Qualitative pattern classification of shear wave elastography for breast masses: How it correlates to quantitative measurements

Objective

To determine the correlation of qualitative shear wave elastography (SWE) pattern classification to quantitative SWE measurements and whether it is representative of quantitative SWE values with similar performances.

Methods

From October 2012 to January 2013, 267 breast masses of 236 women (mean age: 45.12 ± 10.54 years, range: 21–88 years) who had undergone ultrasonography (US), SWE, and subsequent biopsy were included. US BI-RADS final assessment and qualitative and quantitative SWE measurements were recorded. Correlation between pattern classification and mean elasticity, maximum elasticity, elasticity ratio and standard deviation were evaluated. Diagnostic performances of grayscale US, SWE parameters, and US combined to SWE values were calculated and compared.

Results

Of the 267 breast masses, 208 (77.9%) were benign and 59 (22.1%) were malignant. Pattern classifications significantly correlated with all quantitative SWE measurements, showing highest correlation with maximum elasticity, r = 0.721 (P < 0.001). Sensitivity was significantly decreased in US combined to SWE measurements to grayscale US: 69.5–89.8% to 100.0%, while specificity was significantly improved: 62.5–81.7% to 13.9% (P < 0.001). Area under the ROC curve (A_z) did not show significant differences between grayscale US to US combined to SWE (P > 0.05).

Conclusion

Pattern classification shows high correlation to maximum stiffness and may be representative of quantitative SWE values. When combined to grayscale US, SWE improves specificity of US.     

Diagnostic performance of qualitative shear-wave elastography according to different color map opacities for breast masses

Purpose

To compare the diagnostic performance of qualitative shear-wave elastography (SWE) according to three different color map opacities for breast masses

Materials and methods

101 patients aged 21–77 years with 113 breast masses underwent B-mode US and SWE under three different color map opacities (50%, 19% and 100%) before biopsy or surgery. Following SWE features were reviewed: visual pattern classification (pattern 1–4), color homogeneity (E_homo) and six-point color score of maximum elasticity (E_col). Combined with B-mode US and SWE, the likelihood of malignancy (LOM) was also scored. The area under the curve (AUC) was obtained by ROC curve analysis to assess the diagnostic performance under each color opacity.

Results

A visual color pattern, E_homo, E_col and LOM scoring were significantly different between benign and malignant lesions under all color opacities (P < 0.001). For 50% opacity, AUCs of visual color pattern, E_col, E_homo and LOM scoring were 0.902, 0.951, 0.835 and 0.975. But, for each SWE feature, there was no significant difference in the AUC among three different color opacities. For all color opacities, visual color pattern and E_col showed significantly higher AUC than E_homo. In addition, a combined set of B-mode US and SWE showed significantly higher AUC than SWE alone for color patterns, E_homo, but no significant difference was found in E_col.

Conclusion

Qualitative SWE was useful to differentiate benign from malignant breast lesion under all color opacities. The difference in color map opacity did not significantly influence diagnostic performance of SWE.     

Value of adding shear wave elastography to routine breast ultrasound examination in assessment of solid breast lesions

Purpose

To assess the additional diagnostic value of share wave elastography in combination with B-mode ultrasound versus B-mode ultrasound alone in characterization of solid breast lesions.

Potential use of point shear wave elastography for the pancreas: A single center prospective study

Aim

Clinical use of point shear wave elastography for the liver has been established, however, few studies demonstrated its usefulness for the pancreas. A prospective study was conducted to clarify its feasibility for the pancreas and its usefulness for the identification of high risk group for pancreatic cancer.

Patients and methods

Consecutive eighty-five patients underwent point shear wave elastography for the pancreas. The success rate of shear wave velocity (SWV) measurement, that is the number of successful measurements over total 10 measurements, was recorded. The SWV of the pancreas measured at non-tumorous area was compared between patients with and without pancreatic cancer. Factors associated with high SWV were determined by logistic regression model.

Results

Sixty patients were included, of these 18 had pancreatic cancer. The success rate of 100% was achieved at the head, the body and the tail of the pancreas in 80%, 83%, and 68% of the patients, respectively. The success rate of ≥80% was achieved in 100%, 100%, and 96% of the patients, respectively. Although mean SWV of the pancreas harboring pancreatic cancer tended to be higher compared with that of the pancreas without cancer (1.51 ± 0.45 m/s vs 1.43 ± 0.28 m/s), they did not reach statistical significance. Multivariate analysis showed that increased amount of alcohol intake was associated with high SWV.

