水冷式单针射频热消融系统可消融范围测定的实验研究

目的 通过离体器官和活体动物实验,确定水冷式单针射频消融系统的功率、时间、消融范围的相关曲线,为实际应用提供理论依据.方法 采用水冷式单针射频消融系统分别对新鲜牛肝脏、健康成年新西兰白兔的肝脏和肌肉组织实施射频消融处理,经多路测温系统实时采集消融区域的温度场数据,以50 ℃为温度区域边界确定实际达到的最大消融范围,并计算离体肝脏组织的比吸收率(SAR).结果在100～130 V治疗电压范围内,治疗过程平稳,阻抗无明显变化,最大单次消融直径达51 mm.在140～170 V治疗电压范围内,较短时间即可达到较大的消融范围,但之后阻抗开始上升,组织消融范围不再继续扩大.在180～200 V电压范围内,几乎都出现快速的阻抗超标、射频治疗自动终止而不能正常完成射频消融.实际测得肝脏组织的SAR与理论值相符.病理学观察证实肝脏、肌肉组织发生了典型的凝固性坏死.结论 该水冷式单针射频消融系统在实验过程中,功放、水冷、测温及控制部分均运行平稳,实际消融效果达到了设计要求和临床治疗的需要.

Abstract：

Objective To determine the power-time-ablation scope correlogram of a water-cooled single needle electrode radiofrequency (RF) ablation system and to establish a theoretical basis for its practical application.Methods RF ablations were performed using a water-cooled single needle electrode radiofrequency ablation system developed by the authors using fresh ox liver as well as liver and muscles of healthy adult New Zealand white rabbits.The temperature of the ablation area was monitored using a multichannel thermometric system.The maximum ablation scope was determined by detecting the rim at which the temperature was no less than 50 °C.The specific absorption rate (SAR) of the isolated liver tissue was calculated.Results In the treatment voltage range of 100-130V,the process was smooth and steady.No impedance variation was obvious.The maximum diameter of a single ablation was 51 cm.With the treatment voltage at 140-170 V,a larger ablation area could be reached in less time,but eventually the impedance began to increase while the ablation area was no longer expanded.When the treatment voltage reached the range of 180-200 V the impedance almost always increased rapidly out of limits,and the treatment system stopped automatically.The measured SAR value was consistent with the theoretical value.Pathology confirmed that both liver tissue and muscle tissue manifested typical coagulative necrosis.Conclusions The power amplifier,cooling,thermometric and control sections of the RF ablation system worked stably,and the practical ablation effect met the design and clinical treatment requirements.     

激光消融正常活体兔肝的超声表现及影响因素

目的 探讨激光消融活体兔肝的超声表现及影响因素.方法 用Echolaser集成激光介入超声系统消融正常兔肝,观察消融灶坏死程度、病理改变及解剖表现.结果 消融灶呈类椭圆形,二维表现为中心规则强回声及周边稍强回声区,后方有轻度声衰减.超声造影显示消融灶呈"充盈缺损区".解剖后,肉眼观消融灶中间为碎渣样碳化区,周边为褐白色样坏死区.HE染色显示消融灶中心呈"空洞样"无染色剂浸染区,周边呈不规则无核红染区,外围可见浸润的炎性细胞.不同功率及时间对消融效果及消融范围有影响且消融灶的大小与功率和时间呈正相关;3 w 10 min组和5 W 6 min组消融范围稳定、可导致消融区组织的完全坏死且两组间的消融范围差异有统计学意义(t=6.78,P<0.05).结论 激光消融对活体兔肝能造成快速、精准、有效、安全的凝固性坏死,消融灶的大小与功率和时间呈正相关.

