Real-time elastography--an advanced method of ultrasound: First results in 108 patients with breast lesions

Assessment of spinal cord injury using ultrasound elastography in a rabbit model in vivo

The effect of the mechanical micro-environment on spinal cord injury (SCI) and treatment effectiveness remains unclear. Currently, there are limited imaging methods that can directly assess the localized mechanical behavior of spinal cords in vivo. In this study, we apply new ultrasound elastography (USE) techniques to assess SCI in vivo at the site of the injury and at the time of one week post injury, in a rabbit animal model. Eleven rabbits underwent laminectomy procedures. Among them, spinal cords of five rabbits were injured during the procedure. The other six rabbits were used as control. Two neurological statuses were achieved: non-paralysis and paralysis. Ultrasound data were collected one week post-surgery and processed to compute strain ratios. Histologic analysis, mechanical testing, magnetic resonance imaging (MRI), computerized tomography and MRI diffusion tensor imaging (DTI) were performed to validate USE results. Strain ratios computed via USE were found to be significantly different in paralyzed versus non-paralyzed rabbits. The myelomalacia histologic score and spinal cord Young's modulus evaluated in selected animals were in good qualitative agreement with USE assessment. It is feasible to use USE to assess changes in the spinal cord of the presented animal model. In the future, with more experimental data available, USE may provide new quantitative tools for improving SCI diagnosis and prognosis.

Ultrasound Elastography to Differentiate the Thrombus and Plaque in Peripheral Arterial Diseases

Purpose

Arterial stiffness and steno-occlusion of the lower-extremity can result from many vascular lesions, including acute thromboembolisms, soft plaques, calcified plaques, or inflammatory disease. Ultrasound (US) elastography measures the tissue deformation response to compression and displays tissue stiffness. This study aimed to evaluate the characteristics of arterial lesions in the lower extremities using US elastography.

Materials and Methods

We retrospectively analyzed the data of 20 patients who visited our institute for arterial disease treatment between May 2016 and November 2017. An US examination with B-mode and strain elastography (SE) was performed of four different lesion types at 45 sites: acute and subacute thromboembolisms, soft plaques, calcified plaques, and thromboangiitis obliterans lesions (TAOs). During SE, stress was externally applied by the operator using the transducer. Strain ratio (SR) was calculated as the fraction of the average strain in the reference area divided by the average strain in the lesion. The SR was compared among different lesion types, with the accompanying vein as the reference region of interest.

Results

The strain was highest in the soft plaques (0.63%±0.23%), followed by the TAOs (0.45%±0.11%), calcified plaques (0.44%±0.13%), and acute thromboembolisms (0.34%±0.23%), which were statistically significant (P=0.026). However, the mean SR was highest for the calcified plaques (2.33%±0.80%), followed by the TAOs (1.63%±0.40%), acute thromboembolisms (1.60%±0.48%), and soft plaques (1.51±0.39), and which were statistically significant (P=0.013).

Conclusion

Despite several limitations, vascular elastography may be useful for differentiating between lesion types in peripheral arterial disease.

Evaluation of Pre-malignant Lesions of the Uterine Cervix by Shear Wave Elastography: A New Diagnostic Tool

The objective of the study was to evaluate the difference in the stiffness between a healthy cervix (no pre-invasive lesions [NPILs]) and a cervix with a pre-invasive lesion (PIL). In the PIL group, we determined whether there was a difference in stiffness between the cervix with persistent low-grade lesions (>2 y, LSIL-persistent) and that with high-grade lesions (HSILs). Evaluation was performed using 2-D shear-wave elastography (SWE) in the midsagittal-plane of the uterine cervix (UC) at 0.5 cm (cervical canal, anterior and posterior cervical lips). In this prospective observational study (consecutive series), we evaluated 96 non-pregnant women: a group with PIL (LSIL-persistent, 22 cases; HSIL, 26 cases) with indications for cervical conization (48 cases) and a group without UC pathology (NPIL, 48 cases). Although we did not observe statistically significant differences (SSDs) in epidemiological characteristics, we did find an SSD in the speed and stiffness between the PIL versus NPIL groups at all evaluated depths (speed: 4.1 m/s vs 3.0 m/s, stiffness: 58.6 and 34.5kPa in the PIL and NPIL groups, respectively, p < 0.001). An SSD in speed and stiffness (speed: 4.9 m/s vs. 3.2 m/s, and stiffness: 76.1 and 38.0 kPa) between the HSIL (26 cases) and LSIL-persistent (22 cases) groups, respectively, was also detected (p < 0.001). The area under the curve of speed differentiation between a cervix with HSILs and without lesions was 73.4% (95% confidence interval [CI]: 63.1-83.7), and the best cutoff of speed was 3.25 m/s (sensitivity = 62.5%, 95% CI: 47.3-76.0), with a specificity of 75.5% (95% CI: 60.4-87.1).

Application of Magnetic Resonance Imaging in Liver Biomechanics: A Systematic Review

MRI-based biomechanical studies can provide a deep understanding of the mechanisms governing liver function, its mechanical performance but also liver diseases. In addition, comprehensive modeling of the liver can help improve liver disease treatment. Furthermore, such studies demonstrate the beginning of an engineering-level approach to how the liver disease affects material properties and liver function. Aimed at researchers in the field of MRI-based liver simulation, research articles pertinent to MRI-based liver modeling were identified, reviewed, and summarized systematically. Various MRI applications for liver biomechanics are highlighted, and the limitations of different viscoelastic models used in magnetic resonance elastography are addressed. The clinical application of the simulations and the diseases studied are also discussed. Based on the developed questionnaire, the papers' quality was assessed, and of the 46 reviewed papers, 32 papers were determined to be of high-quality. Due to the lack of the suitable material models for different liver diseases studied by magnetic resonance elastography, researchers may consider the effect of liver diseases on constitutive models. In the future, research groups may incorporate various aspects of machine learning (ML) into constitutive models and MRI data extraction to further refine the study methodology. Moreover, researchers should strive for further reproducibility and rigorous model validation and verification.

Interobserver and intermethod variability in data interpretation of breast strain elastography in suspicious breast lesions

Background/aim

Strain elastography has the disadvantage of being operator-dependent. Interobserver variability is observed during image acquisition and interpretation. This study aimed to analyze the interobserver and intermethod variability of strain elastography in image interpretation and evaluate the diagnostic performance combining elasticity score and strain ratio with ultrasonography.

Materials and methods

A retrospective study was conducted on 70 breast lesions evaluated with B-mode ultrasonography and strain elastography. B-mode ultrasonography findings, elasticity scores, and strain ratio values were evaluated using static images by two radiologists. BI-RADS assessment of the lesions and the decision of both observers as to whether the biopsy was required using B-mode ultrasonography, and the combined ultrasonography+elasticity score, and the combined ultrasonography+elasticity score+strain ratio were compared with the histopathological results. Also, the interobserver agreement was analyzed for all the combinations.

