Delineation of Post-Procedure Ablation Regions with Electrode Displacement Elastography with a Comparison to Acoustic Radiation Force Impulse Imaging

We compared a quasi-static ultrasound elastography technique, referred to as electrode displacement elastography (EDE), with acoustic radiation force impulse imaging (ARFI) for monitoring microwave ablation (MWA) procedures on patients diagnosed with liver neoplasms. Forty-nine patients recruited to this study underwent EDE and ARFI with a Siemens Acuson S2000 system after an MWA procedure. On the basis of visualization results from two observers, the ablated region in ARFI images was recognizable on 20 patients on average in conjunction with B-mode imaging, whereas delineable ablation boundaries could be generated on 4 patients on average. With EDE, the ablated region was delineable on 40 patients on average, with less imaging depth dependence. Study of tissue-mimicking phantoms revealed that the ablation region dimensions measured on EDE and ARFI images were within 8%, whereas the image contrast and contrast-to-noise ratio with EDE was two to three times higher than that obtained with ARFI. This study indicated that EDE provided improved monitoring results for minimally invasive MWA in clinical procedures for liver cancer and metastases.     

Physiological Motion Reduction Using Lagrangian Tracking for Electrode Displacement Elastography

Minimally invasive treatments such as microwave ablation (MWA) have been growing in popularity for extending liver cancer survival rates in patients, when surgery is not an option. As a non-ionizing, real-time alternative to contrast-enhanced computed tomography, electrode displacement elastography (EDE) has shown promise as an imaging modality for MWA. Despite imaging efficacy, motion artifacts caused by physiological motion result in unintended speckle pattern variance, thereby inhibiting consistent and accurate ablated region visualization. To combat these unavoidable motion artifacts, a Lagrangian deformation tracking (LDT) approach based on freehand EDE was developed to track tissue movement and better define tissue properties. For validating LDT efficacy, a spherical inclusion phantom as well as seven in vivo data sets were processed, and strain tensor images were compared with identical time sampled images estimated using a traditional Eulerian approach. In vivo results revealed greater consistency among visualized LDT strain tensor images, with segmented ablated regions exhibiting standard deviation reductions of up to 98% when compared with Eulerian strain tensor images. Additionally, Lagrangian strain tensor images provided Dice coefficient improvements up to 25%, and success rates improved from approximately 50% to nearly 100% for ablated region visualization.     

超声引导下微波消融治疗甲状腺乳头状癌颈部转移性淋巴结的价值分析

目的 探讨超声引导下微波消融治疗甲状腺乳头状癌颈部转移性淋巴结的安全性及有效性。方法 回顾性分析2017年7月至2020年10月于我院行微波消融治疗的20例甲状腺乳头状癌颈部转移性淋巴结患者,共36枚淋巴结。比较微波消融前后病灶最大径、体积、体积缩小率及血清Tg等生化指标的改变,分析不同消融功率对病灶最大径、体积及体积缩小率的影响。结果 20例患者均成功接受微波消融治疗,整个消融过程未见明显严重并发症,消融术后1例患者出现低钙血症,但于术后1周恢复正常。微波消融术后1个月病灶最大径、体积较消融前略增大,差异无统计学意义(P＞0.05)。在随后的3,6,12,18及24个月时病灶最大径、体积均较术前显著减小,差异均具有统计学意义(P＜0.05)。微波消融术后血清Tg水平较消融前降低,差异具有统计学意义(P＜0.05)。不同消融功率下病灶最大径、体积及体积缩小率均未见明显差异(P＞0.05)。结论 超声引导下微波消融治疗甲状腺乳头状癌颈部转移性淋巴结安全、有效,对手术风险较大及拒绝手术治疗的患者不失为一种良好的替代治疗方法。     

Comparison of Displacement Tracking Algorithms for in Vivo Electrode Displacement Elastography

