Real-time elastography for the differentiation of benign and malignant breast lesions: a meta-analysis

In vivo estimation of perineal body properties using ultrasound quasistatic elastography in nulliparous women

OBJECTIVE

The perineal body must undergo a remarkable transformation during pregnancy to accommodate an estimated stretch ratio of over 3.3 in order to permit vaginal delivery of the fetal head. Yet measurements of perineal body elastic properties are lacking in vivo, whether in the pregnant or non-pregnant state. The objective of this study, therefore, was to develop a method for measuring perineal body elastic modulus and to test its feasibility in young nulliparous women.

METHODS

An UltraSONIX RP500 ultrasound system was equipped with elastography software. Approximately 1 Hz free-hand sinusoidal compression loading of the perineum was used to measure the relative stiffness of the perineal body compared to that of a custom reference standoff pad with a modulus of 36.7 kPa. Measurements were made in 20 healthy nulliparous women. Four subjects were invited back for second and third visits to evaluate within- and between-visit repeatability using the coefficient of variation.

RESULTS

The mean ± SD elastic compression modulus of the perineal body was 28.9 ± 4.7 kPa. Within- and between-visit repeatability averaged 3.4% and 8.3%, respectively.

CONCLUSION

Ultrasound elastography using a standoff pad reference provides a valid method for evaluating the elastic modulus of the perineal body in living women.

[Can breast elastography change our strategies? Technology, impact and limitations]

Compression or static elastography is based on images deformation (induced by slight manual compression/decompression to the breast) and tissue movement is color-encoded in color map and classified into five scores of increasing malignancy (score of 1 to 3: benign and 4 to 5: malignant). The elasticity shear wave is measured from the propagation velocity of shear waves in the lesions and is expressed in kPa or m/s and in color map. Reproducibility is satisfactory for the two technologies even if the static elastography is only semi-quantitative. Elastography is helpful for lesions classified BI-RADS 3 and 4 and especially when the PPV of these lesions in B mode is low<10% (BI-RADS 3 and 4a). For these two technologies, cancer and biopsy rates are reduced by at least 30% (with threshold values for the shear wave technology of 30kPa and 3m/s depending on the manufacturer). False positives are found with the fibrotic lesions and false negatives by colloid tumors and DCIS. Correlation with prognostic factors is discussed.

Intrapartum ultrasound: A useful method for evaluating labor progress and predicting operative vaginal delivery

The last step of a successful pregnancy is the safe delivery of the fetus. An important question is if the delivery should vaginal or operative. In addition to the use of conventional antenatal ultrasound, the use of intrapartum ultrasound to evaluate fetal head station, position, cervical ripening, and placental separation is promising. This review evaluates and summarizes the usefulness of intrapartum ultrasound for the evaluation of labor progress and predicting successful operative vaginal delivery.

Successful induction of labor: prediction by preinduction cervical length, angle of progression and cervical elastography

OBJECTIVE

To examine the potential value of preinduction cervical length, cervical elastography and angle of progression (AOP) in prediction of successful vaginal delivery and induction-to-delivery interval.

METHODS

This was a prospective study in 99 women with singleton pregnancy undergoing preinduction ultrasound assessment at 35-42 weeks' gestation. Cervical length, elastographic score at the internal os and AOP were determined. Regression analysis was used to assess the relationship between cervical length and both AOP and elastographic score. Logistic regression analysis was used to determine which of the maternal characteristics (cervical length, AOP, elastographic score) were significant predictors of vaginal delivery and induction-to-delivery interval.

RESULTS

Vaginal delivery occurred in 66 (66.7%) cases and Cesarean delivery was performed in 33 (33.3%) cases. There were significant correlations between cervical length and both AOP (r = - 0.319) and elastographic score (r = 0.368). Significant independent prediction of vaginal delivery and induction-to-delivery interval was provided by nulliparity and cervical length, with no additional significant contribution from electrographic score or AOP.

CONCLUSIONS

In women undergoing induction of labor, AOP and elastographic score at the internal os are unlikely to be useful in prediction of vaginal delivery and induction-to-delivery interval.

Value of Strain Elastography Ultrasound in Differentiation of Breast Masses and Histopathologic Correlation

OBJECTIVE

US elastography is an emerging technique that can be used during breast US examination. The increasing awareness of breast cancer led to an increase in mammography and breast US examinations. The specificity of these techniques is not high enough to prevent unnecessary biopsies. There is still a need for a more specific technique that can overcome this problem. This study aimed to evaluate the value of strain elastography in breast lesions.

