Accuracy of quantitative ultrasound elastography for differentiation of malignant and benign breast abnormalities: a meta-analysis

Ultrasound strain elastography to improve diagnostic performance of breast lesions by reclassifying BI-RADS 3 and 4a lesions: a multicentre diagnostic study

OBJECTIVES

To investigate the added value of strain elastography (SE) by recategorizing ultrasound (US) breast imaging reporting and data system (BI-RADS) 3 and 4a lesions.

METHODS

A total of 4371 patients underwent US and SE with BI-RADS 2-5 categories solid breast lesions were included from 32 hospitals. We evaluated the elastographic images according to elasticity scores (ES) and strain ratios (SR). Three combined methods (BI-RADS + ES, BI-RADS + SR, BI-RADS + ES + SR) and two reclassified methods were used (method one: upgrading BI-RADS 3 and downgrading BI-RADS 4a, method two: downgrading BI-RADS 4a alone). The diagnostic performance and the potential reduction of unnecessary biopsies were evaluated.

RESULTS

Combining BI-RADS with SE had a higher area under the curve (AUC) than BI-RADS alone (0.822-0.898 vs 0.794, P < .01). For reclassified method one, the sensitivity, specificity, and accuracy were 99.36%, 66.70%, 78.36% for BI-RADS + ES and 98.01%, 66.45%, 77.72% for BI-RADS + SR, and 99.42%, 66.70%, 78.38% for BI-RADS + ES + SR, respectively. For reclassified method two, the sensitivity, specificity, and accuracy were 99.17%, 70.72%, 80.87% for BI-RADS + ES and 97.76%, 81.75%, 87.46% for BI-RADS + SR, and 99.23%, 69.83%, 80.32% for BI-RADS + ES + SR, respectively. Downgrading BI-RADS 4a alone had higher AUC, specificity, and accuracy (P < .01) and similar sensitivity (P > .05) to upgrading BI-RADS 3 and downgrading BI-RADS 4a. Combining SE with BI-RADS could help reduce unnecessary biopsies by 17.64%-55.20%.

CONCLUSIONS

Combining BI-RADS with SE improved the diagnostic performance in distinguishing benign from malignant lesions and could decrease false-positive breast biopsy rates. Downgrading BI-RADS 4a lesions alone might be sufficient for achieving good diagnostic performance.

ADVANCES IN KNOWLEDGE

Downgrading BI-RADS category 4a lesions alone had higher AUC, specificity, and accuracy, and similar sensitivity to upgrading or downgrading BI-RADS category 3 and 4a lesions.

Mathematical Models for Ultrasound Elastography: Recent Advances to Improve Accuracy and Clinical Utility

Changes in biomechanical properties such as elasticity modulus, viscosity, and poroelastic features are linked to the health status of biological tissues. Ultrasound elastography is a non-invasive imaging tool that quantitatively maps these biomechanical characteristics for diagnostic and treatment monitoring purposes. Mathematical models are essential in ultrasound elastography as they convert the raw data obtained from tissue displacement caused by ultrasound waves into the images observed by clinicians. This article reviews the available mathematical frameworks of continuum mechanics for extracting the biomechanical characteristics of biological tissues in ultrasound elastography. Continuum-mechanics-based approaches such as classical viscoelasticity, elasticity, and poroelasticity models, as well as nonlocal continuum-based models, are described. The accuracy of ultrasound elastography can be increased with the recent advancements in continuum modelling techniques including hyperelasticity, biphasic theory, nonlocal viscoelasticity, inversion-based elasticity, and incorporating scale effects. However, the time taken to convert the data into clinical images increases with more complex models, and this is a major challenge for expanding the clinical utility of ultrasound elastography. As we strive to provide the most accurate imaging for patients, further research is needed to refine mathematical models for incorporation into the clinical workflow.

Combining Potential Strain Elastography and Radiomics for Diagnosing Breast Lesions in BI-RADS 4: Construction and Validation a Predictive Nomogram

RATIONALE AND OBJECTIVES

To develop a nomogram by integrating B-mode ultrasound (US), strain ratio (SR), and radiomics signature (RS) effectively differentiating between benign and malignant lesions in the Breast Imaging Reporting and Data System (BI-RADS) 4.

MATERIALS AND METHODS

We retrospectively recruited 709 consecutive patients who were assigned a BI-RADS 4 and underwent curative resection or biopsy between 2017 and 2022. US images were collected before surgery. A RS was developed through a multistep feature selection and construction process. Histology findings served as the gold standard. Univariate and multivariate regression analysis were employed to analyze the clinical and US characteristics and identify variables for developing a nomogram. The calibration and discrimination of the nomogram were conducted to evaluate its performance.

RESULTS

The study included a total of 709 patients, with 497 in the training set and 212 in the validation set. In the training set, the B-mode US had an AUC of 0.84 (95% confidence interval [CI], 0.80, 0.87). The SR demonstrated an AUC of 0.78 (95% CI, 0.74, 0.82), while the RS showed an AUC of 0.85 (95% CI, 0.81, 0.88). Notably, the nomogram exhibited superior performance compared to the conventional US, SR, and RS (AUC=0.93, both p < 0.05, as per the Delong test). The clinical usefulness of the nomogram was favorable.

CONCLUSION

The calibrated nomogram can be specifically designed to predict the malignancy of breast lesions in the BI-RADS 4 category.

Proposal and comparison of quality measures in Crawling Waves Sonoelastography

Ultrasound shear-wave elastography has emerged as a promising non-invasive technique for assessing tissue stiffness and elasticity, enabling the detection and monitoring of pathological changes for disease diagnosis, treatment and monitoring. Crawling Waves Sonoelastography (CWS) is an elastography approach that generates mechanical waves to measure Shear Wave Speed (SWS). However, current estimation techniques for CWS present important limitations such as the presence of artifacts leading to potential diagnostic inaccuracies. The paper proposes two quality parameters for CWS, the coefficient of variation and the normalized spectral deviation, which can be evaluated and used to discard regions where SWS measurements are inaccurate. The proposed quality parameters are tested on gelatin homogeneous and heterogeneous phantoms. Evaluation is carried out across frequencies ranging from 200 Hz to 500 Hz. Results show that both methods can help reduce the variation in SWS and increase the CNR by up to 6dB while reducing the bias by up to 20%.

Best Practice Guideline - DEGUM Recommendations on Breast Ultrasound

Alongside mammography, breast ultrasound is an important and well-established method in assessment of breast lesions. With the "Best Practice Guideline", the DEGUM Breast Ultrasound (in German, "Mammasonografie") working group, intends to describe the additional and optional application modalities for the diagnostic confirmation of breast findings and to express DEGUM recommendations in this Part II, in addition to the current dignity criteria and assessment categories published in Part I, in order to facilitate the differential diagnosis of ambiguous lesions.The present "Best Practice Guideline" has set itself the goal of meeting the requirements for quality assurance and ensuring quality-controlled performance of breast ultrasound. The most important aspects of quality assurance are explained in this Part II of the Best Practice Guideline.

Diagnostic performance of mammography and ultrasound in breast cancer: a systematic review and meta-analysis

PURPOSE

The purpose of this study was to assess the diagnostic performance of mammography (MMG) and ultrasound (US) imaging for detecting breast cancer.

METHODS

Comprehensive searches of PubMed, Scopus and EMBASE from 2008 to 2021 were performed. A summary receiver operating characteristic curve (SROC) was constructed to summarize the overall test performance of MMG and US. Histopathologic analysis and/or close clinical and imaging follow-up for at least 6 months were used as golden reference.

RESULTS

Analysis of the studies revealed that the overall validity estimates of MMG and US in detecting breast cancer were as follows: pooled sensitivity per-patient were 0.82 (95% CI 0.76-0.87) and 0.83 (95% CI 0.71-0.91) respectively, The pooled specificities for detection of breast cancer using MMG, and US were 0.84 (95% CI 0.73-0.92) and 0.84 (95% CI 0.74-0.91) respectively. AUC of MMG, and US were 0.8933 and 0.8310 respectively. Pooled sensitivity and specificity per-lesion was 76% (95% CI 0.62-0.86) and 82% (95% CI 0.66-0.91) for MMG and 94% (95% CI 0.87-0.97) and 84% (95% CI 0.74-0.91) for US.

