Sa rin, L. K., and Meyer, D. (eds.) : Ophthalmic Ul trasound: An International Symposium. St. Louis, C. V. Mosby, 1969, p. 249. 2. Ossoinig, K.: Basics, methods, and results of ultrasonography used in diagnosis of intraorbital tumors. In Gitter, K. A., Keeney, A. H., Sarin, L. K., and Meyer, D. (eds.): Ophthalmic Ultra sound: An International Symposium. St. Louis, C. V. Mosby, 1969, p. 282. 3. Coleman, D. J. : Reliability of ocular and or bital diagnosis with B-scan ultrasound. Part 1 : Ocular diagnosis. Am. J. Ophth. 73:521, 1972. 4. Buschmann, W., Voss, M., and Kemmerling, S. : Acoustic properties of normal human orbit tis sues. Ophth. Res. 1:3S4, 1970.
M.D.
New York, New York In order to determine the reliability of our ultrasonic diagnosis of orbital disease, 100 cases studied by orbital ultrasonography were analyzed by long term follow-up or pathologic correlation. The cases are as con secutive as possible, and deletions were made only when adequate diagnoses were not available. The distribution of pathology in this series of 100 cases is representative of that found in the cases referred for orbital ultra sonic examination at the Edward S. Harkness Eye Institute. This is a pre-selected group in that much exophthalmos, particularly of endocrine etiology, had already been diag nosed and did not require ultrasonic evalua tion. Patients with possible lacrimal gland tumors are not included in this series. Orbital diagnosis with ultrasound is dis tinctly different from ocular diagnosis. Ascan orbital tracings may be difficult to inter pret because the orbit, unlike the globe, has few discrete landmarks clearly separated by acoustically homogeneous tissue such as the vitreous or aqueous. We use primarily Bscan ultrasound because it provides two-di mensional sections of the orbit, facilitating orientation and permitting recognition of normal or pathologic retro-ocular ultrasonic tissue patterns. Patients are usually referred for orbital ultrasonograms because the ophthalmologist suspects orbital tumor, due to exophthalmos or retinal striae. Ultrasonic evaluation can From the Ultrasound Laboratory of the Edward S. Harkness Institute of Ophthalmology, New York. This study was supported by Public Health Service Grant EY-00275-06 from the National Eye Institute. Reprint requests to D. Jackson Coleman, M.D., Edward S. Harkness Institute of Ophthalmology, Columbia-Presbyterian Medical Center, 635 West 165th Street, New York, New York 10032.
determine the presence of tumors and can chart their position and extent. METHOD
Our A-, B-, and M-scan techniques for orbital diagnosis were developed during the past several years through experience with over 1000 patients. We have drawn freely from the experience of Purnell, 1 who pre sented a classic description and categoriza tion of retrobulbar B-scan ultrasound pat terns. Techniques of orbital compression, as described by Ossoinig,2 were not generally used in this series. B-scan procedure is in general the same as outlined for ocular diagnosis in Part 1 of this study.3 Scans are made horizontally in order to avoid overhanging orbital bone. The transducers used are ceramic (PZT) at 5 mHz and lithium sulfate at 10 and 15 mHz, focused at 50 mm. In cases of orbital diag nosis, almost all scans are performed at these lower frequencies of 5, 10, or 15 mHz to ob tain the penetration necessary to reach the orbital apex. Higher frequency ultrasound is readily absorbed in tissue, and penetrates poorly. With lower frequencies, resolution is sacrificed to obtain penetration. Conse quently, in the figures presented, the ocular structures appear less well resolved than in those figures shown in Part 1, the ocular sec tion. If evaluation of the globe is also de sired, the previously described ocular scan procedure is carried out first, and then lower frequency and increased gain are employed for the orbital scan. The use of differenti ated and non-differentiated pulse-triggering, as well as linear pulse-triggering techniques, are identical to those described in the ocular section.
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B-scan ultrasonograms of the orbit can be classified in four diagnostic categories: (1) normal, (2) tumor, (3) inflammatory change or vascular anomaly, and (4) foreign body. Further subdivision of the second and third categories can be made, as shown in a flow chart describing our diagnostic classification (Fig.l).
sound velocities of 1462 m/sec for fat com pared with 1615 m/sec for optic nerve and 1631 m/sec for muscle. This sharp difference in velocities causes the acoustic impedance mismatches which outline the transitions be tween tissue types. The relatively uniform tissue structures of muscles and nerve return only low amplitude echoes, thus often giving the appearance of dark or empty areas.
