Fine-grained Adaptive Visual Prompt for Generative Medical Visual Question Answering

Medical Visual Question Answering (MedVQA) serves as an automated medical assistant, capable of answering patient queries and aiding physician diagnoses based on medical images and questions. Recent advancements have shown that incorporating Large Language Models (LLMs) into Med-VQA tasks significantly enhances the capability for answer generation. However, for tasks requiring fine-grained organlevel precise localization, relying solely on language prompts struggles to accurately locate relevant regions within medical images due to substantial background noise. To address this challenge, we explore the use of visual prompts in Med-VQA tasks for the first time and propose fine-grained adaptive visual prompts to enhance generative MedVQA. Specifically, we introduce an Adaptive Visual Prompt Creator that adaptively generates region-level visual prompts based on image characteristics of various organs, providing fine-grained references for LLMs during answer retrieval and generation from the medical domain, thereby improving the model's precise cross-modal localization capabilities on original images. Furthermore, we incorporate a Hierarchical Answer Generator with Parameter-Efficient Fine-Tuning (PEFT) techniques, significantly enhancing the model's understanding of spatial and contextual information with minimal parameter increase, promoting the alignment of representation learning with the medical space. Extensive experiments on VQA-RAD, SLAKE, and DME datasets validate the effectiveness of our proposed method, demonstrating its potential in generative MedVQA.