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Ingrid U. Scott, MD, MPH; Timothy G. Murray, MD; J. Randall Hughes, BS

Arch Ophthalmol. 1998;116:897-899.

ABSTRACT
Objective  To investigate the sensitivity of echography vs magnetic resonance imaging (MRI) or computed tomography (CT) for detecting extraocular extension of choroidal malignant melanoma.

Design and Setting  Retrospective review at a university referral center.

Participants  All patients with histopathologically proven extraocular extension of choroidal malignant melanoma evaluated at the Bascom Palmer Eye Institute, Miami, Fla, between January 1, 1988, and August 31, 1997.

Interventions  The histopathology records of all patients who underwent enucleation for choroidal malignant melanoma or biopsy of an extraocular nodule during the study period were reviewed. The records and imaging studies of patients who were found to have extraocular extension of choroidal malignant melanoma were then reviewed to determine the sensitivity of preoperative echography vs MRI or CT for detecting extraocular tumor extension.

Results  A review of 297 histopathology records identified 13 patients with extraocular extension of choroidal malignant melanoma. Three patients with only microscopic extraocular tumor extension were excluded from the study. Of the remaining 10 patients, all underwent ocular echography preoperatively, 5 underwent orbital MRI, and 2 underwent orbital CT scanning to evaluate for extraocular extension of tumor. Extraocular tumor extension was demonstrated in 10 patients (100%) with echography and in 2 (29%) of 7 patients with MRI (2 of 5 patients) or CT (0 of 2 patients). In no instance did MRI or CT demonstrate extraocular tumor extension that was not identified with echography.

Conclusion  At this institute, ocular echography is more sensitive than MRI or CT for the detection of extraocular extension of choroidal malignant melanoma.

INTRODUCTION

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UVEAL MELANOMA is the most common intraocular malignant neoplasm in adults, with an incidence of 6 to 7 cases per million people in the United States.^1-3 Several studies have demonstrated the poorer prognosis of uveal malignant melanoma associated with extraocular tumor extension.^4-9 In addition to its prognostic significance, extraocular extension of uveal melanoma has important therapeutic implications.¹⁰ It has recently been reported that magnetic resonance imaging (MRI) has proved to be more sensitive and specific than echography for the detection of extraocular extension of uveal melanoma.¹¹ In addition, echography has been reported to be unreliable in the assessment for extraocular extension of uveal melanoma.^12-13 The current study was undertaken to investigate the sensitivity of echography vs MRI or computed tomography (CT) for the detection of extraocular extension of choroidal malignant melanoma.

METHODS

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This study conformed to the policies and procedures outlined by the Institutional Review Board of the University of Miami School of Medicine, Miami, Fla. The histopathologic records of all patients who underwent enucleation for choroidal malignant melanoma or biopsy of an extraocular nodule at the Bascom Palmer Eye Institute, Miami, between January 1, 1988, and August 31, 1997, were reviewed. The records and imaging studies of the patients who were found to have extraocular extension of choroidal malignant melanoma were then reviewed.

The patients who were evaluated with MRI or CT underwent these imaging studies before being seen at the Bascom Palmer Eye Institute. Per the practice pattern at this institute, all new patients with uveal melanoma are evaluated with echography.

All patients who had surgical therapy at the Bascom Palmer Eye Institute for choroidal malignant melanoma during the study period were evaluated preoperatively with echography. Therefore, the rate of false-positive echography reports of extraocular extension of choroidal malignant melanoma could be calculated after reviewing the echographic records of all such patients. All patients with choroidal malignant melanoma evaluated for extraocular extension with MRI or CT scanning could not be accurately identified, and therefore, the rate of false-positive MRI or CT reports of extraocular tumor extension could not be determined.

Echograms were obtained using 1 of 2 ultrasound units: either the Ophthascan S and Mini-A (Alcon Surgical, Irvine, Calif) or System-ABD (Innovative Imaging Inc, Sacramento, Calif). The B-scan (2-dimensional image) probes were 10 MHz, and the A-scan (1-dimensional image) probes were 8 MHz. A- and B-scan images were used to evaluate each tumor and the adjacent orbital tissue. The B-scan sound-beam image sector covered 45° to 60° and was slowly swept through the tumor from margin to margin using transverse and longitudinal orientations. Transverse scans were oriented 90° to the meridian or clock hour of the tumor location and were shifted in an anteroposterior direction, giving successive circumferential sections through the tumor. Longitudinal scans were oriented along meridians or clock hours and were shifted from side to side, displaying successive radial cross-sections. Several millimeters of tissue outside the tumor margins was included in both scan orientations. A medium-gain setting was used to obtain the best resolution. In some cases, a standardized or diagnostic A scan was used to evaluate the integrity of the sclera.