Abstract：

Objective To explore the ultrasound performance and related factors on the role of normal living rabbit's liver by laser ablation. Methods The rabbit's liver tissue were ablated by Echolaser integrated laser interventional ultrasound system, and the necrosis of the lesion and performance of pathology and anatomy were observed. Results The outline of the lesion was ellipse like. The two-dimensional US showed regular hyperecho area in the center, mild strong echo in the peripheral and mild attenuation backward. Contrast enhanced ultrasound (CEUS) showed a "filling defect" of contrast media in the ablated area. After dissection, the center of the lesion was slag-like carbon, the peripheral was necrosis area; HE staining showed: the center of the lesion was cavity like and dye-free,peripheral area was irregular red staining, the surrounding area was infiltrative inflammatory cells. Different power and time leaded to differences of the ablative effect and lesion size:the more power and time,the bigger of the ablative size. The ablative effect and lesion size was stable in 3 W 10 min and 5 W 6 min groups and caused the complete necrosis of the zone, there existed statistical differences among the two groups. Conclusions Laser ablation can cause fast, precise, effective and safe necrosis of the liver tissue, and the more power and time, the bigger of the ablative size.     

The effects of local wet hyperthermia combined with microwave ablation on tumor growth and serum levels of interferon-β and interleukine-12 in mouse models of mammary carcinoma

Objective To investigate the effects of local wet hyperthermia combined with microwave ablationon tumor growth and serum levels of interferon-β(IFN-β)and interleukine-12(IL-12).Methods An experimental mouse model beating mammary carcinoma was established in Balb/c mice and then treated with microwave ablation after 14 d.Seven d after ablation,local wet hyperthermia was administered once weekly for 2 weeks.Tumor growth and lung metastasis,as well as the survival of bearing tumor mice were observed.The serum levels of IFN-β and IL-12 were detected with enzyme-linked immuno sorbent assay(ELISA). Results When local wet hyperthermia was combined with microwave ablation tumor growth and lung metastasis were significantly less than when microwave ablation or local wet hyperthermia was used alone(P＜0.05).Furthermore,the survival of bearing tumor mice in combined therapy group prolonged significantly compared with those receiving either therapy alone(P＜0.05).Serum levels of IFN-β and IL-12 were also significantly higher in combined therapy group compared with the other groups (P＜0.05). Conclusions Local wet hyperthermia combined with microwave ablation is more effective than either local wet hyperthermia or microwave ablation alone in retarding tumor growth,which may be related to the enhanced immune response.     

Application of curved ablation in liver cancer with special morphology or location: Report of two cases

BACKGROUND Liver cancer is one of the most common malignant tumors with a high incidence and mortality.Hepatitis-liver cirrhosis-liver cancer is known as the trilogy of liver cancer.At present,due to significant development of imaging interventions,they occupy an irreplaceable position in the field of liver cancer treatment,especially ultrasound-guided ablation.Because patients with liver cancer often present with liver cirrhosis,which leads to morphological deformation of the liver,it is difficult to perform a linear ablation of liver cancer in the areas near the phrenic top and within large blood vessels,among others.The present study reports on two cases of liver cancer that have been subjected to curvilinear ablation.After 1 mo,magnetic resonance imaging showed complete ablation,demonstrating that ultrasound-guided curved ablation is feasible and effective in the treatment of liver cancer.CASE SUMMARY Two patients were treated at the Liver Disease Department of the Xixi Hospital Affiliated to Zhejiang University of Chinese Medicine in 2019.Because the first liver cancer patient’s tumor was located close to the diaphragm,it was difficult to complete a straight needle ablation procedure in one session.In order to achieve accurate and minimally invasive treatment of this tumor,a curved needle ablation procedure was designed.The second patient presented with a hepatic cyst in front of the tumor.In order not to damage the hepatic cyst,a looper needle ablation technique was used.The procedure was successfully completed in both cases.CONCLUSION Curved ablation is a new technique that can be used to treat tumors situated in a variety of locations,providing new ideas for interventional techniques.Its operation difficulty is higher and further animal experiments are necessary to improve the operation procedure.     