T H E NORMAL ORBIT
T H E ABNORMAL ORBIT
RESULTS
The normal retrobulbar echo pattern (Fig. Acoustically abnormal orbits show vary 2) is an inverted pyramid shaped, acousti ing degrees of deviation from this normal cally opaque (white) area bounded by the orbital pattern. Most of these abnormalities globe anteriorly and indented posteriorly by may be classified into three groups: tumors, an acoustically empty (black) triangle that inflammatory change or vascular anomaly, or widens towards the orbital apex. This trian foreign body (Fig. 1). Some orbits were ab gle is formed by the optic nerve. Scans above normal, but showed only minimal changes. and below the nerve produce echo patterns These were reported as "abnormal scan with that appear as acoustically opaque (white) non-specific changes." crescents. Scans are made horizontally in or In general, the characteristic shape of the der to avoid overhanging orbital bone. normal orbital ultrasonic pattern is so consis The source of the echoes producing the tent that comparison of an abnormal orbit relatively uniform orbital patterns is not ab with the same patient's normal orbit is not re solutely known, but most observers agree quired. In cases of cavernous sinus throm with Purnell, 1 who postulated that orbital fat bosis, optic neuritis, arachnoid cysts, and globules provide the major source of these other conditions where only very subtle ultraechoes. M-scans of the orbit have demon sonically detectable changes occur, compari strated marked vascular pulsatile activity so son with the other, normal, orbit is obtained. a vascular contribution to these echoes must Tumors—When definite tumors were also be considered. found with B-scan ultrasound, they pre The optic nerve pattern uniformly appears sented four general diagnostic patterns: as an area of little or no reflectance, forming solid, cystic, angiomatous, or infiltrative (Fig. 1). The most characteristic tumor pat the triangular notch. The anterior angle of the triangle is relatively acute (40°) nor tern is that of a mass with a sharply defined mally, and rounding of this area can be a acoustic boundary impinging on the normal retrobulbar echo pattern. The globe may be clue to an enlarged optic nerve. compressed in the adjacent area. This wellThe outer wall of the retrobulbar pattern defined edge may precede either an acousti is formed by the orbital wall and/or the reccally solid or an acoustically cystic mass. Se tus muscles. In scans made through the globe rial sectioning of the orbit can determine the center, the rectus muscle outline can often be extent of the tumor and its position in the seen and the shadows traced forward to the orbit. globe at the region of muscle attachment. The orbital apex is not easily seen but can be Solid tumors (rounded outline, poor approximated by the confluence of the optic sound transmission). Solidity of a tumor is nerve and the rectus muscle shadows. indicated ultrasonically by: (1) high sound Buschmann4 has measured acoustic char absorption (marked acoustic attenuation) acteristics of orbital tissues and reported resulting in the inability to penetrate to the
706
AMERICAN JOURNAL OF OPHTHALMOLOGY
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Unknown orbit I (B-scan)
i
Acoustically abnormal orbit
Acoustically normal orbit
I
Foreign body
Mass lesion
i—
Rounded
Γ
l_ 1
Good transmission Poor transmission cystic tumor solid tumor (for (for example: example: meningioma, mucocoele, glioma, dermoid) neurofibroma) Fig. 1 (Coleman). Ultrasonic
Irregular
L_ —
Good transmission angiomatous tumor (for example: hemangioma, lymphangioma)
i
1
Inflammatory change Diffuse (for example : cellulitis)
I
Localized (for 1 example: endocrine abscess granuloma)
Poor transmission infiltrative tumor (for example: lymphoma, metastatic cancer) characterization of cases referred for orbital evaluation.
orbital wall ; (2) the presence of low-ampli tude "internal reflections" which indicate a homogeneous tissue with only a few acoustic discontinuities (or more precisely, acoustic impedance mismatches). The presence of
high-amplitude echoes usually indicates such discontinuities as large blood vessels or con nective tissue septae. Tumors that are usually rounded in ultra sonic appearance and exhibit high sound ab-
Opiic Nerve
Fig. 2 (Coleman). A normal retrobulbar fat pattern is shown in a horizontal section through the optic nerve. The optic nerve appears as an acoustically empty triangle. The globe shows less resolution of anterior segment structures at the lower frequencies (5 and 10 mHz) used to study the orbit when com pared with 15 and 20 mHz resolution used to study the globe.
