Department of Radiology, Third Affiliated Hospital of Nantong University and Nantong Third People's Hospital, #99 Youth Middle Road, Chongchuan District, Nantong, 226000, Jiangsu, China.
Department of Pathology, Third Affiliated Hospital of Nantong University and Nantong Third People's Hospital, #99 Youth Middle Road, Chongchuan District, Nantong, 226000, Jiangsu, China.
Abdom Radiol (NY). 2024 Nov;49(11):3834-3846. doi: 10.1007/s00261-024-04259-y. Epub 2024 Jun 24.
This study aimed to evaluate the enhancement patterns in the hepatobiliary phase (HBP) and pathological features of nodule-in-nodule-type hepatocellular carcinoma (NIN-HCC) patients.
In this single-institution retrospective study, 27 consecutive cirrhosis patients with 29 histologically confirmed NIN-HCCs who underwent preoperative examination via Gd-EOB-DTPA-enhanced MRI were enrolled from January 2016 to September 2023. Two blinded radiologists assessed the imaging features of both the inner and outer nodules in NIN-HCCs to reach a consensus on the Liver Imaging Reporting & Data System (LI-RADS) categories of the lesions. Based on the different enhancement patterns of the inner and outer nodules in the HBP, NIN-HCCs were classified into different groups and further divided into different types. Imaging features and LI-RADS categories were subsequently compared among the groups. Pathological findings for NIN-HCCs were also evaluated.
Among 29 NIN-HCCs, all inner nodules showed hypervascularity, with a maximum diameter of 13.2 ± 5.5 mm; 51.7% (15/29) showed "wash-in with washout" enhancement; and 48.3% (14/29) showed "wash-in without washout" enhancement. All outer nodules showed hypovascularity, with a maximum diameter of 25.6 ± 7.3 mm, and 51.9% (14/29) showed a washout appearance on PVP. Among all the lesions, the maximum diameter was 27.5 ± 6.8 mm; 12 (41.4%) lesions were LR-4, and 17 (58.6%) lesions were LR-5. NIN-HCCs were classified into hypointense (62.1%, 18/29) and isointense (37.9%, 11/29) groups based on the signal intensity of the outer nodules in the HBP. In the hypointense group, 2 (6.9%) of the inner nodules were hypointense (type A), 11 (37.9%) were isointense (type B), and 5 (17.2%) were hyperintense (type C) compared to the background hypointense outer nodules. In the isointense group, 9 (31.0%) of the inner nodules were hypointense (type D), 2 (6.9%) were isointense (type E), and no (0%) was hyperintense (type F) compared to the background isointense outer nodules. There were no significant differences in the diameter, dynamic enhancement patterns of the inner or outer nodules, or LI-RADS scores of the lesions between the hypointense group and the isointense group (all P > 0.05). Histologically, the inner nodules of NIN-HCCs were mainly composed of moderately differentiated HCC (75.9% 22/29), whereas the outer nodules consisted of either well-differentiated HCC or high-grade dysplastic nodules (HGDNs).
NIN-HCCs exhibit specific MRI findings closely associated with their pathological features. The spectrum of HBP enhancement patterns provides valuable insights into the underlying cell biological mechanisms of these lesions. NIN-HCC subtypes may be used as a morphologic marker in the early stage of multistep hepatocarcinogenesis.
本研究旨在评估结节内结节型肝细胞癌（NIN-HCC）患者肝胆期（HBP）的强化模式和病理特征。
这是一项单中心回顾性研究，纳入了 2016 年 1 月至 2023 年 9 月期间因肝硬化接受钆塞酸二钠增强 MRI 检查并经组织学证实为 29 个 NIN-HCC 的 27 例连续患者。两名盲法放射科医生评估了 NIN-HCC 内外结节的影像学特征，以达成对肝脏影像报告和数据系统（LI-RADS）病变类别的共识。根据 HBP 中外结节的不同强化模式，将 NIN-HCC 分为不同组，并进一步分为不同类型。随后比较了各组的影像学特征和 LI-RADS 类别。还评估了 NIN-HCC 的病理发现。
在 29 个 NIN-HCC 中，所有内结节均表现为富血供，最大直径为 13.2±5.5mm；51.7%（15/29）表现为“快进快出”强化；48.3%（14/29）表现为“快进慢出”强化。所有外结节均表现为乏血供，最大直径为 25.6±7.3mm，51.9%（14/29）在门静脉期（PVP）呈洗脱表现。所有病变的最大直径为 27.5±6.8mm；12 个（41.4%）病变为 LR-4，17 个（58.6%）病变为 LR-5。根据 HBP 中外结节的信号强度，NIN-HCC 分为低信号（62.1%，18/29）和等信号（37.9%，11/29）两组。在低信号组中，2 个（6.9%）内结节表现为低信号（A 型），11 个（37.9%）表现为等信号（B 型），5 个（17.2%）表现为高信号（C 型），与背景低信号外结节相比。在等信号组中，9 个（31.0%）内结节表现为低信号（D 型），2 个（6.9%）表现为等信号（E 型），无（0%）表现为高信号（F 型），与背景等信号外结节相比。低信号组与等信号组之间，结节直径、内外结节的动态增强模式或病变的 LI-RADS 评分均无显著差异（均 P>0.05）。组织学上，NIN-HCC 的内结节主要由中分化 HCC 组成（75.9%，22/29），而外结节则由高分化 HCC 或高级别异型增生结节（HGDN）组成。
NIN-HCC 具有特定的 MRI 表现，与病理特征密切相关。HBP 强化模式的范围为这些病变的细胞生物学机制提供了有价值的见解。NIN-HCC 亚型可能作为多步骤肝癌发生早期的形态学标志物。