Study on expression of endothelin in experimental cerebral concussion in rats

Objective:To study changes and significance of endothelin (ET) in rat cerebral concussion.Methods 80 Wistar male rats were used for animal model of cerebral concussion,which were sacrificed on 1,3,7,14 and 30 days after injury and the brain tissue were taken off.The expression of ET was studied in the course of cerebral concussion by means of immunohistochemistry.Results:Typical clinical manifestation was observed in the 100g group in which the pathological changes included cerebral vascular constriction and dilatation,congestion and edema of cerebral tissue,neuronal degeneration,necrosis,and obviously decreased even disappeared Nissl bodies.Increased expression of ET was observed on the first day,the positive area was seen in the plasma of endothelial cells in cerebral cortex,hippocampus,cerebellum and thalamus.ET expression peak occurred on the 7th day,the positive area was also found in the plasma of Purkinje cells in the cerebellum.Decreased ET expression was found on 14th day and returned to normal level on the 30th day.Conclusion:The main pathological changes of cerebral concussion contained blood circulation disorder,and degeneration and necrosis of substantial cells.ET was involved n the brain tissue injury during the pathological process of cerebral concussion and might be related to regulation of cerebral vascular reaction,and neuron degeneration and necrosis.     

Long-term survival of two patients with recurrent pancreatic acinar cell carcinoma treated with radiofrequency ablation: A case report

BACKGROUND Pancreatic acinar cell carcinoma (PACC) is a rare type of malignant pancreatic cancer that represents approximately 1%of all pancreatic neoplasms.Due to its very low incidence,only a few retrospective studies are available.Although surgery is the first choice for treatment,most patients experience recurrence(mainly in the liver) and there are no clear recommendations for patients with advanced disease.CASE SUMMARY We report two patients with PACC treated with sturgery who experienced tumour recurrence in the liver.Patient 1 carried a germline mutation in the APC gene.Both patients were treated with gemcitabine plus oxaliplatin and gemcitabine plus capecitabine as first-and second-line therapies,respectively.After a favoturable response to chemotherapy,the patients underwent radiofrequency ablation of the remaining liver metastases.For patient 1,we documented a relapse in the liver after a disease-free period of 9 mo,and treatment with gemcitabine plus capecitabine was restarted.The patient achieved a complete response,and he remains alive without evidence of disease recurrence after six years.After radiofrequency ablation,patient 2 experienced disease-free survival for 21 mo,when peritoneal relapse was diagnosed and treated with chemotherapy.The patient achieved a stable disease state for nearly two years;nevertheless,further progressive disease was documented,and he died seven years after the first relapse.CONCLUSION PACC presents different biological behaviours than pancreatic adenocarcinoma.Multidisciplinary treatment involving local ablative therapies may be considered for PACC.     

The role of microwave physiotherapy for patients undergoing mastectomy

Objective:To evaluate the role of physiotherapy in surgical oncology,Methods:A clinical trial was carried out in which chosen physiotherapy‘s microwave was used to treat patients who underwent radical mastectomy.Besides chemotherapy,which were given to all cases,the microwave thermotherapy was given to the test group during the postoperative period as ewll.Results:The result showed that the microwave therapy wa convenient for patients bound up by dressing after the operation.It could relieve the pain and lymphedema of the upper,limb,promote wound ealing,as ewll as resumption of upper extremity function.Conclusions:The authors believe that there should be synergetic actions between thermotherapy and chemotherapy,and microwave physiotherapy is beneficial to breast cancer patients after radical operations.     

地塞米松对脑损伤大鼠核转录因子-κB水平的影响

Objective To explore the effects of dexamethasone on nuclear factor-kB (NF-κB) expression in brain tissue after traumatic brain injury (TBI). Methods Forty rats were randomly divided into two groups: dexamethasone treatment and no treatment, and severe brain injury was produced by gas percussion in both groups. At 0, 6, 24, 72 and 120 hours after injury, 5 rats of each group were executed and the histopathological changes in brain tissue in rats were observed by hematoxylin-eosin (HE) stain. The expression of NF-κB in brain tissue of rats was detected by immunohistochemical method. Results NF-κB expression was significantly up-regulated at 6 hours in brain tissue of rats after TBI (P<0.05), reaching the highest level at 24 hours (P<0. 01). It showed a tendency to lower, but was still high at 120 hours after TBI (P<0. 05 or P<0. 01). After treatment with dexamethasone, NF-κB level was lowered at 6, 24 and 72 hours (all P<0. 01). Conclusion NF-κB expression is up-regulated in brain tissue in early period after TBI, and keeps on a high level, thus inducing inflammatory response to produce secondary injury to brain tissue. Dexamethasone shows protective effects by regulating the levels of NF-κB and prevents secondary injury which is caused by the inflammatory cytokines in rat brain tissue after TBI.     

