Practice guideline for the performance of breast ultrasound elastography

Role of Real-Time Elastography in the Evaluation of Cervical Lymph Nodes in Patients with Kikuchi Disease

The purpose of this study was to compare the use of conventional ultrasound (US) and real-time elastography (RTE) in Kikuchi disease (KD, n = 48) and malignant cervical lymphadenopathy (n = 100) and to evaluate the role of RTE in patients suspected of having KD. In univariate analysis, conventional US revealed each benign feature more frequently in KD than in malignant lymphadenopathy (p < 0.05). However, a considerable number of cases (29, 60.4%) of KD were assessed as malignant with US. KD was assessed as benign by RTE more frequently than malignant lymphadenopathy (37 [77.1%] vs. 37 [37.0%], p < 0.001). In multivariate analysis, perinodal hyper-echogenicity was predictive of KD (odds ratio: 67.25, confidence interval: 10.95-413.04, p < 0.001). There was a tendency for KD to be assessed as malignant with conventional US, but benign with RTE. RTE can help to avoid unnecessary biopsy in patients suspected of having KD on the basis of conventional US.

Applications of Ultrasound in the Resection of Brain Tumors

Neurosurgery makes use of preoperative imaging to visualize pathology, inform surgical planning, and evaluate the safety of selected approaches. The utility of preoperative imaging for neuronavigation, however, is diminished by the well-characterized phenomenon of brain shift, in which the brain deforms intraoperatively as a result of craniotomy, swelling, gravity, tumor resection, cerebrospinal fluid (CSF) drainage, and many other factors. As such, there is a need for updated intraoperative information that accurately reflects intraoperative conditions. Since 1982, intraoperative ultrasound has allowed neurosurgeons to craft and update operative plans without ionizing radiation exposure or major workflow interruption. Continued evolution of ultrasound technology since its introduction has resulted in superior imaging quality, smaller probes, and more seamless integration with neuronavigation systems. Furthermore, the introduction of related imaging modalities, such as 3-dimensional ultrasound, contrast-enhanced ultrasound, high-frequency ultrasound, and ultrasound elastography, has dramatically expanded the options available to the neurosurgeon intraoperatively. In the context of these advances, we review the current state, potential, and challenges of intraoperative ultrasound for brain tumor resection. We begin by evaluating these ultrasound technologies and their relative advantages and disadvantages. We then review three specific applications of these ultrasound technologies to brain tumor resection: (1) intraoperative navigation, (2) assessment of extent of resection, and (3) brain shift monitoring and compensation. We conclude by identifying opportunities for future directions in the development of ultrasound technologies.

Semi-Quantitative Strain Ratio in the Differential Diagnosis of Breast Masses: Measurements Using One Region-of-Interest

The purpose of this study was to evaluate the diagnostic performances of semi-quantitative strain ratio measured by using one region-of-interest (ROI) on breast US elastography images. Two hundred one breast masses of 165 women (mean age: 47.2 y) were included. Ultrasonography (US) and elastography images of the masses were obtained and prospectively analyzed according to elasticity pattern, strain ratio, and final Breast Imaging-Reporting and Data System (BI-RADS) assessments. Of the 201 breast masses, 127 (63.2%) were benign and 74 (36.8%) were malignant. Elastography pattern and strain ratio (cut-off of 1.44) had significantly higher specificity than gray-scale US, 39.4% and 61.4% versus 29.1%, respectively (all p < 0.05). Area under the receiver operating characteristics curve (Az) was highest for gray-scale US (0.646), without statistical significances, than for elastography pattern (0.596, p = 0.159) or strain ratio (0.625, p = 0.610). Semi-quantitative strain ratio measured from one ROI has comparable diagnostic performances to gray-scale US, which may contribute to more accurate differential diagnosis of breast masses seen on US.

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.

Magnetic resonance elastography (MRE) in cancer: Technique, analysis, and applications

Tissue mechanical properties are significantly altered with the development of cancer. Magnetic resonance elastography (MRE) is a noninvasive technique capable of quantifying tissue mechanical properties in vivo. This review describes the basic principles of MRE and introduces some of the many promising MRE methods that have been developed for the detection and characterization of cancer, evaluation of response to therapy, and investigation of the underlying mechanical mechanisms associated with malignancy.