Hepatocellular carcinoma and liver metastases are common hepatic malignancies presenting with high mortality rates. Minimally invasive microwave ablation (MWA) yields high success rates similar to surgical resection. However, MWA procedures require accurate image guidance during the procedure and for post-procedure assessments. Ultrasound electrode displacement elastography (EDE) has demonstrated utility for non-ionizing imaging of regions of thermal necrosis created with MWA in the ablation suite. Three strategies for displacement vector tracking and strain tensor estimation, namely coupled subsample displacement estimation (CSDE), a multilevel 2-D normalized cross-correlation method, and quality-guided displacement tracking (QGDT) have previously shown accurate estimations for EDE. This paper reports on a qualitative and quantitative comparison of these three algorithms over 79 patients after an MWA procedure. Qualitatively, CSDE presents sharply delineated, clean ablated regions with low noise except for the distal boundary of the ablated region. Multilevel and QGDT contain more visible noise artifacts, but delineation is seen over the entire ablated region. Quantitative comparison indicates CSDE with more consistent mean and standard deviations of region of interest within the mass of strain tensor magnitudes and higher contrast, while Multilevel and QGDT provide higher CNR. This fact along with highest success rates of 89% and 79% on axial and lateral strain tensor images for visualization of thermal necrosis using the Multilevel approach leads to it being the best choice in a clinical setting. All methods, however, provide consistent and reproducible delineation for EDE in the ablation suite.     

Evaluation of Microwave Ablation Efficacy by Strain Elastography and Shear Wave Elastography in ex Vivo Porcine Liver

The aim of this study was to evaluate the efficacy of microwave ablation by ultrasound (US), strain elastography (SE) and shear-wave elastography (SWE). An ex vivo model of porcine liver was adopted. According to ablation power and duration, 30 samples were divided into three groups: group 1 (45 W, 30 s), group 2 (45 W, 15 s) and group 3 (30 W, 30 s). US was used to measure the largest transverse diameter (D1), vertical diameter (D2) and anteroposterior diameter (D3) of the ablated area. SE was used to measure the largest transverse diameter (SEL1), vertical diameter (SEL2) and anteroposterior diameter (SEL3). The actual size of the ablated area was measured as the largest transverse diameter (L1), vertical diameter (L2) and anteroposterior diameter (L3). SWE values and temperatures were measured in the central lesion (region a), marginal area (region b) and unablated area (region c). At 1 h post-ablation, the values measured by US (D1, D2, D3) were all significantly smaller than the ablated area (L1, L2, L3) in all three groups. Except for SEL2 in group 1, there was no significant difference in the results between SEL and L among the three groups. All SWE results were significantly higher post-ablation than pre-ablation in the central lesion (region a) and marginal area (region b, all p values <0.05). In regions a, b and c, the temperatures measured immediately and 5 min post-ablation were all higher than that measured pre-ablation. These results suggest that SE and SWE can be used to evaluate the ablation efficacy of liver tissue.     

Early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma: utility of gray scale harmonic ultrasonography with a microbubble contrast agent.

OBJECTIVE: To evaluate the utility of gray scale harmonic ultrasonography with a microbubble contrast agent in the early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma. METHODS: Seventy-five patients with 81 nodular hepatocellular carcinomas (1.3-4.8 cm) treated with percutaneous radio frequency ablation were evaluated with contrast-enhanced gray scale harmonic ultrasonography after intravenous bolus injection of a galactose-based microbubble contrast agent. The vascularity within the ablation zones was evaluated with a continuous scan for 3 to 5 seconds between 15 and 30 seconds after initiation of contrast agent injection. To evaluate the perfusion of the ablation zones, intermittent stimulated acoustic emission imaging was performed with a rapid sweeping technique from the end of the continuous scan. All patients underwent follow-up 3-phase helical computed tomography at 1 month after radio frequency ablation and were followed for at least 1 year. The results of contrast-enhanced ultrasonography were compared with those of follow-up computed tomography in terms of the presence or absence of residual unablated tumors. RESULTS: In 10 (12%) of the 81 treated hepatocellular carcinomas, contrast-enhanced ultrasonography showed either nodular or crescentic enhancing foci at the margins of ablation zones, suggesting residual unablated tumors. Contrast-enhanced computed tomography obtained 1 month after radio frequency ablation confirmed the residual unablated tumors in the same 10 lesions. Diagnostic agreement between 1-month follow-up computed tomography and contrast-enhanced ultrasonography was achieved in all 81 cases (100%). CONCLUSIONS: Contrast-enhanced gray scale harmonic ultrasonography can be a reliable alternative to contrast-enhanced computed tomography in the early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma.     