MATERIALS AND METHODS

In this study, 110 lesions of 96 patients were evaluated with strain elastography. Five score system was used for lesion scoring. The histopathologic results of lesions were obtained and were accepted as gold standard. The sensitivity, specificity, PPV and NPV of the technique were calculated. Histopathologic and strain elastography results were correlated.

RESULTS

The sensitivity of US strain elastography was calculated as 83%, the specificity as 89%, the positive predictive value as 79% and the negative predictive value as 91%. There were no score 1 lesions. All score 2 lesions were benign. Score 5 had the highest true positivity rate.

CONCLUSION

We believe that ultrasound elastography is an effective imaging technique that can be used as an adjunct for differential diagnosis, prior to the decision to biopsy a lesion in certain cases.

Comparison of strain and shear wave elastography for the differentiation of benign from malignant breast lesions, combined with B-mode ultrasonography: qualitative and quantitative assessments

Our aim was to compare the diagnostic performance of strain elastography (SE) and shear-wave elastography (SWE), combined with B-mode ultrasonography (US), in breast cancer. For 79 breast lesions that underwent SE and SWE, two radiologists reviewed five data sets (B-mode US, SWE, SE and two combined sets). Qualitative and quantitative elastographic data and Breast Imaging Reporting and Data System (BI-RADS) categories were recorded. The area under the receiver operating characteristic curve (AUC) was evaluated. No significant difference in the AUC between the two elastography methods was noted. After subjective assessment by reviewers, the AUC for the combined sets was improved (SWE, 0.987; SE, 0.982; B-mode US, 0.970; p < 0.05). When SE and SWE were added, 38% and 56% of benign BI-RADS category 4a lesions with a low suspicion of cancer were downgraded without false-negative results, respectively. SE and SWE performed similarly. Therefore, addition of SE or SWE improved the diagnostic performance of B-mode US, potentially reducing unnecessary biopsies.

Main controversies in breast cancer

In this article, we have reviewed available evidence for diagnosis, treatment, and follow-up in female breast cancer (BC). Into daily clinical practice some controversies are occurred. Especially, in the diagnosis field, despite the fact that the optimal age in which screening mammography should start is a subject of intense controversy, there is a shift toward the beginning at the age of 40 although it is suggested that the net benefit is small for women aged 40 to 49 years. In addition, a promising tool in BC screening seems to be breast tomosynthesis. Other tools such as 3D ultrasound and shear wave elastography (SWE) are full of optimism in BC screening although ultrasonography is not yet a first-line screening method and there is insufficient evidence to recommend the systemic use of the SWE for BC screening. As for breast magnetic resonance imaging (MRI), even if it is useful in BC detection in women who have a strong family history of BC, it is not generally recommended as a screening tool. Moreover, based on the lack of randomized clinical trials showing a benefit of presurgical breast MRI in overall survival, it's integration into breast surgical operations remains debatable. Interestingly, in contrast to fine needle aspiration, core biopsy has gained popularity in presurgical diagnosis. Furthermore, after conservative surgery in patients with positive sentinel lymph nodes, the recent tendency is the shift from axillary dissection to axillary conserving strategies. While the accuracy of sentinel lymph node after neoadjuvant chemotherapy and second BC surgery remains controversial, more time is needed for evaluation and for determining the optimal interval between the two surgeries. Additionally, in the decision between immediate or delayed breast reconstruction, there is a tendency in the immediate use. In the prevention of BC, the controversial issue between tamoxifen and raloxifene becomes clear with raloxifene be more profitable through the toxicities of tamoxifen. However, the prevention of bone metastasis with bisphosphonates is still conflicting. Last but not least, in the follow-up of BC survivors, mammography, history and physical examination are the means of an early detection of BC recurrence. ed.

Freehand elastography for determination of breast cancer size: comparison with B-mode sonography and histopathologic measurement

OBJECTIVES

Elastography assesses the strain of soft tissues and is used to enhance diagnostic accuracy in evaluating breast tumors, but minimal data exist on its ability to accurately assess tumor size. This study was performed to assess the preoperative accuracy of measuring the size of biopsyproven breast cancer lesions with elastography and conventional B-mode sonography compared with the reference standard size measured by histopathologic examination.