Results

There was very good agreement (weighted κ = 0.865) between the observers for the elasticity scores. Very good agreement was observed between the observers for BI-RADS assessments using the combined ultrasonography+elasticity score and the combined ultrasonography+elasticity score+strain ratio (weighted κ = 0.848, and 0.902, respectively). Area under the curve of B-mode ultrasonography, the combined B-mode ultrasonography+elasticity score, and the combined B-mode ultrasonography+elasticity score+strain ratio, were calculated as 0.859, 0.866, and 0.916 for observer 1, and 0.851, 0.829, and 0.916 for observer 2, respectively. There were no statistically significant differences between the observers’ diagnostic performances in any of the combinations (P = 0.703, 0.067, and 0.972, respectively).

Conclusion

In the evaluation and further assessment of breast lesions, semiquantitative strain ratio calculation may help improve diagnostic accuracy by reducing interpretational variety, when used together with B-mode ultrasonography and elasticity scoring, especially for inexperienced individuals.

Combining real-time elastography with fine-needle aspiration biopsy to identify malignant thyroid nodules

Objectives

To evaluate the diagnostic performance of real-time elastography (RTE) combined with fine-needle aspiration (FNA) biopsy in identifying malignant thyroid nodules.

Methods

This was a single-centre, retrospective study and involved patients who had underogone partial or total thyroidectomy from 01 January 2014 to 31 December 2018 at our centre. Eligible patients were at least18 years of age, had reliable grayscale ultrasound imaging results, a RTE evaluation and had undergone a FNA biopsy.

Results

Data were available from 437 patients. A high RTE score was a significant independent risk factors for malignancy. RTE plus FNA biopsy increased diagnostic accuracy compared with either method alone and the sensitivity and specificity of the combined model were 86% and 78%, respectively.

Conclusions

The combination of RTE imaging with FNA biopsy improves the diagnostic performance in differentiating benign and malignant thyroid nodules.

Evaluation of the Perinodular Stiffness Potentially Predicts the Malignancy of Thyroid Nodules

OBJECTIVES

To evaluate the surrounding tissue stiffness measured by sound touch elastography for differential diagnosis of thyroid nodules (TNs).

METHODS

Thirty-nine benign and 90 malignant TNs were included in this study. The conventional ultrasound features, the maximum Young modulus value of the stiffness of the TNs (recorded as E), and the stiffness of the 0.5-, 1.0-, 1.5-, and 2.0-mm perinodular regions of the TNs (recorded as E_shell0.5 , E_shell1.0 , E_shell1.5 , and E_shell2.0 , respectively) were prospectively analyzed and compared to histopathologic results. The abundance of collagen fibers at various widths in the perinodular regions of the TNs was evaluated by Masson staining and ImageJ software (National Institutes of Health, Bethesda, MD). The fibrous structures in the perinodular regions of the TNs were classified.

RESULTS

The various E_shell values of malignant TNs were significantly higher than those of benign TNs (P < .001 for all). E_shell0.5 correlated highly with E in the malignant TNs and in all samples (r = 0.722 and 0.772; P < .001 for both). _Eshell2 yielded the highest area under the receiving operating characteristic curve value (0.96) for the differential diagnosis of TNs. The abundance of collagen fibers in the 2-mm perinodular region of the TNs was closely correlated with E_shell2 in the malignant TNs and in all samples (r =0.729 and 0.867; P < .001). The E_shell2 values for different levels of disorder of the tissue surrounding TNs were significantly different (P < .01 for all).

CONCLUSIONS

Perinodular stiffness measured by sound touch elastography improved the diagnostic accuracy in TNs.

Evaluation of Optic Nerve Head Biomechanical Properties in Pseudoexfoliation Glaucoma with Real-time Elastography

PURPOSE

To investigate the biomechanical properties of the optic nerve head in patients with Pseudoexfoliation (PEX) glaucoma using Real-time Elastography (RTE) and to compare these results with those of Primary Open Angle Glaucoma (POAG) patients and healthy subjects.

METHODS

Twenty eyes of 20 PEX glaucoma patients (PEX group), 20 eyes of 20 POAG patients (POAG group), and 20 eyes of 20 healthy subjects (control group) were enrolled in this prospective study. The strain Ratios of Orbital Fat to Optic Nerve head (ROFON) and lateral rectus muscle to optic nerve head (RLRON) were determined. Comparisons were performed using Chi-square, Kruskal Wallis, Mann-Whitney U, and One-way ANOVA tests.

RESULTS

The strain ratios of orbital fat to optic nerve head were 2.34, 6.85 and 1.76 in PEX glaucoma, POAG, and control groups, respectively (p<0.001). The strain ratios of the lateral rectus muscle to the optic nerve head were 0.51, 0.82, and 0.55 in PEX glaucoma, POAG, and control groups, respectively (p=0.256).

CONCLUSION

The strain ratios of orbital fat to optic nerve head were different in PEX glaucoma patients than in POAG and control groups. RTE can provide biomechanical assessment of the optic nerve head in a non-invasive, quick, easily accessible, and user-friendly manner.

Utility of Ultrasound Strain Elastography to Differentiate Benign from Malignant Lesions of the Breast

Background

The purpose of this study was to determine the utility and diagnostic performance of strain elastography (SE) in differentiating benign from malignant lesions of the breast.

Methods

In this prospective study, 50 palpable breast masses in 50 patients were examined by mammography, B-mode ultrasound (US) and SE. Lesions were categorized using Breast Imaging Reporting and Data System (BIRADS) scoring based on mammographic and sonographic features. Elasticity scores were assessed on a five-point scale based on the distribution of strain, and the lesion size on SE imaging and B-mode (elasticity imaging/B mode [EI/B] ratio) was compared. Findings were correlated with the BIRADS assessment and diagnostic performance of sonoelastography was evaluated taking histopathology as reference standard.

Results

Histopathology revealed 29 (58%) malignant and 21 (42%) benign lesions. Infiltrative ductal carcinoma and fibroadenoma were the most common malignant and benign lesions, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of SE was 100%, 76.1%, 85.2%, 100%, and 90%, respectively. Higher elasticity score was significantly associated with malignant histopathology (P < 0.00001). The mean EI/B ratio for malignant lesions was 1.36 ± 0.24 while that of benign lesions was 1.03 ± 0.30 (P = 0.000).

Conclusion

Real-time SE of the breast, with its superior sensitivity and specificity, could provide improved characterization of benign and malignant breast masses compared with mammography and conventional US. Due to greater diagnostic accuracy, SE can be an effective adjunctive tool to B-mode US in predicting malignancy of breast, as well as in reducing the need for biopsies in benign breast lesions.

Utility of Ultrasound Elastography to Differentiate Benign from Malignant Cervical Lymph Nodes

Background:

The purpose of this study was to evaluate the usefulness of strain elastography and acoustic radiation force impulse (ARFI) imaging in the differentiation of benign and malignant cervical lymph nodes (LNs).