地塞米松对脑损伤大鼠核转录因子-κB水平的影响

Objective To explore the effects of dexamethasone on nuclear factor-kB (NF-κB) expression in brain tissue after traumatic brain injury (TBI). Methods Forty rats were randomly divided into two groups: dexamethasone treatment and no treatment, and severe brain injury was produced by gas percussion in both groups. At 0, 6, 24, 72 and 120 hours after injury, 5 rats of each group were executed and the histopathological changes in brain tissue in rats were observed by hematoxylin-eosin (HE) stain. The expression of NF-κB in brain tissue of rats was detected by immunohistochemical method. Results NF-κB expression was significantly up-regulated at 6 hours in brain tissue of rats after TBI (P<0.05), reaching the highest level at 24 hours (P<0. 01). It showed a tendency to lower, but was still high at 120 hours after TBI (P<0. 05 or P<0. 01). After treatment with dexamethasone, NF-κB level was lowered at 6, 24 and 72 hours (all P<0. 01). Conclusion NF-κB expression is up-regulated in brain tissue in early period after TBI, and keeps on a high level, thus inducing inflammatory response to produce secondary injury to brain tissue. Dexamethasone shows protective effects by regulating the levels of NF-κB and prevents secondary injury which is caused by the inflammatory cytokines in rat brain tissue after TBI.     

地塞米松对脑损伤大鼠核转录因子-κB水平的影响

Objective To explore the effects of dexamethasone on nuclear factor-kB (NF-κB) expression in brain tissue after traumatic brain injury (TBI). Methods Forty rats were randomly divided into two groups: dexamethasone treatment and no treatment, and severe brain injury was produced by gas percussion in both groups. At 0, 6, 24, 72 and 120 hours after injury, 5 rats of each group were executed and the histopathological changes in brain tissue in rats were observed by hematoxylin-eosin (HE) stain. The expression of NF-κB in brain tissue of rats was detected by immunohistochemical method. Results NF-κB expression was significantly up-regulated at 6 hours in brain tissue of rats after TBI (P<0.05), reaching the highest level at 24 hours (P<0. 01). It showed a tendency to lower, but was still high at 120 hours after TBI (P<0. 05 or P<0. 01). After treatment with dexamethasone, NF-κB level was lowered at 6, 24 and 72 hours (all P<0. 01). Conclusion NF-κB expression is up-regulated in brain tissue in early period after TBI, and keeps on a high level, thus inducing inflammatory response to produce secondary injury to brain tissue. Dexamethasone shows protective effects by regulating the levels of NF-κB and prevents secondary injury which is caused by the inflammatory cytokines in rat brain tissue after TBI.     

经皮微波消融良性肝局灶性病变的初步研究

目的 探讨运用经皮微波热消融治疗良性肝局灶性病变的原则和价值.方法 应用15G水冷式微波电极经皮消融14例15个良性肝局灶性病变,直径(26.2±13.6)mm(10～57 mm).结果 微波消融治疗次数为(1.4±0.5)次(1～2次),总治疗时间为(837±574)s(300～2057 s).随访1～35个月,中位随访期6个月.治疗后1个月增强影像检查显示,病灶均被微波消融所致凝固性坏死区完全覆盖.随访3个月以上者12例,随访影像检奁显示消融区范围逐渐缩小.围手术期和随访中无一例出现并发症.消融治疗副作用主要有局部疼痛不适(12/14例)、发热(8/14例)、肝酶学指标升高(14/14例)等,前两者持续时间1～9 d,肝酶学指标升高于治疗后1周左右恢复至治疗前水平.结论 经皮微波热消融具有安全、微创、消融彻底、毒副作用低等特点,在把握好适应证的前提下,可作为良性肝局灶性病变的一种可选择的治疗方法.     