METHODS

Elastography and conventional B-mode sonography were performed on 69 women with histologically proven breast cancer, and tumor sizes on both modalities were recorded. These measurements were compared with the final pathologic size, which was used as the reference standard. The sizes and differences between sonographic, elastographic, and pathologic measurements were statistically tested, and an analysis of equivalence to the reference standard was performed using Bland-Altman plots.

RESULTS

There was a significant difference between sizes on elastography and pathologic examination, with elastography overestimating the tumor size (P = .0187). Sonography slightly underestimated the tumor size, but this finding was not significant (P = .36). Bland-Altman plots confirmed that sonography but not elastography was an acceptable standard compared with the pathologic size.

CONCLUSIONS

Breast elastography but not B-mode sonography overestimates the size of breast tumors compared with the final pathologic size.

Elastography, a sensitive tool for the evaluation of neoadjuvant chemotherapy in patients with high-grade serous ovarian carcinoma

The aim of the present study was to evaluate tumor stiffness by ultrasound elastography, which has the potential to provide additional information that is useful in predicting the response to neoadjuvant chemotherapy (NACT) in high-grade serous ovarian carcinoma (HGSC) patients. In total, 32 patients with International Federation of Gynecology and Obstetrics stage III and IV epithelial ovarian cancer treated with NACT underwent transvaginal and transabdominal sonography, followed by elastography and finally, by interval cytoreductive surgery. Histopathological analysis revealed 24 (75%) HGSCs. The mean elasticity score was statistically higher for the post-NACT lesions than for the pre-NACT lesions (3.13±0.57 vs. 2.04±0.51, respectively; P<0.001). The median elasticity score for the pre-NACT lesions on the four-point scale was 2, and the score for the post-NACT lesions was 4. Cases of post-NACT with scores of 3 and 4 had a higher optimal cytoreduction rate than cases with scores of 1 and 2 (93.8 vs. 25.0%, respectively; P<0.001). When the post-NACT elasticity scores of 3 and 4 were used for the prediction of optimal cytoreduction, elastography exhibited 88.2% sensitivity, 85.7% specificity, a 93.8% positive predictive value, a 75.0% negative predictive value and 87.5% accuracy. The results of the current study suggested that elastography is a sensitive tool for the evaluation of NACT in patients with HGSC and that it may aid gynecologists in choosing the optimal cytoreduction.

Investigation of publication bias in meta-analyses of diagnostic test accuracy: a meta-epidemiological study

Background

The validity of a meta-analysis can be understood better in light of the possible impact of publication bias. The majority of the methods to investigate publication bias in terms of small study-effects are developed for meta-analyses of intervention studies, leaving authors of diagnostic test accuracy (DTA) systematic reviews with limited guidance. The aim of this study was to evaluate if and how publication bias was assessed in meta-analyses of DTA, and to compare the results of various statistical methods used to assess publication bias.

Methods

A systematic search was initiated to identify DTA reviews with a meta-analysis published between September 2011 and January 2012. We extracted all information about publication bias from the reviews and the two-by-two tables. Existing statistical methods for the detection of publication bias were applied on data from the included studies.

Results

Out of 1,335 references, 114 reviews could be included. Publication bias was explicitly mentioned in 75 reviews (65.8%) and 47 of these had performed statistical methods to investigate publication bias in terms of small study-effects: 6 by drawing funnel plots, 16 by statistical testing and 25 by applying both methods. The applied tests were Egger’s test (n = 18), Deeks’ test (n = 12), Begg’s test (n = 5), both the Egger and Begg tests (n = 4), and other tests (n = 2). Our own comparison of the results of Begg’s, Egger’s and Deeks’ test for 92 meta-analyses indicated that up to 34% of the results did not correspond with one another.

Conclusions

The majority of DTA review authors mention or investigate publication bias. They mainly use suboptimal methods like the Begg and Egger tests that are not developed for DTA meta-analyses. Our comparison of the Begg, Egger and Deeks tests indicated that these tests do give different results and thus are not interchangeable. Deeks’ test is recommended for DTA meta-analyses and should be preferred.