Conclusion

The SWV of the pancreas was measured with excellent success rate. However, tendency of higher SWV obtained from the pancreas harboring pancreatic cancer needed to be further investigated.     

超声弹性成像诊断乳腺癌的临床价值

目的分析超声弹性成像对乳腺癌的影像学表现,探讨超声弹性成像在乳腺癌诊断的价值。方法回顾性分析37例经病理证实的乳腺癌患者,超声弹性成像的诊断符合率。结果超声弹性成像诊断乳腺癌敏感性87.50%,特异性76.92%,准确性83.78%。结论超声弹性成像诊断乳腺癌有较高的临床价值。     

Quantitative assessment of liver fibrosis in chronic viral hepatitis C patients using shear wave elastography with elastography point quantification feature

Introduction

Hepatic fibrosis is the underlying pathological condition in chronic hepatitis C virus (HCV) infection. Shear wave elastography (SWE) with elastography point quantification (ElastPQ) feature is a recently developed method for measuring tissue elasticity.

弹性成像对超声引导乳腺肿块穿刺活检指导价值研究

目的探讨超声弹性成像对超声引导BI-RADS 4级乳腺肿块穿刺活检的指导价值。方法回顾性分析141例经超声引导下BI-RADS 4级乳腺肿块穿刺活检患者的临床资料。所有患者穿刺前均进行常规超声及弹性成像检查,以BI-RADS分级及弹性评分评价乳腺肿块的良恶性。结果 BI-RADS分级为4a级的阴性预测值(NPV)为89.6%,弹性评分≤3分的NPV为95.5%,两者比较,差异无统计学意义(P>0.05);BI-RADS分级为4b级的阳性预测值(PPV)为59.3%,弹性评分≥4分的PPV为85.3%,两者比较,差异有统计学意义(P<0.05);BI-RADS分级为4c级的PPV为89.7%,弹性评分≥4分的PPV为96.9%,两者比较,差异无统计学意义(P>0.05);BI-RADS分级≥4b级的PPV为72.0%,弹性评分≥4分的PPV为90.9%,两者比较,差异有统计学意义(P<0.05)。结论弹性评分<3分的4a级乳腺肿块可以短期随访观察;弹性评分为5分的4c级乳腺肿块建议直接手术治疗;对于良恶性难以鉴别的4b级乳腺肿块,超声弹性成像可以进一步提高其PPV,建议穿刺活检明确诊断。     

The application of Virtual Touch tissue quantification (VTQ) in diagnosis of thyroid lesions: A preliminary study

Objectives

Virtual Touch tissue quantification (VTQ) is a quantified ultrasound (US) acoustic radiation force impulse (ARFI) imaging method that provides numerical measurements (wave-velocity values) of tissue stiffness. The purpose of this study was to detect whether VTQ could be applied to differentiate between benign and malignant thyroid lesions.

Methods

Healthy subjects’ thyroid tissue and thyroid lesions were examined by VTQ to analyze their elasticity after conventional ultrasound. All the thyroid lesions were analyzed pathologically after surgery and correlated the VTQ values with the pathological results.

Results

The VTQ value of healthy thyroid tissue, the benign lesions, and the malignant lesions were 1.69 ± 0.41 m/s, 2.03 ± 0.42 m/s, and 3.10 ± 1.08 m/s, respectively. The VTQ value of the malignant lesions was higher than that of the healthy thyroid tissue and the benign lesions (both p < 0.001). The VTQ value of the benign lesions was higher than that of the healthy thyroid tissue (p < 0.001). With a cutoff value of 2.42 m/s, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for differentiating between the benign and the malignancy lesions were 80.00%, 89.23%, 87.05%, 69.56%, and 93.54%, respectively.

Conclusions

VTQ could provide quantitative elasticity measurements, which might play an important role in differentiating between benign and malignant thyroid lesions.     

Clinical application of qualitative assessment for breast masses in shear-wave elastography

Purpose

To evaluate the interobserver agreement and the diagnostic performance of various qualitative features in shear-wave elastography (SWE) for breast masses.

