From the Departments of Clinical Radiology (N.F., A.N., K. Ishigami, Y.U., D.K., K.M., K. Ishimatsu, H.H.), Advanced Imaging and Interventional Radiology (Y.A.), and Molecular Imaging and Diagnosis (T.N.), Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Radiographics. 2020 Jan-Feb;40(1):72-94. doi: 10.1148/rg.2020190037. Epub 2019 Dec 13.
Gadoxetic acid, a hepatobiliary-specific contrast medium used for MRI, is becoming increasingly important in the detection and characterization of hepatic mass lesions. This medium is taken up by functioning hepatocytes, and the liver parenchyma is strongly enhanced in the hepatobiliary phase (HBP), during which hepatic mass lesions without functioning hepatocytes commonly show hypointensity. However, some hepatic mass lesions show hyperintensity in the HBP. Focal nodular hyperplasia (FNH) and FNH-like lesions show hyperintensity in the HBP owing to the uptake of gadoxetic acid by hyperplastic normal hepatocytes. The tumor cells of some types of hepatocellular adenoma (eg, β-catenin-activated type, inflammatory type) and hepatocellular carcinoma (eg, green hepatoma) can show uptake of gadoxetic acid. Retention of gadoxetic acid in the extracellular space can cause hyperintensity of fibrotic tumors or hemangiomas during the HBP owing to the extracellular contrast agent characteristics of gadoxetic acid. During the HBP, peritumoral retention is observed in some tumors, such as hepatocellular carcinomas, gastrointestinal stromal tumors, and neuroendocrine tumors. Gadoxetic acid is excreted into the bile; therefore, biliary tract enhancement can be observed in the cystic components of intraductal papillary neoplasms of the bile duct. Intratumoral bile ducts can be observed in malignant lymphomas. Knowledge of these specific mechanisms, which can cause hyperintensity during the HBP depending on the pathologic or molecular background, is important not only for precise imaging-based diagnoses but also for understanding the pathogenesis of hepatic mass lesions. RSNA, 2019 See discussion on this article by Lalwani.
钆塞酸，一种用于 MRI 的肝胆特异性对比剂，在检测和描述肝脏肿块病变方面变得越来越重要。这种造影剂被有功能的肝细胞摄取，在肝胆期（HBP）时肝脏实质得到强烈增强，而无功能肝细胞的肝脏肿块病变通常显示为低信号。然而，一些肝脏肿块病变在 HBP 中显示为高信号。局灶性结节增生（FNH）和 FNH 样病变在 HBP 中显示高信号，是由于增生的正常肝细胞摄取了钆塞酸。某些类型的肝细胞腺瘤（如β-连环蛋白激活型、炎症型）和肝细胞癌（如绿色肝癌）的肿瘤细胞可以摄取钆塞酸。由于钆塞酸具有细胞外造影剂的特性，在 HBP 期间，细胞外空间的钆塞酸滞留可导致纤维瘤或血管瘤呈高信号。在 HBP 期间，一些肿瘤（如肝细胞癌、胃肠道间质瘤和神经内分泌肿瘤）可见肿瘤周围组织的滞留。钆塞酸被排泄到胆汁中；因此，胆管内乳头状肿瘤的囊状成分可观察到胆管内增强。恶性淋巴瘤可观察到肿瘤内胆管。了解这些根据病理或分子背景导致 HBP 中高信号的特定机制，不仅对精确的基于成像的诊断很重要，而且对了解肝脏肿块病变的发病机制也很重要。RSNA，2019 请参阅 Lalwani 对此文的讨论。