Real-time elastography in the diagnosis of patients suspected of having prostate cancer: a meta-analysis

The goal of the study described here was to assess the performance of real-time elastography (RTE) in the detection of prostate cancers using a meta-analysis. A literature search of PubMed, Medline, Embase and the Cochrane Library was conducted. Published studies that evaluated the diagnostic performance of RTE in the diagnosis of prostate cancer and using the histopathology of the radical prostatectomy specimen as a reference standard were included. Sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and area under the curve were calculated to examine the accuracy of RTE. A total of seven studies that included 508 patients were analyzed. The pooled sensitivity and specificity for the diagnosis of prostate cancer by RTE were 0.72 (95% confidence interval: 0.70-0.74) and 0.76 (0.74-0.78), respectively. The summary diagnostic odds ratio was 12.59 (7.26-21.84), and the area under the curve was 0.841 (Q* = 0.773). In conclusion, RTE imaging has high accuracy in the detection of prostate cancers using the histopathology of the radical prostatectomy specimen as the reference standard and may reduce the number of core biopsies in the future.

Stiffness of the surrounding tissue of breast lesions evaluated by ultrasound elastography

OBJECTIVE

To evaluate the stiffness of the surrounding tissue of breast lesions using the strain ratio assessment method by ultrasound (US) elastography.

METHODS

This was an institutional ethics committee approved prospective study. A total of 127 breast lesions in 118 women (mean age 48.23 ± 14.32, range 20-90) were examined with conventional and elastographic US. The strain ratio assessment method was utilized to semi-quantitatively evaluate the stiffness of the breast lesions and the surrounding tissue.

RESULTS

Fifty-five lesions were malignant and 72 were benign. The strain ratio of the surrounding tissue was significantly higher in malignant cases (1.49 ± 0.67) than in benign ones (1.17 ± 0.44) (P = 0.001), and yielded an Az value of 0.669 in the diagnosis of breast lesions. There was a significant high positive correlation between the strain ratio of the lesion and the strain ratio of the surrounding tissue in the malignant group (r = 0.740, P < 0.001), and a significant moderate positive correlation in the benign group (r = 0.595, P < 0.001).

CONCLUSION

The stiffness of the surrounding tissue of malignant breast lesions was higher than that of benign lesions. The strain ratio of the surrounding tissue and the lesions was significantly correlated, and has potential for breast lesion diagnosis.

KEY POINTS

• Stiffness of the surrounding tissue of malignant breast lesions was increased. • Stiffness of the surrounding tissue correlated with stiffness of breast lesions. • Stiffness of the surrounding tissue has potential use in diagnosis of breast lesions.

Diagnostic value of elastography using acoustic radiation force impulse imaging and strain ratio for breast tumors

Purpose

The aim of this study was to determine whether the combination of B-mode ultrasonography (BUS), acoustic radiation force impulse (ARFI) elastography, and strain ratio (SR) provides better diagnostic performance of breast lesion differentiation than BUS alone.

Methods

ARFI elastography and SR evaluations were performed on patients with 157 breast lesions diagnosed by BUS from June to September 2013. BUS images were classified according to the Breast Imaging-Reporting and Data System. ARFI elastography was performed using Virtual Touch™ tissue imaging (VTI) and Virtual Touch™ tissue quantification (VTQ). In VTI mode, we evaluated the color-mapped patterns of the breast lesion and surrounding tissue. The lesions were classified into five categories by elasticity score. In VTQ mode, each lesion was assessed using shear wave velocity (SWV) measurements. SR was calculated from the lesion and comparable lateral fatty tissue. We compared the diagnostic performance of BUS alone and the combination of BUS, ARFI elastography, and SR evaluations.

Results

Among the 157 lesions, 40 were malignant and 117 were benign. The mean elasticity score (3.7±1.0 vs. 1.6±0.8, p<0.01), SWV (4.23±1.09 m/sec vs. 2.22±0.88 m/sec, p<0.01), and SR (5.69±1.63 vs. 2.69±1.40, p<0.01) were significantly higher for malignant lesions than benign lesions. The results for BUS combined with ARFI elastography and SR values were 97.5% sensitivity, 92.3% specificity, 93.6% accuracy, a 79.6% positive predictive value (PPV), and a 99.1% negative predictive value. The combination of the 3 radiologic examinations yielded superior specificity, accuracy, and PPV compared to BUS alone (p<0.01 for each).

Conclusion

ARFI elastography and SR evaluations showed significantly different mean values for benign and malignant lesions. Moreover, these two modalities complemented BUS and improved the diagnostic performance of breast lesion detection. Therefore, ARFI elastography and SR evaluations can be used as complementary modalities to make more accurate breast lesion diagnoses.