Materials and Methods:

In this prospective study, 50 enlarged cervical LNs (33 benign and 17 malignant) were examined by B-mode ultrasound (US), color Doppler, and strain elastography. Elastographic patterns (1–5) were categorized based on distribution of hard area within LN. The shear wave velocity (SWV) of LNs was evaluated by ARFI imaging. Diagnostic performance of sonoelastographic parameters was compared taking histopathology of LN as a reference standard. Optimal cutoff value of the mean SWV values for predicting malignancy was determined using receiver operating characteristic curve analysis.

Results:

Among US parameters, borders of LN had the highest diagnostic accuracy (80%), while echogenicity had the least (48%). Majority of benign LNs (n = 31) had elastography patterns 1 and 2, while majority of malignant LNs (n = 16) had patterns 3–5 (P = 0.000). The sensitivity, specificity, and accuracy of elastography were 94.1%, 93.9%, and 94%, respectively. The mean SWV of benign LNs (1.670 ± 0.367 m/s) differed significantly from malignant LNs (2.965 ± 0.826 m/s; P = 0.000). A cutoff value of 2.05 m/s predicted malignancy with 88.2% sensitivity and 84.8% specificity and gave an area under the curve of 0.949 (95% confidence interval: 0.70–1.20).

Conclusion:

Elastography has high diagnostic accuracy in differentiating benign and malignant cervical LNs and can be potentially useful in selecting the LN with high probability of malignancy, on which fine-needle aspiration cytology/biopsy can be performed.

Determination of the Relationships Between intra- and Extraoral Tongue Hardness, Thickness, and Pressure Using Ultrasonic Elastography

Involved with various bodily functions, including ingestion and swallowing, the tongue is an important organ. We measured resting tongue hardness using real-time tissue elastography (RTE) to establish a simple tongue evaluation for patients who may have limited capacities to follow commands. Relationships between tongue hardness, thickness, and pressure were investigated, using both intra- and extraoral probes. Assessments were performed for a total of 27 healthy adults (11 male, 16 female, average age 26.4 ± 1.8 years). Measurements of tongue hardness and thickness were made using strain ratios (SR), and averaged across nine images. Maximum tongue pressure was determined using a tongue pressure device. A negative correlation was observed between intraorally measured tongue hardness and maximum tongue pressure (r = -0.76, p < 0.01). A positive correlation between extraorally measured tongue thickness and maximum tongue pressure was observed (r = 0.59, p < 0.01). Additionally, significant differences were observed between males and females with regards to intraorally measured tongue hardness (p = 0.02), maximum tongue pressure (p = 0.02), and extraorally measured tongue thickness (p < 0.01). The results of this study demonstrated the clinical applicability of RTE-based tongue hardness measurements, and suggest the feasibility of predicting tongue strength based on extraoral tongue thickness measurements.

Combining Total Variation Regularization with Window-Based Time Delay Estimation in Ultrasound Elastography

A major challenge of free-hand palpation ultrasound elastography (USE) is estimating the displacement of RF samples between pre- and post-compressed RF data. The problem of displacement estimation is ill-posed since the displacement of one sample by itself cannot be uniquely calculated. To resolve this problem, two categories of methods have emerged. The first category assumes that the displacement of samples within a small window surrounding the reference sample is constant. The second class imposes smoothness regularization and optimizes an energy function. Herein, we propose a novel method that combines both approaches, and as such, is more robust to noise. The second contribution of this work is the introduction of the L1 norm as the regularization term in our cost function, which is often referred to as the total variation (TV) regularization. Compared to previous work that used the L2 norm regularization, optimization of the new cost function is more challenging. However, the advantages of using the L1 norm are twofold. First, it leads to substantial improvement in the sharpness of displacement estimates. Second, to optimize the cost function with the L1 norm regularization, we use an iterative method that further increases the robustness. We name our proposed method tOtal Variation Regularization and WINDow-based time delay estimation (OVERWIND) and show that it is robust to signal decorrelation and generates sharp displacement and strain maps for simulated, experimental phantom and in-vivo data. In particular, OVERWIND improves strain contrast-to-noise ratio (CNR) by 27.26%, 144.05%, and 49.90% on average in simulation, phantom, and in-vivo data, respectively, compared to our recent Global Ultrasound Elastography (GLUE) method.

Ultrasound Elastography Use in Lower Extremity Lymphedema: A Systematic Review of the Literature

Lower extremity lymphedema (LEL) is mainly assessed clinically. Ultrasound elastography (UE) is a promising imaging tool to assess this disorder. We conducted a systematic literature review to describe the studies evaluating the use of UE in LEL. The PubMed database was queried for studies that evaluated the use of UE in LEL. The keywords "elastography" AND "lymphedema" were used for the search. Original articles in English were included in our study, whereas reviews were excluded. Our search resulted in 12 articles, 4 of which met the inclusion criteria. UE methods included free-hand real-time tissue elastography and UE with transducer in B mode. The imaging parameters applied were the tissue strains and the area of red region, respectively. All studies tested UE use in the assessment of LEL, and only one considered its use for staging. All studies but one found a difference in strain parameters for assessment of patients with LEL. Our systematic review has shown that UE appears to be a great tool in the assessment of LEL in moderate-to-advanced stages of disease. However, further studies using new effective methods are needed to evaluate patients with early lymphedema.

Comparison of Diagnostic Performance of B-Mode Ultrasonography and Shear Wave Elastography in Cervical Lymph Nodes

The purpose of this study was to compare the diagnostic performance of B-mode ultrasonography (US) and shear wave elastography (SWE) for differentiating benign from malignant cervical lymph nodes (LNs). This study evaluated 130 cervical LNs in 127 patients. On conventional B-mode US, short-axis and long-axis diameters, long-to-short-axis ratio, cortical morphology, border, and presence of necrosis or calcification were evaluated. Maximum elasticity value (Emax) was collected for SWE. The area under the receiver operator characteristic curve (AUC), sensitivity, and specificity of B-mode US features and SWE were compared. Final histopathologic results showed 89 benign and 41 metastatic LNs. Among the B-mode US features, cortical morphology had the highest AUC (0.884). When 54 kPa of Emax was applied as a cutoff value, the SWE showed significantly lower AUC than cortical morphology (0.734, P = 0.02). Both sensitivity and specificity for cortical morphology on B-mode US were higher than for Emax (80.5% vs 65.9%, P = 0.212 and 89.9% vs 76.4%, P = 0.026, respectively). Conventional B-mode US resulted in higher diagnostic yield than SWE in evaluating cervical LNs in our study. However, further studies on potential factors that may affect the SWE velocity are needed to validate the diagnostic value of SWE.

Comparative Study of Pattern-Based Versus Size Ratio Ultrasound Strain Elastographic Techniques on Breast Masses

OBJECTIVES

The aim of this study was to compare the diagnostic performance of strain elastographic techniques involving pattern-based elastography versus size ratio elastography on breast masses.