Magnetic resonance imaging was performed at 1.5 T with a commercially available unit (model Edge, Picker International, Cleveland, Ohio). Unenhanced T₁- and T₂-weighted axial images were obtained through the orbits with a section thickness of 2 mm. In addition, axial and coronal T₁-weighted images were obtained with fat suppression and after the intravenous administration of gadopentetate dimeglumine (0.2 mL/kg). Axial and coronal CT scans through the orbits were obtained using a commercially available unit (model TCT600, Toshiba International Inc, Tokyo, Japan) before and after the intravenous administration of diatrizoate meglumine, with a section thickness of 2 mm.

RESULTS

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A review of 297 histopathology reports identified 13 patients with extraocular extension of choroidal malignant melanoma. Three patients with only microscopic extraocular tumor extension were excluded from the study. Of the remaining 10 patients, all underwent ocular echography preoperatively, 5 underwent orbital MRI, and 2 underwent orbital CT scanning to evaluate for the extraocular extension of tumor. Extraocular tumor extension was demonstrated in 10 patients (100%) with echography and in 2 (29%) of 7 patients with MRI (2 of 5 patients) or CT (0 of 2 patients). In no patient did MRI or CT demonstrate extraocular tumor extension that was not identified with echography. Figure 1 and Figure 2 demonstrate the echographic and MRI or CT images of 2 patients in whom extraocular tumor extension was identified with echography but not with MRI or CT scan.

View larger version (77K): [in this window] [in a new window] Figure 1. Top, Transverse echographic section showing choroidal malignant melanoma (arrowhead) and extraocular tumor nodule (arrow). Bottom, An axial T2-weighted magnetic resonance imaging section through orbits reveals no evidence of extraocular tumor extension.

View larger version (90K): [in this window] [in a new window] Figure 2. Top, Vertical axial echographic section through the lens and optic nerve (ON) showing choroidal malignant melanoma (arrowhead) and extraocular tumor extension (arrow) just superior to the optic nerve. Bottom, An axial computed tomographic section through orbits reveals no evidence of extraocular tumor extension.

During the study period, there were only 7 false-positive echography reports of extraocular extension of choroidal malignant melanoma. In 6 of these patients, an area suggestive of extrascleral tumor extension was noted, but follow-up echographic evaluations performed by the same echographer revealed no evidence of extraocular tumor. In the 1 remaining patient, only a single echographic evaluation was performed, which revealed a lesion typical for choroidal melanoma "with possible extrascleral extension" (Figure 3), yet no extraocular extension was noted on histopathologic examination after enucleation. Thus, the rate of false-positive echography reports of extraocular extension of choroidal malignant melanoma is 7 (2.4%) of 297 if follow-up echographic evaluations are not considered and only 1 (0.3%) of 297 if follow-up echographic evaluations are taken into account.

View larger version (153K): [in this window] [in a new window] Figure 3. Longitudinal (top) and transverse (bottom) echographic sections through choroidal malignant melanoma (arrowheads) showing nodular lucency (arrows) suspected to represent extraocular tumor extension. Extraocular tumor extension was not confirmed on histopathologic examination after enucleation.

COMMENT

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The ability to demonstrate extraocular extension of choroidal melanoma is important for both prognostic and therapeutic reasons. Although ultrasonography is frequently used to aid in the diagnosis of choroidal melanoma,¹⁴ it is commonly believed that CT and MRI scans are superior to echography for detecting extraocular extension of choroidal melanoma.^{11, 15-16} In fact, echography has been reported to be unreliable in the assessment for extraocular extension of choroidal melanoma,^12-13 and CT scanning has often been used to confirm or refute echographic evidence of extraocular extension.^15-16 Magnetic resonance imaging has reportedly been proved to be more sensitive and specific than echography in the detection of extraocular extension of uveal melanoma.¹¹ In the study reported by Hosten et al,¹¹ as in the current report, MRI was performed at 1.5 T with a section thickness of 2 mm, both unenhanced and enhanced with gadopentetate dimeglumine. Hosten et al reported that among 7 patients in whom extraocular extension of uveal melanoma was confirmed with histological examination, ophthalmoscopy, or surgical procedure, extraocular tumor extension was detected by MRI in 6 patients and by echography in 3 patients.