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Fig. 3 (Coleman). Meningioma of the orbit demonstrating typical rounded anterior border and evi dence of acoustic absorption by the mass. The posterior edge of the mass is relatively well outlined here, but often is absent or poorly seen, as in Figures 4 and 5. sorption are the neurogenic tumors such as meningioma (Figs. 3 and 4 ) , glioma (Fig. 5), neurofibroma, or neurilemmoma. Cystic tumors (rounded outline, good sound transmission). In the cystic tumor pattern, a sharp leading edge of a mass is also seen. However, no acoustic reflections are noted from within the tumor. A marked reflection from the orbital wall posterior to these masses can usually be seen. This ability to transmit sound well is characteristic of fluid filled masses or cysts. These character istics have been noted in those cases of mucoceles (Figs. 6 and 7), orbital cysts, and dermoids (Fig. 8) which have been exam ined. Angiomatous tumors (irregular outline, good sound transmission). These tumors show finger-like acoustically "empty" pro trusions extending anteriorly into the retrobulbar fat pattern much in the manner of the optic nerve shadow. These indentations show relatively good sound transmission, but do not have a sharply defined posterior bound
ary, as do the orbital cysts. These patterns are usually associated with hemangioma or lymphangioma and often extend along the rectus muscles. Occasionally,' an "end" of one of these fingers can be transected, giving the appearance of a small cyst in the orbit (Figs. 9 and 10). Other hemangiomas and lymphangiomas may appear as relatively well-outlined tumor masses (Figs. 11 and 12). They are intermediate in transmission between the solid and cystic categories but may resemble the typical cystic pattern. Infiltrative tumors (irregular outline, poor sound transmission). The final tumor type presents a jaggedly indented retrobulbar pat tern. Acoustic transmission is poor, as in solid tumors. The outlines differ from those produced by inflammatory changes (de scribed below) in that they are sharp walled and discrete, and good transmission to out line the orbital wall is missing. This tumor pattern was termed "invasive" by Purnell. In our experience it is the most difficult to identify, as inflammatory changes often pro-
708
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Fig. 4 (Coleman). Meningioma of the orbit showing rounded anterior border and displacement of the optic nerve.
Fig. S (Coleman). Glioma of the orbit showing rounded mass surrounding the optic nerve shadow. Compression of the globe is evident in the region of the optic disk.
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\
709
Transducer artifact
I
ft
Fig. 6 (Coleman). Mucocele of the orbit extending from region of the ethmoid. The mass appears rounded and internal reflections are minimal, The well-defined outlining of the orbital wall at the apex is characteristic of fluid filled masses.
Fig. 7 (Coleman). Mucocele of orbit showing absence of internal reflections. Comparison of echo amplitude at the back of the mass with echoes from adjacent orbital walls demonstrates good transmission and probable cystic structure.
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Fig. 8 (Coleman). Dermoid of the orbit with poorly outlined mass in the region temporal to the nerve. The posterior margin is partially outlined at low gain (i.e., with limited amplification) indicating moderately good transmission. This tumor was not seen by radiographie techniques.
y
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Fig. 9 (Coleman). Hemangioendothelioma of orbit showing finger-like extension of tumor along tem poral orbital wall and evidence of good sound transmission.
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ßilobed
TUMOR
Fig. 10 (Coleman). Lymphangioma of orbit demonstrating irregular outline and apparent cystic area produced by transecting an extension of the tumor.
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TUMOR;
Fig. 11 (Coleman). Lymphangioma of orbit showing rounded outline and moderate acoustic transmis sion. The interior of the mass is prominent but transmission of sound was moderately good.