Materials and methods

A total of 153 breast lesions in 152 women who underwent B-mode ultrasound and SWE before biopsy were included. Qualitative analysis in SWE was performed using two different classifications: E values (Ecol; 6-point color score, Ehomo; homogeneity score and Esha; shape score) and a four-color pattern classification. Two radiologists reviewed five data sets: B-mode ultrasound, SWE, and combination of both for E values and four-color pattern. The BI-RADS categories were assessed B-mode and combined sets. Interobserver agreement was assessed using weighted κ statistics. Areas under the receiver operating characteristic curve (AUC), sensitivity, and specificity were analyzed.

Results

Interobserver agreement was substantial for Ecol (κ = 0.79), Ehomo (κ = 0.77) and four-color pattern (κ = 0.64), and moderate for Esha (κ = 0.56). Better-performing qualitative features were Ecol and four-color pattern (AUCs, 0.932 and 0.925) compared with Ehomo and Esha (AUCs, 0.857 and 0.864; P < 0.05). The diagnostic performance of B-mode ultrasound (AUC, 0.950) was not significantly different from combined sets with E value and with four color pattern (AUCs, 0.962 and 0.954). When all qualitative values were negative, leading to downgrade the BI-RADS category, the specificity increased significantly from 16.5% to 56.1% (E value) and 57.0% (four-color pattern) (P < 0.001) without improvement in sensitivity.

Conclusion

The qualitative SWE features were highly reproducible and showed good diagnostic performance in suspicious breast masses. Adding qualitative SWE to B-mode ultrasound increased specificity in decision making for biopsy recommendation.     

Breast ultrasound elastography—Results of 193 breast lesions in a prospective study with histopathologic correlation

Purpose

To evaluate the diagnostic performance of ultrasound elastography in breast masses.

Material and methods

193 lesions (129 benign, 64 malignant) were analyzed with the EUB 8500 Logos-ultrasonic-unit (Hitachi Medical, Japan) and a linear-array-transducer of 7.5-13-MHz. Standard of reference was cytology (FNAfine needle aspiration) or histology (core biopsy). The elastic-score was classified according to a 6-point colour-scale (Ueno classification; 1-3 = benign, 4-5 = malignant). Conventional B-mode ultrasound (US) findings were classified according to the BI-RADS classification. Statistical analysis included sensitivity, specificity, ROC-analysis and kappa-values for intra-/interobserver reliability.

Results

The mean score for elasticity was 4.1 ± 0.9 for malignant lesions, and 2.1 ± 1.0 for benign lesions (p < 0.001). With a best cut-off point between elasticity scores 3 and 4, sensitivity was 96.9%, and specificity 76%. Setting a best cut-off point for conventional US between BI-RADS 4 and 5, sensitivity was 57.8%, and specificity 96.1%. Elastography provided higher sensitivity and lower specificity than conventional US, but two lesions with elasticity score 1 were false negative, whereas no lesion scored BI-RADS 1-3 were false negative. ROC-curve was 0.884 for elastography, and 0.820 for conventional US (p < 0.001). Weighted kappa-values for intra-/interobserver reliability were 0.784/0.634 for BI-RADS classification, and 0.720/0.561 for elasticity scores.

Conclusion

In our study setting, elastography does not have the potential to replace conventional B-mode US for the detection of breast cancer, but may complement conventional US to improve the diagnostic performance.     

Clinical application of breast elastography: State of the art

Breast elastography is a new sonographic imaging technique for the characterization of focal breast lesions in addition to conventional ultrasonography (US) and mammography. Elastography provides a non-invasive evaluation of the stiffness of a lesion. Two different technical approaches are available for clinical use: free-hand elastography (USE) and shear wave elastography (SWE). Initial results of these techniques in clinical trials suggest that elastography substantially improves the US capability in differentiating benign from malignant breast lesions, thus reducing the number of breast biopsies in benign nodules. This review paper, based on an extensive literature search, highlights the basics of breast elastography, including main technical features, how to do suggestions, limit and pitfalls, and presents the results of major clinical studies.     

Reproducibility of real-time shear wave elastography in the evaluation of liver elasticity

Objective

To evaluate the reproducibility of real-time shear wave elastography in assessing liver elasticity in healthy volunteers.

