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TM Viechnicki, JP S Garcia, RB Rosen, PT Finger; Three Dimensional Ultrasound (3DUS) Imaging for Optic Nerve Melanocytoma . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1156.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the role of 3D ultrasound imaging for peripapillary melanocytomas. Methods: Four patients with clinically diagnosed melanocytomas were imaged using a 3D B-scan ultrasound system (OTI, Canada). Tumor height and basal dimensions were determined by interactive analysis of the 3D reconstruction. Tumor volume and topographic characteristics were determined as follows: 3 points on the tumor periphery were chosen to define a plane. Then a proprietary software program (courtesy of Shane Dunne, PhD-OTI) computed the central axis of the tumor as the line perpendicular to this plane passing through the center of the three points. The posterior border of the tumor was modeled as a hemispherical surface. The program displayed the entire series of para-sagittal slices one after the other in an animated sequence. The diameter and precise centering of this model curve was adjusted by the ultrasonographer. The anterior surface of the tumors was automatically determined by the program (based on changes in acoustic impedance). Distances between the anterior and posterior borders were computed at all points, and the lateral margins were located in each image wherever the distance dropped to near zero. Results: Transverse, longitudinal, coronal, volumetric and topographic studies were performed on four melanocytomas. Tumor apex (height) ranged from 0.7 - 1.8mm. Minimum basal dimensions ranged from 1.7 - 3.1mm. Maximum basal dimensions ranged from 2.7 - 4.6mm. Tumor volumes ranged from 1.1 - 9.0mm3. Internal reflectivity was low - medium for one tumor, and medium - high for 3 tumors. Coronal sections of all 4 tumors revealed no intra-neural involvement. Conclusion: Three dimensional ultrasound imaging is a valuable technique for evaluating intraocular tumors. We present the first report of 3D ultrasound imaging of disc melanocytomas. Coronal images, uniquely available by 3D reconstruction, were helpful in evaluating the optic nerve. Automated topographic analysis of tumor dimensions and volume will be useful in quantifying changes in tumor size through time.
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