肺恶性肿瘤射频消融术后系列CT评估

Lung malignancies treated with percutaneous radiofrequency ablation: evaluation with follow-up CT

目的 探讨肺恶性肿瘤射频消融术后系列CT表现,提高CT判断肺肿瘤射频消融疗效的价值。方法 对2008年3月-2011年12月解放军总医院收治的28例肺恶性肿瘤患者共34个病灶进行了CT引导下经皮射频消融术,其中原发性肺癌20例21个病灶,转移性肺癌8例13个病灶,病灶最大径1.5-5.0 cm,平均3.6 cm。所有患者射频消融术后即刻、1个月、3个月、6个月行胸部螺旋CT扫描,6个月后每6个月重复CT扫描1次。将患者分为完全消融组（A组）和不完全消融或术后复发组（B组）,分析两组系列CT表现。结果 术后即刻：A组病灶普遍性密度减低,轮廓模糊,周围见完整磨玻璃密度围绕,增强扫描无强化。术后1~3个月：A组表现为边缘清晰的类圆形均匀密度影,体积可大于治疗前,增强扫描无强化;B组无特异性。术后3~6个月：A组消融灶较前不同程度缩小,增强扫描不强化或边缘轻微强化。术后6个月以上：A组消融灶逐渐缩小,呈不规则条带或索条影,可轻微均匀强化。B组病灶随时间延长逐渐增大,或表现为缩小后再次增大,形态不规则,增强扫描明显不均匀强化。结论 肺癌射频消融术6个月以后,CT显示病灶逐渐缩小,增强扫描无强化或轻微均匀强化是完全消融的可靠征象。而病灶逐渐增大或缩小后再次增大以及明显不均匀强化提示不完全消融或复发。

Objective To investigate the follow-up CT findings of pulmonary neoplasms after treatment with radiofrequency ablation （RFA） and improve the value of CT in estimating the efficacy of RFA in treatment of malignant lung tumor. Methods Thirty-four pulmonary neoplasms in 28 patients admitted to our hospital from March 2008 to December 2011 underwent percutaneous CT- guided RFA. Twenty-one neoplasms in 20 patients were primary lung cancer and 13 tumors in 8 patients were metastases. The mean pretreatment tumor maximal diameter was 3.6 cm （range, 1.5-5.0 cm）. All patients underwent follow-up contrast-enhanced helical CT scan immediately, 1, 3, 6 months later, and then every 6 months, after undergoing RFA. Patients were divided into two groups, the complete ablation group （Group A） and the incomplete ablation or recurrence group （Group B）. The serial CT appearance and its evolution were assessed on follow-up CT. Results The main CT findings of Group A were as follows： 1.The tumor density decreased generally with a blurred boundary and an enveloped ground-glass opacity surrounding tumor, and no enhancement showed on immediate post-treatment CT. 2. The ablated area appeared as a demarcated oval homogeneous unenhanced solid lesion on the CT obtained 1-3 months after treatment. The lesion size might become slightly larger compared with pre-treatment. 3. From 3 to 6 months after treatment, the lesion size decreased variably without or with slight periphery enhancement. 4. The treated lesion size gradually decreased after the 6-month follow-up CT examination and generally showed as an irregular line or strip seldom with slight enhancement. In Group B, there were no typical findings indicating whether the tumor was incomplete ablation compared with that of the complete ablation on the early follow-up CT scans. However, 3 months later, the ablated lesions gradually increased or grew again after previous shrank with various degrees of inhomogeneous enhancement. Conclusion The gradual decrease of lesion size with or without slight homogeneous enhancement on beyond 6-month follow-up CT examination indicates the complete ablation. On the contrary, the gradual increase or enlarging again following the previous decrease with strong inhomogeneous enhancement implies the incomplete ablation or recurrence.