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J. E. Anderson, J. P. S. Garcia, Jr., P. T. Finger; B-Scan Ultrasound Imaging of Choroidal Melanomas: 12MHz versus 20MHz. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2578.
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© ARVO (1962-2015); The Authors (2016-present)
To compare 12MHz and 20MHz B-scan ultrasound imaging in the evaluation of choroidal melanoma.
A retrospective comparative review of 23 examinations on 23 choroidal melanomas evaluated at the Ocular Tumor Service of The New York Eye and Ear Infirmary. Choroidal melanomas were sequentially examined with both the 12MHz and 20MHz B-scan ultrasound imaging (OTI-Scan 1000, Ophthalmic Technologies Inc. [OTI], Toronto, Ontario, Canada). Observations regarding image resolution from both modalities were compared (i.e. the ability to clearly discern the layers of the ocular wall and lesion including retina, choroid, and sclera). Evaluation of internal reflectivity and tumor height were determined utilizing the height-width (H-W) and intensity profiling (IP) methods provided with the system.
All 23 examinations were included in the study. The 12MHz images were found to be more grainy with less clearly defined retinal, choroidal, and scleral interfaces compared to the 20MHz images. Internal reflectivity measured with 12MHz ultrasound was high in 26% (n=6), high to moderate in 22% (n=5), and moderate in 52% (n=12) of examinations; internal reflectivity measured with 20MHz ultrasound was considered high in 9% (n=2), high to moderate in 9% (n=2), moderate in 30% (n=7), moderate to low in 9% (n=2), and low in 43% (n=10) of examinations. Using the H-W and IP methods of tumor height determination, values were comparable with 12MHz (H-W mean: 3.4mm, range: 0.9-12.7) (IP mean: 3.4mm, range: 0.9-12.9) and 20MHz imaging (H-W mean: 3.3mm, range: 0.9-12.6) (IP mean: 3.3mm, range: 0.8-12.7).
Both 20MHz and 12MHz frequency B-scan ultrasonography provided comparable height determinations for choroidal melanoma. B-scans at 20 MHz tended to exhibit lower internal tumor-reflectivity than images generated at 12MHz. However, images generated with the higher frequency 20MHz B-scan probe provided better resolution of the retina, choroid, tumor and sclera.
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