CONCLUSIONS

The meta-analysis found that, US and MMG has similar diagnostic performance in detecting breast cancer on per-patient basis after corrected threshold effect. However, on a per-lesion basis US was found to have a better diagnostic accuracy than MMG.

Ultrasound Elastography: Basic Principles and Examples of Clinical Applications with Artificial Intelligence—A Review

Ultrasound elastography (USE) or elastosonography is an ultrasound-based, non-invasive imaging method for assessing tissue elasticity. The different types of elastosonography are distinguished according to the mechanisms used for estimating tissue elasticity and the type of information they provide. In strain imaging, mechanical stress is applied to the tissue, and the resulting differential strain between different tissues is used to provide a qualitative assessment of elasticity. In shear wave imaging, tissue elasticity is inferred through quantitative parameters, such as shear wave velocity or longitudinal elastic modulus. Shear waves can be produced using a vibrating mechanical device, as in transient elastography (TE), or an acoustic impulse, which can be highly focused, as in point-shear wave elastography (p-SWE), or directed to multiple zones in a two-dimensional area, as in 2D-SWE. A general understanding of the basic principles behind each technique is important for clinicians to improve data acquisition and interpretation. Major clinical applications include chronic liver disease, breast lesions, thyroid nodules, lymph node malignancies, and inflammatory bowel disease. The integration of artificial intelligence tools could potentially overcome some of the main limitations of elastosonography, such as operator dependence and low specificity, allowing for its effective integration into clinical workflow.

Determining the elastography strain ratio cut off value for differentiating benign from malignant breast lesions: systematic review and meta-analysis

Background

Elastography is an addition to grey-scale ultrasonic examination that has gained substantial traction within the last decade. Strain ratio (SR) has been incorporated as a semiquantitative measure within strain elastography, thus a potential imaging biomarker. The World Federation for Ultrasound in Medicine and Biology (WFUMB) published guidelines in 2015 for breast elastography. These guidelines acknowledge the marked variance in SR cut-off values used in differentiating benign from malignant lesions. The objective of this review was to include more recent evidence and seek to determine the optimal strain ratio cut off value for differentiating between benign and malignant breast lesions.

Methods

Comprehensive search of MEDLINE and Web of Science electronic databases with additional searches via Google Scholar and handsearching set from January 2000 to May 2020 was carried out. For retrieved studies, screening for eligibility, data extraction and analysis was done as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Diagnostic Test Accuracy (PRISMA-DTA) Statement guidelines of 2018. Quality and risk of bias assessment of the studies were performed using the revised Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool.

Results

A total of 424 articles, 412 from electronic database and 12 additional searches were retrieved and 65 studies were included in the narrative synthesis and subgroup analysis. The overall threshold effect indicated significant heterogeneity among the studies with Spearman correlation coefficient of Logit (TPR) vs Logit (FPR) at − 0.301, p-value = 0.015. A subgroup under machine model consisting seven studies with 783 patients and 844 lesions showed a favourable threshold, Spearman’s correlation coefficient,0.786 (p = 0.036).

Conclusion

From our review, currently the optimal breast SR cut-off point or value remains unresolved despite the WFUMB guidelines of 2015. Machine model as a possible contributor to cut-off value determination was suggested from this review which can be subjected to more industry and multi-center research determination.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40644-022-00447-5.

Transvaginal Shear Wave Elastography for Assessment of Endometrial and Subendometrial Pathologies: A Prospective Pilot Study

OBJECTIVE

To assess the role of shear wave elastography (SWE) in characterizing different endometrial and subendometrial pathologies.

METHODS

Seventy-three women with pathologically proven endometrial and subendometrial pathologies were enrolled in this prospective study and assessed with transvaginal SWE. The elasticity values (in kiloPascals), and the ratio of mean elasticity of the endometrial lesion to myometrial elasticity (E/M ratio) were compared in different pathologies.

RESULTS

There was a statistically significant difference (P <.001) in the mean, minimum, and maximum elasticity of the pathologies as well as the E/M ratio (P <.00001). In the analysis of the subgroups, the mean elasticity of endometrial polyp was statistically significantly lower than other subgroups (P <.01), while submucosal leiomyoma and focal adenomyoma had significantly higher values than other subgroups (P <.01). No statistically significant difference was noted in the mean elasticity of carcinoma and hyperplasia (P-.19).

CONCLUSION

SWE is a potential adjunct to ultrasound that provides an additional paradigm to characterize endometrial and subendometrial masses.

Quantitative Evaluation of Hepatic Steatosis Using Advanced Imaging Techniques: Focusing on New Quantitative Ultrasound Techniques

Nonalcoholic fatty liver disease, characterized by excessive accumulation of fat in the liver, is the most common chronic liver disease worldwide. The current standard for the detection of hepatic steatosis is liver biopsy; however, it is limited by invasiveness and sampling errors. Accordingly, MR spectroscopy and proton density fat fraction obtained with MRI have been accepted as non-invasive modalities for quantifying hepatic steatosis. Recently, various quantitative ultrasonography techniques have been developed and validated for the quantification of hepatic steatosis. These techniques measure various acoustic parameters, including attenuation coefficient, backscatter coefficient and speckle statistics, speed of sound, and shear wave elastography metrics. In this article, we introduce several representative quantitative ultrasonography techniques and their diagnostic value for the detection of hepatic steatosis.

Ultrasound elastography

Physicians have used palpation as a diagnostic examination to understand the elastic properties of pathology for a long time since they realized that tissue stiffness is closely related to its biological characteristics. US elastography provided new diagnostic information about elasticity comparing with the morphological feathers of traditional US, and thus expanded the scope of the application in clinic. US elastography is now widely used in the field of diagnosis and differential diagnosis of abnormality, evaluating the degree of fibrosis and assessment of treatment response for a range of diseases. The World Federation of Ultrasound Medicine and Biology divided elastographic techniques into strain elastography (SE), transient elastography and acoustic radiation force impulse (ARFI). The ARFI techniques can be further classified into point shear wave elastography (SWE), 2D SWE, and 3D SWE techniques. The SE measures the strain, while the shear wave-based techniques (including TE and ARFI techniques) measure the speed of shear waves in tissues. In this review, we discuss the various techniques separately based on their basic principles, clinical applications in various organs, and advantages and limitations and which might be most appropriate given that the majority of doctors have access to only one kind of machine.

Utility of B-Mode, Color Doppler and Elastography in the Diagnosis of Breast Cancer: Results of the CD-CONFIRM Multicenter Study of 1351 Breast Solid Masses

The usefulness of color Doppler ultrasound (CD) in distinguishing between benign and malignant breast lesions remains controversial. Our prior study, the Japan Association of Breast and Thyroid Sonology (JABTS) BC-04 study (malignant: 839, benign: 569), found CD was useful in breast cancer diagnosis, and we developed CD diagnostic criteria. The first aim of the current study (the CD-CONFIRM study) was to evaluate the usefulness of the CD diagnostic criteria. The second aim was to evaluate the relationship between CD and elastography. We evaluated ultrasound images of breast masses from 13 institutions (malignant: 639, benign: 712). While the sensitivity of B-mode alone was very high and was not significantly improved with CD, the specificity was significantly improved with CD (61.2%-69.2%, p < 0.0001). Furthermore, the specificity of the combination of B-mode and CD improved significantly with the addition of elastography (72.8%-79.0%, p < 0.0001). This study found that the CD criteria are useful, and CD and elastography are independent.

US-Elastography for Breast Lesion Characterization: Prospective Comparison of US BIRADS, Strain Elastography and Shear wave Elastography

PURPOSE

 To evaluate the diagnostic performance of strain elastography (SE) and 2 D shear wave elastography (SWE) and SE/SWE combination in comparison with conventional multiparametric ultrasound (US) with respect to improving BI-RADS classification results and differentiating benign and malignant breast lesions using a qualitative and quantitative assessment.

