Variability of standardized echographic ultrasound using 10 mHz and high-resolution 20 mHz B scan in measuring intraocular melanoma.

BACKGROUND

The purpose of this study was to evaluate the applicability and variability of echographic imaging using 10 mHz and high-resolution 20 mHz B scanning for measurement of intraocular tumors.

METHODS

This prospective consecutive study comprises 27 eyes in 27 patients with uveal melanoma. Each patient was examined by three experienced examiners independently on three occasions within a two-week time frame in a blinded manner. The height of the lesion was measured by all examiners using the 10 mHz B, 20 mHz B, and 8 mHz A scan probes. Additionally, basal diameter was examined using the 10 and 20 mHz B scan.

RESULTS

Tumor height measurements for all examiners using the standardized A scan tended to be higher than for both B scan measurements. Statistical analysis revealed significant differences in tumor height between B and A scan measurements. No difference in tumor height was found between the two B scan techniques (P = 0.239). Basal tumor diameter measurements revealed significant differences between 10 mHz and 20 mHz B scans (P < 0.001 and P = 0.001, respectively). For the 10 mHz B scan, basal diameter results tended to be larger than for the 20 mHz B scan. No difference was found for interobserver variation in all A scan and B scan examinations. The mean standard deviation of the difference in tumor height measurements between the examiners was ±0.24 mm for the 8 mHz A scan, ±0.46 mm for the 10 mHz B scan, and ±0.42 mm for the 20 mHz B scan. Both the 10 mHz and more precise 20 mHz B scan evaluations underestimated tumor height.

CONCLUSION

The 20 mHz ultrasound probe, despite its theoretically higher resolution, is not able to replace A scan measurements of tumor height.