目的：评价单源双能CT平扫能谱曲线鉴别不典型小肝癌与异常灌注灶的价值。方法：回顾性分析行能谱CT三期增强扫描、经病理证实或临床诊断为小肝癌（SHCC）及动脉期异常灌注（HPD）的患者32例，共35个病灶（SHCC 16个，HPD 19个）。入组不典型SHCC的CT表现为动脉期明显强化，门脉期、平衡期近等密度，呈“快进不出”。测量平扫及动脉期SHCC、HPD及相应背景肝的混合能量CT值、单能量为40 keV及140 keV的CT值，计算能谱曲线斜率。使用组内相关系数（ICC）分析两观察者测量结果一致性。使用配对样本t检验分析平扫时SHCC与背景肝、HPD与背景肝的混合能量CT值及能谱曲线斜率的差异；采用独立样本t检验分析平扫及动脉期SHCC与HPD的混合能量CT值、能谱曲线斜率的差异。结果：两观察者测量一致性良好（ICC值均>0.75）。动脉期SHCC与HPD混合能量CT值、能谱曲线斜率差异无统计学意义。平扫时，SHCC与背景肝、HPD与背景肝、SHCC与HPD混合能量CT值差异无统计学意义；而SHCC与背景肝、SHCC与HPD能谱曲线斜率差异有统计学意义（（0.19±0.12）与（0.00±0.12），（0.19±0.12）与（0.04±0.17），P<0.05），HPD与背景肝能谱曲线斜率差异无统计学意义。结论：单源双能CT平扫能谱曲线为鉴别常规CT三期强化难以区分的不典型SHCC与HPD，提供了全新的简便易行、安全可靠的检测手段。

Objective: To assess the spectral curve from noncontrast CT imaging in differentiating atypical small hepatocellular carcinnoma(SHCC) from hepatic perfusion disorders(HPD) with single-source dual-energy CT. Methods: Thirty-two histopathologically or clinically proven SHCC and HPD patients, who underwent spectral CT enhancement scanning using spectrum imaging modality(GSI) were retrospectively enrolled with 35 lesions, including 16 SHCC and 19 HPD. The atypical SHCCs were hyperattenuating in arterial phase and nearly isodense in portal venous and equilibrium phases. On polychromatic images(QC images), CT value(CT(QC) value) of SHCC, HPD and appropriate background were measured in noncontrast and arterial phase, and then on monochromatic(40 keV and 140 keV) images, thus the slope of the energy spectrum was calculated. The data from two observers were analyzed with intra-class correlation coefficients(ICC） to assess inter-observer agreement. The differences of CT(QC) value and spectral curve slope between SHCC and liver background, HPD and appropriate background were compared by paired t-test. The differences of CT(QC) value and spectral curve slope between SHCC and HPD on noncontrast and arterial phase images were compared by independent t-test. Results: The inter-observer agreements were good(ICC>0.75). In arterial phase, there were no differences of CT(QC) value or spectral curve slope between SHCC and HPD. On unenhanced imaging, there were no differences of CT(QC) value between SHCC and background, HPD and background, or SHCC and HPD. However, there were significant differences of spectral curve slope between SHCC and background, SHCC and HPD((0.19±0.12) vs (0.00±0.12), (0.19±0.12) vs (0.04±0.17), P<0.05). There was no difference of spectral curve slope between HPD and background. Conclusion: The single-source dual-energy CT noncontrast imaging provides a new convenient, safe and reliable method on the basis of spectral curve features to identify atypical SHCC and HPD which were difficult to differentiate on three phase enhanced imaging by conventional CT.