Are Irregular Hypoechoic Breast Masses on Ultrasound Always Malignancies?: A Pictorial Essay

Irregular hypoechoic masses in the breast do not always indicate malignancies. Many benign breast diseases present with irregular hypoechoic masses that can mimic carcinoma on ultrasonography. Some of these diseases such as inflammation and trauma-related breast lesions could be suspected from a patient's symptoms and personal history. Careful ultrasonographic examination and biopsy could help to differentiate these from malignancies.

Quantitative Lesion-to-Fat Elasticity Ratio Measured by Shear-Wave Elastography for Breast Mass: Which Area Should Be Selected as the Fat Reference?

OBJECTIVES

To investigate whether the diagnostic performance of lesion-to-fat elasticity ratio (Eratio) was affected by the location of the reference fat.

METHODS

For 257 breast masses in 250 women who underwent shear-wave elastography before biopsy or surgery, multiple Eratios were measured with a fixed region-of-interest (ROI) in the mass along with multiple ROIs over the surrounding fat in different locations. Logistic regression analysis was used to determine that Eratio was independently associated with malignancy adjusted for the location of fat ROI (depth, laterality, and distance from lesion or skin). Mean (Emean) and maximum (Emax) elasticity values of fat were divided into four groups according to their interquartile ranges. Diagnostic performance of each group was evaluated using the area under the ROC curve (AUC). False diagnoses of Eratio were reviewed for ROIs on areas showing artifactual high or low stiffness and analyzed by logistic regression analysis to determine variables (associated palpable abnormality, lesion size, the vertical distance from fat ROI to skin, and elasticity values of lesion or fat) independently associated with false results.

RESULTS

Eratio was independently associated with malignancy adjusted for the location of fat ROI (P<0.0001). Among four groups of fat elasticity values, the AUC showed no significant difference (<25th percentile, 25th percentile~median, median~75th percentile, and ≥75th percentile; 0.973, 0.982, 0.967, and 0.954 for Emean; 0.977, 0.967, 0.966, and 0.957 for Emax). Fat elasticity values were independently associated with false results of Eratio with the cut-off of 3.18 from ROC curve (P<0.0001). ROIs were set on fat showing artifactual high stiffness in 90% of 10 false negatives and on lesion showing vertical striped artifact or fat showing artifactual low stiffness in 77.5% of 71 false positives.

CONCLUSION

Eratio shows good diagnostic performance regardless of the location of reference fat, except when it is placed in areas of artifacts.

Characterization of breast lesions: comparison of digital breast tomosynthesis and ultrasonography

Objective

To compare the diagnostic performance of digital breast tomosynthesis (DBT) and conventional breast ultrasound (US) to characterize breast lesions as benign or malignant.

Materials and Methods

A total of 332 women, presenting for screening examinations or for breast biopsy between March and June 2012 were recruited to undergo digital mammography (DM), DBT, and breast US examination. Among them, 113 patients with 119 breast lesions depicted on DM were finally included. Three blinded radiologists performed an enriched reader study and reviewed the DBT and US images. Each reader analyzed the lesions in random order, assigned Breast Imaging Reporting and Data System (BI-RADS) descriptors, rated the images for the likelihood of malignancy (%) and made a BI-RADS final assessment. Diagnostic accuracy, as assessed by the area under the receiver operating characteristic curve, sensitivity, and specificity of DBT and US were compared.

Results

Among the 119 breast lesions depicted on DM, 75 were malignant and the remaining 44 were benign. The average diagnostic performance for characterizing breast lesions as benign or malignant in terms of area under the curve was 0.899 for DBT and 0.914 for US (p = 0.394). Mean sensitivity (97.3% vs. 98.7%, p = 0.508) and specificity (44.7% vs. 39.4%, p = 0.360) were also not significantly different.

Conclusion

Digital breast tomosynthesis may provide similar reader lesion characterization performance to that of US for breast lesions depicted on DM.