Accuracy of visual scoring and semi-quantification of ultrasound strain elastography--a phantom study

Purpose

The aim of this study was to evaluate the performance of strain elastography in an elasticity phantom and to assess which factors influenced visual scoring, strain histograms and strain ratios. Furthermore this study aimed to evaluate the effect of observer experience on visual scorings.

Materials and Methods

Two operators examined 20 targets of various stiffness and size (16.7 to 2.5 mm) in an elasticity phantom at a depth of 3.5 cm with a 5–18 MHz transducer. Two pre-settings were used yielding 80 scans. Eight evaluators, four experienced, four inexperienced, performed visual scorings. Cut-offs for semi-quantitative methods were established for prediction of target stiffness. Data was pooled in two categories allowing calculations of sensitivity and specificity. Statistical tests chi-square test and linear regression as relevant.

Results

Strain ratios and strain histograms were superior to visual scorings of both experienced and inexperienced observers (p = 0.025, strain histograms vs. experienced observers, p<0.001, strain histograms vs. inexperienced observers, p = 0.044 strain ratios vs. experienced observers and p = 0.002 strain ratios vs. inexperienced observers). No significant difference in predicting target stiffness between strain ratios and strain histograms (p = 0.83) nor between experienced and inexperienced observers (p = 0.054) was shown when using four categories. When pooling data in two groups (80 kPa/45 kPa vs. 14/8 kPa) the difference between the observers became significant (p<0.001). Target size had a significant influence on strain ratios measurements (p = 0.017) and on visual scorings (p<0.001) but not on the strain histograms(p = 0.358). Observer experience had significant effect on visual scorings(p = 0.003).

Conclusion

Strain ratios and strain histograms are superior to visual scoring in assessing target stiffness in a phantom. Target size had a significant impact on strain ratios and visual scoring, but not on strain histograms. Experience influenced visual scorings but the difference between experienced and inexperienced observers was only significant when looking at two classes of target stiffness.

In Vivo response to compression of 35 breast lesions observed with a two-dimensional locally regularized strain estimation method

The objective of this study was to assess the in vivo performance of our 2-D locally regularized strain estimation method with 35 breast lesions, mainly cysts, fibroadenomas and carcinomas. The specific 2-D deformation model used, as well as the method's adaptability, led to an algorithm that is able to track tissue motion from radiofrequency ultrasound images acquired in clinical conditions. Particular attention was paid to strain estimation reliability, implying analysis of the mean normalized correlation coefficient maps. For all lesions examined, the results indicated that strain image interpretation, as well as its comparison with B-mode data, should take into account the information provided by the mean normalized correlation coefficient map. Different trends were observed in the tissue response to compression. In particular, carcinomas appeared larger in strain images than in B-mode images, resulting in a mean strain/B-mode lesion area ratio of 2.59 ± 1.36. In comparison, the same ratio was assessed as 1.04 ± 0.26 for fibroadenomas. These results are in agreement with those of previous studies, and confirm the interest of a more thorough consideration of size difference as one parameter discriminating between malignant and benign lesions.

Elastography for the differentiation of benign and malignant liver lesions: a meta-analysis

The objective of this paper was to evaluate the overall accuracy of elastography in the diagnosis of benign and malignant liver lesions by liver biopsy as the gold standard. Literature databases were searched. The studies which were related to evaluate the diagnostic value of elastography for differentiation in benign and malignant liver lesions in English or Chinese were included. The summary receiver operating characteristic (SROC) curve was performed, and the areas under the curve (AUC) were also calculated to present the accuracy of the elastography for the diagnosis of benign and malignant liver lesions. Six studies which included a total of 448 liver lesions in 384 patients were analyzed. The summary sensitivity and specificity of elastography for the differentiation of malignant liver lesions were 85% (95% CI, 80 to 89%) and 84% (95% CI, 80 to 88%), respectively. And the summary diagnostic odds ratio was 46.33 (95% CI, 15.22 to 141.02), and the SROC was 0.9328. Elastography has a high sensitivity and specificity differentiation for benign and malignant liver lesions. As a non-invasive method, it is promising to be applied to clinical practice. To estimate elastography objectively, a large, prospective, international, and multi-center study is still needed.

