Ultrasonographic measurement of uveal melanoma thickness: interobserver variability

We retrospectively reviewed ultrasonographic data on 32 uveal melanomas that had been studied both at a referral institution and at our centre within a six-week period. Generally there were good correlations between ultrasonographic measurements of tumour thickness. The mean absolute difference in ultrasound measurements of tumour thickness was 0.64 mm (range 0-2.2 mm); the mean tumour thickness was 5.2 mm (range 3.5-10.2 mm). Tumour diameter, location, the relative ultrasonographic experience with uveal melanoma, type of equipment, and tumour thickness all affected the interobserver variation of measurement.