A pure mucocele-like lesion of the breast diagnosed on ultrasonography-guided core-needle biopsy: is imaging follow-up sufficient?

Purpose:

To evaluate the upgrade rate of ultrasonography (US)-guided core-needle biopsy (CNB) of the breast for a pure mucocele-like lesion (MLL), to evaluate the clinical and radiologic features, and to correlate the image-pathologic features further on to guide the management of MLL.

Methods:

Between January 2003 and February 2013, 14-gauge US-guided CNB was performed in 18,111 cases. Thirty-two cases associated with MLL were identified, and five cases of MLLs associated with breast carcinoma or with other high-risk breast lesions (i.e., atypical ductal hyperplasia [ADH], papillary lesions, lobular carcinoma in situ, and radial scar complex) were excluded. Among these 27 pure MLLs, 21 cases with surgical or vacuum-assisted excision (VAE) pathology were included in our study. Medical records, mammograms, and ultrasonograms were reviewed for the clinical and radiologic features of the cases.

Results:

Among the 21 cases with pure MLLs at CNB, the final pathology showed a 0% proportion of cases upgraded to malignancy. All the 21 cases with either surgical or VAE pathology were benign MLLs including three cases of focal involvement of ADH (14.3%). The common features were mammographic features of microcalcifications that were round in shape and had a grouped distribution. The US features included oval shape, circumscribed margin, parallel orientation, complex solid and cystic echo pattern, no posterior feature, and complex solid and cystic echoic masses. The predominant Breast Imaging Reporting and Data System (BIRADS) category was 4A. All the lesions showed image-pathologic concordance.

Conclusion:

For pure MLL on US-guided CNB with image-pathologic concordance, close imaging follow-up might be considered instead of surgical excision.

Ultrasound elastography for thyroid nodules: recent advances

Ultrasonography (US)-based elastography has been introduced as a noninvasive technique for evaluating thyroid nodules that encompasses a variety of approaches such as supersonic shear imaging and acoustic radiation force impulse imaging as well as real-time tissue elastography. However, the diagnostic performances for differentiating malignant thyroid nodules from benign ones with elastography as an adjunctive tool of gray-scale US is still under debate. In this review article, diagnostic performances of conventional US and a combination of conventional US and elastography are compared according to the type of elastography. Further, the interobserver variability of elastography is presented according to the type of elastography.

Usefulness of ultrasound elastography in reducing the number of Breast Imaging Reporting and Data System category 3 lesions on ultrasonography

Purpose:

To evaluate the negative predictive value (NPV) of ultrasound (US) elastography for non-palpable Breast Imaging Reporting and Data System (BI-RADS) category 3 lesions on ultrasonography and to determine whether US elastography is helpful in reducing the number of BI-RADS category 3 lesions on ultrasonography.

Methods:

Two hundred seventy-six consecutive, non-palpable BI-RADS category 3 lesions in 256 women who underwent US elastography and US-guided core biopsy, and who had at least 12 months of follow-up data, comprised our study group. The BI-RADS final assessment category and elasticity score were prospectively and independently classified. The rate of malignancy and NPV according to the elasticity score were analysed. We also investigated whether there was a subset of BI-RADS category 3 lesions that were of benign histology but negative on elastography.

Results:

Of the 276 non-palpable BI-RADS category 3 lesions, three lesions (1.0%) were finally confirmed as ductal carcinomas in situ. No cancers were found in the remaining 273 lesions with benign biopsy histology at a mean follow-up of 39.4 months (range, 12 to 72 months). The NPV of a negative elasticity score (elasticity score of 1) was 99.3% (165 of 166). If BI-RADS category 3 lesions showing a negative elasticity score were downgraded to BI-RADS category 2, 60.4% (165 of 273) of them with benign histology could have been safely followed without biopsy with an increased malignancy rate from 1% (3 of 276) to 1.8% (2 of 110), which is not significantly higher (P=0.626).

Conclusion:

US elastography has the potential to reduce the number of BI-RADS category 3 lesions on ultrasonography.