肝脏剪切波弹性成像影响因素的研究进展

剪切波弹性成像可通过探测组织内剪切波传播速度定量反映组织硬度,可用于无创评估肝纤维化。纤维化程度被认为是影响肝脏弹性的重要影响因素,但随着研究的深入,发现还有诸多因素对肝脏弹性测值准确性有影响。本文对炎症、脂肪肝、胆汁淤积、肝脏淤血、进食、呼吸、肥大细胞增多症、性别和年龄、测量深度和次数对肝脏剪切波弹性成像的影响进行综述。     

弹性成像5分评分法与应变率比值法鉴别诊断肝脏良恶性病变

目的 比较弹性成像5分评分法与应变率比值法对肝脏良恶性病变的鉴别诊断价值。 方法 对165例患者(共183个肝脏局灶性病变)进行肝脏弹性成像检查,分别对病灶进行弹性评分及应变率比值测定。以病理结果作为金标准,构建ROC曲线并计算曲线下面积,分别计算弹性评分法和应变率比值用于鉴别诊断肝脏良恶性肿瘤的敏感度、特异度、准确率、阳性预测值和阴性预测值;比较两种方法对肝脏局灶性病变的诊断效能。 结果 采用应变率比值鉴别诊断肝脏良恶性病灶时,曲线下面积为0.85;采用弹性评分时,曲线下面积为0.82,二者差异无统计学意义(P=0.14)。应变率比值诊断肝脏良恶性肿瘤的敏感度、特异度、准确率、阳性预测值及阴性预测值分别为71.26%(62/87)、91.67%(88/96)、81.97%(150/183)、88.57%(62/70)、77.88%(88/113);弹性评分诊断肝脏恶性肿瘤的敏感度、特异度、准确率、阳性预测值及阴性预测值分别为88.51%(77/87)、60.42%(58/96)、73.77%(135/183)、66.96%(77/115)、85.29%(58/88)。应变率比值法的特异度高于弹性评分法(P<0.05),但其敏感度较低(P<0.05),二者准确率差异无统计学意义(P>0.05),二者诊断能力的差异主要体现在弹性评分为3分的病灶中。 结论 应用弹性成像鉴别诊断肝脏局灶性病变的良恶性时,应变率比值法及弹性评分法各有优缺点,在临床应用中应结合具体情况选择合理方法。     

Three-dimensional electrode displacement elastography using the Siemens C7F2 fourSight four-dimensional ultrasound transducer

Because ablation therapy alters the elastic modulus of tissues, emerging strain imaging methods may enable clinicians for the first time to have readily available, cost-effective, real-time guidance to identify the location and boundaries of thermal lesions. Electrode displacement elastography is a method of strain imaging tailored specifically to ultrasound-guided electrode-based ablative therapies (e.g., radio-frequency ablation). Here tissue deformation is achieved by applying minute perturbations to the unconstrained end of the treatment electrode, resulting in localized motion around the end of the electrode embedded in tissue. In this article, we present a method for three-dimensional (3D) elastographic reconstruction from volumetric data acquired using the C7F2 fourSight four-dimensional ultrasound transducer, provided by Siemens Medical Solutions USA, Inc. (Issaquah, WA, USA). Lesion reconstruction is demonstrated for a spherical inclusion centered in a tissue-mimicking phantom, which simulates a thermal lesion embedded in a normal tissue background. Elastographic reconstruction is also performed for a thermal lesion created in vitro in canine liver using radio-frequency ablation. Postprocessing is done on the acquired raw radio-frequency data to form surface-rendered 3D elastograms of the inclusion. Elastographic volume estimates of the inclusion compare reasonably well with the actual known inclusion volume, with 3D electrode displacement elastography slightly underestimating the true inclusion volume.     