MATERIALS AND METHODS

 In this prospective study, 130 histologically proven breast masses were evaluated with baseline US, color Doppler ultrasound (CDUS), SE and SWE (Toshiba Aplio 500 with a 7-15 MHz wide-band linear transducer). Each lesion was classified according to the BIRADS lexicon by evaluating the size, the B-mode and color Doppler features, the SE qualitative (point color scale) and SE semi-quantitative (strain ratio) methods, and quantitative SWE. Histological results were compared with BIRADS, strain ratio (SR) and shear wave elastography (SWE) all performed by one investigator blinded to the clinical examination and mammographic results at the time of the US examination. The area under the ROC curve (AUC) was calculated to evaluate the diagnostic performance of B-mode US, SE, SWE, and their combination.

RESULTS

 Histological examination revealed 47 benign and 83 malignant breast lesions. The accuracy of SR was statistically significantly higher than SWE (sensitivity, specificity and AUC were 89.2 %, 76.6 % and 0.83 for SR and 72.3 %, 66.0 % and 0.69 for SWE, respectively, p = 0.003) but not higher than B-mode US (B-mode US sensitivity, specificity and AUC were 85.5 %, 78.8 %, 0.821, respectively, p = 1.000).

CONCLUSION

 Our experience suggests that conventional US in combination with both SE and SWE is a valid tool that can be useful in the clinical setting, can improve BIRADS category assessment and may help in the differentiation of benign from malignant breast lesions, with SE having higher accuracy than SWE.

Contribution of Sonoelastographic Scoring to B-Mode Sonography in the Evaluation of Breast Masses

Objectives:

The study aims were to evaluate the contribution of sonoelastography to Breast Imaging Reporting, and Data System (BI-RADS) scoring of breast images.

Materials and Methods:

Two observers evaluated the BI-RADS category, Tsukuba score, and the strain index of 83 lesions of 73 consecutive patients. A new scoring system was established to evaluate the lesions by using the BI-RADS score, Tsukuba score, and strain index ratio.

Results:

There was a statistically significant difference between the strain index value of benign (3.08 ± 2.71) and malignant group (4.62 ± 2.70) ( P < .05). The sensitivity and specificity were 59.1% and 65.1% for the 3.12 cut-off value for the strain index. In the receiver operating characteristic (ROC) analysis, the area under the curve (AUC) of the only BI-RADS score was 0.834, both BT (BI-RADS + revised Tsukuba score) score and the total score (BI-RADS + revised Tsukuba score + strain index score) was 0.843. The interclass correlation coefficient for the two observers’ measurements of the strain index was weak, with .266 ( P < .05).

Conclusion:

The potential contribution of sonoelastography on lesion characterization is still controversial. In this study, the agreement among the observers was inadequate, and the contribution of sonoelastography on BI-RADS classification was limited. In addition, in the daily practice of sonoelastograpic evaluation, the Tsukuba score, was easier to apply and should be used rather than strain index measurements.

Diagnostic and Predictive Values of Strain Ratios in the Regions of Interests in Reference Tissue for Breast Tumor

PURPOSE

To investigate the diagnostic and predictive value of strain ratios in the regions of interests (ROIs) in reference tissue for breast tumor.

PATIENTS AND METHODS

A total of 707 lesions in 665 consecutive patients were examined with B-mode Breast Imaging-Reporting and Data System (BI-RADS) and Ultrasonic elastography (UE). Elasticity score (ES) and strain ratio (SR) in each lesion were calculated. Receiver operating characteristic (ROC) curves were used to assess the diagnostic value of BI-RADS, ES, SR1, SR2, BI-RADS combined with ES (BI-RADS+ES), BI-RADS combined with SR1 (BI-RADS+SR1), and BI-RADS combined with SR2 (BI-RADS+SR2). The sensitivity, specificity, and areas under the ROC curves (Az) were obtained. Scatter plots were generated to demonstrate the correlation between SR1 and SR2. Kruskal-Walls H-test, Mann-Whitney U-test and one-way ANOVA were performed to evaluate SRs and tumor-related variables. Multiple linear regression analysis was carried out to determine variables independently associated with SRs.

RESULTS

BI-RADS had high sensitivity and low specificity in the diagnosis of breast tumor. The specificity of BI-BADS combined with ES or SR was even higher. The Az value of BI-RADS+ES or BI-RADS+SRs was higher than that of BI-RADS (P < 0.001). The Az value of ES was higher than those of SR1 and SR2 (P < 0.001), and those of SR1 and SR2 were similar. SR1 and SR2 were highly positively correlated. There was no statistical difference between Az values of BI-RADS+ES, BI-RADS+SR1, and BI-RADS+SR2. Indistinct margin, high histologic grade, histological type, and negative human epidermal growth factor receptor (Her-2) were associated with SR1 and SR2. Progesterone receptor (PR) status and molecular subtype were associated with SR2. Histologic grade and tumor margin were significantly associated with SR1, and tumor margin was associated with SR2.

CONCLUSION

SRs in different ROIs in the reference tissue at the same depth showed no different diagnostic value for breast tumor. Both SR1 and SR2 could be useful in assessing the biological characteristics of invasive breast carcinoma.

[Ultrasound elastography techniques in breast cancer]

BACKGROUND

Elasticity assessment of breast lesions can also be used as an associated criterion in the B‑mode ultrasound (US) assessment for differentiation between benign or malignant lesions.

OBJECTIVES

The goal was to identify techniques available to measure US elasticity, assess the use of B‑mode BI-RADS® classification combined with elastography, and identify which artefacts influence the US elasticity result.

MATERIALS AND METHODS

Based on different studies and meta-analyses, clinical application in daily routine of the presented US elastography techniques will be investigated concerning the statistical performance of semi-quantitative and quantitative cut-off values to differentiate benign from malignant lesions.

RESULTS

Supported by meta-analyses, all presented US elastography techniques improve the specificity by decreasing the B‑mode sensitivity. In the literature the semi-quantitative and quantitative cut-off values often vary considerably. The interobserver variability of strain elastography shows a fair agreement and the interobserver variability of shear wave elastography a substantial agreement.

CONCLUSIONS

Considering the limitations and artefacts of each technique, US elastography is able to enhance the true positive and true negative results. In the case of a higher B‑mode BI-RADS® classification (4b, 4c, 5) or in a high-risk situation to develop breast cancer, a large core needle biopsy should be performed despite lesion softness in elastography.

Risk-predicted dual nomograms consisting of clinical and ultrasound factors for downgrading BI-RADS category 4a breast lesions - A multiple centre study

Purpose: To develop and to validate a risk-predicted nomogram for downgrading Breast Imaging Reporting and Data System (BI-RADS) category 4a breast lesions. Patients and Methods: We enrolled 680 patients with breast lesions that were diagnosed as BI-RADS category 4a by conventional ultrasound from December 2018 to June 2019. All 4a lesions were randomly divided into development and validation groups at the ratio of 3:1. In the development group consisting of 499 cases, the multiple clinical and ultrasound predicted factors were extracted, and dual-predicted nomograms were constructed by multivariable logistic regression analysis, named clinical nomogram and ultrasound nomogram, respectively. Patients were twice classified as either "high risk" or "low risk" in the two nomograms. The performance of these dual nomograms was assessed by an independent validation group of 181 cases. Receiver Operating Characteristic (ROC) curve and diagnostic value were calculated to evaluate the applicability of the new model. Results: After multiple logistic regression analysis, the clinical nomogram included 2 predictors: age and the first-degree family members with breast cancer. The area under the curve (AUC) value for the clinical nomogram was 0.661 and 0.712 for the development and validation groups, respectively. The ultrasound nomogram included 3 independent predictors (margins, calcification and strain ratio), and the AUC value in this nomogram was 0.782 and 0.747 in the development and validation groups, respectively. In the development group of 499 patients, approximately 50.90% (254/499) of patients were twice classified "low risk", with a malignancy rate of 1.18%. In the validation group of 181 patients, approximately 47.51% (86/181) of patients had been twice classified as "low risk", with a malignancy rate of 1.16%. Conclusions: A dual-predicted nomogram incorporating clinical factors and imaging characteristics is an applicable model for downgrading the low-risk lesions in BI-RADS category 4a and shows good stability and accuracy, which is useful for decreasing the rate of invasive examinations and surgery.