植入式微波消融活体猪肾实验研究

目的通过研究植入式微波对正常活体猪肾实质的消融作用,为微波消融肾脏肿瘤的临床应用提供实验依据。方法采用水循环内冷式硬质微波针,微波发射频率为2450 MHz,能量输出50～80 W/600 s,观察不同能量条件下微波对活体猪肾实质的消融作用。结果植入式微波在不同能量条件下消融灶的形态均为椭球形,由消融中心向外周依次分别为组织炭化区、消融凝固区、充血反应区和正常组织区。不同区域病理表现各异。实验中分别统计了不同能量状态下消融范围（最大长径、宽径和体积）和天线周围温度变化。结论植入式微波消融技术可在活体猪肾实质形成类圆形消融坏死区,消融范围可随能量改变而变化。     

超声弹性成像观察肝脏凝固灶:体外实验

目的 运用实验手段探讨超声弹性成像(EI)在肝脏凝固灶中的应用.方法 选取新鲜离体猪肝,通过无水乙醇注射和微波消融两种方法产生不同形态的凝固灶,观察实验前、后的EI图,利用虚拟声触诊定量(VTQ)技术测定作用区的剪切波传播速度.实验结束后切开标本记录实际凝固灶形态、范围.结果 无水乙醇注射和微波消融均可使局部肝组织发生凝固性坏死,EI图上表现为红色硬变区,且不随时间延长而衰减,较常规二维超声更接近凝固灶形态,但与实际仍有一定差异.作用区的剪切波速度较实验前明显增高(P＜0.01),也表明凝固性坏死的肝组织硬度增加.结论 EI可从力学角度提供凝固灶信息,应用简捷、无创,是常规超声的有益补充.     

Correlations Between B‐Mode Ultrasonic Image Texture Features and Tissue Temperature in Microwave Ablation

Objective. The purpose of this study was to find the correlations between B‐mode ultrasonic tissue texture features and tissue temperature in microwave ablation. Methods. A total of 20 in vitro porcine liver samples were used for microwave ablation experiments. B‐mode ultrasonic images under various temperatures were acquired. The texture features of the differential images based on the gray level histogram, including the mean of the gray scale (MGS), standard deviation of the gray scale, and entropy of the gray scale (ENT), and those based on the gray level co‐occurrence matrix, including the contrast (CON), angular second moment (ASM), inverse difference moment (IDM), and correlation, were extracted. Correlations between the features and liver sample temperature were analyzed. In addition, water bath heating experiments were also performed on 15 in vitro porcine liver samples for analysis validation. Results. The correlation coefficients across the MGS, ENT, and ASM in 4 directions (0°, 45°, 90°, and 135°), the CON and IDM in 3 directions (45°, 90°, and 135°), and a temperature range of 15°C to 90°C were high and greater than 0.9 during microwave ablation. All texture features of the differential B‐mode ultrasonic images changed with rising temperature from 25°C to 60°C during water bath heating. Conclusions. Changes in image features reflect changes in tissue temperature during microwave ablation.     

超声监视下不同能级微波消融甲状腺肿瘤的疗效对比研究

目的筛选甲状腺肿瘤细胞凋亡的低能级微波消融参数,探讨低能级微波消融甲状腺肿瘤的安全性及有效性。方法建立裸鼠皮下甲状腺未分化癌模型,随机分为12组进行不同功率的微波消融。在消融前后分别进行超声造影,评估消融效果;术后24 h取肿瘤组织行HE染色观察病理变化,TUNEL及流式细胞仪凋亡检测法检测肿瘤组织凋亡坏死情况。结果HE染色显示微波消融可诱导肿瘤组织发生凋亡与坏死,随着消融功率的增加,肿瘤组织中凝固性坏死区域增加。TUNEL结果示8W组凋亡指数明显高于0W、5W、6W、7W组(P<0.01);8W组与9W、10W、11W、12W、13W、14W、15W组凋亡指数相比无差异(P>0.05)。流式细胞仪检测结果示,8W组存活率明显低于0W、5W、6W、7W组(P<0.01),而8W组与9W、10W、11W、12W、13W、14W、15W组存活率相比无差异(P>0.05)。结论超声引导下低能级微波消融治疗甲状腺肿瘤是有效及安全。     

