用学习方法修正简化物理模型误差,提升超声CT成像精度与鲁棒性。
Learned Correction Methods for Ultrasound Computed Tomography Imaging Using Simplified Physics Models
- 在测量域和图像域分别学习补偿线性化波传播的误差。
- 测量域校正使肿瘤检测任务表现最佳,图像误差最低。
- 联合两种校正方式最优,但任务性能略降,适合高保真成像需求。
超声计算机断层扫描(USCT)是一种新兴的乳腺成像技术。基于精确波动物理的重建方法可生成高分辨率、定量的声学属性图像,但计算成本高昂。使用简化线性模型可降低计算开销,但牺牲了准确性。本文系统比较了多种利用简化线性模型进行USCT重建的学习方法,重点研究在测量域和图像域中对线性化波传播误差的补偿策略。在四个基于解剖真实数值幻影的虚拟成像研究中,评估了数据驱动与模型驱动方法的性能。图像质量通过相对均方根误差(RRMSE)、结构相似性指数(SSIM)以及肿瘤检测的任务评估进行衡量。结果显示,测量域校正产生的图像视觉伪影较少,任务性能显著更优;图像域校正虽对训练数据有较强偏差,导致幻觉现象,但对测量噪声更具鲁棒性。结合两种校正方式在RRMSE和SSIM上表现最佳,但任务性能有所下降。本研究系统评估了融合近似物理模型的学习除重建方法,证明了引入物理先验的重要性,并表明测量域校正相比图像域校正具有更好的任务性能与分布外泛化能力。
原文摘要 · Abstract (English)
Ultrasound computed tomography (USCT) is an emerging modality for breast imaging. Image reconstruction methods that incorporate accurate wave physics produce high resolution quantitative images of acoustic properties but are computationally expensive. The use of a simplified linear model in reconstruction reduces computational expense at the cost of reduced accuracy. This work aims to systematically compare different learning approaches for USCT reconstruction utilizing simplified linear models. This work considered various learning approaches to compensate for errors stemming from a linearized wave propagation model: correction in the data and image domains. The resulting image reconstruction methods are systematically assessed, alongside data-driven and model-based methods, in four virtual imaging studies utilizing anatomically realistic numerical phantoms. Image quality was assessed utilizing relative root mean square error (RRMSE), structural similarity index measure (SSIM), and a task-based assessment for tumor detection. Correction in the measurement domain resulted in images with minor visual artifacts and highly accurate task performance. Correction in the image domain demonstrated a heavy bias on training data, resulting in hallucinations, but greater robustness to measurement noise. Combining both forms of correction performed best in terms of RRMSE and SSIM, at the cost of task performance. This work systematically assessed learned reconstruction methods incorporating an approximated physical model for USCT imaging. Results demonstrated the importance of incorporating physics, compared to data-driven methods. Learning a correction in the data domain led to better task performance and robust out-of-distribution generalization compared to correction in the image domain.
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