光子计数CT（photon-counting CT，PCCT）是近年来CT成像领域的重大技术突破，采用新型半导体探测器直接检测和计数X射线光子，实现高精度的多能量信息采集。相比传统的能量积分探测器CT（energy-integrating detector CT，EID-CT），PCCT具备显著的技术优势，包括超高空间分辨率（最小探测器像素尺寸0.15×0.18 mm）、更优的对比噪声比（对比噪声比提升15%～45%）以及更低的辐射剂量（较EID-CT辐射剂量降低20%～90%）。同时，PCCT可生成标准化CT值图像，提供稳定可靠的多次测量数据，有利于组织成分定量。PCCT还能直接获取多个能量仓数据，实现真实的多能量成像。在肝脏疾病诊断中，PCCT在平扫状态下可定量分析肝脏的脂肪和铁含量，其70 keV标准化CT值与MRI-质子密度脂肪分数高度相关；在增强扫描中，PCCT显著提高了乏血供肿瘤的检出率和边界显示，并可通过碘图进行可靠的定量强化评估。此外，PCCT可在超低剂量下一站式获得既可用于肝脏病变微循环灌注血流动力学功能数据测量，又同时满足临床诊断及术前规划需求的多期单能量CT增强图像，而不需要额外增加对比剂及再次补充三期常规增强扫描，从而实现了低辐射剂量和低对比剂的双低优势，有助于其在临床评估肝脏病变方面的应用。本文将聚焦PCCT在肝脏弥漫性与肿瘤性疾病诊治中的应用进展，旨在为PCCT在肝病精准诊疗中的推广应用提供理论依据和实践指导。

Photon-counting computed tomography (PCCT) represents a significant technological breakthrough in the field of CT imaging in recent years. This innovative technology utilizes novel semiconductor detectors to directly detect and count individual X-ray photons, enabling high-precision multi-energy data acquisition. Compared with traditional energy-integrating detector CT (EID-CT), PCCT offers significant technical advantages, including ultra-high spatial resolution (with a minimum detector pixel size of 0.15×0.18 mm), improved contrast-to-noise ratio (CNR increase of 15%-45%), and substantial radiation dose reduction (20%-90%). Moreover, PCCT can generate standardized CT value images, ensu-ring stable and reproducible quantitative measurements suitable for tissue composition analysis. With its ability to acquire data across multiple energy bins, PCCT achieves true multi-energy spectral imaging. In liver diseases, PCCT enables non-enhanced quantification of hepatic fat and iron content, with 70 keV standardized CT values showing a strong correlation with MRI-derived proton density fat fraction (PDFF). During contrast-enhanced scans, PCCT significantly improves the detection rate and lesion margin delineation of hypovascular tumors and allows accurate enhancement quantification through iodine maps. Additionally, PCCT enables ultra-low-dose, one-stop imaging that simultaneously provides functional hemodynamic parameters of hepatic microcirculation and high-quality multiphasic monoenergetic CT images for clinical diagnosis and preoperative planning—without the need for additional contrast medium or supplementary triphasic scans. This dual benefit of low radiation and contrast dose supports its clinical utility in liver imaging. This review focuses on recent advances in the application of PCCT in the diagnosis and treatment of diffuse and neoplastic liver diseases, aiming to provide theoretical foundations and practical insights for its broader implementation in precision hepatology.