The role of tissue elasticity in the differential diagnosis of benign and malignant breast lesions using shear wave elastography

Background

Elastography is a promising way to evaluate tissue differences regarding stiffness, and the stiffness of the malignant breast lesions increased at the lesion margin. However, there is a lack of data on the value of the shear wave elastography (SWE) parameters of the surrounding tissue (shell) of different diameter on the diagnosis of benign and malignant breast lesions. Therefore, the purpose of our study was to evaluate the diagnostic performance of shell elasticity in the diagnosis of benign and malignant breast lesions using SWE.

Methods

Between September 2016 and June 2017, women with breast lesions underwent both conventional ultrasound (US) and SWE. Elastic values of the lesions peripheral tissue were determined according to the shell size, which was automatically drawn along the edge of the lesion using the following software guidelines: (1): 1 mm; (2): 2 mm; and (3): 3 mm. Quantitative elastographic features of the inner lesions and shell, including the elasticity mean (E_mean), elasticity maximum (E_max), and elasticity minimum (E_min), were calculated using an online-available software. The receiver operating characteristic curves (ROCs) of the elastographic features was analyzed to assess the diagnostic performance, and the area under curve (AUC) of each elastographic feature was obtained. Logistic regression analysis was used to predict significant factors of malignancy, permitting the design of predictive models.

Results

This prospective study included 63 breast lesions of 63 women. Of the 63 lesions, 33 were malignant and 30 were benign. The diagnostic performance of E_max-3shell was the highest (AUC = 0.76) with a sensitivity of 60.6% and a specificity of 83.3%. According to stepwise logistic regression analysis, the E_max-3shell and the E_min-3shell were significant predictors of malignancy (p < 0.05). The AUC of the predictive equation was 0.86.

Conclusions

SWE features, particularly the combination of E_max-3shell and E_min-3shell can improve the diagnosis of breast lesions.

Can strain US-elastography with strain ratio (SRE) improve the diagnostic accuracy in the assessment of breast lesions? Preliminary results

PURPOSE

To assess the diagnostic value of strain ratio elastography (SRE), a semiquantitative elastosonographic method based on the displacement of the tissue from an external source (manual compression with the transducer), as compared and in combination with conventional ultrasound for the differentiation of breast lesions.

METHODS

One hundred and eighty-two patients with breast lesions consecutively underwent B-mode, color Doppler US, and strain US-elastography. Each lesion was classified according to the BI-RADS lexicon by evaluating the size, the B-mode, and color Doppler features and then evaluated by SRE. Histology proven by biopsy was used as the gold standard and the patients with malignant lesions subsequently underwent operations. The diagnostic performance of each method was assessed with 2 × 2 contingency tables and ROC curve analysis. To maximize the SRE sensitivity and specificity, the SRE cut-off value was calculated using the Youden test.

RESULTS

Histological examination revealed 66 benign and 116 malignant breast lesions. The conventional ultrasound showed sensitivity and specificity for the differentiation of benign and malignant lesions of 86.2% and 75.8%, respectively. Similar results were found for strain US-elastography with a cut-off of 2.49, with sensitivity and specificity of 89.7% and 72.7%, respectively. The association of conventional ultrasound with the SRE value increased the sensitivity (98.3%) but decreased the specificity compared with conventional US alone (63.6%).

CONCLUSION

Strain US-elastography can be associated with BI-RADS US examination. According to our preliminary results, it helped increase the sensitivity although it decreased the specificity. However, further multicenter studies on a larger population are warranted.

Ultrasound and Clinical Characteristics of False-negative Results in Mammography Screening of Dense Breasts

OBJECTIVE

We analyzed the clinical and ultrasound characteristics associated with false-negative mammography results in women with dense breasts.

MATERIALS AND METHODS

The present study included 191 women (mean age, 54.47 ± 11.61 years; range, 31-75 years) who had presented from July 2015 to June 2018 with pathologically confirmed breast cancer. The mammography, conventional ultrasound, and elastography imaging results of these patients were reviewed. Breast density and screening cancer probability from mammography and conventional ultrasound imaging were scored using the Breast Imaging Reporting and Data System. Multivariate logistic regression analysis was performed to identify the factors independently associated with the false-negative results on breast mammographic screening.

RESULTS

Of 191 confirmed breast cancer cases, 55 (28.8%) were assigned to category ≤ 3, and 136 (71.2%) were assigned to category ≥ 4a according to the mammography findings. All the breasts were graded mammographically as dense. A rougher margin (odds ratio [OR], 8.123; 95% confidence interval [CI], 1.731-38.127) was the strongest independent factor associated with negative results, followed by a lower stiffness ratio (OR, 7.773; 95% CI, 2.574-23.473), negative axillary lymph node status (OR, 5.066; 95% CI, 1.028-24.955), and softer lesions (OR, 1.037; 95% CI, 1.001-1.075).

CONCLUSION

Women with dense breasts, a lower lesion/glandular tissue stiffness ratio, and softer cancer can easily lead to a misdiagnosis using mammography. By giving sufficient attention to the margin, earlier stage cancer with negative lymph node status are more likely to benefit from supplemental ultrasound imaging.

Modeling Uncertainty of Strain Ratio Measurements in Ultrasound Breast Strain Elastography: A Factorial Experiment

Strain elastography (SE) is a technique in which images of localized tissue strains are used to detect the relative stiffness of tissues. The application of SE in differentiating malignant breast lesions from benign ones has been broadly investigated. The strain ratio (SR) between the background and the breast tumor has been used and its results have been mixed. Due to the complex nature of tissue elasticity and how it relates to the strain fields measured in SE, the exact reason is not known. In this study, we apply a novel design-of-experiments-based metamodeling approach to mechanical simulation of SE in the human breast. To our knowledge, such a study has not been reported in the ultrasound SE literature. More specifically, we first conduct a screening study to identify the biomechanical factors/simulation inputs that most strongly determine SR. We then apply a response surface experimental design to these factors to produce a metamodel of SR as a function of said factors. Results from the screening study suggest that the SR measurements are primarily influenced by three factors: the initial shear modulus of the lesion, the elastic nonlinearity of the lesion, and the precompression applied during acquisition. In order to investigate the implications of these results, stochastic inputs for these three factors associated with the malignant and benign cases were applied to the resulting response surface. The resulting optimal cutoffs, sensitivity, and specificity were generally in line with a majority (>60%) of 19 clinical trials in the literature.

Breast Cancer Assessment With Pulse-Echo Speed of Sound Ultrasound From Intrinsic Tissue Reflections: Proof-of-Concept

PURPOSE

The aim of this study was to differentiate malignant and benign solid breast lesions with a novel ultrasound (US) technique, which measures speed of sound (SoS) using standard US transducers and intrinsic tissue reflections and scattering (speckles) as internal reference.

MATERIALS AND METHODS

This prospective, institutional review board-approved, Health Insurance Portability and Accountability Act-compliant prospective comparison study was performed with prior written informed consent from 20 women. Ten women with histological proven breast cancer and 10 with fibroadenoma were measured. A conventional US system with a linear probe was used for SoS-US (SonixTouch; Ultrasonix, Richmond, British Columbia, Canada). Tissue speckle reflections served as a timing reference for the US signals transmitted through the breasts. Relative phase inconsistencies were detected using plane wave measurements from different angular directions, and SoS images with 0.5-mm resolution were generated using a spatial domain reconstruction algorithm. The SoS of tumors were compared with the breast density of a larger cohort of 106 healthy women.

RESULTS

Breast lesions show focal increments ΔSoS (meters per second) with respect to the tissue background. Peak ΔSoS values were evaluated. Breast carcinoma showed significantly higher ΔSoS than fibroadenomas ([INCREMENT]SoS > 41.64 m/s: sensitivity, 90%; specificity, 80%; area under curve, 0.910) and healthy breast tissue of different densities (area under curve, 0.938; sensitivity, 90%; specificity, 96.5%). The lesion localization in SoS-US images was consistent with B-mode imaging and repeated SoS-US measurements were reproducible.

CONCLUSIONS

Using SoS-US, based on conventional US and tissue speckles as timing reference, breast carcinoma showed significantly higher SoS values than fibroadenoma and healthy breast tissue of different densities. The SoS presents a promising technique for differentiating solid breast lesions.

