MRI联合同位素示踪法显像兔VX2乳腺癌内乳前哨淋巴结的实验研究

Breast cancer is now the most common malignancy in women to threaten the physical and mental health. In addition to the axillary lymph node status, the internal mammary lymph node (IMLN) metastasis is an another major independent prognostic indicator in breast cancer, which has the same value as the axillary lymph node status in predicting distant metastasis and long-term relapse; when both are positive, the influence on outcomes is additive. And the status of internal mammary lymph node is both important factors for accurate clinical staging, prognostic evaluation and important evidence on post-operative adjunctive therapy for breast cancer patients. However, several studies have demonstrated that surgical dissection of internal mammary lymph node is not associated with increasing rate of survival. Nowadays, axillary sentinel lymph node (SLN) biopsy is a standard procedure in the staging of breast cancer. However, routine performance of the internal mammary sentinel lymph node biopsy in breast cancer patients remains a subject of debate, but it will be a trend to guide he internal mammary radiotherapy with internal mammary metastasis. A selective internal mammary sentinel lymph node biopsy is necessary for the high-risk metastasis, which could avoid the blindness on the internal mammary therapy and carry out the rule of individual therapy for breast cancer patients. However, the visualization rate of internal mammary sentinel lymph node is low, which becomes the most important barrier for the procedure of the internal mammary sentinel lymph node biopsy clinically. Isotope tracer method for internal mammary sentinel lymph node mapping is now the most common in clinical, but this method has high false negative rate and many influencing factors. Nowadays, there has no report about interstitial magnetic resonance lymphography for internal mammary sentinel lymph node mapping using ultrasonic guidance mammary parenchyma injection of gadolinium contrast. The aim of our study is evaluate the value in the detection of internal mammary sentinel lymph node on rabbit VX2 breast cancer using the methods of interstitial magnetic resonance lymphography combined with isotope tracer method of 99Tcm-sulfur colloid; then discuss the influence factors for internal mammary sentinel lymph node mapping and the regular pattern of the metastasis in internal mammary sentinel lymph node using enhanced MRI scanning. And these finding could be used to provide an envidence for clinic selecting the breast cancer patients who is more suitable for the procedure of internal mammary sentinel lymph node biopsy.

乳腺癌内乳淋巴结转移对远处转移及远期复发的预测价值同腋窝淋巴结转移的价值相当，是影响患者临床准确分期及预后评估的重要因素，也是患者术后选择辅助治疗方案的重要依据。为避免乳腺癌内乳区治疗的盲目性，有选择地进行内乳前哨淋巴结活检是必要的。然而，乳腺癌内乳前哨淋巴结显像率较低，不利于内乳区前哨淋巴结活检术的广泛开展。同位素示踪法是目前最常见的内乳前哨淋巴结显像方法，但假阴性率较高，且影响因素较多；目前关于超声引导下乳腺实质内注射钆对比剂的MR间质淋巴管造影显像内乳前哨淋巴结的研究国内外还未见报道。本研究旨在探讨MR间质淋巴管造影检查联合99Tcm-硫胶体示踪法提高兔VX2乳腺癌内乳前哨淋巴结显像率的可行性，并结合MRI增强扫描进一步分析内乳前哨淋巴结显像的影响因素及转移性内乳淋巴结的影像学特征，为临床初筛乳腺癌内乳前哨淋巴结活检患者提供参考依据。

乳腺癌内乳淋巴结转移对远处转移及远期复发的预测价值与腋窝淋巴结转移的价值相当，是影响患者临床准确分期及预后评估的重要因素，也是患者术后选择辅助治疗方案的重要依据。为避免乳腺癌内乳区治疗的盲目性，有选择地进行内乳前哨淋巴结活检 (internal mammary sentinel lymph node biopsy, IM-SLNB)是必要的；然而，乳腺癌IM-SLN显像率较低，不利于IM-SLNB的广泛开展。本研究的重点是探讨MRI间质淋巴管造影(magnetic resonance lymphography, MR-LG)检查联合99Tcm-硫胶体示踪法提高兔VX2乳腺癌内乳前哨淋巴结 (internal mammary sentinel lymph nodes, IM-SLN) 显像率的可行性。研究结果显示MR-LG检查在对比剂注射后5min扫描较注射后即可扫描可显示更多的内乳区淋巴管(36 VS 25)，且肿瘤大小及腋淋巴结数目对内乳淋巴管的显示有统计学意义(P=0.032, 0.040)；MR-LG中9只荷瘤兔共显示11枚IM-SLN，其中7只(77.8%, 7/9)与SLNB检出的IM-SLN一致。尽管MR-LG检查显示IM-SLN的数目有限，且体积较小，但70.6%(36/51)的荷瘤兔MR-LG上均清楚显示了内乳区淋巴管，这也进一步说明了MR-LG检查显像IM-SLN是可行的，如何进一步提高IM-SLN的显示率是我们今后需要继续探讨的课题。此外，为了进一步评估99Tcm-SPECT在腋窝SLN显像和定位中的价值，我们进一步探讨了99Tcm-SPECT与CT间质淋巴造影(CT-LG)同机融合检查在检出和定位腋窝SLN的价值，研究结果显示其可有效检出和准确定位腋窝SLN，且与CT-LG检查在检出SLN方面无明显统计学差异(x2=1.497, P=0.454)，可有望为临床准确识别及定位SLN提供一种新的检查方法。