CT引导下两种消融方法治疗非手术性肺部恶性肿瘤的临床研究

目的评估射频消融及微波消融两种方法,对比在非手术性肺内恶性肿瘤（包括原发性无法手术的肺癌、肺部转移癌或复发性肺癌）的临床疗效。方法2006年10月至2010年10月无法手术的肺内恶性肿瘤患者120例,其中男90例,女30例;年龄42～76岁,平均55岁。随机分为射频消融组（RFA）75例,微波消融组（MWA）45例。对比研究两组治疗前后癌肿cT下治疗情况,及两组治疗效果的差异。结果两组患者在直径〈3cm的患者中,RFA组定位时间较MWA组短,差异有统计学意义（P〉0．05）;在直径〉5cm的患者中,RFA组治疗时间较MWA组短,差异有统计学意义（P〉0．05）;直径〉3cm而〈5cm的患者中,两组定位时间及治疗时间比较差异无统计学意义（P〈0．05）。结论采用射频消融及微波消融治疗无法手术治疗的肺内恶性肿瘤患者,两种方法疗效可靠;射频消融定位时间较短,有利于治疗肿瘤较大的患者。     

Assessment of therapeutic response in hepatocellular carcinoma treated with percutaneous radio frequency ablation: comparison of multiphase helical computed tomography and power Doppler ultrasonography with a microbubble contrast agent.

OBJECTIVE: To compare the results of multiphase helical computed tomography and power Doppler ultrasonography with a microbubble contrast agent in the assessment of the therapeutic response to radio frequency ablation in hepatocellular carcinoma. METHODS: In 66 patients with 73 nodular hepatocellular carcinomas ranging from 1.0 to 4.0 cm (mean, 2.6 cm) in diameter, contrast-enhanced power Doppler ultrasonography was performed after intravenous bolus injection of a galactose-based microbubble contrast agent before and after radio frequency ablation. The results of the studies were compared with the findings of follow-up 3-phase helical computed tomography. All patients were regularly followed up with computed tomography for more than 1 year (range, 13-19 months). RESULTS: In 8 (11%) of 73 hepatocellular carcinomas, immediate follow-up computed tomography obtained within 2 hours after radio frequency ablation showed focal enhancing portions within the treated lesions, suggesting residual non-necrotic tumors. All 8 of these tumors had intratumoral flow signals on contrast-enhanced power Doppler ultrasonography. The diagnostic agreement between computed tomography and contrast-enhanced power Doppler ultrasonography was achieved in 100%. Among the remaining 65 hepatocellular carcinomas with the absence of residual tumors at both immediate follow-up computed tomography and contrast-enhanced power Doppler ultrasonography, subsequent follow-up computed tomography showed local regrowth at the margins of 10 lesions (15%). CONCLUSIONS: The results of contrast-enhanced power Doppler ultrasonography closely correlated with those of immediate follow-up computed tomography for detecting residual tumors in hepatocellular carcinomas treated with radio frequency ablation. Both techniques, however, showed a limitation in detecting small or microscopic residual tumors and in predicting local regrowth in the treated lesions.     