Methods

Forty-two volunteers were studied in day 1. Shear wave elastography studies were performed by using the ultrasound system Aixplorer™ (SuperSonic Imagine S.A., Aix-en-Provence, France) with a convex broadband probe. Measurements were carried by two operators, an expert (operator 1) and a novice (operator 2). Examinations were performed on the right lobe of the liver. Each operator performed 10 consecutive measurements in each volunteer. In a subset of volunteers (n = 18) measurements were performed twice on two different days (day 1 and day 2). Intraobserver and interobserver agreement were assessed by intraclass correlation coefficient.

Results

Intraobserver agreement between measurements performed in the same subject in the same day (day 1 or day 2) showed intraclass correlation coefficient values of 0.95 (95% confidence interval, 0.93–0.98) and 0.93 (95% confidence interval, 0.90–0.96) for operator 1 and operator 2, respectively. Intraobserver agreement between measurements performed in the same subject in different days showed intraclass correlation coefficient values of 0.84 (95% confidence interval, 0.69–0.98) and 0.65 (95% confidence interval, 0.39–0.91) for operator 1 and operator 2, respectively. Interobserver agreement was 0.88 (95% confidence interval, 0.82–0.94).

Conclusions

The results of this study show that shear wave elastography is a reliable and reproducible noninvasive method for the assessment of liver elasticity. Expert operator had higher reproducibility of measurements over time than novice operator.     

The clinical value of ultrasound elastography in predicting malignant thyroid nodules

Objective

This study aims to evaluate the clinical value of ultrasound elastography (USE) in providing information on the nature of the thyroid nodules. This was performed using the elastography score and strain ratio in differentiating thyroid benign and malignant nodules and the histopathological examination was used as the diagnostic standard of reference.

Methods

We examined 84 thyroid nodules in 62 patients with ultrasound elastography. Elastography score was assigned based on a four-point scale according to the classification proposed by Itoh et al. with a score of 1 (low stiffness over the entire nodule) to a score of 4 (high stiffness over the entire nodule). Thyroid strain ratio (normal tissue to lesion strain ratio) was calculated. Histopathological results were the standard reference. The area under the curve (AUC) and the best cut-off point were both obtained using receiver-operating characteristic (ROC) curve analysis. The sensitivity, specificity, and accuracy of both techniques were calculated.

Results

Fifty-four of the 84 nodules had scores of 1 and 2, and 50 of these nodules were diagnosed histopathologically as benign. Thirty of the 84 nodules had a score of 3 and 4, and 21 of these nodules were diagnosed histopathologically as malignant. The scores of 1 and 2 with Itoh criteria were significantly seen in benign nodules, whereas, scores of 3 and 4 were significantly seen in malignant nodules (p < 0.05) with sensitivity 84%, specificity 84.7%, PPV 70%, NPV 92.6% and accuracy 84.5%. The mean SR for the benign nodules and malignant ones was significantly different (2.92 ± 0.96 vs. 4.53 ± 0.82, p < 0.001). With ROC analysis, the best cut-off strain ratio point was 3.5 for differentiating benign and malignant nodules with area under the curve (AUC) = 0.87 (0.8–0.95). The sensitivity of the strain ratio was 88%, while the specificity was 86.4%, PPV = 73.3%, NPV = 94.4% and accuracy = 86.9%.

Conclusions

Both the elastographic score and strain ratio are higher in malignant nodules than those in benign ones. Ultrasound elastography can provide quantitative information on thyroid nodule helping in differentiating benign and malignant ones.     

Logistic回归模型评估超声弹性成像对乳腺良恶性结节的诊断价值

目的:采用logistic回归分析建立乳腺结节超声特征参数为变量的诊断模型,评价超声弹性成像对乳腺良恶性结节的鉴别诊断价值.方法:以术后病理结果为金标准,回顾性分析132例患者共185枚乳腺结节的超声声像图特点,甄别出有价值的超声参数,建立logistic回归模型,评价其诊断效能及预测能力.结果:二分类logistic...     