微波消融灶组织病理变化与超声弹性成像图对照的实验研究

目的研究微波消融灶大体标本不同区域与弹性成像图相应区域问的关系,探讨超声弹性成像评价微波消融组织病理改变的可行性。方法单导水冷2450MHz微波,作用功率50w,作用时间200s,消融离体猪臀部肌组织,消融前、消融后即刻行静态超声弹性检查,分别测量弹性图的蓝色区及蓝色区＋绿色区大小。消融后测量大体标本灰白色＋灰粉色区及灰白色区大小。大体标本常规甲醛固定,石蜡切片,HE染色,光镜下观察各消融区域组织细胞变化,并采用配对t检验比较大体标本测值及镜下检查结果同弹性图相应测值。结果共进行了30次微波消融,形成30个消融灶。所有消融灶最终均能获得满意的弹性成像图。消融后消融灶剖面大体观呈以天线为长轴的椭圆形,由中心向外依次分为：棕黄色区,光镜下肌细胞完全破坏、崩解;灰白色区,硬而致密;光镜下肌细胞凝固性坏死;灰粉色区,光镜下肌细胞形态大致正常,细胞问水肿。消融后,弹性图像显示消融灶呈椭圆形,中心为较均匀蓝色,周边呈宽度较均匀一致绿色,与周围混杂颜色的正常组织分界清楚。弹性图蓝色区＋绿色区（灰白色区＋灰粉色区）长、宽、高测值分别为（3．750±0．289）、（2．773±0．264）、（2．223±0．229）cm,大体标本总消融区长、宽、高测值分别为（3．768±0．277）、（2．668±0．337）、（2．291±0．378）cm。2种方法长、宽、高测值的差异均无统计学意义（t=-0．568、1．994、1．078,P均〉0．05）,且有相关性（r=-0．86、0．69、0．62,P均〈0．01）。弹性图蓝色区长、宽、高测值分别为（3．307±0．231）、（2．260±0．269）、（1．827±0．271）cm,大体标本灰白色区长、宽、高测值分别为（3．280±0．273）、（1．980±0．373）、（1．840±0．297）cm。2种方法长、高测值的差异亦无统计学意义（t=0．576、0．238,P均〉0．05）,且有相关性（F0．76、0．71,P均〈0．01）。结论微波消融后超声弹性图像的蓝色区＋绿色区与消融灶标本灰白色区＋灰粉色区（凝固性坏死区＋水肿区）相对应,蓝色区与灰白色区（凝固性坏死区）相对应,超声弹性成像可以初步反映组织的热损伤程度。     

体外肝组织微波消融范围的研究

目的 研究微波消融治疗在离体人肝组织的消融灶形态及范围.方法 通过在不同初始功率、作用时间下对离体人肝组织进行单针微波消融,超声及大体解剖观察消融灶的形态及范围,镜下观察消融灶病理学变化.结果 相同初始功率组消融灶随作用时间延长而增大;在相同作用时间下初始功率70 W组消融灶大于初始功率50 W组,其差异均有统计学意义（P＜0.05）.超声显示消融灶范围较大体解剖测量范围大,两者比较差异具有统计学意义（P＜0.05）.病理检查见消融灶中心凝固区肝组织均凝固坏死,距凝固区边缘0.5 cm处有1例可见残存水肿肝细胞、1 cm处有17例可见残存肝细胞组织.结论 微波消融灶呈椭圆形,其范围随初始功率及作用时间增加而扩大,超声测量比大体解剖消融范围大,消融灶与周围组织间有移行带.     