METHODS

Female patients presenting to the radiology department for ultrasound (US)-guided biopsies, fine-needle aspirations, or localizations of breast masses were invited to undergo US elastographic assessments of the lesions before the breast procedures. The masses were evaluated for color score and color map size ratio elastographic assessments with one US machine and size ratio and grayscale strain pattern elastographic assessments with another machine. With the histopathologic diagnosis as the reference standard, the sensitivity, specificity, and area under the receiver operating characteristic curve were compared among the 4 groups.

RESULTS

A total of 154 breast masses from 139 women were assessed. The sensitivity and specificity were 0.615 (95% confidence interval, 0.470-0.747) and 0.824 (0.736-0.892), respectively for the color score, 0.962 (0.868-0.995) and 0.765 (0.670-0.843) for the size ratio, 0.904 (0.790-0.968) and 0.745 (0.649-0.826) for the color map size ratio, and 0.635 (0.490-0.764) and 0.422 (0.324-0.523) for the grayscale strain pattern. The areas under the receiver operating characteristic curve were 0.729 for the color score, 0.874 for the size ratio (P = .001 with the color score as a reference), 0.836 for the color map size ratio (P = .002), and 0.556 for the grayscale strain pattern (P < .001).

CONCLUSIONS

Size ratio elastography had higher sensitivity and better diagnostic accuracy compared to color score elastography. This superiority was demonstrated on two different US systems, and size ratio elastography should thus be considered over color score elastography in the adjunctive US assessment of breast lesions.

Does Shear Wave Elastography Score Over Strain Elastography in Breast Masses or Vice Versa?

OBJECTIVE

This study was done to compare parameters of strain elastography (SE) and shear-wave elastography (SWE) for differentiation of benign and malignant breast masses and determine their best cut-offs.

MATERIAL AND METHODS

B mode ultrasound (USG), SE, and SWE were performed in 199 breast masses. During SE, 5-point visual elastography score (SE_{visual score}) and strain ratio (SE_{strain ratio}) were obtained. During SWE, mean and maximum elasticity values in kilopascals, and shear wave ratio were obtained in two orthogonal planes. The shear wave mean average (SWE_{mean avg}), shear wave maximum average (SWE_{max avg}) and shear wave ratio average (SWE_{ratio avg}) were calculated by averaging the respective values in the two planes. The SE and SWE parameters of every mass were correlated with its histopathology.

RESULTS

The areas under the receiver operating characteristic curve of SE_{visual score}, SE_{strain ratio}, SWE_{mean avg}, SWE_{max avg}, and SWE_{ratio avg} were 0.815, 0.814, 0.846, 0.846, and 0.799, respectively.

CONCLUSIONS

The best cut-off values that achieved the highest sensitivity and specificity for SE_{strain ratio}, SWE_{mean avg}, SWE_{max avg}, and SWE_{ratio avg} were 3.91, 113 kPa, 123.5 kPa, and 7.32, respectively. Quantitative parameter of SE showed comparable diagnostic performance with quantitative parameters of SWE.

A Model-Based Approach to Investigate the Effect of a Long Bone Fracture on Ultrasound Strain Elastography

The mechanical behavior of long bones and fractures has been under investigation for many decades due to its complexity and clinical relevance. In this paper, we report a new subject-specific methodology to predict and analyze the mechanical behavior of the soft tissue at a bone interface with the intent of identifying the presence and location of bone abnormalities with high accuracy, spatial resolution, and contrast. The proposed methodology was tested on both intact and fractured rabbit femur samples with finite element-based 3-D simulations, created from actual femur computed tomography data, and ultrasound elastography experiments. The results included in this study demonstrate that elastographic strains at the bone/soft tissue interface can be used to differentiate fractured femurs from the intact ones on a distribution level. These results also demonstrate that coronal plane axial shear strain creates a unique contrast mechanism that can be used to reliably detect fractures (both complete and incomplete) in long bones. Kruskal-Wallis test further demonstrates that the contrast measure for the fracture group (simulation: 2.1286±0.2206; experiment: 2.7034 ± 1.0672) is significantly different from that for the intact group (simulation: 0 ± 0; experiment: 1.1540±0.6909) when using coronal plane axial shear strain elastography ( < 0.01). We conclude that: 1) elastography techniques can be used to accurately identify the presence and location of fractures in a long bone and 2) the proposed model-based approach can be used to predict and analyze strains at a bone fracture site and to better interpret experimental elastographic data.

Benign lesion evaluation: Factors causing the "stiff rim" sign in breast tissues using shear-wave elastography

OBJECTIVE:

To investigate the factors causing the "stiff rim" sign in breast lesions using shear-wave elastography.

METHODS:

A total of 907 patients with 907 lesions were included retrospectively in this study. Traditional ultrasound and shear-wave elastography imaging were both performed. Patients age, maximum diameter, depth, distance, echogenicity, shape, boundary, margin, internal components, CDFI, calcification, echogenicity attenuation and longitudinal growth of lesions were observed and calculated by both univariate and multivariate analyses.

RESULTS:

Univariate analyses indicated that the age, depth, shape, margin, internal components, CDFI, calcification and pathology showed significant difference between the benign lesions with and without a "stiff rim", whereas there was no correlation of "stiff rim" with maximum diameter, distance, boundary, echogenicity, echo attenuation and longitudinal growth of the lesions. Multivariate analysis expressed that CDFI, margin, internal components, depth and age were significantly associated with the "stiff rim" sign in breast benign lesions, whereas there was no correlation with the pathology, shape or calcification of the lesions.

CONCLUSIONS:

The "stiff rim" sign can be helpful for differentiation between benign and malignant lesions. Older patients with a "stiff rim" sign whose benign masses are deep, poorly defined, heterogeneous and have a positive CDFI should be examined more closely to avoid unnecessary false-positives.

ADVANCES IN KNOWLEDGE:

The "stiff rim" sign can be helpful for differentiation between benign and malignant lesions. Positive CDFI, poorly defined margin, heterogeneous internal components, deep depth and older age were significantly associated with the "stiff rim" sign in benign breast lesions.

Evaluation of the Stiffness of Tissues Surrounding Thyroid Nodules with Shear Wave Elastography

OBJECTIVES

This study evaluated the stiffness of tissue surrounding thyroid nodules using shear wave elastography (SWE).

METHODS

A total of 128 thyroid nodules in 108 patients were examined with conventional ultrasound imaging and SWE. The maximum Young modulus value was measured to evaluate the stiffness of the thyroid nodules (E) and the 2-mm perinodular region (E_shell ). The number of thyroid fibrocytes was evaluated by Masson trichrome staining and image-processing software. The arrangement of the fibrous structure was also classified.

