Objective: To investigate the spatial distribution pattern of local tumor progression (LTP) for hepatocellular carcinoma (HCC) ≤5 cm after microwave ablation. Methods: A retrospective analysis was performed on 169 HCCs with matched MRI before and after ablation from December 2009 to December 2019. A tumor MRI was reconstructed using three-dimensional visualization technology. LTP was classified as contact or non-contact, early or late stage, according to whether LTP was in contact with the edge of the ablation zone and the occurrence time (24 months). The tumor-surrounded area was divided into eight quadrants by using the eight-quadrant map method. An analysis was conducted on the spatial correlation between the quadrant where the ablative margin (AM) safety boundary was located and the quadrant where different types of LTP occurred. The t-test, or rank-sum test, was used for the measurement data. 2-test for count data was used to compare the difference between the two groups. Results: The AM quadrant had a distribution of 54.4% LTP, 64.2% early LTP stage, and 69.1% contact LTP, suggesting this quadrant was much more concentrated than the other quadrants (P < 0.001). Additionally, the AM quadrant had only 15.2% of non-contact type LTP and 17.1% of late LTP, which was not significantly different from the average distribution probability of 12.5% (100/8%) among the eight quadrants (P = 0.667, 0.743). 46.6% of early contact type LTP was located at the ablation needle tip, 25.2% at the body, and 28.1% at the caudal, while the location distribution probabilities of non-early contact LTP were 34.8%, 31.8%, and 33.3%, respectively. Conclusion: LTP mostly occurs in areas where the ablation safety boundary is the shortest. However, non-contact LTP and late LTP stages exhibit the feature of uniform distribution. Thus, this type of LPT may result from an inadequate non-ablation safety boundary.
目的： 探索≤5 cm肝细胞癌（HCC）微波消融后局部进展（LTP）的空间分布规律。 方法： 回顾性分析2009年12月至2019年12月169枚具有消融前后匹配MRI的HCC。运用三维可视化技术重建肿瘤MRI，根据LTP是否与消融区边缘接触及发生时间（24个月），将LTP分类为接触型或非接触型LTP，早期或晚期LTP，利用八象限地图法将肿瘤周围空间划分8个象限，分析消融最短安全边界（AM）所在象限与不同类型LTP发生象限空间关系。计量资料用t检验或者秩和检验；计数资料用χ(2)检验比较两组的差异。 结果： 54.4% LTP分布于AM所在象限，64.2%早期LTP及69.1%接触型LTP分布于AM所在象限，较其他象限显著集中（P<0.001)；仅15.2%非接触型LTP及17.1%晚期LTP分布于AM所在象限，与八象限平均分布概率12.5%差异无统计学意义（P = 0.667，0.743）。46.6%早期接触型LTP位于消融针尖端方位，25.2%位于体部方位，28.1%位于尾部方位,而非早期接触型LTP的位置分布概率分别为34.8%，31.8%和33.3%。 结论： LTP多数发生于消融最短安全边界所在区域，但非接触型LTP及晚期LTP呈均匀分布特点，这类LTP可能为非消融安全边界不足导致。.
Keywords: Hepatocellular carcinoma; Recurrence; Spatial distribution characteristics; Thermal ablation.