兔VX2恶性骨肿瘤周围水肿与肿瘤浸润范围的关系：能谱CT、MR与病理学对照研究

The correct judgment of infiltrative range of bone tumors before surgical procedure has significant impact on the surgical operation plan and prognosis of the patients. The image resolution of radiography and conventional CT for soft tissue is low, thus the marrow infiltration of tumor can't be predicated in vivo.Marrow edema can be displayed clearly on MRI, but can cause the over-evaluation of the tumor infiltration range.So far,little is known about the mechanism of edema around tumor and its ralationship with the invasive scope of tumor.The results of our prelimimary experiment suggest that the marrow and soft tissue edema around tumor inclde pure edema, inflammtory infiltration, tumor micro-infiltration.There is remarkable difference of spectral curve slope and ADC value between the pure edema and inflammatory infiltration. To verify the hypothesis, the rabbit model of VX2 malignant tumor and spectral curve combined with DWI-ADC map were used to explore the relationship between the edema and tumor infiltration scope. Our study will begin from the two viewpoints of spectral curve and ADC map to reveal the internal elemens of edema around the tumor, to provide a new way for the accurate judgment of tumor range.

恶性骨肿瘤术前正确判断肿瘤浸润范围对手术方式及患者预后有重大影响，但此一直是临床工作的难点之一。X线平片和常规CT软组织分辨率较低，且无法活体判定肿瘤区域骨髓的浸润情况，MR能清晰显示骨髓水肿，但往往造成肿瘤范围的过度评价。迄今对骨肿瘤周围水肿产生机制及其与肿瘤浸润范围的关系仍知之甚少。我们的预实验结果提示骨肿瘤周围骨髓与软组织水肿包括单纯水肿、炎性浸润、肿瘤微观浸润三个部分，骨肿瘤微观浸润区域的能谱曲线斜率和ADC值与单纯水肿与炎性浸润区域有明显区别。为了验证这一假说，我们将通过兔VX2恶性骨肿瘤模型，采用能谱CT的能谱曲线结合MR的弥散加权的ADC图进行论证，探讨水肿与肿瘤浸润范围的关系。本研究将从水肿区域的能谱CT曲线及ADC图这两个新视点为揭示肿瘤周围水肿的内部微观成分奠定基础，为术前准确判断肿瘤范围提供新的思路。

恶性骨肿瘤术前正确判断肿瘤浸润范围对手术方式及患者预后有重要作用，但是临床工作的难点。平片和常规CT无法活体判定肿瘤区域骨髓的浸润情况，MR能清晰显示骨髓水肿，但易造成肿瘤范围的过度评价。本研究的目的在于通过影像学方法区分模型兔恶性骨肿瘤移行区内的单纯水肿区、炎性浸润区和肿瘤微观浸润区，为外科精确切除恶性骨肿瘤提供可靠方法。方法：1.建立100只兔恶性骨肿瘤模型，三周后行常规MRI及DCE-MRI检查，留取右小腿制备大体标本及病理切片，通过观察病理切片中髓腔内肿瘤远端的边界，将模型兔标本分为微观浸润组和无微观浸润组，测量前组肿瘤边缘实性区、微观浸润区、无肿瘤细胞区的血流动力学参数；测量后组肿瘤边缘实性区及无肿瘤细胞区相应参数，获得容积转移系数Ktrans值、速率转移常数Kep值、细胞外血管外容积分数Ve值、血管内容积分数Vp值，通过统计学方法比较相应区域各参数之间是否存在差异，并计算不同参数区分不同区域的准确性。2.对恶性骨肿瘤兔模型行MR-DWI和常规序列检查，结合大体标本和影像图像，确定ADC图上的微观浸润区域和单纯水肿区域。分别测取b=500、700 和900 时恶性骨肿瘤移行区域的微观浸润区域和单纯水肿区域的ADC 值，并进行统计学分析，对不同b 值组的ADC 值对恶性骨肿瘤移行区域的微观浸润区域和单纯水肿区域的鉴别诊断效能采用受试者操作特征曲线（ROC）进行分析。结果：1.动态增强MR灌注定量参数Ktrans值及Kep值能有效区分肿瘤边缘实性区、微观浸润区及无肿瘤细胞区，其中Ktrans值准确性最高。2. MR-DWI 序列恶性骨肿瘤移行区域的微观浸润区和单纯水肿区ADC 值明显不同。不同b 值对两区域的ADC 值有明显影响，b=900 时获得的ADC 值的诊断效能最佳。以b=900，ADC=1.58×10-3 可作为鉴别恶性骨肿瘤移行区域的微观浸润区域与单纯水肿区域的阈值，敏感度和特异性分别为84.00%、76.00%。结论：定量参数Ktrans值及Kep值能有效区分肿瘤边缘实性区、微观浸润区及无肿瘤细胞区。MR-DWI 序列ADC 值对区分恶性骨肿瘤移行区域的微观浸润区和单纯水肿区具有重要价值。