Quantitative Sonoelastographic Assessment of the Normal Uterus Using Shear Wave Elastography: An Initial Experience

OBJECTIVES

To describe the sonoelastographic characteristics of the normal endometrium, myometrium, and cervix and to assess their variability with age and different menstrual phases.

METHODS

A total of 56 women were enrolled in this prospective study, who underwent transvaginal ultrasound examinations, including B-mode imaging and shear wave elastography. The elasticity parameters (in kilopascals) of the normal endometrium, myometrium, and cervix were studied. The variability of the mean elasticity value of the endometrium in different menstrual phases and age groups was analyzed. The variability of the mean elasticity of the cervix across different age groups was also studied.

RESULTS

The mean age of the participants was 40 years (range, 25-69 years). The normal mean elasticity values ± SDs were 25.54 ± 8.56 kPa for the endometrium, 40.24 ± 8.59 kPa for the myometrium, and 18.90 ± 4.22 kPa for the cervix. A mean endometrial-to-myometrial elasticity ratio was calculated, which was found to be 0.65 ± 0.22. There was no significant difference in the mean endometrial elasticity values for women in different menstrual phases (P = .176) or in different age groups (P = .376). There was no significant difference in the mean cervical elasticity with age (P = .192).

CONCLUSIONS

Shear wave elastography is a promising adjunct to ultrasound for the evaluation of the uterus, and the results from this study may provide normal data, which may further help in diagnosing various uterine diseases.

Comparison of the Fat-to-Lesion Strain Ratio and the Gland-to-Lesion Strain Ratio With Controlled Precompression in Characterizing Indeterminate and Suspicious Breast Lesions on Ultrasound Imaging

OBJECTIVES

The purpose of this study was to compare the diagnostic performance of the fat-to-lesion strain ratio (FLR) and gland-to-lesion strain ratio (GLR) for patients with indeterminate or suspicious breast lesions on ultrasound (US) imaging under a controlled precompression technique and to see whether the technique improves the reproducibility of FLR and GLR measurement.

METHODS

Fifty-three lesions in 39 consecutive patients who had scheduled core biopsy or excision surgery based on US findings were examined by US elastography. Each lesion was acquired under controlled precompression by 2 sonographers independently. Both the FLR and GLR of the lesion were calculated. For diagnostic performance, the sensitivity, specificity, negative predictive value, positive predictive value, and accuracy were obtained. Interobserver reliability between different sonographers was assessed by the intraclass correlation coefficient (ICC).

RESULTS

Forty lesions were benign, and 13 lesions were malignant. Both the FLR and GLR were significantly higher in malignant than benign lesions (P < .05). The FLR yielded higher accuracy and specificity compared to the GLR (accuracy, 79.2% versus 60.4%; and specificity, 87.5% versus 50.0%). With the controlled precompression applied at less than 25% during elastography, the interobserver agreement was excellent for FLR measurements (ICC, 0.853; 95% confidence interval, 0.738-0.920) and GLR measurements (ICC, 0.779; 95% confidence interval, 0.619-0.87).

CONCLUSIONS

The FLR performed better than the GLR in the detection of breast malignancy; thus, fatty tissue was a better reference tissue for calculating the strain ratio on malignant breast tumor elastography. Keeping precompression to less than 25% will enable different operators to acquire similar elastograms with reproducible FLR and GLR readings.

The Japanese Breast Cancer Society Clinical Practice Guidelines for Breast Cancer Screening and Diagnosis, 2018 Edition

This article updates readers as to what is new in the Japanese Breast Cancer Society Clinical Practice Guidelines for Breast Cancer Screening and Diagnosis, 2018 Edition. Breast cancer screening issues are covered, including matters of breast density and possible supplemental modalities, along with appropriate pre-operative/follow-up diagnostic breast imaging tests. Up-to-date clinical practice guidelines for breast cancer screening and diagnosis should help to provide patients and clinicians with not only evidence-based breast imaging options, but also accurate and balanced information about the benefits and harms of intervention, which ultimately enables shared decision making about imaging test plans.

Diagnostic Performance of Multimodal Sound Touch Elastography for Differentiating Benign and Malignant Breast Masses

OBJECTIVES

Evaluating the value of screening breast masses by separate or combined use of multimodal Sound Touch Elastography.

METHODS

Women with 159 masses (mean size, 14.86 ± 6.57 mm; range, 5.30-30.00 mm) were enrolled in the study. The pathology results were adopted as diagnostic standards. The abilities of Young's modulus (E), shear modulus (G), and shear wave (C) to differentiate malignant and benign breast masses based on receiver operating characteristic curves were evaluated, and the optimal cutoff values were obtained. Sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were calculated. Then, the values were combined to perform an overall analysis of Sound Touch Elastography using evidence-based medicine, construct forest plots, and calculate areas under the summary receiver operating characteristic curves, pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic scores.

RESULTS

A total of 159 masses with a mean size of 14.86 ± 6.57 mm (range, 5.30-30.00 mm) were included. For the various parameters, the diagnostic values were as follows: G_max  > E_max  > C_max  > C_sd  > E_sd  > G_sd  > E_mean  > G_mean  > C_mean . There were no significant differences in E_min , G_min , or C_min . When the 9 parameters were combined, the pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic scores and areas under the summary receiver operating characteristic curves were 84% (95% confidence interval [CI], 79%-88%), 82% (95% CI, 80%-84%), 4.75 (95% CI, 4.15-5.43), 0.20 (95% CI, 0.15-0.25), 3.19 (95% CI, 2.84-3.54) and 90.2% (95% CI, 87%-92%), respectively.

CONCLUSIONS

Sound Touch Elastography can be recognized as a new ultrasound-based diagnostic method for differentiation between benign and malignant breast masses.

Feasibility of a Support Vector Machine Classifier for Myofascial Pain Syndrome: Diagnostic Case-Control Study

OBJECTIVES

Myofascial pain syndrome (MPS) is the most common cause of chronic pain worldwide. The diagnosis of MPS is subjective, which has created a need for a robust quantitative method of diagnosing MPS. We propose that using a support vector machine (SVM) along with ultrasound (US) texture features can differentiate between healthy and MPS-affected skeletal muscle.

METHODS

B-mode US video data were collected in the upper trapezius muscle of healthy (29) participants and patients with active (21) and latent (19) MPS, using an acquisition method outlined in previous works. Regions of interest were extracted and filtered to obtain a unique set of 917 images where texture features were extracted from each region of interest to characterize each image. These texture features were then used to train 4 separate binary SVM classifiers using nested cross-validation to implement feature selection and hyperparameter tuning. The performance of each kernel was estimated on the data and validated through testing on a final holdout set.

RESULTS

The radial basis function kernel classifier had the greatest Matthews correlation coefficient performance estimate of 0.627 ± 0.073 (mean ± SD) along with the largest area under the curve of 91.0% ± 3.0%. The final holdout test for the radial basis function classifier resulted in 86.96 accuracy, a Matthews correlation coefficient of 0.724, 88% sensitivity, and 86% specificity, validating our earlier performance estimates.

CONCLUSIONS

We have demonstrated that specific US texture features that have been used in other computer-aided diagnostic literature are feasible to use for the classification of healthy and MPS muscle using a binary SVM classifier.

Multicenter Prospective Study of Color Doppler Ultrasound for Breast Masses: Utility of Our Color Doppler Method

The use of color Doppler ultrasound (CD) for distinguishing between benign and malignant breast lesions remains controversial. This study (JABTS BC-04 study) was aimed at confirming the usefulness of our CD diagnostic criteria. We evaluated ultrasound images of 1408 solid breast masses from 16 institutions in Japan (malignant: 839, benign: 569). Multivariate analysis indicated that vascularity (amount of blood flow), vascular flow pattern ("surrounding marginal flow" or "penetrating flow") and the incident angle of penetrating flow were significant findings for distinguishing between benign and malignant lesions. However, the sensitivity and specificity of B-mode alone did not improve significantly with CD addition (97.6% → 97.9%, 38.3% → 41.5%, respectively). We explored the causes of these negative results and found that age should have been considered when evaluating vascularity. Simulation experiments suggested that specificity is significantly improved when age is taken into consideration (38.3% → 46.0%, p < 0.001) and we thereby improved our diagnostic criteria.

