Analysis of breast cancer extension using new imaging technology, 3-D MRI

[导言]现在，随着保乳治疗被接受为治疗方案之一，对肿瘤扩展的定义变得更加重要。[材料与方法]对34例乳腺癌患者术前行MRI检查，然后用最大密度投影法(MIP)对肿瘤范围进行三维评估。[结果与讨论]获得了3种不同的成像模式：1)定位型(n=20)，2)节段型(n=11)，3)随机扩散型(n=3)。在局限型标本中，18例在TDLU中明确，2例发现癌在导管内扩散至乳头，最长达4 cm。节段型癌多沿TDLU至大管的导管-小叶系统分布。MRI中染色清晰的肿瘤在组织学上显示为DCIS，形成实性肿块。常规钼靶摄影和超声检查低估了14例MRI诊断为节段型或随机广泛型患者中的6例，提示MRI更适合于术前评估肿瘤的分布。然而，10%(2/20)的局限型患者在MRI中没有被显示，这需要进一步的研究来发展临床应用MRI在保乳手术中的诊断技术。

[Introduction]Now, definition of carcinoma extension becomes more important, as breast conserving therapy is accepted as one of the treatment options. This study was initiated to clarify the ability of magnetic resonance imaging (MRI) in defining the extension of breast carcinoma, in comparison with the pathologic finding created by subserial sectioning of the specimens.[Materials and Methods]Prior to surgery the MRI was performed to 34 patients with breast cancer, then extension of tumors were 3 dimensionally assessed in maximum intensity projection (MIP). Each 3-D MIP was compared to the respective pathologic distribution of carcinoma obtained by subserial mapping.[Results and Discussion]Three imaging patterns were obtained, e.g., 1) localized (n=20), 2) segmental (n=11), and 3) random extensive (n=3) types. Among the specimens classified in localized type, 18 were defined in the TDLU,and intraductal spread of carcinoma to the nipple as long as 4 cm of extension, was observed in 2 specimens. In most of the specimens with segmental type carcinomas distributed along the duct-lobular system from the TDLU to the large duct. Clearly stained tumors in the MRI were histologically revealed to be DCIS which forms solid mass. Three were categorized as random extensive type with linear architecture, and were histologically defined to be carcinomas with diffuse stromal invasion as intraductal spread.Conventional mammography and ultrasonography underestimated carcinoma extension in 6 of the 14 patients who were categorized as segmental, or random extensive type by the MRI,suggesting that the MRI is more appropriate to estimate carcinoma distribution prior to surgery. Ten percent (2/20) of patients with localized type, however, were not visualized in the MRI.Further investigation is required to develop the diagnostic technology in clinical utilization of MRI for breast conserving surgery.