Abstract
Purpose :
Differentiation between choroidal nevi and small choroidal melanomas can be challenging and relies largely on clinical assessment and sequential examinations. This study evaluates the utility of optical coherence tomography angiography (OCTA) to detect differences between the vasculature of choroidal melanomas and nevi, and to assess how vascular visualization differs between spectral domain (SD) and swept source (SS) OCTA.
Methods :
Patients seen at the New England Eye Center diagnosed with a choroidal nevus or a treatment-naïve choroidal melanoma were recruited for this study. Lesions were imaged with ultra-wide field fundus photography, SD-OCTA (6x6mm scan) and SS-OCTA (12x12mm scan). Ultrasonography (US) was used to determine lesion depth. Lesions were graded for general characteristics including basal diameter, and distance from the fovea and optic nerve. High-risk clinical features including presence of overlying fluid, orange pigment, overlying drusen, shaggy photoreceptors, break in Bruch’s membrane, acoustic hollowness and depth were assessed for each lesion. OCTA images were analyzed for the presence of visible vasculature within the lesion, as well as increased or decreased choriocapillaris (CC) flow signal over the lesion relative to the surrounding, unaffected CC.
Results :
Twenty-two nevi and five treatment naïve choroidal melanomas were imaged. Of 22 nevi scanned, 12 (54%) were not elevated (choroidal freckles) and 10 (46%) were raised on US; all melanomas were raised. Nine of ten (90%) raised nevi showed decreased CC flow. In contrast, 10 of 12 (83%) choroidal freckles showed increased CC flow. Logistic regression analysis showed a significant association between decreased CC flow over a lesion and an increasing number of high-risk clinical features (p = 0.0075). All melanomas and 60% of raised nevi had internal vascular structures that were identifiable on SS-OCTA, but their visualization was limited on SD-OCTA .
Conclusions :
SS-OCTA is superior to SD-OCTA for identification of internal vascular structures in raised nevi and choroidal melanomas, both imaging modalities are equivalent for assessment of choroidal freckles. Loss of CC flow over a lesion is significantly associated with an increasing number of high-risk clinical features, highlighting its prospect as a biomarker to assess the malignant potential of choroidal nevi.
This is a 2020 Imaging in the Eye Conference abstract.