FlowOCT: Wavelet Flow Matching for OCT-to-OCTA Translation

Abstract

Retinal angiography provides critical vascular information, yet optical coherence tomography angiography (OCTA) acquisition remains slower and less accessible than conventional structural OCT. A key open question is: how angiographic signals can be recovered? To address the issues of artifacts and structural blurring in existing generative methods, we propose a wavelet flow matching-based model, FlowOCT. This method operates directly on OCT wavelet coefficients, learning frequency-specific velocity fields to map them to the OCTA wavelet distribution. To ensure anatomical accuracy of the vasculature, we introduce constraints such as depth-wise contrastive alignment and two-dimensional projection consistency. Given the sparse nature of vascular signals in OCTA data, a structure-focused loss function and corresponding evaluation metrics are designed. Experiment results show that FlowOCT outperforms existing methods in terms of both image quality and perceptual similarity. Downstream diagnostic tasks further validate its superior authenticity and generalization capability. Code is available at https://github.com/cnu-medilab/FlowOCT.