| Mostly primary liver cancer (PLC for short) was found lately and insidious onset. Because many patients have cirrhosis background with poor liver function reserve and the presence of comorbidities and other factors, fewer than 30% of patients are suitable for surgery. Radio-frequency ablation(RFA) provides a new therapeutic approach for patients with liver cancer who were unable or unwilling to surgery. RFA has been considered to be a reliable method for creating thermally induced coagulation necrosis. In the past ten years, per-cutaneous RFA has become a promising therapeutic option, especially for the treatment of primary and secondary liver tumors, due to its easy operating, low invasiveness, and its cost-effectiveness.However, until recently, despite technologic advances in RF generators and electrodes, a major limitation of monopolar RFA has been the small size of the thermal induced ablation zone (<4 cm in diameter) which is less than desirable to encompass both the tumor and a peritumoral safety margin in most clinical situations. Technologic advnces include multiprobe arrays, pulsed techniques, internally-cooled electrodes, and saline-enhanced electrodes. Large HCC, particularly for liver cancer greater than 5cm, the ablated tissues which were surrounding the ablated radio-frequency electrode can reach to 100 ℃ rise or even higher during ablation in a short time, these tissues around the electrode were rapidly gasification and carbonization, inhibit RF heat conduction out and limitate the tissue ablation range, thus the clinical application of radio-frequency ablation could not be spread. In clinical application, with such a technique it is difficult to completely cover the entire range of tumor-free and around the tumor. Therefore, in order to treat tumors larger than 2.5 cm in diameter, including a minimal 1-cm margin of healthy tissue and safety margin, multiple overlapping ablations are required to encompass the whole tumor and the surrounding healthy tissue. Multi-time and multi-point stacking radio frequency ablation between the ablation catheter is easy to produce not-been-ablated residual region (also named "air leakage effect") which can lead to inadequate cure, cause residual tumor or tumor relapse after RFA treatment. Therefore, one of the most important aspect of development goal of radio-frequency ablation is expanding the range of single-time radio frequency ablation. Also, in order to improve the clinical efficacy of saline-enhanced multi-pole electric needle radio-frequency ablation, it is necessary to compare the coagulation necrosis range induced by saline-enhanced multi-polar radio-frequency ablation with the coagulation necrosis range of tradition RFA and multipolar radio-frequency ablation.Multipolar RFA, campared with molo-polar RFA, in early trials, multi-polar RFA induced elliptical ablation zones with small short-axis diameters, therefore we still need to organize multiple treatment sessions. Jang et al reported that two-needle electrodes could produce larger areas of coagulation necrosis than two sequential mono-polar RFA. Recently, studies have demonstrated that, due to the high electrical conductivity of saline, saline or hyper tonic saline-enhanced multi-polar RFA could create larger lesions than mono-polar RFA. However, no studies have determined the optimal concentrations and volumes of NaCl solutions needed to achieve larger coagulation necrosis areas. In order to verify the efficacy of using multi-polar internally Cool-tip Electrode Radio-frequency Ablation Applicator with a perfused Saline-Augmented Needle, it is impulsive to find the optimal concentration and speed of perfusion NaCl and compared its thermal necrosis range with traditional mode.Cool-tip RFA system has three separate RF needle electrode, on the basis of multi-electrode needle, we designed a new type of saline enhanced-Cool multipolar radio-frequency ablation needle. We put a brine into the traditional three electrode needle and conduct an experimental study using isolated exvivo liver doing expandable radio-frequency ablation with the cold cycle per-fusion electrode. This RF electrodes using infusion pump for ablated tissue per-fusion in different proportion of saline, avoiding the carbonization and gasification of the ablated lesions and make up to the necrosis dimension of 7.5cm, such RFA also known as "saline-enhanced cool-tip multipolar radio-frequency ablation ". This research firstly using of a new type and conventional electrode needle electrode to ablate on the isolated liver to explore the relationship between the range of radio-frequency ablation with saline concentration and per-fusion rates, in order to select the best saline concentration and perfusion speed. Then we use the optimal ratio of saline concentration and perfusion rate compared with conventional radio-frequency ablation, we assess the effection of saline-enhanced multipolar radio-frequency ablation by gross and pathological features of ablated tissues. Then,20 cases of liver cancer who were treated with the needle electrode radio-frequency ablation were retrospectively analyzed to explore the clinical efficacy of saline-enhanced per-fusion radio-frequency ablation.Our research included the following three aspects:1. Experimental study of saline proportion and perfusion rate of saline-enhanced cool-tip radio-frequency ablation on isolated liver2. Experimental study of saline-enhanced cool-tip radio-frequency ablation on isolated liver3. Clinical Efficacy of using saline-enhanced cool-tip radio-frequency ablation in liver cancerPart One:Experimental study of saline proportion and perfusion rate of saline-enhanced cool-tip radio-frequency ablation[Objective] In early radio-frequency ablation, its clinical application is limited due to the short dimension of radiation frequency ablation is less man 1.8cm. The cool-tip electrode, the per-fusion electrode and multi-polar electrode enables the dimension of radio-frequency ablation rise up to 3cm, so it can satisfy the clinical radio-frequency ablation requirements for the small liver cancer. In this study, we use cool-tip RFA multi-polar perfusion radio-frequency ablation on the isolated liver in order to investigate the optimal saline concentration and saline per-fusion rate to make the maximum range of ablation lesions.