Comparative Diagnostic Accuracy of Contrast-Enhanced Ultrasound and Shear Wave Elastography in Differentiating Benign and Malignant Lesions: A Network Meta-Analysis

Background: We performed a network meta-analysis to compare the diagnostic accuracy of contrast-enhanced ultrasound (CEUS) and shear wave elastography (SWE) in differentiating benign and malignant lesions in different body sites.

Methods: A computerized literature search of Medline, Embase, SCOPUS, and Web of Science was performed using relevant keywords. Following data extraction, we calculated sensitivity, specificity, positive likelihood ratio (LR), negative LR, and diagnostic odds ratio (DOR) for CEUS, and SWE compared to histopathology as a reference standard. Statistical analyses were conducted by MetaDiSc (version 1.4) and R software (version 3.4.3).

Results: One hundred and fourteen studies (15,926 patients) were pooled in the final analyses. Network meta-analysis showed that CEUS had significantly higher DOR than SWE (DOR = 27.14, 95%CI [2.30, 51.97]) in breast cancer detection. However, there were no significant differences between CEUS and SWE in hepatic (DOR = −6.67, 95%CI [−15.08, 1.74]) and thyroid cancer detection (DOR = 3.79, 95%CI [−3.10, 10.68]). Interestingly, ranking analysis showed that CEUS achieved higher DOR in detecting breast and thyroid cancer, while SWE achieved higher DOR in detecting hepatic cancer. The overall DOR for CEUS in detecting renal cancer was 53.44, 95%CI [29.89, 95.56] with an AUROC of 0.95, while the overall DOR for SWE in detecting prostate cancer was 25.35, 95%CI [7.15, 89.89] with an AUROC of 0.89.

Conclusion: Both diagnostic tests showed relatively high sensitivity and specificity in detecting malignant tumors in different organs. Network meta-analysis showed that CEUS had higher diagnostic accuracy than SWE in detecting breast and thyroid cancer, while SWE had higher accuracy in detecting hepatic cancer. However, the results were not statistically significant in hepatic and thyroid malignancies. Further head-to-head comparisons are needed to confirm the optimal imaging technique to differentiate each cancer type.

Optimal Endobronchial Ultrasound Strain Elastography Assessment Strategy: An Explorative Study

BACKGROUND

In lung cancer staging, mediastinal lymph nodes are currently aspirated using endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) based on size and FDG-PET avidity. EBUS strain elastography (SE) is a new technique that may help predict the presence of malignancy. However, a standardized assessment strategy for EBUS-SE measurement is lacking.

OBJECTIVES

The aim of this study was to determine the optimal assessment strategy for investigating the predictive value of EBUS-SE in mediastinal lymph nodes.

METHODS

Two qualitative visual analogue scale strain scores and two semiquantitative strain elastography measurements (a strain histogram and strain ratio) were acquired in 120 lymph nodes of 63 patients with (suspected) lung cancer. The dataset was randomized into an 80% training dataset to determine cut-off values. Performance was consecutively tested on the remaining 20% and the overall dataset.

RESULTS

The semiquantitative mean histogram scoring strategy with a cut-off value of 78 (range 0-255) showed the best and most reproducible performance in prediction of malignancy with 93% overall sensitivity, 75% specificity, 69% positive predictive value, 95% negative predictive value, and 82% accuracy. Combining the EBUS-SE mean histogram scoring outcome with PET-CT information increased the post-test probability of disease in relevant clinical scenarios, having a positive test likelihood ratio of 4.16 (95% CI 2.98-8.13) and a negative test likelihood ratio of 0.14 (95% CI 0.04-2.81) in suspicious lymph nodes based on FDG-PET or CT imaging.

CONCLUSIONS

EBUS-SE can potentially help predict lymph node malignancy in patients with lung cancer. The best semiquantitative assessment method is the mean strain histogram technique.

Length Scale Matters: Real-Time Elastography versus Nanomechanical Profiling by Atomic Force Microscopy for the Diagnosis of Breast Lesions

Real-time elastography (RTE) is a noninvasive imaging modality where tumor-associated changes in tissue architecture are recognized as increased stiffness of the lesion compared to surrounding normal tissue. In contrast to this macroscopic appraisal, quantifying stiffness properties at the subcellular level by atomic force microscopy (AFM) reveals aggressive cancer cells to be soft. We compared RTE and AFM profiling of the same breast lesion to explore the diagnostic potential of tissue elasticity at different length scales. Patients were recruited from women who were scheduled for a biopsy in the outpatient breast clinic of the University Hospital Basel, Switzerland. RTE was performed as part of a standard breast work-up. Individual elastograms were characterized based on the Tsukuba elasticity score. Additionally, lesion elasticity was semiquantitatively assessed by the strain ratio. Core biopsies were obtained for histologic diagnosis and nanomechanical profiling by AFM under near-physiological conditions. Bulk stiffness evaluation by RTE does not always allow for a clear distinction between benign and malignant lesions and may result in the false assessment of breast lesions. AFM on the other hand enables quantitative stiffness measurements at higher spatial, i.e., subcellular, and force resolution. Consequently, lesions that were false positive or false negative by RTE were correctly identified by their nanomechanical AFM profiles as confirmed by histological diagnosis. Nanomechanical measurements can be used as unique markers of benign and cancerous breast lesions by providing relevant information at the molecular level. This is of particular significance considering the heterogeneity of tumors and may improve diagnostic accuracy compared to RTE.

Preliminary Results of Acoustic Radiation Force Impulse Imaging by Combined Qualitative and Quantitative Analyses for Evaluation of Breast Lesions

OBJECTIVES

The purpose of this study was to evaluate the application of a new elastographic technique, acoustic radiation force impulse (ARFI) imaging, and its diagnostic performance for characterizing breast lesions.

METHODS

One hundred consecutive female patients with 126 breast lesions were enrolled in our study. After routine breast ultrasound examinations, the patients underwent ARFI elasticity imaging. Virtual Touch tissue imaging (VTI) and Virtual Touch tissue quantification (Siemens Medical Solutions, Mountain View, CA) were used to qualitatively and quantitatively analyze the elasticity and hardness of tumors. A receiver operating characteristic curve analysis was performed to evaluate the diagnostic performance of ARFI for discrimination between benign and malignant breast lesions.

RESULTS

Pathologic analysis revealed 40 lesions in the malignant group and 86 lesions in the benign group. Different VTI patterns were observed in benign and malignant breast lesions. Eighty lesions (93.0%) of benign group had pattern 1, 2, or 3, whereas all pattern 4b lesions (n = 20 [50.0%]) were malignant. Regarding the quantitative analysis, the mean VTI-to-B-mode area ratio, internal shear wave velocity, and marginal shear wave velocity of benign lesions were statistically significantly lower than those of malignant lesions (all P < .001). The cutoff point for a scoring system constructed to evaluate the diagnostic performance of ARFI was estimated to be between 3 and 4 points for malignancy, with sensitivity of 77.5%, specificity of 96.5%, accuracy of 90.5%, and an area under the curve of 0.933.

CONCLUSIONS

The application of ARFI technology has shown promising results by noninvasively providing substantial complementary information and could potentially serve as an effective diagnostic tool for differentiation between benign and malignant breast lesions.

3-D Single Breath-Hold Shear Strain Estimation for Improved Breast Lesion Detection and Classification in Automated Volumetric Ultrasound Scanners

Automated breast volume scanner (ABVS) is an ultrasound imaging modality used in breast cancer screening. It has high sensitivity but limited specificity as it is hard to discriminate between benign and malignant lesions by echogenic properties. Specificity might be improved by shear strain imaging as malignant lesions, firmly bonded to its host tissue, show different shear patterns compared to benign lesions, often loosely bonded. Therefore, 3-D quasi-static elastography was implemented in an ABVS-like system. Plane wave instead of conventional focused transmissions were used to reduce scan times within a single breath hold. A 3-D strain tensor was obtained and shear strains were reconstructed in phantoms containing firmly and loosely bonded lesions. Experiments were also simulated in finite-element models (FEMs). Experimental results, confirmed by FEM-results, indicated that loosely bonded lesions showed increased maximal shear strains (~2.5%) and different shear patterns compared to firmly bonded lesions (~0.9%). To conclude, we successfully implemented 3-D elastography in an ABVS-like system to assess lesion bonding by shear strain imaging.

