# Discrepancies between Fundus Photography and Multimodal Imaging in Mapping of Choroidal Tumor Borders

## TL;DR

This study compares how well fundus photography and multimodal imaging map the borders of choroidal tumors, finding that some tumors, especially less pigmented ones, are better assessed with OCT.

## Contribution

The study identifies discrepancies in tumor border mapping using fundus photography versus multimodal imaging, particularly for nonpigmented tumors.

## Key findings

- Unimodal assessments (CFP and SLO) generally agreed well with multimodal assessments (median HD95 <1 mm).
- Nonpigmented and mixed-pigmented tumors showed significantly higher HD95 than pigmented lesions.
- Incorporating EDI-OCT may reduce discrepancies in tumor border mapping.

## Abstract

Accurate choroidal tumor border mapping is required for their management. We compared border mapping accuracy between unimodal assessment (color fundus photography [CFP] or scanning laser ophthalmoscopy [SLO]) against a multimodal assessment (CFP, SLO, and OCT) and identified tumor characteristics that affect performance.

A cross-sectional diagnostic accuracy study.

Sixty-four choroidal lesions (61% nevi, 39% melanomas; median basal diameter 5.65 mm, median thickness 1.85 mm) from 63 patients at tertiary ocular oncology clinics in Victoria, Australia. No separate control group was included.

Two ocular oncologists independently delineated lesion margins on CFP and SLO. Multimodal assessment was established by agreement. Agreement between unimodal and multimodal assessments was quantified using the 95th percentile Hausdorff Distance (HD95).

The HD95 in millimeters between unimodal and multimodal tumor borders. Dice coefficient summary statistics are also provided.

Overall, unimodal CFP and SLO assessments had good agreement with multimodal assessments (median HD95 <1 mm for each grader and device). However, HD95 was >2 mm in 5% (grader 1) and 9% (grader 2) of CFP assessments and in 2% (grader 1) and 3% (grader 2) of SLO assessments. Nonpigmented and mixed-pigmented tumors showed significantly higher HD95 than pigmented lesions for most grader-modality pairs, particularly for grader 1 on CFP and SLO (P < 0.05).

Choroidal tumor margin assessment was accurate on CFP and SLO as compared with a multimodal assessment that included enhanced-depth imaging OCT (EDI-OCT). However, the borders of a subset of tumors, especially those with reduced pigmentation, were inaccurately determined when using fundus photography alone. Incorporating EDI-OCT into choroidal tumor border mapping may reduce these discrepancies.

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