超声弹性分级与应变率比值鉴别诊断甲状腺微小结节

目的 评价超声弹性成像分级与弹性应变率比值法对直径≤1 cm甲状腺微小结节的诊断价值。方法 对手术病理证实的55例患者的72个直径≤1 cm甲状腺结节的超声弹性图像进行分析,弹性分级分为4级,计算甲状腺组织与结节的弹性应变率比值。分别绘制弹性分级法及弹性应变率比值法的ROC曲线,评价其诊断价值。结果 甲状腺良、恶性结节的超声弹性分级及弹性应变率比值差异均有统计学意义(P<0.001)。超声弹性分级及弹性应变率比值判断甲状腺占位性病灶的ROC曲线下面积分别为0.851、0.890(P=0.124)。甲状腺良、恶性小结节弹性应变率比值诊断界值为2.85。结论 超声弹性分级法同弹性应变率比值法均能够有效地鉴别诊断甲状腺微小结节的性质。     

SE-EPI磁共振弹性成像评价肝硬化食管胃底静脉曲张

目的 探讨SE-EPI磁共振弹性成像(MRE)评价肝硬化患者食管胃底静脉曲张(GEV)程度的价值。方法 对89例肝硬化患者行SE-EPI序列MRE扫描、实验室及胃镜检查。以胃镜检查GEV程度为金标准,对诊断GEV、轻/中重度GEV的可能影响因素进行判定,并进行GEV分级与影响因素的相关性分析。结果 脾容积及肝、脾弹性值均为诊断GEV的独立影响因素,诊断比值比分别为1.02(95%CI 1.01~1.03)、2.37(95%CI 1.50~3.75)及2.76(95%CI 1.59~4.82,P均<0.01)。仅脾弹性值为鉴别轻度与中重度GEV的独立影响因素,诊断比值比为2.42(95%CI 1.71~3.43,P<0.01)。GEV分级与血小板与天冬氨酸氨基转移酶比值指数、肝弹性值具有中等程度相关性(r=0.42、0.55,P均<0.001),与脾弹性值、脾容积具有较高相关性(r=0.77、0.60,P均<0.001)。结论 SE-EPI MRE是一种简单、无创的评估GEV的方法。     

基于磁共振弹性成像技术的肝纤维化分级方案

目的 探讨一种基于磁共振弹性成像技术的肝纤维化分级方案.方法 在介绍磁共振弹性成像原理和生物力学模型的基础上,讨论肝脏磁共振弹性成像需要考虑的关键技术和细节.结果 给出了具体可行的研究方案与实验步骤.结论 研究方案与实验步骤具有可操作性,动物体模预临床研究可弥补临床难以获取整个纤维化程度的缺陷.     

超声弹性成像观察正常成年女性乳腺组织

目的 探讨超声弹性成像在正常成年女性乳腺组织中的应用.方法 收集41名正常成年女性,根据年龄分为青年组(11名)、中青年组(10名)、中年组(10名)和老年组(10名),以弹性成像技术观察乳腺组织,采用乳腺整体5分评分法测量乳腺的皮下脂肪层、腺体层(中央区、内带、中带和外带)和胸壁肌层的弹性成像评分.结果 弹性评分:脂肪组织＜腺体层＜胸壁肌层.腺体层的弹性评分随年龄增加而增大(P＜0.05),而脂肪层和胸壁肌层的弹性评分不受年龄影响.除青年组外,乳腺中央区的弹性评分低于其他分区(P＜0.05),而内带、中带与外带间的弹性评分差异无统计学意义.结论 采用弹性成像技术可以很好地评判正常成年女性乳腺组织的硬度,半定量评价不同年龄段女性乳腺组织的差异.     

Liver Fibrosis Assessment Using Transient Elastography Guided with Real-Time B-mode Ultrasound Imaging: A Feasibility Study