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Fig. 12 (Coleman). Hemangiopericytoma of the orbit showing rounded outline and moderately good sound transmission.
duce similar appearances, especially when edema is present around the optic nerve. Metastatic tumors and lymphomas (Figs. 13 and 14) are represented in this category, as are orbits that have had prior surgery. It is not always possible to classify orbital tumors in the four categories noted above, since tumors do not always appear the same anatomically. In general, however, the pat tern and absorption characteristics outlined have been highly consistent for the tumor types noted. Other ultrasonic techniques can augment the available information. M-scan ultrasound offers a technique for evaluating differences between solid or tissue-filled as against fluid-filled tumors. It provides a means of studying vascular effects as well as the effect of pressure on the globe and com pression of orbital contents. This technique will be described separately as it was not used during most of the present series. Inflammatory changes of the orbit— Scans of these patients, referred with a question of possible tumor of the orbit, showed characteristic changes not noted in
the tumor group. In endocrine disease, a dis tinct orbital wall outline can be seen along the major portion or the entire area adjacent to the rectus muscles. An acoustically clear space corresponding to the thickness of the rectus muscles is noted anterior to the orbital wall (Fig. 15). In all of these cases, there is little or no incursion on the retrobulbar echo pattern, and there is a normal optic nerve shadow. In some patients, a small rounded "mass" is noted directly adjacent to the optic nerve at the orbital apex. These "masses" are considered to represent sections of su perior and inferior rectus muscles. The group of patients whose scans were categorized as inflammatory disease on follow-up proved to have thyroid exophthalmopathy, pseudotumor, myositis, or reactive lymphoid hyperplasia. The inflammatory changes can be diffuse, as in cellulitis (Fig. 16), or localized, as in abcess or granuloma (Fig. 17). Areas of localized inflammation can also be detected in optic nerve disease, or inflammation of Tenon's capsule (Figs. 18 and 19). Also, inflammatory tissue can form
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Fig. 13 (Coleman). Lymphosarcoma of orbit demonstrating irregular outline and poor sound trans mission.
Fig. 14 (Coleman). Lymphoma of orbit with irregular outline of tumor mass and evidence of poor acoustic transmission.
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Fig. IS (Coleman). Enlarged rectus muscles seen in thyroid exophthalmos. Exceptionally good out lining of the orbital wall adjacent to the rectus muscles is characteristic of this disease.
Fig. 16 (Coleman). Cellulitis of the orbit showing diffuse sponge-like character. No mass outline is seen.
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Nerv f\,upticOptic nerw Inflammatory Focus
j
Fig. 17 (Coleman). Granuloma of the orbital apex presenting as a definite mass with moderate trans missions. Such tumors are often acoustically indistinguishable from orbital tumors of neoplastic origin. a discrete mass which may appear acousti cally as a tumor (Fig. 17). These masses may have ultrasonic characteristics resem bling any of the true mass lesions. The granulomatous "tumor" appearance is most diffi cult to distinguish from the tumor of neo plastic origin. Foreign bodies—Only one orbital foreign body was seen in this series. This was a piece of wood not seen by x-ray, but ultrasonically localized. In general, small metallic foreign bodies are not easily detectable with ultra sound, but by using special amplitude orien tation techniques (or M-scan in the case of magnetic foreign bodies) they can often be outlined. A storage scope photograph of the wood splinter encountered in this series is shown in Figure 20. STATISTICAL RESULTS
In this series of 100 cases, the ultrasonograms in 59 were considered to exhibit evi dence of orbital tumor. In 11 cases, findings were considered normal, and in one case an orbital foreign body was localized. In the re
maining 29 cases, ultrasonograms were clas sified as showing inflammatory changes, or simply as being abnormal (possible tumor). In regard to the reliability of these diag noses (Table 1), no case classified as normal, or as showing inflammatory change, was later found to have tumor. Two cases classi fied as abnormal (possible tumor) were later found to have orbital tumors. Of the 59 cases thought to exhibit evidence of orbital tumor, seven were found by biopsy not to have tumor, or showed remission following corticosteroid treatment. Of the remaining 52, there were 12 found to have tumorous masses of an inflammatory nature (classified as granulomas), and in 40 the presence of a neoplastic orbital lesion was confirmed. This series thus presents a false-positive rate of 12%. There were no false negatives in detection of orbital tumors in this series, but in two cases of tumor, the scans were classed only as abnormal or suspicious. The false positive diagnoses are presumed to be caused by inflammatory tissue, such as granuloma, pseudotumor or myositis which
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N
'
Optic Nerve
Fig. 18 (Coleman). Inflammation surrounding optic nerve and extending temporally in the region of Tenon's capsule.
\
Inflammation
y.