[Methods] we carried out 40 times RFA on 20 isolated liver in vitro using saline-enhanced cool-tip radio-frequency. Firstly, we set a different saline concentration:0.9%,6%,12%,24% and 26%. Secondly, we set different saline infusion rates in the best saline concentration:0.5ml/min, 1.0ml/min and 2.0ml/min. We observe the morphology of each ablation lesion, measure the longitudinal axis and horizontal axis of the ablation lesions, the frontier tip length of ablation and calculated the ablation lesion volume. We conduct linear correlation analysis with the P value less than 0.05 considered statistically significant. The differences between each set of groups are suitable for ANOVA with P value less than 0.05 considered statistically significant.[Results] 6% concentration of saline-enhanced cool-tip radio-frequency (35.5 ± 8.9mm) can produce larger necrotic lesions of minor diameter of ablation lesion than the 0.9% concentration of saline-enhanced cool-tip radio-frequency needle (29.1 ±4.8mm). Higher concentration of saline-enhanced cool-tip radio-frequency needle did not increase the minor axis diameter:33.1 ±5.5mm (12%),32.5±6.1mm (24%), 36.3+7.7mm (26%) (P> 0.05). The optimal perfusion rate of saline solution is the concentration of 6% saline with the rate of lml/min (35.8±5.2mm),or 2ml/min (33.7 ± 8.6mm) than the rate of 0.5ml/min (28.4±6.2mm, P<0.05), they can produce greater minor axis diameter of ablation lesion.[Conclusion] 6% concentration of saline-enhanced cool-tip radio frequency needle with the rate of lml/min can produce the greatest short-axis diameter ablation lesion.Part Two. Experimental study of saline-enhanced cool-tip radio-frequency ablation on isolated liver[Objective] The purpose of this study was to validate the hypertonic-saline-enhanced multipolar radiofrequency ablation (RFA) technique using a perfused electrode to increase RF-created coagulation necrosis, to compare that technique with NS (natural saline) augmented needle and conventional multipolar RFA.[Methods] A total of 18 ablations were performed in explanted porcine livers. We created 6 thermal ablation zones in each group:a conventional multipolar mode (group A), a multipolar mode with instillations of concentrations of 0.9% NaCl solution (group B) and a multipolar mode with instillations of concentrations of 6% NaCl solution (group C). In group B and C, one 18-gauge open perfused electrodes were placed into porcine livers, the NaCl solution was instilled into the tissue through the electrode with the injection rates of 60mL/h. Six ablations zones were created for each of the groups. During RFA, we measured and compared the dimensions and volumes of the ablation zones, also evaluated those pathology results through gross observation and microscopic observation with HE staining.[Results] Multipolar RFA with 6% NaCl solution created largest short-axis diameters and volumes of coagulation necrosis (3.89±0.09mm,40.01 ±2.86mm3) among the three groups (conventional group:2.31±0.04mm,8.99±0.52mm3 and 0.9% NaCl solution group:3.17±0.05mm,21.79±1.05mm3). The multipolar mode with 6% NaCl perfusion showed a more rapid increase in necrosis diameters than the other two modes (P<0.05).[Conclusions] Multipolar RFA with instillation of 6% NaCl solution through an open perfusion system demonstrates better efficacy in creating a larger ablation zone than does conventional modes and 0.9% NaCl solution modes. Therefore, hypertonic saline-enhanced multipolar RFA seems to be a promising approach for treating larger liver tumors.Part Three. Clinical Efficacy of using saline-enhanced cool-tip radio-frequency ablation in liver cancer[Objective] Compared with traditional surgery, radiofrequency ablation is less invasive and faster recovery after treatment with good repeatability. It provides a new treatment method for patients suffered from liver cancer who are unable or unwilling to undergo surgical treatment. Our been done experiments showed that hypertonic saline-enhanced multipolar radiofrequency can produce larger lesions than the conventional RF ablation lesions. This study was designed to explore the clinical efficacy of hypertonic saline-enhanced multipolar radiofrequency ablation under CT guidance and its safety and adverse reactions.[Methods] Between January 2014 and June 2014,20 patients suffered from liver cancer with 34 tumors were underewent CT-guided 6% concentration hypertonic saline-enhanced multipolar radiofrequency ablation, in which 12 patients with a single tumor,6 patients with double tumors, two patients with three tumors; 24 cases with the largest tumor diameter less than 4cm,10 cases with the tumor diameter more than 4cm; They were followed up to December 2015.[Results] After conducted by 6% concentration hypertonic saline-enhanced multipolar radiofrequency,26 tumors were complete ablated (26/34,76.4%), where 20 (20/24,83.3%) patients with the tumor diameter less than 4cm,6(6/10,60%) patients with the tumor diameter more than 4cm; 8(8/34,23.5%)tumors were incomplete ablated. Follow-up to December 2015,14 patients (14/20,70%) were still alive; six cases (6/20,30%) died,2 case(2/20,10%) with the survival time less than 6 months,4 cases (4/20,20%) with the survival time between six months to 12 months. 14 cases of AFP-positive patients,10 patients (10/14,71.4%) decreased to normal levels,2 cases(2/14,14.3%) have AFP level decreased but still higher than normal,2 cases (2/14,14.3%) with AFP level continue to rise. After radiofrequency ablation, two patients suffered from sub-liver-capsule bleeding; most of the patients had some degrees of fever and abdominal pain.[Conclusion] CT-guided 6% concentration hypertonic saline-enhanced multipolar radiofrequency ablation for patients with invassive trauma, fewer complications, confirm better recent efficacy. It is a safe and effective treatment for liver cancer. For tumor diameter less than 4cm, once ablation has a high rate of complete ablation; for tumor diameter larger than 4cm, we need to conduct multi-time multi-locus overlapping ablation technical methods in order to produce greater range of ablation.
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