Liver fibrosis is a kind of chronic damage of the liver and can lead to cirrhosis, one of the top 10 causes of death in the Western world. However, there is still a lack of noninvasive methods for diagnosing liver fibrosis. Fibroscan (Echosens, Paris, France), a device based on A-mode transient elastography, has shown promising results. In this study, a transient elastography system with real-time B-mode imaging for non-invasive liver fibrosis assessment, named Liverscan, was developed; its performance was tested and compared with that of the Fibroscan. A specific measurement probe was designed and fabricated with a B-mode ultrasound transducer fixed along the axis of a mechanical vibrator. It was integrated with the Liverscan to measure liver stiffness based on the shear wave propagation in liver tissues. The system was validated by mechanical indentation test using custom-made agar-gelatin phantoms with different stiffness. To further test its feasibility, in vivo measurements were conducted in 67 volunteers (age, 34 ± 3 years; body mass index, 21.3 ± 2.8 kg/m²; Mean ± SD., 34 male and 33 female), including 20 patients with various liver diseases, and 28 (19 male and 9 female) being tested by both Liverscan and Fibroscan. A significant linear correlation between the stiffness measured by the mechanical indentation test and that by the Liverscan (r = 0.973; p < 0.001) was obtained. The in vivo liver stiffness measured by Liverscan was also correlated with that by Fibroscan significantly (r = 0.886; p < 0.001). There was a significant difference in liver stiffness between the 20 patients and the other healthy subjects (14.1 ± 3.4 kPa vs. 10.5 ± 2.1 kPa; p = 0.001). The intra- and inter-observer tests indicated that the measurements were repeatable with intra-class correlation coefficients being 0.987 (p < 0.001) and 0.988 (p < 0.001), respectively. This study demonstrated that Liverscan with a specifically designed probe was able to measure and differentiate liver of different stiffness using the established measurement protocol under the guidance of real-time B-mode ultrasound imaging.     

超声弹性成像在子宫内膜病变中的研究进展

子宫内膜病变是女性常见的妇科疾病,包括黏膜下肌瘤、子宫内膜息肉、子宫内膜增生和子宫内膜癌等。子宫内膜增生是癌前病变,早期诊断可有效降低恶变率。超声弹性成像现已逐渐应用于妇科领域。本文对超声弹性成像的分类、原理及其在子宫内膜病变诊断中的应用进展进行综述。     

利用剪切波弹性成像监控肝脏温度变化的实验研究

目的 进行利用剪切波弹性成像（Shear wave elastography,SWE）监控肝脏温度变化的实验研究,以探讨SEW是否可用于肝肿瘤光热消融治疗时正常肝脏组织温度值的精准评价。方法 以水浴法对新鲜离体猪肝进行加热。利用SWE结合肝组织病理切片分析肝组织自35℃升温至85℃时的组织硬度值;利用SWE结合肝组织病理切片分析肝组织维持一定温度10分钟后组织硬度值的变化。结果 在55℃～85℃时,肝组织硬度值随温度增高而增加,各温度组间比较有统计学差异（P<0.05）,肝组织病理切片有明显变化。当肝组织温度为55-80时,肝组织维持温度值10分钟前后肝组织硬度值比较均无统计学差异（P>0.05）,肝组织病理切片有明显变化。结论 肝组织温度值为55℃～80℃时,可以通过SWE测量肝组织硬度值这一参数精确评价光热治疗时正常肝组织的温度值变化。     

Liver Ultrasound Elastography: An Update to the World Federation for Ultrasound in Medicine and Biology Guidelines and Recommendations

The World Federation for Ultrasound in Medicine and Biology has produced these guidelines for the use of elastography techniques in liver diseases. For each available technique, the reproducibility, results and limitations are analyzed, and recommendations are given. This set of guidelines updates the first version, published in 2015. Since the prior guidelines, there have been several advances in technology. The recommendations are based on the international published literature, and the strength of each recommendation is judged according to the Oxford Centre for Evidence-Based Medicine. The document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of liver diseases.     

Quantitative Assessment of Skin Stiffness Using Ultrasound Shear Wave Elastography in Systemic Sclerosis