CEUS Versus MRI in Evaluation of the Effect of Microwave Ablation of Breast Cancer

Percutaneous microwave ablation (MWA) is a new minimally invasive technique for breast cancer treatment. The aim of this research was to compare the differences in performance between contrast-enhanced ultrasound (CEUS) and magnetic resonance imaging (MRI) with respect to the curative effect of MWA in the treatment of breast cancer. Between 2015 and 2019, 26 patients with breast cancer underwent ultrasound-guided MWA. All patients underwent both CEUS and MRI within 3 d after ablation. If either of the two imaging modalities revealed suspicious enhancement of the ablation zone and the ultrasound-guided biopsy confirmed residual tumor in the suspicious area, supplementary MWA was applied. The diagnostic efficacy of CEUS and MRI within 3 d after ablation was evaluated based on a >6-mo follow-up of 26 patients. Two cases were diagnosed with residual tumors by ultrasound that were missed by MRI. Three cases were diagnosed with residual tumors by MRI that were missed by CEUS. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of CEUS in the diagnosis of complete ablation were 100%, 40%, 87.5%, 100% and 88.5%, respectively. The sensitivity, specificity, PPV, NPV and accuracy of MRI in the diagnosis of complete ablation were 100%, 60%, 91.3%, 100% and 92.3%, respectively. Within 3 d, both CEUS and MRI can efficiently assess the efficacy of MWA of breast cancer.     

Role of Echocardiography in Pulmonary Vein Ablation for Atrial Fibrillation

Pulmonary vein ablation is increasingly used for patients with difficult to manage atrial fibrillation. Echocardiography plays a central role in the assessment of patients undergoing ablation therapy, not only in the pre-ablation patient selection and post-ablation assessment, but also in the peri-procedural guidance. Newer echocardiographic techniques including atrial mechanics measurements are also reviewed.     

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.     

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。     

实时剪切波弹性成像评估乳腺良性结节微波消融效果的价值探讨

目的探讨实时剪切波弹性成像(SWE)技术在评估乳腺良性结节微波消融效果的应用价值。方法选取23例乳腺良性结节患者(共25个结节),分别于行微波消融治疗前后行常规超声、超声造影及SWE检查,比较超声造影与SWE显示的有效消融区横切面及纵切面最大径,以及消融前后消融区的杨氏模量值,包括最大弹性值(E_(max))、平均弹性值(E_(mean))、弹性标准差(E_(sd))及病灶与正常脂肪组织弹性比(E_(ratio))。结果微波消融术后,超声造影显示有效消融区无造影剂灌注;SWE显示消融区以红黄相间的不均匀彩色改变为主,与周围组织分界清晰,两种方法获得的消融区横切面及纵切面最大径比较差异均无统计学意义。消融区杨氏模量值(E_(max)、E_(mean)、E_(sd)及E_(ratio))均较术前显著增加,差异均有统计学意义(均P0.01)。结论 SWE可较准确地反映乳腺结节微波消融术后的消融范围,并能够定量分析消融区硬度变化,有望成为无创、有效评价消融效果的方法。     

Changes in Doppler parameters of portal pressure after interventional management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has many options for management; some of them are complicated by development of portal hypertension (PHT). Doppler ultrasound is an effective method to diagnose and monitor PHT changes after HCC ablation procedures. The aim of this study is to investigate changes in portal pressure hemodynamics of HCC patients following treatment with different interventional strategies: radiofrequency ablation (RFA), microwave ablation (MWA), and transarterial chemoembolization (TACE). A total of 60 patients with HCC were divided into three main groups, and each group received a different type of therapy (RFA, MWA, and TACE). Full medical record and basic investigations were performed including Doppler ultrasound and upper GIT endoscopy for evaluation of PHT parameters, and then repeated after three months of ablation. RFA is associated with the increased splenic artery resistive index, while MWA has no significant impact on PHT indices. TACE has led to a marked increase in liver vascular index with significant decrease in hepatic artery resistive index and PHI after treatment. No significant changes in esophageal varices were observed by upper GIT endoscopy following all ablation methods. RFA is quite safe but associated with degree of PHT. On the contrary, TACE is associated with improved PHT parameters. MWA has no significant association to development of PHT following the technique. Doppler ultrasound could be used as a reliable and effective method of evaluation of PHT post ablation for HCC.     