RESULTS

The mean age ± SD of the 108 patients was 33.12 ± 13.34 years (range, 18-80 years). Thirty-nine thyroid nodules were classified as benign and 89 as malignant. E_shell was significantly higher for malignant nodules (95.0 ± 21.9 kPa) compared with benign nodules (48.1 ± 17.0 kPa; P < .001). E_shell yielded an area under the receiver operator characteristic curve value of 0.951, which was used for the diagnosis of nodules. There was a high positive correlation between E and E_shell in the malignant group (R = 0.722; P < .001) and a moderate positive correlation in the benign group (R = 0.601; P < .001). Percentages of fibrocytes correlated highly with E_shell in all samples as well as in malignant samples (R = 0.867 and R = 0.729, respectively; P < .001). The degree of disorder of the tissue surrounding thyroid nodules was positively correlated with E_shell (R = 0.833).

CONCLUSIONS

Perinodular stiffness has potential to improve diagnosis of thyroid nodules.

Factors Affecting the Quality of Breast Quasistatic Ultrasound Elastograms

OBJECTIVES

To explore factors affecting the quality of quasistatic ultrasound elastograms of the breast and to evaluate their accuracy in distinguishing benign and malignant breast lesions.

METHODS

A total of 663 patients with 702 breast lesions were recruited. All patients received both conventional ultrasonography and quasistatic elastography. Patients' breast lesions were divided into A and B groups according to satisfactory and unsatisfactory elastographic examinations. Group A included 590 satisfactory elastograms, whereas Group B included 112 unsatisfactory elastograms. Various factors-maximum depth of the lesion, maximum transverse diameter of the lesion, thickness of the adipose layer, thickness of the glandular layer, thickness of the breast, distance between the nipple and lesion, age, body mass index, and menopausal status-were analyzed and compared between the groups to gauge their effects on the quality of the elastograms.

RESULTS

Significantly deeper lesions, higher maximum transverse lesion diameters, thicker adipose layers, thicker glandular layers, and thicker breasts were identified in group B patients compared to group A patients (P < .05). Multivariate logistic regression analyses showed that the maximum depth of the lesion, thickness of the adipose layer, and thickness of the breast were independent factors in the quality of elastograms. The area under the curve for the maximum depth of the lesion was 0.986 with the optimal cutoff threshold of 2.5 cm.

CONCLUSIONS

Quasistatic elastography can be a supplementary approach to conventional ultrasonography in helping improve the diagnostic accuracy of breast lesions. The depth and size of breast lesions are correlated with the quality of elastograms.

Further characterization of changes in axial strain elastograms due to the presence of slippery tumor boundaries

Elastography measures tissue strain, which can be interpreted under certain simplifying assumptions to be representative of the underlying stiffness distribution. This is useful in cancer diagnosis where tumors tend to have a different stiffness to healthy tissue and has also shown potential to provide indication of the degree of bonding at tumor-tissue boundaries, which is clinically useful because of its dependence on tumor pathology. We consider the changes in axial strain for the case of a symmetrical model undergoing uniaxial compression, studied by characterizing changes in tumor contrast transfer efficiency (CTE), inclusion to background strain contrast and strain contrast generated by slip motion, as a function of Young's modulus contrast and applied strain. We present results from a finite element simulation and an evaluation of these results using tissue-mimicking phantoms. The simulation results show that a discontinuity in displacement data at the tumor boundary, caused by the surrounding tissue slipping past the tumor, creates a halo of "pseudostrain" across the tumor boundary. Mobile tumors also appear stiffer on elastograms than adhered tumors, to the extent that tumors that have the same Young's modulus as the background may in fact be visible as low-strain regions, or those that are softer than the background may appear to be stiffer than the background. Tumor mobility also causes characteristic strain heterogeneity within the tumor, which exhibits low strain close to the slippery boundary and increasing strain toward the center of the tumor. These results were reproduced in phantom experiments. In addition, phantom experiments demonstrated that when fluid lubrication is present at the boundary, these effects become applied strain-dependent as well as modulus-dependent, in a systematic and characteristic manner. The knowledge generated by this study is expected to aid interpretation of clinical strain elastograms by helping to avoid misinterpretation as well as provide additional diagnostic criteria stated in the paper and stimulate further research into the application of elastography to tumor mobility assessment.

Role of Acoustic Radiation Force Impulse Elastography in the Characterization of Focal Solid Hepatic Lesions

Objective:

The purpose of the study is to investigate the usefulness of acoustic radiation force impulse (ARFI) elastography in the characterization of focal solid liver lesions as benign, malignant, or metastatic using ARFI two-dimensional (2D) imaging and ARFI quantification (shear wave velocities [SWVs]).

Materials and Methods:

Sixty lesions were included in this study. The lesions were classified into three groups: Group I included benign lesions (n = 25), Group II included malignant lesions (n = 27), and Group III included metastatic lesions (n = 8). ARFI elastography was performed in all these patients using a Siemens ACUSON S 2000™ ultrasound machine. Stiffness and size of the lesions were assessed on ARFI 2D images in correlation with B-mode ultrasound images. SWVs were obtained in these lesions for the quantification of stiffness.

Results:

In ARFI 2D images, malignant lesions were predominantly stiffer and larger, while benign lesions were softer and similar in size (P < 0.05). The mean SWVs in benign, malignant, and metastatic lesions were 1.30 ± 0.35 m/s, 2.93 ± 0.75 m/s, and 2.77 ± 0.90 m/s, respectively. The area under receiver operating characteristic curve of SWV for differentiating benign from malignant lesions was 0.877, suggesting fair accuracy (95% confidence interval: 0.777–0.976); with a cutoff value of 2 m/s, showing sensitivity: 92%; specificity: 96%; positive predictive value: 96%; negative predictive value: 93% (P < 0.05). Statistically significant difference exists in SWV of benign and malignant or metastatic lesions.

Conclusion:

ARFI elastography with 2D imaging and quantification might be useful in the characterization of benign and malignant liver lesions.

The value of shear wave elastography in predicting for undiagnosed small cervical lymph node metastasis in nasopharyngeal carcinoma: A preliminary study

BACKGROUND

To investigate the diagnostic value of shear wave elastography (SWE) in identifying cervical small lymph node metastases in nasopharyngeal carcinoma (NPC) patients.

MATERIALS AND METHODS

This prospective study was approved by the local institutional review board. From July 2014 to March 2016, 114 sLNs from 62 newly diagnosed NPC patients (47 men, 15 women) were assessed. Target small lymph nodes (sLNs), which were undiagnosed by magnetic resonance imaging (MRI), were defined as scattered cervical lymph nodes that had no evidence of central necrosis or extracapsular spread and exhibited a maximum transverse diameter ≥5 mm and <10 mm in MRI. The mean (Emean), minimum (Emin) and maximum (Emax) of the elasticity indices (EIs) were measured by SWE at the stiffest part of the sLN (kPa). Biopsy pathology was served as the reference standard. Diagnostic performances were assessed using receiver operating curve (ROC) analysis on a node-by-node basis.

