Evaluation of 20-MHz high-frequency ultrasonography for the diagnosis of choroidal nevi.

Purpose: Evaluate short-term intraoperator reproducibility of ultrasonographic measurements of choroidal nevi using 10- and 20-MHz probes, and the efficacy of the high-frequency probes for the diagnosis of choroidal nevi.

Methods: Diameters and thicknesses of choroidal nevi were measured using a 10-MHz probe and a high-frequency long focal length 20-MHz probe (Quantel Medical™). The first part of the study evaluated intraoperator reproducibility of measurements of choroidal nevi with 10- and 20-MHz probes and the second part of the study allowed the comparisons of the measurements of largest tumor diameter (LDT) of choroidal nevi of 40 patients between the 10- and 20-MHz probes. The two-way random average agreement intraclass correlation coefficients (ICC), Bland-Altman plot, and a paired t test were used.

Results: The intraoperator reproducibility of choroidal nevi measurements with 10- and 20-MHz probes was excellent (ICC > 0.9, n = 20). Four flat nevi, not detectable at 10 MHz, could be located with the high-frequency probe (p = 0.12). There was no significant difference in thickness or LTD measurements between the 10- and 20-MHz probes (n = 31). Both techniques showed an excellent agreement (ICC > 0.8) for thickness and LTD measurements. All the choroidal nevi that were not measurable with the 10-MHz probe (n = 7) were measured with the 20-MHz probe.

Conclusion: The high-frequency 20-MHz probe allows additional detection and measurements of flat choroidal nevi. When detectable, the ultrasonographic measurements of thickness and diameter of choroidal nevi are similar with both the 10- and the 20-MHz probes.