PURPOSE: To establish a preoperative protocol for ultrasonographically guided percutaneous radiofrequency (RF) ablation of large liver tumors that is based on mathematic models and clinical experience and to evaluate the role of this protocol in RF ablation. MATERIALS AND METHODS: A regular prism and a regular polyhedron model were used to develop a preoperative protocol for liver tumor ablation. This protocol enabled the authors to minimize the number of ablation spheres, optimize the overlapping mode, and determine the electrode placement process. One hundred ten patients with 121 liver tumors were treated by using this protocol. Sixty-nine patients had 74 hepatocellular carcinomas (HCCs), and 41 had 47 metastases to the liver (ie, metastatic liver carcinomas [MLCs]). Patients underwent follow-up helical computed tomography (CT) 1 month and every 2-3 months after RF ablation. Ablation was considered a success if no contrast enhancement was detected in the treated area on the CT scan obtained at 1 month. RESULTS: A total of 536 ablations were performed in the 121 tumors. The ablation success rate was 87.6% (106 of 121 tumors); the local recurrence rate, 24.0% (29 of 121 tumors); and the estimated mean recurrence-free survival, 17.1 months. Twenty-five patients underwent 38 re-treatments for local tumor recurrence. Major complications occurred in seven patients. Of these patients, only one, who had a tumor close to the colon, had a colon perforation 1 week after RF and required surgical intervention. CONCLUSION: The described protocol for treatment of large tumors had a success rate of 87.6% and a local recurrence rate of 24.0%.

Background Introperitoneal hemorrhage is one of the most common complications of radiofrequency (RF)ablation of hepatic tumors. This study was designed to investigate the reason and management of intraperitoneal hemorrhage occurred during or after percutaneous RF ablation of hepatic tumors. Methods Three hundred and fifty-six patients with hepatic tumors have been treated at 592 procedures of ultrasound guided RF ablation. Intraperitoneal hemorrhage occurred in 5 patients(0.8%). The reasons and management of intraperitoneal hemorrhage in these 5 cases were retrospectively analyzed. Results Two patients with liver metastasis and one hepatocellular carcinoma (HCC) patient suffered from hemorrhage during the RF treatment. Two patients with recurrent HCC after surgery developed hemorrhage 20 minutes or 4 hours after RF treatment. One case of hemorrhage was due to the inappropriate electrode positioning induced liver laceration while treating a 1cm liver metastasis near the liver capsule. One was due to the injury of a small vessel by the RF needle in another liver metastasis patient. Three cases were due to tumor rupture with two cases induced by cough or position change after treating large protruding HCC lesions. Four (80%) of the 5 cases of hemorrhage were rapidly identified by ultrasound. The causes and sites of bleeding during the RF treatment in three cases were confirmed through ultrasound, which were successfully treated using RF coagulation to achieve hemostasis of the bleeding site. Two patients with post-ablation hemorrhage recovered in one hour and 24 hours, respectively after given blood transfusion and other conservative measures. No surgical intervention was required. Two patients died of wide spread metastasis 23-36 months afterwards and the other three patients have lived for 18-25 months to date. Conclusions It is important to perform close monitoring during and after RF ablation in order to identify intraperitoneal hemorrhage in time. RF ablation of the bleeding sites was a simple and effective management when the bleeding site could be confirmed by ultrasound. The hemorrhage due to the rupture of large and protruding liver tumors could be serious and should be considered as contraindication for RF treatment.

Background The advent of second generation agent-SonoVue arid low mechanical index real-time contrast enhanced uhrasonography (CEUS) imaging have been shown to improve the diagnostic performance of ultrasonography in hepatocellular carcinoma (HCC). But no report has described the effect of high mechanical index (MI) post-CEUS This study aimed to investigate the value of post-CEUS in displaying tissue structures of HCC. Methods Seventy-six HCCs in 65 patients were included in the study Each patient undm~ent three scans, high-MI (MI: 0.15-1.6) pre-contrast ultrasound, low-MI (Mi: 0.04-0.08) CEUS with contrast agent SonoVue, and high-MI post-contrast ultrasound, which was performed within 3 minutes after CEUS The size, boundary, echogenicity, internal echotexture arid posterior acoustic enhancement of the HCCs in the conventional scans before and after CEUS were evaluated According to pathological evidence, diagnosis rates of pre-contrast, CEUS arid post-contrast scans were determined arid compared The potential mechanism of post-contrast ultrasound imaging was also discussed. Results Compared with pre-contrast, post-contrast ultrasound showed improvement in image quality in most HCCs: twenty-six (34.2%) more lesions showed well defined margins and fourteen (18.4%) more nodules showed halo sign; twenty-three (30.3%) lesions demonstrated enlarged in sizes; changes in echogenicity were seen in 30 lesions(39.5%): eighteen(23.7%) more lesions showed heterogeneeity and 20 (26.3%) more lesions showed "mosaic" or "nodule-in-nodule" sign: twelve (15.8%) more lesions showed posterior acoustic enhancement Post-contrast ultrasound showed increased diagnostic accuracy of 93.4% (71/76), compare with 88.2% (67/76) of CEUS alone. Conclusions High-MI post-contrast ultrasound utilizes harmonic signals during the rupture of microbubbles, and significantly improves the display of echo-characteristics of HCCs in ultrasound images, which adds diagnostic values for CEUS Post-contrast ultrasound could play an important role in tissue characterization, and may be included in CEUS protocols.

目的：总结射频消融（radiofrequency ablation，RFA）对肝恶性肿瘤的治疗效果，探讨并发症类型及处理措施。方法：对343例778个肝恶性肿瘤行582人次超声引导RFA治疗。其中原发性肝癌（HCC）212例，448个癌灶，肿瘤最大径平均4.0cm，根据国际抗癌协会的肿瘤分期，其中63例（29.7%）为Ⅰ～Ⅱ期，149例（70.3%）为Ⅲ～Ⅳ期（含43例手术切除后复发癌）。肝转移癌（MLC）131例，330个癌灶，癌灶直径平均为3.9cm，原发灶69.5%（91例）来自胃肠道。治疗原则为消融范围超过癌周0.5～1.0cm；对较大肝肿瘤，采用较规范的计算方案指导射频治疗。治疗中密切观察图像异常改变，监测生命体征，以便及时发现出血及周围损伤。治疗后24 h内或1个月后增强CT检查肿瘤无活性为治疗成功。随访时间为2～62个月。结果：射频治疗成功率HCC为95.5%（428/448灶），MLC为96.4%（318/330灶）；局部复发率分别为8 5%（38/448灶），11.8%（39/330灶）。共有138例（40.2%）由于肿瘤复发或新生而进行2～11次治疗。随访343例1年、2年和3年的生存率，HCC分别为87.7%，67.4%和56.8%，其中63例早期癌分别为92.9%，82.8%，74.5%；MLC分别为81.6%，50.8%，27.2%。本组并发症的发生率占2.4%（14/582人次），多发生于治疗中或治疗后即刻，主要为机械性损伤、热损伤等，分别为出血5例，肠穿孔1例，邻近脏器结构损伤5例，胆汁瘘2例，皮肤烫伤1例。结论：RFA作为一种肝肿瘤的局部微创治疗方法，对早期肝癌可获得手术治疗效果；对中晚期肝癌、肝癌术后复发、肝转移癌等临床治疗困难的病例，也可提供有效而相对安全的治疗手段。重视并发症的表现并采用相应的对症处理措施，可提高患者生存质量，延长生存期。