Optic Nierve
Fig. 19 (Coleman). Inflammation of Tenon's capsule showing an acoustically clear area surrounding the posterior of the globe and contiguous with the optic nerve shadow.
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^
Foreign Body (wood)
Fig. 20 (Coleman). Orbital foreign body. Wood splinter photographed from the storage or monitor oscilloscope. This foreign body was not radiopaque. Generally, small foreign bodies are difficult to see in the orbit unless they are well oriented to the beam or have exceptional acoustic reflectance.
did not appear as discrete tumor-like masses at the time of surgical examination. Usually additional ultrasonic inflammatory signs are present to place these patients in the inflam matory category but our tendency to over-di agnose must be recognized by the referring physician. This does not mean that the ultra sonic diagnosis should be discounted when it alone shows the presence of a tumor, for in the group of 40 neoplastic tumors, seven tu mors were detected only by ultrasound al though a battery of other diagnostic tests was employed.
CONCLUSION
Ultrasonography of the orbit is a rapid, safe and atraumatic clinical test. In the preoperative evaluation of exophthalmos, ultra sonography should be added to the armamen tarium of diagnostic techniques such as con ventional x-rays, tomography, radioactive isotope scanning, and angiography. Orbital ultrasonography offers better than 85% reliability in diagnosing the presence of an orbital tumor. Rare false-negatives, and approximately 12% false-positives occur in our hands.
TABLE 1 RELIABILITY OF ULTRASONIC DIAGNOSIS
Ultrasonic Diagnosis
Normal Tumor Abnormal (suspicious) or inflammatory changes Foreign body
Total Cases
Verification of Ultrasonic Diagnosis
Reliability of Diagnosis
By Pathology
By Long-term Follow-up
FalseFalsepositive negative
Percent Correct
11 59
7 58
4 1
0 7
0 0
100 88
29 1
18 1
11 0
0 0
2 0
93 100
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Those cases found to have inflammatory change on ultrasonic evaluation fall in the thyroid or orbital pseudotumor group. In these cases, the use of corticosteroids to re duce inflammation and repeated ultrasonic evaluation over a period of time has been effective in reaching the proper diagnosis. SUMMARY
One hundred orbital ultrasonograms were assessed to determine the diagnostic reliabil ity of ultrasound. Ultrasonic diagnoses were made using B-scan, A-scan, and M-scan. In 59 cases, ultrasonograms were thought to show the presence of a tumor, and in seven these findings proved to be false-positives, a rate of 12%. Of the 11 scans classified as normal there were no false-negatives. One orbital foreign body was seen. In 29 cases, ul trasonograms were classified as suspicious or indicative of inflammatory change. In this series, B-scan ultrasonography proved a reli able, safe, and atraumatic method of examin ing the orbit for tumor or inflammatory change. Often these changes can be evalu ated in no other way. In this series, seven tu mors were detected only by ultrasound al
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though a battery of other diagnostic tests was employed. Ultrasonic evaluation provides the surgeon with the maximum information available prior to surgical exploration as to the size and position of an orbital tumor, en abling optimal patient management. ACKNOWLEDGMENTS
I thank Louise Franzen for assisting in all phases of preparing this report, Dr. Robert Jack for re viewing the manuscript, and Diana Scott for typing the manuscript. Mr. E. G. Bethke prepared the il lustrations. Margaret Cubberly prepared the photo graphs. REFERENCES
1. Purnell, E. W. : Ultrasonic interpretation of orbital disease. In Gitter, K. A., Keeney, A. H., Sa rin, L. K., and Meyer, D. (eds.) : Ophthalmic Ul trasound: An International Symposium. St. Louis, C. V. Mosby, 1969, p. 249. 2. Ossoinig, K.: Basics, methods, and results of ultrasonography used in diagnosis of intraorbital tumors. In Gitter, K. A., Keeney, A. H., Sarin, L. K., and Meyer, D. (eds.): Ophthalmic Ultra sound: An International Symposium. St. Louis, C. V. Mosby, 1969, p. 282. 3. Coleman, D. J. : Reliability of ocular and or bital diagnosis with B-scan ultrasound. Part 1 : Ocular diagnosis. Am. J. Ophth. 73:521, 1972. 4. Buschmann, W., Voss, M., and Kemmerling, S. : Acoustic properties of normal human orbit tis sues. Ophth. Res. 1:3S4, 1970.