植入式水冷915 MHz与2450 MHz微波消融的猪活体肝脏的实验对比

目的 对比植入式水冷915 MHz和2450 MHz微波在活体猪肝脏消融实验中的消融范围及热场特性.方法 根据频率不同分两组实验.915 MHz和2450 MHz微波天线沿特制支架插入活体猪肝脏后,平行天线裂隙旁开5 mm、10 mm、15 mm、20 mm 间距的A(5,0)、B(10,0)、C(15,0)、D(20,0)四点分别放置测温针,均以60 W、600 s条件辐射,计算机采集测温数据,消融后测量消融区范围并比较两组消融范围的大小,分析温升曲线并比较两组的温升速率及所达最高温度.结果 915 MHz微波较2450 MHz微波在活体猪肝消融中可获得更大的消融横径和纵径;915 MHz微波和2450 MHz微波两者距离天线越近的位点温升速率越快,所达最高温度亦越高;对应B、C、D点上915 MHz微波较2450 MHz微波具有更快的温升速率及更高的温度.结论 915 MHz微波与2450 MHz微波相比,915MHz微波可获得更大的消融范围,具有更高的热效率.     

Ultrasound-based elastography: a novel approach to assess radio frequency ablation of liver masses performed with expandable ablation probes: a feasibility study

OBJECTIVE: The purpose of this study was to evaluate the technical feasibility of ultrasound-based elastography as a tool for assessing the size and shape of the coagulation necrosis caused by radio frequency ablation (RFA) probes using expandable electrodes ex vivo as well as in a patient with a liver metastasis. METHODS: A commercially available expandable RFA probe was used to create a 3-cm ablation in a piece of bovine liver. The ablation probe was used in situ to induce tissue deformation for elastography before and after ablation. Ultrasonic radio frequency data were processed to generate elasticity strain images. The appearance of the ablation zone was compared with magnetic resonance imaging and a gross section specimen. One patient with malignant metastatic disease to the liver and a clinical indication for RFA was investigated for the feasibility of percutaneous elastography of RFA using the same technique. Sonographic strain images were compared with the appearance of the nonenhancing ablation zone on contrast-enhanced computed tomography. RESULTS: Ex vivo, the ablation zone on ultrasound-based elastography was represented by an area of increased stiffness and was well demarcated from the nonablated surrounding tissue. The size and shape of the ablated zone on the strain image correlated well with the gross specimen and the magnetic resonance imaging appearance. Strain images obtained from the patient showed results similar to those of the ex vivo experiment and correlated well with the nonenhancing area of ablation on contrast-enhanced computed tomography. CONCLUSIONS: Ultrasound-based elastography may be a promising tool for displaying the ablation zone created by expandable RFA probes.     

剪切波弹性成像评价肝脏微波消融灶边界的实验研究

目的探讨超高速剪切波弹性成像（SWE）在定量评估肝脏微波消融边界中的可行性与准确性。 方法取健康雄性5月龄五指山猪15只，行开腹直视下肝脏微波消融术，消融功率选定40 W，根据消融时间分设为15 s、30 s、60 s三组。消融后即刻采用SWE测量消融灶的弹性模量值。术后利用HE染色、烟酰胺腺嘌呤二核苷酸（NADH）黄递酶组织化学染色评估肝组织的损伤程度。 结果本实验共进行有效消融156次，有效SWE测量740次，得到有效病理结果131个。消融灶弹性模量值呈阶梯式同心圆分布，从中心向外周可分为3个区域。同一消融时间下弹性模量值在周边正常组织区域、消融边界区域、消融中心区域阶梯式增高（P均<0.01）。消融功率40 W，消融时间15 s、30 s、60 s在周边正常组织区域和消融边界区域的弹性模量值差异无统计学意义（P均>0.05），但在消融中心区域，其弹性模量值随消融时间的缩短而呈阶梯式降低，［60 s：（97.16±14.58）kPa>30 s：（77.84±9.64）kPa>15 s：（38.92±3.12）kPa］，差异有统计学意义（F=2 131.832，P<0.01）。不同消融时间的消融边界区域弹性模量值保持在22.68~23.56 kPa。 结论微波消融灶消融边界区域弹性模量值范围相对固定，SWE有助于定量评估肝脏微波消融边界，其在超声消融的监测与评估方面具有较强的实用价值。