A multimodal instruction dataset and benchmark for ultrasound understanding.

While promising in general medical imaging like CT and MRI, large vision-language models (LVLMs) struggle in ultrasonography due to a profound visual-semantic gap and a scarcity of instruction-following data. Translating the inherently noisy and operator-dependent ultrasound images into precise clinical descriptions remains a complex reasoning challenge for general-purpose vision-language models. To bridge this gap, we develop SonoInstruct, a large-scale multi-source dataset curated from over 30 ultrasound sources, providing 110k+ images and 260k+ instruction-following instances. For comprehensive evaluation, we establish SonoBench, a multi-dimensional benchmark suite that assesses eight core capabilities, including performance in out-of-distribution (OOD) scenarios. To verify the effectiveness of our dataset, we fine-tuned Qwen3-VL-2B-Instruct on SonoInstruct, yielding Qwen3-VL-2B-Sono, which achieves a 30.3% relative improvement over the base model on the SonoBench benchmark. These results demonstrate that SonoInstruct effectively bridges the gap between noisy sonographic images and clinical reasoning, establishing a robust foundation for AI-driven ultrasound applications.