Small hepatocellular carcinoma: therapeutic effectiveness of percutaneous radio frequency ablation therapy with a LeVeen needle electrode.

OBJECTIVE: To evaluate the therapeutic effectiveness of percutaneous radio frequency ablation of small (< or =3-cm) hepatocellular carcinoma with a LeVeen needle electrode. METHODS: Thirty patients (mean age, 65.7 years) with 32 hepatocellular carcinomas (range, 1.2-3.0 cm; mean, 2.3+/-0.5 cm) underwent percutaneous radio frequency ablation to the center of the hepatocellular carcinoma after expansion of the inner needles. The manufacturer's recommended radio frequency ablation protocol was used. Posttreatment contrast-enhanced color Doppler sonography, contrast-enhanced computed tomography, and fine-needle biopsy were performed to assess the radio frequency ablation-induced coagulated necrosis. RESULTS: Severe intratreatment pain made us abort radio frequency ablation in 2 patients. Complete tumor necrosis was achieved in 1 treatment session with 1 needle electrode insertion in 28 (93.4%) of 30 nodules (28 patients). We found no residual focus on both color Doppler sonography and computed tomography after any of the sessions. In follow-ups ranging from 3 to 15 months (mean, 8.4 months), no local recurrence was found in cases with complete tumor ablation. CONCLUSIONS: Radio frequency ablation with the LeVeen needle electrode was effective, obtaining complete coagulated necrosis with a safety margin when used for the treatment of small hepatocellular carcinomas.     

Ablation of large HCCs using a new saline-enhanced expandable radiofrequency device

PurposeEvaluation of a new device designed to achieve large volumes of necrosis in hepatocellular carcinoma (HCC) nodules by application of radiofrequency ablation (RFA).Materials and Methods29 consecutive patients with 31 HCC nodules ≥3 cm in diameter (range 3–7.5 cm; mean diameter 5.5 cm) underwent ultrasound (US) guided percutaneous RFA using an expandable electrode with 7 active arrays and saline injection designed to create tissue ablation in areas of up to 7 cm (Starburst XLi-enhanced RFA device). Treatment was performed in general anesthesia (6 patients) or deep sedation (23 patients). Treatment efficacy was assessed by three-phase contrast-enhanced computed tomography (CT) and bimonthly US follow-up.ResultsOne to three electrode insertions (mean number 1.6) were performed in each patient. CT showed complete necrosis in 23/31 HCC nodules (74%) in 22 patients. Follow-up of these 22 patients ranged from 2 to 15 months (mean time 8.3 months). In 6/22 patients (28%) intrahepatic recurrence occurred within 5–10 months (mean time 8.3 months). Major complications were post-ablation syndrome in 7/29 (24%), peritoneal effusion in 4/29 (14%), pleural effusion in 2/29 (7%) and transient obstructive jaundice in 1/29 (3.4%) patients. One patient died 6 months after treatment because of tumor progression.ConclusionsIn the treatment of large HCC nodules, Starburst XLi-enhanced is an effective and safe device.     

