Spatial-temporal Hierarchical Reinforcement Learning for Interpretable Pathology Image Super-Resolution

TL;DR

This paper introduces STAR-RL, a hierarchical reinforcement learning framework for pathology image super-resolution that improves interpretability, avoids sub-optimal recovery, and enhances tumor diagnosis accuracy.

Contribution

It presents the first hierarchical RL approach reformulating super-resolution as an interpretable, patch-level decision process with spatial-temporal management, improving recovery quality and diagnosis.

Findings

STAR-RL outperforms existing methods on degraded medical images.

It significantly improves tumor diagnosis accuracy.

The approach generalizes well across various degradation types.

Abstract

Pathology image are essential for accurately interpreting lesion cells in cytopathology screening, but acquiring high-resolution digital slides requires specialized equipment and long scanning times. Though super-resolution (SR) techniques can alleviate this problem, existing deep learning models recover pathology image in a black-box manner, which can lead to untruthful biological details and misdiagnosis. Additionally, current methods allocate the same computational resources to recover each pixel of pathology image, leading to the sub-optimal recovery issue due to the large variation of pathology image. In this paper, we propose the first hierarchical reinforcement learning framework named Spatial-Temporal hierARchical Reinforcement Learning (STAR-RL), mainly for addressing the aforementioned issues in pathology image super-resolution problem. We reformulate the SR problem as a Markov decision process of interpretable operations and adopt the hierarchical recovery mechanism in patch level, to avoid sub-optimal recovery. Specifically, the higher-level spatial manager is proposed to pick out the most corrupted patch for the lower-level patch worker. Moreover, the higher-level temporal manager is advanced to evaluate the selected patch and determine whether the optimization should be stopped earlier, thereby avoiding the over-processed problem. Under the guidance of spatial-temporal managers, the lower-level patch worker processes the selected patch with pixel-wise interpretable actions at each time step. Experimental results on medical images degraded by different kernels show the effectiveness of STAR-RL. Furthermore, STAR-RL validates the promotion in tumor diagnosis with a large margin and shows generalizability under various degradations. The source code is available at https://github.com/CUHK-AIM-Group/STAR-RL.