Strain Ratio as a Quantification Tool in Strain Imaging

Ultrasound-based strain imaging is available in several ultrasound (US) scanners. Strain ratio (SR) can be used to quantify the strain recorded simultaneously in two different user-selected areas, ideally exposed to the same amount of stress. The aim of this study was to evaluate SR variability when assessed in an in-vitro setup with a tissue-mimicking phantom on resected tissue samples and in live tissue scanning with endoscopic applications. We performed an in vivo retrospective analysis of SR variability used for quantification of elastic contrasts in a tissue-mimicking phantom containing four homogenous inclusion in 38 resected bowel wall lesions and 48 focal pancreatic lesions. Median SR and the inter-quartile range (IQR) were calculated for all external and endoscopic ultrasound (EUS) applications. The IQR and median provide a measure of SR variability focusing on the two percentiles of the data closest to the median value. The overall SR variability was lowest in a tissue-mimicking phantom (mean QR/median SR: 0.07). In resected bowel wall lesions representing adenomas, adenocarcinomas, or Crohn lesions, the variability increased (mean IQR/Median: 0.62). During an in vivo endoscopic examination of focal pancreatic lesions, the variability increased further (mean IQR/Median: 2.04). SR variability increased when assessed for different targets with growing heterogeneity and biological variability from homogeneous media to live tissues and endoscopic application. This may indicate a limitation for the accuracy of SR evaluation in some clinical applications.

Accuracy of tumor size measurement: comparison of B-mode ultrasound, strain elastography, and 2D and 3D shear wave elastography with histopathological lesion size

BACKGROUND

Predicting the exact extent of a breast tumor is of great importance for oncologic treatment strategies. Different types of elastography can be used as new tools for measuring lesion size.

PURPOSE

To provide evidence regarding the accuracy of tumor size measurement of strain elastography (SE), two-dimensional (2D) and three-dimensional (3D) shear wave elastography (SWE), and conventional B-image ultrasound.

MATERIAL AND METHODS

In this prospective study, the diameter of 105 malignant breast lesions was measured by SE, 2D and 3D SWE, and B-mode ultrasound. The histopathological lesion size was compared to all imaging-based measuring methods.

RESULTS

The mean lesion size of all breast carcinomas was 1.54 cm. B-mode ultrasound underestimates breast cancer size in 65.7 % of all cases in this study ( P < 0.0001). Mean lesion size was more accurately determined by SE, 2D and 3D SWE compared to B-mode ultrasound. Absolute differences between measured and actual lesion are smaller for B-mode ultrasound (0.26 cm) than for SE (0.41 cm) and 2D and 3D SWE (0.41 cm and 0.44 cm, respectively).

CONCLUSION

B-mode ultrasound allows more accurate lesion size measurement than SE and 2D or 3D SWE but has a significantly higher risk of underestimating tumor size which could lead to incomplete margins during surgery. 3D SWE was not superior to 2D SWE or SE but by trend more precise in predicting the size of invasive lobular carcinoma.

Diagnostic accuracy of sonoelastography in different diseases

The objective of this study was to evaluate the diagnostic accuracy of sonoelastography in patients of primary and secondary health care settings. Google scholar, PubMed, Medline, Medscape, Wikipedia and NCBI were searched in October 2017 for all original studies and review articles to identify the relevant material. Two reviewers independently selected articles for evaluation of the diagnostic accuracy of sonoelastography in different diseases based on titles and abstracts retrieved by the literature search. The accuracy of sonoelastography in different diseases was used as the index text, while B-mode sonography, micro pure imaging, surgery and histological findings were used as reference texts. Superficial lymph nodes, neck nodules, malignancy in thyroid nodules, benign and malignant cervical lymph nodes, thyroid nodules, prostate carcinoma, benign and malignant breast abnormalities, liver diseases, parotid and salivary gland masses, pancreatic masses, musculoskeletal diseases and renal disorders were target conditions. The data extracted by the two reviewers concerning selected study characteristics and results were presented in tables and figures. In total, 46 studies were found for breast masses, lymph nodes, prostate carcinoma, liver diseases, salivary and parotid gland diseases, pancreatic masses, musculoskeletal diseases and renal diseases, and the overall sensitivity of sonoelastography in diagnosing all these diseases was 83.14% while specificity was 81.41%. This literature review demonstrates that sonoelastography is characterized by high sensitivity and specificity in diagnosing different disorders of the body.

Automated classification of focal breast lesions according to S-detect: validation and role as a clinical and teaching tool

PURPOSE

To assess the diagnostic performance and the potential as a teaching tool of S-detect in the assessment of focal breast lesions.

METHODS

61 patients (age 21-84 years) with benign breast lesions in follow-up or candidate to pathological sampling or with suspicious lesions candidate to biopsy were enrolled. The study was based on a prospective and on a retrospective phase. In the prospective phase, after completion of baseline US by an experienced breast radiologist and S-detect assessment, 5 operators with different experience and dedication to breast radiology performed elastographic exams. In the retrospective phase, the 5 operators performed a retrospective assessment and categorized lesions with BI-RADS 2013 lexicon. Integration of S-detect to in-training operators evaluations was performed by giving priority to S-detect analysis in case of disagreement. 2 × 2 contingency tables and ROC analysis were used to assess the diagnostic performances; inter-rater agreement was measured with Cohen's k; Bonferroni's test was used to compare performances. A significance threshold of p = 0.05 was adopted.

RESULTS

All operators showed sensitivity > 90% and varying specificity (50-75%); S-detect showed sensitivity > 90 and 70.8% specificity, with inter-rater agreement ranging from moderate to good. Lower specificities were improved by the addition of S-detect. The addition of elastography did not lead to any improvement of the diagnostic performance.

CONCLUSIONS

S-detect is a feasible tool for the characterization of breast lesions; it has a potential as a teaching tool for the less experienced operators.

A Normalized Shear Deformation Indicator for Ultrasound Strain Elastography in Breast Tissues: An In Vivo Feasibility Study

The shear deformation under loads contains useful information for distinguishing benign breast lesions from malignant ones. In this study, we proposed a normalized shear deformation indicator (NSDI) that was derived from the concept of principal strains. Since the NSDI requires both high-quality axial and lateral (parallel and perpendicular to the beam, resp.) displacement estimates, a strategy combining high-quality speckle tracking with signal “denoising” was employed. Both techniques were previously published by our group. Finite element (FE) models were used to identify possible causes for elevated NSDI values in and around breast lesions, followed by an analysis of ultrasound data acquired from 26 biopsy-confirmed in vivo breast lesions. We found that, theoretically, the elevated NSDI values could be attributed to two factors: significantly hardened tissue stiffness and increasing heterogeneity. The analysis of in vivo data showed that the proposed NSDI values were higher (p < 0.05) among malignant cancers as compared to those measured from benign ones. In conclusion, our preliminary results demonstrated that the calculation of NSDI value is feasible and NSDI could add value to breast lesion differentiation with current clinical equipment as a postprocessing tool.

Strain Elastography - How To Do It?

Tissue stiffness assessed by palpation for diagnosing pathology has been used for thousands of years. Ultrasound elastography has been developed more recently to display similar information on tissue stiffness as an image. There are two main types of ultrasound elastography, strain and shear wave. Strain elastography is a qualitative technique and provides information on the relative stiffness between one tissue and another. Shear wave elastography is a quantitative method and provides an estimated value of the tissue stiffness that can be expressed in either the shear wave speed through the tissues in meters/second, or converted to the Young's modulus making some assumptions and expressed in kPa. Each technique has its advantages and disadvantages and they are often complimentary to each other in clinical practice. This article reviews the principles, technique, and interpretation of strain elastography in various organs. It describes how to optimize technique, while pitfalls and artifacts are also discussed.

Strain histograms are equal to strain ratios in predicting malignancy in breast tumours

Objectives

To assess whether strain histograms are equal to strain ratios in predicting breast tumour malignancy and to see if either could be used to upgrade Breast Imaging Reporting and Data System (BI-RADS) 3 tumours for immediate biopsy.