The current study demonstrates that at our institute, ocular echography is more sensitive than MRI or CT for the detection of extraocular extension of choroidal malignant melanoma, and the false-positive rate of echographic evaluation for extraocular extension of choroidal melanoma is low. Of course, sensitivity (as well as specificity) of any diagnostic modality is a function of the prevalence of the disease, and the prevalence of extraocular tumor extension in the current series is low. Also, the ability to detect extraocular extension of uveal melanoma may vary according to the skill and experience of the echographer, and further studies are needed to compare the sensitivity and specificity of echography vs other imaging modalities for the detection of extraocular extension of uveal melanoma.

AUTHOR INFORMATION

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Accepted for publication February 27, 1998.

This study was supported in part by fellowships from the Heed Ophthalmic Foundation, Cleveland, Ohio, and Ronald G. Michels, Baltimore, Md (both to Dr Scott).

Reprints: Timothy G. Murray, MD, Bascom Palmer Eye Institute, 900 NW 17th St, Miami, FL 33136.

From the Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Fla.

REFERENCES

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1. Wilkes SR, Robertson DM, Kurland LT, Campbell RJ. Incidence of uveal malignant melanoma in the resident population of Rochester and Olmsted County, Minnesota. Am J Ophthalmol. 1979;87:639-641. ISI | PUBMED 2. Scotto J, Faumeni JF, Lee JAH. Melanomas of the eye and other noncutaneous sites: epidemiology aspects. J Natl Cancer Inst. 1976;56:489-491. 3. Cutler SJ, ed, Young JL, ed. Third national cancer survey incidence data. Natl Cancer Inst Monogr. 1975;41:1-454. 4. Barr CC, McLean IW, Zimmerman LE. Uveal melanoma in children and adolescents. Arch Ophthalmol. 1981;99:2133-2136. FREE FULL TEXT 5. Affeldt JC, Minckler DS, Azen SP, Yeh L. Prognosis in uveal melanoma with extrascleral extension. Arch Ophthalmol. 1980;98:1975-1979. FREE FULL TEXT 6. McLean IW, Foster WD, Zimmerman LE. Prognostic factors in small malignant melanomas of the choroid and ciliary body. Arch Ophthalmol. 1977;95:48-58. FREE FULL TEXT 7. Shammas HF, Blodi FC. Orbital extension of choroidal and ciliary body melanomas. Arch Ophthalmol. 1977;95:2002-2005. FREE FULL TEXT 8. Jensen OA. Malignant melanomas of the human uvea: recent follow-up of cases in Denmark, 1943-1952. Acta Ophthalmol (Copenh). 1970;48:1113-1128. 9. Starr HJ, Zimmerman LE. Extrascleral extension and orbital recurrence of malignant melanomas of the choroid and ciliary body. Int Ophthalmol Clin. 1962;2:369-385. FULL TEXT 10. Shields JA, Shields CL. Current management of posterior uveal melanoma. Mayo Clin Proc. 1993;68:1196-1200. ISI | PUBMED 11. Hosten N, Bornfeld N, Wassmuth R, et al. Uveal melanoma: detection of extraocular growth with MR imaging and US. Radiology. 1997;202:61-67. FREE FULL TEXT 12. De Keizer RJW, Vielvoye GJ, De Wolff-Rouendaal D. CT-scan and intraocular tumours: detection and assessment of size and extrascleral growth of uveal melanomas. Doc Ophthalmol. 1986;61:285-294. FULL TEXT | ISI | PUBMED 13. Lemay M, Roxburgh STD, Lee WR. The role of ultrasound in the investigation and management of suspected ocular melanomas. Doc Ophthalmol Proc Ser. 1981;29:85-91. 14. Char DH, Stone RD, Irvine AR, et al. Diagnostic modalities in choroidal melanoma. Am J Ophthalmol. 1980;89:223-230. ISI | PUBMED 15. Serop SG, Verbraeken H, Hanssens M. The value of medical imaging techniques in the diagnosis of extra-ocular extension of malignant melanoma of the choroid: a case report. Bull Soc Belge Ophtalmol. 1993;248:53-58. PUBMED 16. Martin JA, Robertson DM. Extrascleral extension of choroidal melanoma diagnosed by ultrasound. Ophthalmology. 1983;90:1554-1559. ISI | PUBMED

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