乳腺癌术前MRI评估胸肌侵犯的价值

Evaluation of Pectoral Muscle Involvement in Breast Cancers with MR Imaging

目的:探讨MRI对乳腺癌胸肌浸润的临床诊断价值,为乳腺癌患者手术中保留胸肌提供影像学依据。方法:20例经手术病理证实的女性乳腺癌患者,行常规MRI平扫和快速角度激发动态增强扫描,分析MRI显示乳后脂肪间隙和胸肌浸润的征象,并以病理结果为标准,分析乳腺MRI评估胸肌浸润的诊断价值。结果:MR平扫示12例乳腺后脂肪间隙中断、消失,4例乳后脂肪间隙不规则变形、狭窄,4例乳后脂肪间隙无明显改变。增强扫描示4例胸肌可见结节状或片状强化灶,2例乳腺癌病灶与胸肌间可见索条状强化带相连,14例胸肌表面比较光整、未见异常强化。手术病理结果示6例胸肌受累;16例乳腺后脂肪间隙受累,其中5例有胸肌浸润。MRI显示胸肌异常强化征诊断乳腺癌胸肌浸润的敏感度为66.7%,特异度为85.7%。结论:胸肌异常强化是乳腺癌胸肌浸润的可靠征象,MRI术前评估乳腺癌胸肌浸润的准确性较高,可作为乳腺癌手术中判断是否保留胸肌的可靠依据。

Objective：To evaluate the ability of breast MR imaging in the detection oft pectoral muscle infiltration in the cases of breast cancers. Methods： 20 patients with breast cancer were undergone with breast dynamic enhanced MR imaging. The tissue plane between the fat posterior to the breast and pectoral muscle was observed,and,whether it was involved by cancers was studied. The results were correlatively compared with those found in histopathology. Results：On plain scans,the tissue plane between the fat posterior to the breast and pectoral muscle was shown interrupted or disappeared in 12, narrowed or irregular shaped in 4, whereas, normal in the remaining 4 of the 20 cases. On enhancing scans, enhancing nodular or patch loci in the pectoral muscles were demonstrated in 4 cases and there were enhancing bundles linking between the cancer lesion and the relative pectoral muscle in 2 cases. The surfaces of the pectoral muscles showed rather smooth and nothing abnormally enhanced was found in 14 of the 20 cases. All the cases were surgically and pathologically confirmed. The results showed： pectoral muscle involvement in 6 cases,infiltration of tissue plane posterior to the breast in 16 cases and 5 of them with pectoral muscle invasion and a cancer focus of lcm in diameter shown underneath the pectoral fascia without involving the tissue plane in 1 case. 6 of the cases in which the pectoral muscles revealed abnormal enhance- ment were all pathologically proven pectoral muscle cancer invasion. For breast cancer cases, in case that the pectoral muscle demonstrated abnormal enhancement on enhancing scans, the sensitivity and specitivity of pectoral muscle cancer invasion were 66.7 % and 85.7 % respectively. Conclusion： On enhancing breast MR scan, pectoral muscle enhancement was a reliable sign of cancer invasion in breast cancers. The accuracy rate of pre-operative breast MR imaging in evaluating the invasion of pectoral muscle by breast cancer was high,therefore,the relative findings might served as reliable signs for the decision of pectoral muscle preservation.