Quantitative assessment of bladder neck compliance by using transvaginal real-time elastography of women

To assess the feasibility of using ultrasound real-time elastography (RTE) to measure bladder neck compliance, we performed real-time elastography measurements by manually applying repetitive compression with the transducer on the scan position of the bladder neck. Instant elastography index (EI) and mean EI of anterior and posterior lips of the bladder neck were calculated. The EI values of anterior and posterior lips of the bladder neck were analyzed in relation to age, body surface area, body mass index, detrusor wall thickness and length, width and thickness of the bladder neck in healthy women. The intra-observer and inter-observer repeatability of measurements in different parts of the bladder neck were assessed using intra-class correlation coefficients with 95% confidence intervals and Bland-Altman analysis. There were no statistically significant differences between elastography measurements made by the same or two different observers in each area measured. There was no significant difference between anterior and posterior lip thickness of the bladder neck. The distribution of the elastography measurements indicated that the anterior lip of the bladder neck was slightly harder than the posterior lip. On the whole, from the results of the study, it was clear that EIs of the bladder neck were related to age in healthy women. Stepwise multiple regression analysis results revealed that age was the only independent factor modulating compliance of the bladder neck in healthy women. It is possible to provide a reproducible semi-quantification of real-time elastography in bladder neck compliance.

Quantitative sonoelastography of the uterine cervix by interposition of a synthetic reference material

OBJECTIVE

To develop a reference material that allows quantitative elastography of the uterine cervix using the calculation of the approximate tissue stiffness expressed as Young's modulus (N/mm(2) ). Further, to test the elastography equipment on phantoms from a clinical perspective regarding the distance dependence and the influence of a heterogeneous material.

DESIGN

Methodological study.

SETTING

Aarhus University Hospital, Denmark.

POPULATION

Six mid- and five full-term pregnant women.

METHODS

Reference caps and phantoms with Young's moduli between 0.07 and 0.40 N/mm(2) were made of silicone and oil. By using reference caps, the approximate Young's moduli of the cervixes were calculated from strain ratios obtained by elastography.

MAIN OUTCOME MEASURES

Approximate Young's modulus of the cervix.

RESULTS

The recordings of the phantoms revealed that the calculation of the approximate Young's moduli became unreliable at distances above 10-15 mm from the transducer. This was further increased for a phantom which included a soft layer imitating the cervical canal. The approximate Young's modulus obtained from the anterior cervical lip was 0.08 N/mm(2) in mid-term and 0.03 N/mm(2) in full-term pregnant women (Wilcoxon rank-sum test, p = 0.01).

CONCLUSION

The reference cap constitutes a promising tool for quantitative elastography of the anterior cervical lip. Figures obtained from the posterior cervical lip are less plausible due to the distance from the transducer and the heterogeneity introduced by the cervical canal. The method has the potential to be used to supplement cervical length assessment when evaluating women at risk of preterm delivery and when planning induction of labor.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Real-time sonoelastography of Achilles tendon in patients with ankylosing spondylitis

OBJECTIVE

Real-time sonoelastography (SE) is a new ultrasound-based imaging technique that provides information on tissue elasticity and stiffness. We determined the efficacy of SE for assessing Achilles tendon abnormalities in patients with ankylosing spondylitis (AS).

MATERIALS AND METHODS

Forty-one consecutive AS patients and 32 asymptomatic healthy subjects were enrolled. Achillodynia was scored on a 0- to 100-mm visual analog scale. A high-resolution ultrasound machine equipped with an elastography-compatible linear probe was used to perform bilateral B-mode ultrasound, Doppler ultrasound, and SE examinations of Achilles tendons. Tendons were divided into proximal, middle, and distal segments. B-mode examinations included tendon thicknesses, echotextures, and enthesopathic findings. SE using color-coded images was performed in the same areas. Normal consistent tendon structures were coded as blue or green, and moderately (yellow) or severely (red) softened areas were considered pathological.

RESULTS

The distal third of the Achilles tendons was the most commonly affected part in the AS patients compared with healthy subjects (p = 0.001), whose middle third was more commonly affected. Achillodynia intensity tended to be higher in patients with pathological B-mode or SE examination findings (p = 0.09 and p = 0.07 respectively). Softening detected by SE in the distal third was associated with enthesopathy findings such as calcaneal bone erosions (Fisher's X (2), p = 0.07) and tendinous enlargement (Fisher's X (2), p = 0.001). B-mode and SE findings had moderate to good correlation in the assessment of Achilles tendon abnormalities.

CONCLUSIONS

Sonoelastography may be useful for the evaluation of tendon abnormalities in patients with AS; in addition; it may be useful for the evaluation of other inflammatory rheumatic conditions.