RESULTS

Of the 114 small cervical lymph nodes, 88 (77.2%) were benign, and 26 (22.8%) were malignant. All SWE EIs were significantly higher in malignant sLNs than in benign sLNs (p < 0.001). Emean exhibited the highest diagnostic value (area under the curve = 0.879 ± 0.036) (p < 0.001) and the corresponding sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 84.6%, 83.0%, 59.5%, 94.8% and 83.3%, respectively. The intra-observer reproducibility of all SWE EIs were significant, with intra-class correlation coefficient (ICC) of 0.745 in Emean, 0.716 in Emax and 0.702 in Emin.

CONCLUSION

Shear wave elastography is an optional supplementary imaging modality to routine MRI examination to diagnose cervical lymph nodes in NPC patients.

Association of conventional ultrasound, elastography and clinicopathological factors with axillary lymph node status in invasive ductal breast carcinoma with sizes > 10 mm

Background

To evaluate whether conventional ultrasound, elastography [conventional strain elastography of elasticity imaging, acoustic radiation force impulse induced strain elastography of virtual touch tissue imaging, and a novel two-dimensional shear wave elastography of virtual touch tissue imaging quantification] and clinicopathological factors are associated with axillary lymph node metastasis in invasive ductal breast carcinoma with sizes > 10 mm.

Materials and Methods

We evaluated 150 breast lesions from 148 patients using the above methods and the clinicopathological factors. Univariate and multivariate logistic regression analysis were performed to determine the axillary lymph node metastasis risk factors. Diagnostic performance was evaluated using receiver operating characteristic curve analysis.

Results

Sixty-three tumors (42%) were node-positive, 87 (58%) were node-negative. Aspect ratio, virtual touch tissue imaging grade, shear wave velocity, pathological invasive tumor size, and histological grade maintained independent significance in predicting nodal involvement. The mean tumor shear wave velocitys (4.60, 6.49, 7.16) increased in proportion to metastatic node number (0, 1-3, ≥ 4, respectively; P < 0.001). For all tumors in this study, the cut-off shear wave velocity was 6.16 m/s and was associated with 64.1% sensitivity, 78.0% specificity and an area under the ROC curve of 0.799 (95% confidence interval, 0.731-0.868).

Conclusions

Aspect ratio, virtual touch tissue imaging grade, shear wave velocity, pathological invasive tumor size and histological grade are independently associated with axillary lymph node metastasis in invasive ductal breast carcinoma with sizes > 10 mm.

Diagnostic potential of real-time elastography (RTE) and shear wave elastography (SWE) to differentiate benign and malignant thyroid nodules: A systematic review and meta-analysis

BACKGROUND

Real-time elastography (RTE) and shear wave elastography (SWE) are noninvasive and easily available imaging techniques that measure the tissue strain, and it has been reported that the sensitivity and the specificity of elastography were better in differentiating between benign and malignant thyroid nodules than conventional technologies.

METHODS

Relevant articles were searched in multiple databases; the comparison of elasticity index (EI) was conducted with the Review Manager 5.0. Forest plots of the sensitivity and specificity and SROC curve of RTE and SWE were performed with STATA 10.0 software. In addition, sensitivity analysis and bias analysis of the studies were conducted to examine the quality of articles; and to estimate possible publication bias, funnel plot was used and the Egger test was conducted.

RESULTS

Finally 22 articles which eventually satisfied the inclusion criteria were included in this study. After eliminating the inefficient, benign and malignant nodules were 2106 and 613, respectively. The meta-analysis suggested that the difference of EI between benign and malignant nodules was statistically significant (SMD = 2.11, 95% CI [1.67, 2.55], P < .00001). The overall sensitivities of RTE and SWE were roughly comparable, whereas the difference of specificities between these 2 methods was statistically significant. In addition, statistically significant difference of AUC between RTE and SWE was observed between RTE and SWE (P < .01).

CONCLUSION

The specificity of RTE was statistically higher than that of SWE; which suggests that compared with SWE, RTE may be more accurate on differentiating benign and malignant thyroid nodules.

The value of quantitative shear wave elastography in differentiating the cervical lymph nodes in patients with thyroid nodules

PURPOSE

This study aimed at evaluating the diagnostic performance of quantitative shear wave elastography (SWE) in differentiating metastatic cervical lymph nodes from benign nodes in patients with thyroid nodules.

METHODS

One hundred and forty-one cervical lymph nodes from 39 patients with thyroid nodules that were diagnosed as papillary thyroid cancer had been imaged with SWE. The shear elasticity modulus, which indicates the stiffness of the lymph nodes, was measured in terms of maximum shear elasticity modulus (maxSM), minimum shear elasticity modulus (minSM), mean shear elasticity modulus (meanSM), and standard deviation (SD) of the shear elasticity modulus.

RESULTS

All the patients underwent thyroid surgery, 50 of the suspicious lymph nodes were resected, and 91 lymph nodes were followed up for 6 months. The maxSM value, minSM value, meanSM value, and SD value of the metastatic lymph nodes were significantly higher than those of the benign nodes. The area under the curve of the maxSM value, minSM value, meanSM value, and SD value were 0.918, 0.606, 0.865, and 0.915, respectively.

CONCLUSIONS

SWE can differentiate metastasis from benign cervical lymph nodes in patients with thyroid nodules, and the maxSM, meanSM, and SD may be valuable quantitative indicators for characterizing cervical lymph nodes.

What Help Could Ultrasound Elastography Give to the Diagnosis of Breast Papillary Lesions?

On the basis of results of our previous studies and the findings of other scholars, the most common histologic type of false-positive diagnosis with strain elastography (SE) was papilloma. The objectives of our study were to evaluate whether SE could contribute to conventional ultrasound differentiation between benign and malignant papillary lesions and between papillary lesions and other common benign breast lesions. Data on 89 papillary lesions at our hospital, including 74 benign and 15 malignant papillary lesions, were included in our study. In addition, 198 non-papillary benign tumors were selected as the control group, including 126 fibroadenomas and 72 cases of fibrocystic mastopathy. All patients gave written informed consent. All patients with breast lesions underwent conventional ultrasound and SE examination. Breast Imaging Recording and Data System (BI-RADS) category and SE score were compared with respect to sensitivity, specificity and accuracy in differentiating between benign and malignant papillary lesions. We then explored the possibility of using BI-RADS combined with SE to differentiate papillary lesions from non-papillary benign tumors. For differentiating between benign and malignant papillary lesions, the area under the receiver operating characteristic curve (AUC) of BI-RADS was 0.568, whereas the AUC values of SE score, strain ratio and BI-RADS combined with SE were 0.517, 0.584 and 0.509, respectively (p > 0.05). For differentiating between papillary lesions and non-papillary benign lesions, the AUC of BI-RADS combined with SE was 0.835, which was higher than the values for BI-RADS (0.775) and SE (SE score: 0.648, strain ratio: 0.661) (p < 0.001). The specificity and accuracy of BI-RADS combined with SE were significantly higher than those for BI-RADS alone without a decrease in sensitivity (p < 0.05). SE could not improve the diagnostic efficiency of BI-RADS in differentiating between benign and malignant papillary lesions. However, BI-RADS combined with SE could improve the specificity of BI-RADS without decrease in sensitivity for differentiating breast papillary lesions from non-papillary benign lesions.