超声引导下经皮微波消融治疗肝细胞性肝癌术后复发灶远期疗效评估

目的评价肝细胞性肝癌(hepatic cellular carcinoma,HCC)手术后复发灶(直径≤5 cm)超声引导下经皮微波消融(microwave ablation,MWA)治疗的远期疗效及其影响因素。方法 2005年5月~2011年12月,89例HCC复发患者行经皮微波消融治疗。所有HCC复发患者在MWA治疗后1个月均行超声造影、增强CT或者增强磁共振检查;以及血生化检查,包括血清甲胎蛋白(AFP)、肝功能等。结果消融治疗1个月后,病灶完全消融率91%(81/89)。HCC经皮MWA治疗后,1、3、5、7年生存率分别为73.3%、53.7%、39.6%、17.3%。肿瘤大小(P=0.046)、肿瘤数目(P=0.001)、Child-Pugh分级(P=O.023)、AFP水平(P=0.003)以及HCC早期复发(≤1年)(P=0.013)为总体生存率的单因素回归分析的危险预后因素。肿瘤数目(P=0.000)、Child-Pugh分级(P=0.000)和AFP水平(P=0.001)是HCC经皮MWA治疗后总体生存率重要的独立危险因素。结论经皮MWA对于肝细胞性肝癌切除术后复发灶是有效、安全的治疗方法 。     

Therapeutic response evaluation of malignant hepatic masses treated by interventional procedures with contrast-enhanced agent detection imaging.

OBJECTIVE: To assess the usefulness of microbubble contrast-enhanced agent detection imaging in evaluating the therapeutic response of malignant hepatic masses to treatment with interventional procedures. METHODS: Fifty-eight patients with 68 hepatocellular carcinomas and 6 metastases who were treated with interventional procedures were evaluated with SH U 508A-enhanced agent detection imaging and helical computed tomography. Helical computed tomography was also performed to help establish the outcome of therapy with unenhanced computed tomography 2 weeks after transcatheter arterial chemoembolization and with dynamic contrast-enhanced computed tomography 1 day after radio frequency ablation or percutaneous ethanol injection. The studies were reviewed separately and randomly, and the sensitivity and specificity of agent detection imaging for detection of viable tumor residue were determined by follow-up imaging performed at least 3 months later. RESULTS: Follow-up computed tomography or magnetic resonance imaging revealed complete tumor responses in 44 (59.5%) of 74 cases after the therapeutic procedures. The sensitivity of agent detection imaging was 94.7% after transcatheter arterial chemoembolization and 72.7% after radio frequency ablation and percutaneous ethanol injection. The specificity of agent detection imaging for the detection of residual tumors was 80% after transcatheter arterial chemoembolization and 79.2% after radio frequency ablation and percutaneous ethanol injection. The false-positive rate for agent detection imaging in cases of radio frequency ablation or percutaneous ethanol injection was 20.8% (5 of 24), resulting from reactive hyperemia or vascularity within the safety margin. In the assessment of the therapeutic effects, the concordance of contrast-enhanced agent detection imaging with helical computed tomography was statistically significant after transcatheter arterial chemoembolization (P < .00001) and radio frequency ablation or percutaneous ethanol injection (P < .02). CONCLUSIONS: Contrast-enhanced agent detection imaging proved useful and as effective as helical computed tomography for evaluating the therapeutic effects of interventional therapeutic procedures for malignant hepatic masses.     

热消融治疗肿瘤的研究进展

伴随现代医学成像技术的快速发展,影像引导热消融技术在越来越多的肿瘤治疗中发挥着不可替代的作用。本文综述了热消融技术的基本细胞学机制,介绍了五种最常见的热消融技术——射频消融（Radiofrequency Ablation, RFA）、微波消融（Microwave Ablation, MWA）、冷冻消融（Cryoablation, CA）、高强度聚焦超声（High-intensity Focused Ultrasound, HIFU）、激光消融（Laser Ablation, LA）,包括各自的基本原理和优缺点,以期指导临床热消融技术的进一步推广和应用。     

超声造影评估肝脏肿瘤微波消融边界的研究进展

微波消融（microwave ablation，MWA）以其微创、疗效好等特点已广泛应用于肝脏肿瘤的治疗，而消融未达到安全边界会造成治疗不彻底的后果，容易引起肿瘤复发，因此消融术后评估消融边界（ablation margin，AM）是治疗中不可或缺的环节。而超声造影（contrast-enhanced ultrasound，CEUS）具有经济、实时、无放射性、无肾毒性等优点，可作为评估AM的重要方法。本文就超声造影评估肝脏肿瘤微波消融边界的研究进展做一综述。