Methods

Ninety-nine breast tumours were examined using B-mode BI-RADS scorings and strain elastography. Strain histograms and ratios were assessed, and areas- under-the-receiver-operating-characteristic-curve (AUROC) for each method calculated. In BI-RADS 3 tumours cut-offs for strain histogram and ratio values were calculated to see if some tumours could be upgraded for immediate biopsy. Linear regression was performed to evaluate the effect of tumour depth and size, and breast density on strain elastography.

Results

Forty-four of 99 (44.4%) tumours were malignant. AUROC of BI-RADS, strain histograms and strain ratios were 0.949, 0.830 and 0.794 respectively. There was no significant difference between AUROCs of strain histograms and strain ratios (P = 0.405), while they were both inferior to BI-RADS scoring (P<0.001, P = 0.008). Four out of 26 BI-RADS 3 tumours were malignant. When cut-offs of 189 for strain histograms and 1.44 for strain ratios were used to upgrade BI-RADS 3 tumours, AUROCS were 0.961 (Strain histograms and BI-RADS) and 0.941 (Strain ratios and BI-RADS). None of them was significantly different from BI-RADS scoring alone (P = 0.249 and P = 0.414). Tumour size and depth, and breast density influenced neither strain histograms (P = 0.196, P = 0.115 and P = 0.321) nor strain ratios (P = 0.411, P = 0.596 and P = 0.321)

Conclusion

Strain histogram analyses are reliable and easy to do in breast cancer diagnosis and perform comparably to strain ratio analyses. No significant difference in AUROCs between BI-RADS scoring and elastography combined with BI-RADS scoring was found in this study.

Elastography in the diagnosis of breast lesions: comparison of different elastographic features

Background Breast elastography is a non-invasive and widely accessible method used in the differential diagnostic procedure in addition to B-mode imaging. Purpose To assess the role of elastographic features in the differentiation of breast lesions and to evaluate the importance of depth in the choice of reference fat tissue for the calculation of strain ratio. Material and Methods From January to August 2015, 242 breast lesions were evaluated using elastographic assessment based on qualitative and semi-quantitative parameters (color map, strain ratio, length ratio) as well as elastographic analysis. Histological findings were considered as gold-standard. Results Sensitivity and specificity of B-mode ultrasound imaging were 90% and 60%, respectively. Color map sensitivity was 98% and specificity 46%; strain ratio sensitivity 81% and specificity 70%; length ratio sensitivity 64% and specificity 76%. Combined analysis of these three elastographic features improved the overall diagnostic performance of any of the three parameters alone, yielded sensitivity similar to that of color map (95%) and specificity comparable to strain ratio and length ratio (70%). There was no significant difference in strain ratio obtained from the reference fat tissue at the same depth as the lesion and at a different depth (sensitivity 77% versus 84%; specificity 70% versus 68%; P < 0.001). Conclusion In our experience, elastography can improve ultrasound characterization of the lesion, particularly if elastographic analysis is performed.

Auto strain ratio system for the quality control of breast strain elastography

PURPOSE

To determine the reproducibility, accuracy, and quantitative values of the auto strain ratio system (ASRS)-a newly developed strain elastography-based program.

MATERIALS AND METHODS

First, the accuracy of ASRS was verified using a breast phantom. A prospective clinical study was then performed in patients. Two hundred and one women (mean age 52.4 years ± SD 14.5) with 232 breast lesions (177 benign and 55 malignant) were enrolled in this study. We assessed the correlation between ASRS and manual strain ratio (MSR), calculating the diagnostic performance to determine the cut-off. The area under the receiver operating characteristic curve (AUC) was calculated.

RESULTS

ASRS was strongly correlated with the subtle differences in phantom stiffness (R = 0.87). In the clinical study, there was a significant correlation between MSR and ASRS with R = 0.79 (P < 0.001). ASRS (cut-off = 3.9) had a sensitivity of 81.8%, specificity of 88.7%, accuracy of 87.1%, positive predictive value of 69.2%, and negative predictive value of 94%. The AUC of ASRS was 0.89.

CONCLUSION

The findings from this study have demonstrated that it is possible to quantify strain elastography and control its accuracy. ASRS is expected to contribute to the standardization of breast elastography.

Kindlin-2 could influence breast nodule elasticity and improve lymph node metastasis in invasive breast cancer

This study investigated the relationship between quantitative parameters of shear wave elastography (SWE, maximum elasticity [Emax], minimum elasticity [Emin], mean elasticity [Emean]), collagen intensity and Kindlin-2 expression in benign and malignant breast nodules, and if Kindlin-2 expression is related with lymph node metastasis. A total of 102 breast nodules from 102 patients were included in our study who underwent ultrasound elastography before surgery or core needle biopsy. There was a significant difference between benign and malignant breast nodules in Emax, Emean, collagen intensity and Kindlin-2 expression, but it had no difference in Emin. Collagen intensity and Kindlin-2 expression both correlated positively with Emax, but not with Emean. Among 38 malignant breast nodules, the average Emax of the metastasis group was higher than that of the non-metastasis group, but it had no statistical significance. Compared with the non-metastasis group, Kindlin-2 expression was considerably higher in the metastasis group. However, there was no difference in collagen intensity between the metastasis group and the non-metastasis group. In conclusion, Kindlin-2 and collagen might contribute to breast nodule elasticity through molecular mechanisms. In breast cancer, overexpression of Kindlin-2 might be a risk factor for lymph node metastasis.

Differentiation of secondary involvement of the breast by lymphoreticular malignancy from fibroadenoma using ultrasound elastography: A report of two cases

Extramedullary lymphoma infiltration of the breast by lymphoblastic lymphoma is very rare and most cases are of B-cell lineage; T-cell neoplasms represent less than 10% of all breast lymphomas. Here, we report one patient with lymphoblastic lymphoma and one patient with leukemia, who have similar lesions in breasts with different ultrasound elastography findings. Ultrasound-guided tru-cut biopsies were performed and the first lesion was confirmed as lymphoma infiltration and the second as fibroadenoma. In cases of breast mass presence in patients with a history of hematologic malignancies such as lymphoma or leukemia, breast infiltration should be kept in mind. Elastography findings can assist in the differentiation of these lesions and further investigations or biopsies can be avoided.

Value of Endobronchial Ultrasound Elastography in Diagnosis of Central Lung Lesions

BACKGROUND Ultrasound elastography is an imaging modality used to show tissue stiffness in tumor pathophysiological processes that promote the formation of stiffer tissues. Endobronchial ultrasound (EBUS) elastography is an ultrasound elastography-based technique for measuring tissue stiffness during EBUS-guided transbronchial needle aspiration (EBUS-TBNA). The diagnostic value of EBUS elastography in central lung lesions remains largely unknown. MATERIAL AND METHODS A total of 57 patients with central lung lesions underwent ultrasonic bronchoscope examination. EBUS with standard B mode evaluation and elastography with grading score measurement were performed before EBUS-guided transbronchial needle aspiration (EBUS-TBNA). Comparison of the diagnosis accuracy in malignant lung lesions between elastography and standard EBUS was made. RESULTS Our data showed that the hypoechoic lesions, uneven echo, distinct boundary, and no air bronchogram were significant indicators of standard EBUS in diagnosis of malignant lung lesions (P<0.01). The differences in elastosonography grading scores between the benign and malignant lung lesions were statistically significance (P<0.01), and the elastography grading score was more sensitive and specific than the standard EBUS criteria in diagnosing malignant lung lesions. The area under the receiver operating characteristic curve (ROC) for the elastography grading score was 0.793. The best cut-off point of the elastography grading score for distinguishing malignant from benign lung lesions was 2.5. The elastography grading score had a sensitivity of 72.2%, specificity of 76.2%, positive predictive value of 83.4%, and negative predictive value of 61.5% for distinguishing malignant from benign lung lesions. The overall accuracy of elastography grading score was 73.7%. CONCLUSIONS BUS elastography can effectively diagnose central lung lesions. The diagnostic accuracy of elastography in malignant lung lesions is higher than that of standard EBUS criteria.