An introduction to primary skin imaging

Dermatology is a field in which clinical examination is heavily relied upon for diagnosis. When required, a tissue biopsy may also be performed to confirm the diagnosis. Recent advances in imaging techniques have been applied to cutaneous lesions to improve diagnostic accuracy without the need for biopsy. These new imaging techniques are reviewed for their developing role in dermatology.

Clinical application of breast elastography: state of the art

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

Breast elastography: the technical process and its applications

Breast elastography is being increasingly used to better characterize breast lesions. Published studies have shown that it improved specificity of B mode ultrasound. Two elastography modes are available: free-hand elastography and shear wave elastography. Free-hand elastography is obtained by a mechanic wave induced by the ultrasound probe, deforming the target, either by small movements induced by breathe. An elastogram is obtained and displayed either as a colour map or a size ratio or elasticity ratio measurement. The second mode is shear wave elastography; two methods are available: Shear Wave Elastography (SWE) and ARFI mode (Acoustic Radiation Force Impulse). Shear wave elastography is less operator-dependent than free-hand elastography mode and provides a quantitative approach. A value of over 80kPa (SWE) or velocity results of over 2m/s (ARFI) are considered as suspicious. False negatives may occur in soft breast cancers (mucinous carcinoma, carcinoma with an inflammatory stroma, etc.) and false positives may be seen with poorly deformable benign lesions such as old fibrous adenomas. In practical use, elastography is a useful complementary tool for undetermined breast lesions categorized as BI-RADS 4a or BI-RADS 3, or for cystic lesions but cannot avoid fine needle aspiration or core biopsy if ultrasound features are clearly suspicious.

Ultrasound elastography: advantages, limitations and artefacts of the different techniques from a study on a phantom

Ultrasound elastography is a technique currently under development. Its use in clinical practice is complicated because of the wide range of techniques used by the different manufacturers and the parameters proposed to characterise tissues. A comparative analysis on five ultrasound diagnostic systems has been performed on a calibrated elasticity phantom and demonstrated that: (1) all systems tested are reliable for simple qualitative analysis: is a nodule present and is it harder or softer than neighbouring tissues? (2) the deformation or hardness ratios between two regions are usually, however, not proportional to the theoretical ratios and only a binary analysis greater than 1 (harder) and less than 1 (softer) is reliable and could be used as a negative predictive value (NPV) for malignant lesions, as has been suggested by some authors; (3) finally, quantitative analysis using shear wave techniques performed variably, reliable measurements being obtained with only one of the systems. Measurements produced by these different systems must not be compared in clinical practice to monitor a patient and the threshold values proposed in the literature must only be used in an analysis carried out with the same system and same probe.

Strain Elastography Ultrasound: An Overview with Emphasis on Breast Cancer Diagnosis

Strain elastography (SE), which estimates tissue strain, is an adjunct to the conventional ultrasound B-mode examination. We present a short introduction to SE and its clinical use. Furthermore, we present an overview of the 10 largest studies performed on the diagnostic accuracy of SE in breast cancer diagnostics. Eight of 10 studies presented data for both SE and B-mode imaging. Seven studies showed better specificity and accuracy for SE than for B-mode imaging in breast cancer diagnosis. Four studies showed an increase in specificity and accuracy when combining B-mode imaging with SE. The ways of combining B-mode imaging with SE in the diagnosis of breast cancer differed between the five studies. We believe that further studies are needed to establish an optimal algorithm for the combination of B-mode ultrasound and SE in breast cancer.

[Palpation and elastography of thyroid nodules in comparison]

In addition to ultrasound, elastography is available for evaluation of thyroid nodules for several years.

AIM

of this study was to verify a statistically significant correlation between palpation and elastography as well as between scintigraphy and elastography, respectively. PATIENTS, METHODES: 97 solitary thyroid nodules in 67 women (mean age 63.0 ± 14.8 years) and 30 men (mean age 63.4 ± 18.5 years) were colour-coded by a colour spectrum from blue (soft) via yellow to red (hard) (Sonix touch ultrasound system, Ultrasonix, Canada) with a 6-14 MHz probe. These colour codes were classified into an elastography score of ES 1 to ES 4.

