Ultrasonographic, three‐dimensional scanning for determination of intraocular tumor volume

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Abstract
Important prognostic information may be gained from knowing the volume of intraocular tumors, such as choroidal melanomas. To measure such volume, we developed an ultrasonographic 3-D scanning system, which operates by an axial, back and forth, half-turn rotation of a commercial sector scanning transducer, applied directly onto a closed eyelid. Control of movement, data acquisition, and image analysis are accomplished by means of a microcomputer and application-specific software. The elapsed time for scanning and digitizing 11 cross-sectional images across a human eyeball, is 4 sec. Outlines of specific structures are traced manually. The system was tested through repeated, in vitro measurements of known volumes of meat; the mean variation coefficient of these measurements was 2.8%. While accurate estimates were obtained on volumes between 0.01-0.25 ml, these are linearly dependent on gain setting. A patient with a choroidal melanoma was scanned repetitively. The procedures of scanning and tracing contributed about equally to the total variance. This method of scanning allows repeatable, reliable, and easily generated measurements of a tumor's volume and, thus, has great potential for use in the diagnosis and treatment of malignant, intraocular tumors.