In the setting of cirrhotic liver, the diagnosis of hepatocellular carcinoma (HCC) is straightforward when typical imaging findings consisting of arterial hypervascularity followed by portal-venous washout are present in nodules larger than 1 cm. However, due to the complexity of hepatocarcinogenesis, not all HCCs present with typical vascular behaviour. Atypical forms such as hypervascular HCC without washout, isovascular or even hypovascular HCC can pose diagnostic dilemmas. In such cases, it is important to consider also the appearance of the nodules on diffusion-weighted imaging and hepatobiliary phase. In this regard, diffusion restriction and hypointensity on hepatobiliary phase are suggestive of malignancy. If both findings are present in hypervascular lesion without washout, or even in iso- or hypovascular lesion in cirrhotic liver, HCC should be considered. Moreover, other ancillary imaging findings such as the presence of the capsule, fat content, signal intensity on T2-weighted image favour the diagnosis of HCC. Another form of atypical HCCs are lesions which show hyperintensity on hepatobiliary phase. Therefore, the aim of the present study was to provide an overview of HCCs with atypical enhancement pattern, and focus on their magnetic resonance imaging (MRI) features.

中文翻译：

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非典型增强型肝细胞癌概述：磁共振成像谱与病理相关性


在肝硬化的情况下，当大于 1 cm 的结节中出现典型的影像学表现（包括动脉血管丰富和门静脉冲刷）时，肝细胞癌 (HCC) 的诊断就很简单。然而，由于肝癌发生的复杂性，并非所有的肝癌都表现出典型的血管行为。非典型形式，例如没有清除的富血管性肝癌、等血管性肝癌甚至乏血管性肝癌，可能会造成诊断困境。在这种情况下，重要的是还要考虑扩散加权成像和肝胆相上结节的出现。在这方面，肝胆相的扩散受限和低信号提示恶性肿瘤。如果这两种表现均出现在未清除的富血管病变中，或者甚至出现在肝硬化肝的等血管或缺血管病变中，则应考虑 HCC。此外，其他辅助影像学检查结果，如胶囊的存在、脂肪含量、T2 加权图像上的信号强度，有利于 HCC 的诊断。另一种形式的非典型 HCC 是肝胆相显示高信号的病变。因此，本研究的目的是概述具有非典型增强模式的 HCC，并重点关注其磁共振成像 (MRI) 特征。