灰阶超声结合超声弹性成像改良评分法在甲状腺实性结节中的应用

目的:探讨超声弹性成像改良评分法在诊断甲状腺结节良恶性中的价值。方法:对45例共71个实性结节进行弹性成像,按新评分法分为五级,并与病理结果进行相关分析。结果:灰阶超声诊断甲状腺疾病良恶性的敏感性、特异性、准确性分别是81%、94%、90.1%;新评分法诊断甲状腺疾病良恶性的敏感性、特异性、准确性分别是85.7%、96%、93%;二者联合使用敏感性、特异性、准确性分别是85.7%、98%、94.4%结论:改良评分法简便、准确、易于操作,与灰阶超声结合有助于提高对甲状腺疾病的诊断。     

Value of mammography and combined grey scale ultrasound and ultrasound elastography in the differentiation of solid breast lesions

Aim of the work

The aim of this work was to evaluate the value of ultrasound elastography (UE) in differentiating benign versus malignant solid breast lesions discovered in mammography and compare it with grey scale ultrasound (US) and mammography.

Methods

From May 2011 to May 2013, 114 solid lesions from 100 consecutive patients discovered during mammography were categorized into benign or malignant by mammography and US and further analyzed with UE. The diagnostic results of the cases were compared with histopathologic findings.

Results

Of 114 lesions, 33 were histologically malignant, and 81 were benign. UE was the most specific (95.1%) of the 3 modalities. The accuracy (81.7%) of UE was equal to mammography and was higher than those of US (82.5% and 71.9%, respectively). A combination of UE and US had the best sensitivity (90.9%) and accuracy (93.8%).

Conclusions

Ultrasound elastography is useful for breast lesion characterization and is an easier and cheaper method and more specific than mammography or US alone, but it is operator dependent. When combined with US, detection accuracy can be greatly improved and the combination potentially could reduce unnecessary biopsy.     

剪切波弹性成像在周围神经病变中的应用进展

现有研究表明剪切波弹性成像可以较为准确地诊断许多类型的周围神经病变,甚至在某些疾病的亚临床阶段即可发现异常。本文就剪切波弹性成像的基本原理及在周围神经系统中的研究及应用做一综述。     

Additional value of qualitative strain ultrasound elastography and strain ratio in predicting thyroid malignancy

Objective

To detect if strain ultrasound elastography and strain ratio have additional value to the conventional grey scale ultrasound in predicting thyroid malignancy.

Computer-assisted assessment of ultrasound real-time elastography: Initial experience in 145 breast lesions

PurposeTo develop and evaluate a computer-assisted method of quantifying five-point elasticity scoring system based on ultrasound real-time elastography (RTE), for classifying benign and malignant breast lesions, with pathologic results as the reference standard.Materials and methodsConventional ultrasonography (US) and RTE images of 145 breast lesions (67 malignant, 78 benign) were performed in this study. Each lesion was automatically contoured on the B-mode image by the level set method and mapped on the RTE image. The relative elasticity value of each pixel was reconstructed and classified into hard or soft by the fuzzy c-means clustering method. According to the hardness degree inside lesion and its surrounding tissue, the elasticity score of the RTE image was computed in an automatic way. Visual assessments of the radiologists were used for comparing the diagnostic performance. Histopathologic examination was used as the reference standard. The Student's t test and receiver operating characteristic (ROC) curve analysis were performed for statistical analysis.ResultsConsidering score 4 or higher as test positive for malignancy, the diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 93.8% (136/145), 92.5% (62/67), 94.9% (74/78), 93.9% (62/66), and 93.7% (74/79) for the computer-assisted scheme, and 89.7% (130/145), 85.1% (57/67), 93.6% (73/78), 92.0% (57/62), and 88.0% (73/83) for manual assessment. Area under ROC curve (A_z value) for the proposed method was higher than the A_z value for visual assessment (0.96 vs. 0.93).ConclusionComputer-assisted quantification of classical five-point scoring system can significantly eliminate the interobserver variability and thereby improve the diagnostic confidence of classifying the breast lesions to avoid unnecessary biopsy.     

实时超声弹性成像技术在乳腺良恶性疾病鉴别诊断中的应用

超声技术在乳腺疾病的诊断中发挥着越来越重要的作用,常规二维超声,彩色多普勒及脉冲多普勒能在对病灶大小,位置,边缘情况,内部回声,血流情况,阻力指数等方面提供很多重要信息。随着医学领域对生物体的组织弹性和超弹性特性的关注,在传统二维超声成像基础上同时使用结合了组织弹性自相关方法的超声弹性成像技术,使组织的质地差异通过超声图像表现出来。该项技术能够获得常规超声所不能探测到的组织弹性信息,在对病变的良恶性鉴别诊断中起到了很大的作用。