Real-Time Ultrasound Elastographic Features of Primary Open Angle Glaucoma

OBJECTIVE

To investigate the significance of ultrasound elastography for evaluating the optic nerve in patients with primary open angle glaucoma (POAG).

METHODS

This prospective, comparative case series included 40 eyes of 40 patients. Twenty eyes with POAG comprised the POAG group, and 20 eyes of 20 patients without glaucoma who admitted to general eye clinic for near vision glasses comprised the control group. All real-time sonographicelastographic examinations were performed by the same physician. The ratio of orbital fat to optic nerve head (ROFON) and lateral rectus to optic nerve head (RLRON) were determined. Statistical analyses were performed using Student t test, Kolmogorov-Smirnov test, and χ test.

RESULTS

The mean ages of the patients in the study and the control groups were 65.10 ± 7.88 years (range, 48-80 years), and 69.15 ± 7.92 years (range, 55-89 years), respectively (P = 0.113). Mean ROFONs were 1.85 and 6.42 (P < 0.05), and mean RLRONs were 0.65 and 1.07 (P < 0.05) in the control and POAG groups, respectively.

CONCLUSIONS

Real-time elastography showed increased ROFON and RLRON in POAG patients. This can help to understand optic nerve head biomechanics and clarify glaucoma damage in early glaucoma cases.

Development of array piezoelectric fingers towards in vivo breast tumor detection

We have investigated the development of a handheld 4 × 1 piezoelectric finger (PEF) array breast tumor detector system towards in vivo patient testing, particularly, on how the duration of the DC applied voltage, the depression depth of the handheld unit, and breast density affect the PEF detection sensitivity on 40 patients. The tests were blinded and carried out in four phases: with DC voltage durations 5, 3, 2, to 0.8 s corresponding to scanning a quadrant, a half, a whole breast, and both breasts within 30 min, respectively. The results showed that PEF detection sensitivity was unaffected by shortening the applied voltage duration from 5 to 0.8 s nor was it affected by increasing the depression depth from 2 to 6 mm. Over the 40 patients, PEF detected 46 of the 48 lesions (46/48)-with the smallest lesion detected being 5 mm in size. Of 28 patients (some have more than one lesion) with mammography records, PEF detected 31/33 of all lesions (94%) and 14/15 of malignant lesions (93%), while mammography detected 30/33 of all lesions (91%) and 12/15 of malignant lesions (80%), indicating that PEF could detect malignant lesions not detectable by mammography without significantly increasing false positives. PEF's detection sensitivity is also shown to be independent of breast density, suggesting that PEF could be a potential tool for detecting breast cancer in young women and women with dense breasts.

Inter- and Intra-Observer Agreement in Ultrasound BI-RADS Classification and Real-Time Elastography Tsukuba Score Assessment of Breast Lesions

Our aim was to prospectively evaluate inter- and intra-observer agreement between Breast Imaging Reporting and Data System (BI-RADS) classifications and Tsukuba elasticity scores (TSs) of breast lesions. The study included 164 breast lesions (63 malignant, 101 benign). The BI-RADS classification and TS of each breast lesion was assessed by the examiner and twice by three reviewers at an interval of 2 months. Weighted κ values for inter-observer agreement ranged from moderate to substantial for BI-RADS classification (κ = 0.585-0.738) and was substantial for TS (κ = 0.608-0.779). Intra-observer agreement was almost perfect for ultrasound (US) BI-RADS (κ = 0.847-0.872) and TS (κ = 0.879-0.914). Overall, individual reviewers are highly self-consistent (almost perfect intra-observer agreement) with respect to BI-RADS classification and TS, whereas inter-observer agreement was moderate to substantial. Comprehensive training is essential for achieving high agreement and minimizing the impact of subjectivity. Our results indicate that breast US and real-time elastography can achieve high diagnostic performance.

Differential diagnosis of idiopathic granulomatous mastitis and breast cancer using acoustic radiation force impulse imaging

PURPOSE

Differentiation of idiopathic granulomatous mastitis (IGM) from carcinoma with routine imaging methods, such as ultrasonography (US) and mammography, is difficult. Therefore, we evaluated the value of a newly developed noninvasive technique called acoustic radiation force impulse imaging in differentiating IGM versus malignant lesions in the breast.

METHODS

Four hundred and eighty-six patients, who were referred to us with a presumptive diagnosis of a mass, underwent Virtual Touch tissue imaging (VTI; Siemens) and Virtual Touch tissue quantification (VTQ; Siemens) after conventional gray-scale US. US-guided percutaneous needle biopsy was then performed on 276 lesions with clinically and radiologically suspicious features. Malignant lesions (n = 122) and IGM (n = 48) were included in the final study group.

RESULTS

There was a statistically significant difference in shear wave velocity marginal and internal values between the IGM and malignant lesions. The median marginal velocity for IGM and malignant lesions was 3.19 m/s (minimum-maximum 2.49-5.82) and 5.05 m/s (minimum-maximum 2.09-8.46), respectively (p < 0.001). The median internal velocity for IGM and malignant lesions was 2.76 m/s (minimum-maximum 1.14-4.12) and 4.79 m/s (minimum-maximum 2.12-8.02), respectively (p < 0.001).

CONCLUSION

The combination of VTI and VTQ as a complement to conventional US provides viscoelastic properties of tissues, and thus has the potential to increase the specificity of US.

Diagnostic Value of Elastography in the Diagnosis of Intermetatarsal Neuroma

The objective of the present study was to characterize the ultrasound and elastographic properties of intermetatarsal neuroma (interdigital neuroma) and their contribution to diagnosis. Eighteen patients with metatarsalgia, who had presented to an orthopedic clinic from April 2013 to February 2015, were diagnosed with 25 intermetatarsal neuromas (11 unilateral [61.11%], 7 bilateral [38.89%]). These patients underwent evaluation with ultrasonography and simultaneous ultrasound strain elastography to assess the elastographic properties of the tissues in the intermetatarsal space. The intermetatarsal neuroma diagnosis was confirmed by histopathologic inspection. The lesion contours, localization, dimensions, and vascularization were evaluated before surgical excision. The elasticity and strain ratio values were compared between the neuroma and adjacent healthy intermetatarsal space. Of the 25 intermetatarsal neuromas, 1 (4%) was not detected by ultrasonography (incidence of detection of 96%). The mean neuroma width was 6.35 (range 3.7 to 13) mm in the coronal plane, and the mean elasticity and strain ratio values were 3.44 (range 1.1 to 5.1) and 9.47 (range 2.3 to 19.3), respectively. The elasticity and strain ratio values were significantly greater in the presence of an interdigital neuroma than in the adjacent healthy intermetatarsal spaces (Z = -3.964, p = .0001 and Z = -3.927, p = .0001, respectively). The diagnostic cutoff values were calculated as 2.52 for elasticity and 6.1 for the strain ratio. Four neuromas (16%) were not demarcated, and the elasticity and strain ratio values for these were lower than those for neuromas with demarcated contours but were greater than those for healthy intermetatarsal spaces (p < .006 and p < .005, respectively). Patients with clinically suspected intermetatarsal neuromas that do not show demarcation and with smaller lesions might benefit from the use of ultrasound elastography for diagnosis.