This study was aimed at investigating the performance of ultrasound shear wave elastography (US-SWE) in the assessment of skin (the dermis) stiffness in patients with systemic sclerosis (SSc). The thickness and elastic modulus of the skin were measured using US-SWE at 6 sites in 60 SSc patients and 60 healthy volunteers: the bilateral middle fingers and forearms and the anterior chest and abdomen. To evaluate clinical scores, the measurements were also extended to 17 skin sites in 30 patients. The diagnostic performance of US-SWE in the differentiation of SSc from healthy skin was determined by receiver operating characteristic (ROC) curve analysis, and the reliability of the measurement was evaluated with intra- and inter-class correlation coefficients. The results of US-SWE were compared with modified Rodnan skin thickness scores. Our results indicated that (i) the elastic modulus values were significantly higher in SSc patients than in controls, with or without normalization by skin thickness; (ii) receiver operating characteristic analysis revealed normalized US-SWE cutoff values with a very high accuracy for right and left fingers (areas under the curve?=?0.974 and 0.949), followed by left forearm (0.841), anterior abdomen (0.797), right forearm (0.772) and anterior chest (0.726); (iii) the reliability of US-SWE measurements was good for all examined sites with intra-observer correlation coefficients of 0.845–0.996 and inter-observer correlation coefficients of 0.824–0.985; and (iv) total scores of skin involvement determined at 17 sites (modified Rodnan skin thickness scores) correlated with skin stiffness (r?=?0.832) and thickness (r?=?0.736). In conclusion, US-SWE is a quantitative method with high specificity, sensitivity and reliability in the detection of SSc involvement. This non-invasive, real-time and operator-independent imaging technique could be an ideal tool for the assessment of SSc disease.     

Normal and shear strain estimation using beam steering on linear-array transducers

In current ultrasound elastography, only the axial component of the displacement vector is estimated and used to produce strain images. A method was recently proposed by our group to estimate both the axial and lateral components of a displacement vector following a uniaxial compression. Previous work evaluated the technique using both simulations and a mechanically translated phased array transducer. In this paper, we present initial results using beam steering on a linear array transducer attached to a commercial scanner to acquire echo signals for estimating 2-D displacement vectors. Single-inclusion and anthropomorphic breast phantoms with different boundary properties between the inclusion and background material are imaged by acquiring echo data along beam lines ranging from -15 degrees to 15 degrees relative to the compression direction. 1-D cross-correlation is used to calculate "angular displacements" in each acquisition direction, yielding axial and lateral components of the displacement vector. Strain tensor components are estimated from these displacements. Features on shear strain images generated for the inclusion phantom agree with those predicted using FEA analysis. Experimental results demonstrate the utility of this technique on clinical scanners. Shear strain tensors obtained using this method may provide useful information for the differentiation of benign from malignant tumors. For the linear array transducer used in this study, the optimum angular increment is around 3 degrees. However, more work is required for the selection of an appropriate value for the maximum beam angle for optimal performance of this technique.     

An Innovative Ultrasound Strain Elastographic Method for the Differential Diagnosis of Breast Tumors

In this monocentric perspective study examining 64 lesions (19 benign and 45 malignant), we tested an innovative ultrasound elastographic method for diagnosing breast tumors. A new region of control and a new index designating the strain ratio (SR) were used. A traditional ultrasound elastographic method was used as the control. The results indicated that the SR ratios of the benign and malignant groups were 0.25 ± 0.22 and 1.10 ± 1.53, respectively, and this difference was statistically significant. The area under the receiver operating characteristic curve of the SR ratio method was 0.95, the cutoff point was 0.37 and the sensitivity and specificity were 95.56% and 94.74%, respectively. The two receiver operating characteristic curves of the traditional method and the SR of the proposed method were significantly different, at a p value of 0.02. Compared with that of the traditional method, the SR obtained with the new method had a larger area under the receiver operating characteristic curve, sensitivity, specificity and objectivity.     

磁共振弹性成像与DWI诊断肝纤维化分期

目的 探讨磁共振弹性成像（MRE）与DWI诊断慢性肝病肝纤维化分期的价值。方法 37例慢性肝病患者均接受MRE与DWI（b=0、50、100、150、200、300、500、800 s/mm²）检查,分别测量肝组织弹性值与表观扩散系数（ADC）值,分析其与肝纤维化分期的相关性,采用受试者工作特征曲线（ROC）对二者诊断慢性肝病肝纤维化分期的效能进行比较。结果 肝弹性值、ADC值与肝纤维化分期呈线性相关（r=0.932、-0.606,P均<0.001）。不同肝纤维化分期弹性值、ADC值差异有统计学意义（F=39.701,P<0.001;F=5.031,P=0.003）。诊断肝纤维化≥F1、≥F2、≥F3期,MRE的ROC曲线下面积大于ADC值,且差异有统计学意义（P<0.05）;诊断F4期两者曲线下面积无统计学差异。弹性值诊断肝纤维化≥F1、≥F2、≥F3、F4期的临界值为2.80、3.11、3.66、3.99 kPa,ADC值诊断的临界值为1.16×10^-3 mm²/s、1.16×10^-3 mm²/s、1.03×10^-3 mm²/s、0.97×10^-3 mm²/s。结论 MRE对肝纤维化分期诊断价值优于DWI技术,而DWI对进展期肝纤维化及肝硬化有一定的诊断价值。     

