磁共振乳腺肿瘤定量动态增强计算稳定性的初步研究

Preliminary study of computational stability about quantitative DCE-MRI in breast neoplasm

目的：探讨不同扫描方法对磁共振乳腺肿瘤定量动态增强的容积转移常数（K^trans）计算准确性影响。方法：41例行磁共振定量动态增强扫描的乳腺肿瘤患者分成A、B两组：A组16例于T1WI平扫图像（T1map）扫描完成后置入静脉留置针并连接高压注射器,由系统进行自动预扫描,确定动态增强序列的中心频率后注射对比剂同时扫描;B组25例于T1WI平扫图像（T1map）扫描开始前置入静脉留置针,T1map扫描结束后,人工设置动态增强序列预扫描参数并扫描,第一期结束后注射对比剂。扫描结束后,图像传输至ADW4.3工作站用cine软件进行图像处理计算肿瘤的K^trans。最后,以WeiHuang等提供的K^trans指标作为鉴别良恶性的评价标准,评价两组扫描方法得出的K^trans与相应病理结果的吻合程度。结果：A组16例患者T1map图和动态增强图像位置有较为明显错位,得出的K^trans与相应病理结果一致者1例,不一致者15例。B组25例患者T1map图和动态增强图像位置较为吻合,出的K^trans与相应病理结果一致者24例,不一致者1例。两组结果差异有统计学意义（χ^2=29.556,P〈0.01）。结论：扫描方案的正确制订与序列扫描参数的合理使用在乳腺肿瘤定量动态增强MRI扫描中有重要作用,尤其是静脉注射的时机选择和中心频率的控制直接影响到K^trans的准确性。

Objective：To discuss the impact about calculating accuracy of volume transfer constant （K^trans）in different scan schedules of quantitating breast dynamic contrast enhanced magnetic resonance imaging.Methods：41 patients with breast neoplasms were divided to two groups （A、B） according to examining time.In group A （16 patients） vein remaining needle was inserted and connected to high pressure injector after T1map scan sequence,then automatic prescanning was carried out to determine central frequency of T1 dynamic contrast enhanced scan and dynamic contrast enhanced scan sequence was performed while contrast media was injected.In group B （25 cases ） vein remaining needle was inserted and connected to high pressure injector before T1map scan sequence,automatic prescanning was skipped after T1map scan sequence,then dynamic contrast enhanced scan sequence was carried out and contrast media was injected after first phase scan.Images transferred to GE ADW4.3 workstation and used cine software to calculate K^trans of neoplasms.In the end,evaluate matching degrees of K^trans of neoplasms with pathologic result using different scan schedules.Results：T1 maps of group A （16 cases） were obvious mismatch with T1 perfusion maps and K^trans value of 1 case was compatible with pathologic result,incompatible in 15 cases.T1 maps of group B （25 cases） were match well with T1 perfusion maps and K^trans value of 24 cases were compatible with pathologic result,incompatible in 1 case.A significant difference was found between those two groups （χ^2=29.556,P〈0.01）.Conclusion：Correct planning of scan program and suitable using of parameter in scanning sequence were important for acquiring of accurate angiogenesis parameters.Time selecting of intravenous injection and controlling of central frequency influenced accuracy of K^trans value directly.