Percutaneous real-time sonoelastography as a non-invasive tool for the characterization of solid focal liver lesions: A prospective study

BACKGROUND

Real-time sonoelastography is currently used for the characterization of superficial solid lesions such as thyroid and breast masses. This study evaluates the usefulness of percutaneous sonoelastography for the characterization of solid focal liver lesions.

METHODS

30 out of 43 patients with 38 known liver lesions were included in a prospective, diagnostic study. Qualitative analysis (pattern of deformation, elasticity type of liver tumour) and semi-quantitative measurements (strain ratio, hardness percentage, histogram) were evaluated. Sensitivity, specificity, positive and negative predictive values were calculated and the area under the receiver operating characteristics curve was constructed.

RESULTS

Patterns A and C-D are specific of benign lesions and metastases respectively. The patterns for haemangiomas, focal nodular hyperplasia and metastases were significantly different to each other in terms of strain ratio, hardness percentage and histogram (p<0.05). A statistically significant difference (p<0.001) was observed between the median values of the 3 measured parameters for benign (1.02; 12%; 47) and malignant lesions (1.66; 65%; 20.5) respectively. The area under the receiver operating characteristics curve values for strain ratio, hardness percentage and histogram were 0.88, 0.89, and 0.86 respectively for cut-off values of 1.2, 45, and 30.

CONCLUSIONS

By percutaneous sonoelastography it is possible to differentiate benign versus malignant focal liver lesions, metastases in particular, with good diagnostic performance.

Assessment for diagnosis of lymph node metastasis in esophageal cancer using endoscopic ultrasound elastography

BACKGROUND

We performed endoscopic ultrasound real-time tissue elastography to more accurately diagnose lymph node metastasis of esophageal cancer. The aim of this study was to evaluate the ability of EUS elastography to distinguish benign from malignant lymph nodes in esophageal cancer patients.

METHODS

The present study had two steps. As the first step (study 1), we developed diagnostic criteria for metastatic lymph nodes using elastography and verified the validity of the criteria. Three hundred and twenty-two lymph nodes from 35 patients treated by surgical resection were included in the study. As the second step (study 2), we preoperatively examined the lymph nodes of esophageal cancer patients with EUS elastography and compared its diagnostic performance with that of the conventional B-mode EUS images. A total of 115 lymph nodes from 31 patients were included.

RESULTS

In study 1, lymph nodes were considered malignant if 50 % or more of the node appeared blue, or if the peripheral part of the lesion was blue and the central part was red/yellow/green. The sensitivity and specificity of the elastography were 79.7 and 97.6 % with an accuracy of 93.8 %, which was significantly higher than the values for conventional B-mode imaging. In study 2, the sensitivity and specificity of the EUS elastography were 91.2 and 94.5 % with an accuracy of 93.9 %, which was also significantly higher than the values for conventional B-mode EUS imaging.

CONCLUSIONS

The present study demonstrated that EUS elastography is useful for diagnosing lymph node metastasis of esophageal cancer.

Ultrasound elastography assessment of bone/soft tissue interface

We report on the use of elastographic imaging techniques to assess the bone/soft tissue interface, a region that has not been previously investigated but may provide important information about fracture and bone healing. The performance of axial strain elastograms and axial shear strain elastograms at the bone/soft tissue interface was studied ex vivo on intact and fractured canine and ovine tibias. Selected ex vivo results were corroborated on intact sheep tibias in vivo. The elastography results were statistically analyzed using elastographic image quality tools. The results of this study demonstrate distinct patterns in the distribution of the normalized local axial strains and axial shear strains at the bone/soft tissue interface with respect to the background soft tissue. They also show that the relative strength and distribution of the elastographic parameters change in the presence of a fracture and depend on the degree of misalignment between the fracture fragments. Thus, elastographic imaging modalities might be used in the future to obtain information regarding the integrity of bones and to assess the severity of fractures, alignment of bone fragments as well as to follow bone healing.

Combined Use of Ultrasound Elastography and B-Mode Sonography for Differentiation of Benign and Malignant Circumscribed Breast Masses

OBJECTIVES

To evaluate the diagnostic performance of combined B-mode sonography and ultrasound elastography for differentiation between benign and malignant breast masses with circumscribed margins.

METHODS

We analyzed 109 pathologically proven circumscribed breast masses. Two radiologists retrospectively reviewed B-mode sonograms and elastograms in consensus. Based on the American College of Radiology Breast Imaging Reporting and Data System, we determined categories of the masses on B-mode sonography. Elastographic scores were assessed by a 3-point scale (negative, 0; equivocal, 1; and positive, 2). When the elastographic score for a lesion was 0 or 2, we downgraded or upgraded the B-mode category, respectively; thus, the reclassified Breast Imaging Reporting and Data System category was defined as the "reclassification category." Mean category values for benign and malignant lesions were compared by a Student t test. The diagnostic performance of B-mode, elastographic, and reclassification assessments was compared by receiver operating characteristic curve analysis.

RESULTS

The mean B-mode category (2.5 versus 1.7), elastographic score (1.7 versus 0.8), and reclassification category (3.2 versus 1.6) were significantly higher in malignant than benign lesions (P < .001). The area under the curve for reclassification assessment was significantly higher than that for B-mode sonography (0.916 versus 0.795; P < .05). With a cutoff value between 1 and 2, the specificity was increased from 26.5% to 42.9% after reclassification.

CONCLUSIONS

For differentiation between benign and malignant circumscribed breast masses, combined use of B-mode sonography and elastography could provide a better diagnostic performance than B-mode sonography alone.

Endoscopic ultrasound: Elastographic lymph node evaluation

Different imaging techniques can bring different information which will contribute to the final diagnosis and further management of the patients. Even from the time of Hippocrates, palpation has been used in order to detect and characterize a body mass. The so-called virtual palpation has now become a reality due to elastography, which is a recently developed technique. Elastography has already been proving its added value as a complementary imaging method, helpful to better characterize and differentiate between benign and malignant masses. The current applications of elastography in lymph nodes (LNs) assessment by endoscopic ultrasonography will be further discussed in this paper, with a review of the literature and future perspectives.