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。     

超声弹性成像在儿童肝脏中的应用进展

目前,超声弹性成像在成人肝脏中的应用相对较多,且日趋规范,在儿童肝脏中亦有一些应用,主要集中在胆道闭锁及慢性肝病方面,在正常儿童肝脏中的研究亦有少量报道。本文就超声弹性成像在儿童肝脏中的应用及其研究进展进行综述。     

Magnetic resonance elastography: Non-invasive mapping of tissue elasticity

Magnetic resonance elastography (MRE) is a phase-contrast-based MRI imaging technique that can directly visualize and quantitatively measure propagating acoustic strain waves in tissue-like materials subjected to harmonic mechanical excitation. The data acquired allows the calculation of local quantitative values of shear modulus and the generation of images that depict tissue elasticity or stiffness. This is significant because palpation, a physical examination that assesses the stiffness of tissue, can be an effective method of detecting tumors, but is restricted to parts of the body that are accessible to the physician's hand. MRE shows promise as a potential technique for 'palpation by imaging', with possible applications in tumor detection (particularly in breast, liver, kidney and prostate), characterization of disease, and assessment of rehabilitation (particularly in muscle). We describe MRE in the context of other recent techniques for imaging elasticity, discuss the processing algorithms for elasticity reconstruction and the issues and assumptions they involve, and present recent ex vivo and in vivo results.     

Assessment of Diffuse Thyroid Disease by Strain Ratio in Ultrasound Elastography

The goal of this study was to explore the value of strain ratio from real-time elastography in the semi-quantitative assessment of diffuse thyroid disease. Fifty-one patients with primary hyperthyroidism, 70 with Hashimoto's thyroiditis, 8 with subacute thyroiditis and 43 with normal healthy thyroids were recruited to measure the strain ratio (SR) of thyroid tissue and sternocleidomastoid muscle (on the same side of the thyroid). SR values of all groups were subjected to statistical analysis. The SRs (mean ± standard deviation) of patients with hyperthyroidism, Hashimoto's thyroiditis and subacute thyroiditis were 2.30 ± 1.08, 7.04 ± 7.74 and 24.09 ± 13.56, respectively. The SR of the control group was 1.76 ± 0.54. SR values ranked in ascending order were control group < hyperthyroidism group < Hashimoto's thyroiditis group < subacute thyroiditis group. There were statistically significant (p < 0.05) differences in thyroid hardness between groups with different diffuse thyroid diseases. SR values of the hyperthyroidism and control groups did not statistically differ (p > 0.05). It is feasible to assess diffuse thyroid disease with strain ratios obtained with ultrasound elastography.     

Comparison of Two Different Ultrasound Devices Using Strain Elastography Technology in the Diagnosis of Breast Lesions Related to the Histologic Results

This study was conducted to provide evidence that elastograms of two different devices and different manufacturers using the same technical approach provide the same diagnoses. A total of 110 breast lesions were prospectively analysed by two experts in ultrasound, using the strain elastography function from two different manufacturers (Hitachi HI-RTE, Hitachi Medical Systems, Wiesbaden, Germany; and Siemens eSie Touch, Siemens Medical Systems, Erlangen, Germany). Results were compared with the histopathologic results. Applying the Bowker test of symmetry, no statistically significant difference between the two elastography functions of these two devices was found (p?=?0.120). The Cohen's kappa of k?=?0.591 showed moderate strength of agreement between the two elastograms. The two examiners yielded moderate strength of agreement analysing the elastograms (Hitachi HI-RTE, k?=?0.478; Siemens eSie Touch, k?=?0.441). In conclusion, evidence is provided that elastograms of the same lesion generated by two different ultrasound devices equipped with a strain elastography function do not significantly differ.