Quantitative Biomarkers Derived from a Novel, Contrast-Free Ultrasound, High-Definition Microvessel Imaging for Differentiating Choroidal Tumors.

Simple Summary: Accurate diagnosis of early-stage choroidal melanoma, the most commonly occurring malignancy of the eye, is extremely important yet highly challenging. Unfortunately, due to challenges in obtaining adequate sampling and the risk of vision loss, intraocular melanoma remains largely a clinical diagnosis, which can be subjective. Most of the existing tools and diagnostic methods lack definitive discriminative features, leading to uncertainties in clinical diagnoses. In this work, we present and evaluate a novel, contrast-free ultrasound-based method for quantitative assessment of microvascular characteristics of choroidal tumors, aiming at distinguishing malignant lesions based on the complex and irregular microvessel formations within them. Using this method, we visualize intratumoral microvascular networks, estimate their morphological features using objective quantitative metrics, and perform statistical analyses demonstrating differences between lesions based on their malignancy status. The results of this preliminary study show promise for further assessment of the method as a complementary diagnostic tool for ocular tumors. Angiogenesis has an essential role in the de novo evolution of choroidal melanoma as well as choroidal nevus transformation into melanoma. Differentiating early-stage melanoma from nevus is of high clinical importance; thus, imaging techniques that provide objective information regarding tumor microvasculature structures could aid accurate early detection. Herein, we investigated the feasibility of quantitative high-definition microvessel imaging (qHDMI) for differentiation of choroidal tumors in humans. This new ultrasound-based technique encompasses a series of morphological filtering and vessel enhancement techniques, enabling the visualization of tumor microvessels as small as 150 microns and extracting vessel morphological features as new tumor biomarkers. Distributional differences between the malignant melanomas and benign nevi were tested on 37 patients with choroidal tumors using a non-parametric Wilcoxon rank-sum test, and statistical significance was declared for biomarkers with p-values < 0.05. The ocular oncology diagnosis was choroidal melanoma (malignant) in 21 and choroidal nevus (benign) in 15 patients. The mean thickness of benign and malignant masses was 1.70 ± 0.40 mm and 3.81 ± 2.63 mm, respectively. Six HDMI biomarkers, including number of vessel segments (p = 0.003), number of branch points (p = 0.003), vessel density (p = 0.03), maximum tortuosity (p = 0.001), microvessel fractal dimension (p = 0.002), and maximum diameter (p = 0.003) exhibited significant distributional differences between the two groups. Contrast-free HDMI provided noninvasive imaging and quantification of microvessels of choroidal tumors. The results of this pilot study indicate the potential use of qHDMI as a complementary tool for characterization of small ocular tumors and early detection of choroidal melanoma. [ABSTRACT FROM AUTHOR]