Measurement of melanocytic choroidal lesions: ultrasound versus ultrawide-field fundus imaging system

Objectives: The aim of this study was to establish the concordance between conventional 20 Mhz ultrasonography and an ultrawide-field (UWF) imaging system (Optos® California) in the measurement of basal diameters of melanocytic choroidal tumors. Methods: A retrospective study comparing diagnostic tests was conducted in patients with untreated melanocytic choroidal lesions (either nevus or melanoma) who had undergone both UWF imaging and ultrasonography. Only cases with a clear visualization of tumor borders in both imaging modalities were included. Longitudinal and transversal base diameters of the melanocytic tumors were measured by 20 MHz US (one observer) and UWF fundus photography (two observers). Interobserver agreement was assessed for UWF imaging first to validate the technique. Then, UWF imaging measurements were compared with 20 MHz US results. Results: In total, 106 patient images were reviewed, of which 61 were excluded due to unclear visualization of tumor margins. We found excellent concordance (from ICC and defined Bland–Altman plots) for interobserver and inter-technique agreement in estimating basal diameters when using pseudocolor composite and red laser images by comparing them with 20 MHz US results. Conclusions: UWF fundus imaging, when complete visualization of the tumor margins is possible, could be as reliable as ultrasonography in the measurement of the basal diameters of choroidal melanocytic tumors.