RESULTS

50 nodules were not palpable, 47 were addressed as "soft" (n = 16), "indifferent" (n = 24) or "hard" (n = 7). Elastography values were higher with increasing stiffness of the palpable nodules. Medians of elastography score were for the soft nodules ES 2, for the indifferent nodules ES 2.5 and for the hard nodules ES 4. A statistically significant correlation could be confirmed by the Jonckheere-Terpstra test (p = 0.01) and Spearman's rank correlation (p = 0.03). No correlation between elastography and scintigraphic uptake could be observed (p = 0.41).

CONCLUSION

In detectable nodules, palpation is correlated with elastography. Since non-palpable nodules may have differences in elasticity too, elastography can provide additional data, which may influence the further diagnostic procedures and treatment essentially. Based on these results, scintigraphy cannot be replaced by elastography.

Three-dimensional shear-wave elastography for differentiating benign and malignant breast lesions: comparison with two-dimensional shear-wave elastography

OBJECTIVES

To evaluate the interobserver agreement and the diagnostic performance of 3D shear-wave elastography (SWE) for breast lesions in comparison with 2D SWE.

METHODS

A total of 163 breast lesions (malignant 48, benign 115) in 146 women who underwent B-mode ultrasound and SWE before biopsy were included. Two radiologists reviewed six data sets (B-mode, SWE, and a combination of both for 2D and 3D ultrasound). B-mode and SWE features were recorded. BI-RADS category was assigned for B-mode and combined sets. Interobserver variability was assessed using the κ statistic. Diagnostic performance of each data set was evaluated using the area under the ROC curve (AUC).

RESULTS

SWE showed substantial to almost perfect agreement, with Ehomo in 2D SWE being higher than in 3D SWE. The AUC of 2D SWE was higher than 3D SWE for all SWE features, significantly so for Ecol (0.933 vs. 0.867, P = 0.002) and Emax (0.961 vs. 0.874, P = 0.006). After adding SWE to B-mode ultrasound, the AUC in 2D ultrasound increased significantly (0.968 vs. 0.912, P = 0.008), but 3D ultrasound showed no significant difference (0.966 vs. 0.935; P = 0.07).

CONCLUSION

For 3D SWE, interobserver agreement was good, but the diagnostic performance was inferior to 2D SWE even after adding to B-mode ultrasound.

KEY POINTS

• Shear-wave elastography (SWE) provides further diagnostic information during breast ultrasound. • 3D SWE diagnostic performance is inferior to 2D SWE. • In 3D SWE, interobserver agreement was good. • 2D B-mode ultrasound showed significant diagnostic improvement when combined with 2D SWE. • 3D B-mode ultrasound performance was not significantly improved when combined with 3D SWE.

Impact of breast mass size on accuracy of ultrasound elastography vs. conventional B-mode ultrasound: a meta-analysis of individual participants

OBJECTIVES

To conduct an individual patient data meta-analysis comparing the diagnostic performance of ultrasound elastography (USE) versus B-mode ultrasound (USB) across size ranges of breast masses.

METHODS

An extensive literature search of PubMed and other medical/general purpose databases from inception through August 2011 was conducted. Corresponding authors of published studies that reported a direct comparison of the diagnostic performance of USE using the elasticity score versus USB for characterisation of focal breast masses were contacted for their original patient-level data set. Summary diagnostic performance measures were compared for each test within and across three mass size groups (<10 mm, 10-19 mm, and >19 mm).

RESULTS

The patient-level data sets were received from five studies, providing information on 1,412 breast masses. For breast masses <10 mm (n = 543; 121 malignant), the sensitivity/specificity of USE and USB were 76 %/93 % and 95 %/68 %, respectively. For masses 10-19 mm of size (n = 528; 247 malignant), sensitivity/specificity of USE and USB were 82 %/90 % and 95 %/67 %, respectively. For masses >19 mm of size (n = 325; 162 malignant), sensitivity/specificity of USE and USB were 74 %/94 % and 97 %/55 %, respectively.

CONCLUSION

Regardless of the mass size, USE has higher specificity and lower sensitivity compared to USB in characterising breast masses. The performance of each of these two tests does not vary significantly by mass size.

Differentiation of benign from malignant solid breast masses: comparison of two-dimensional and three-dimensional shear-wave elastography

OBJECTIVES

To prospectively compare the diagnostic performances of two-dimensional (2D) and three-dimensional (3D) shear-wave elastography (SWE) for differentiating benign from malignant breast masses.

METHODS

B-mode ultrasound and SWE were performed for 134 consecutive women with 144 breast masses before biopsy. Quantitative elasticity values (maximum and mean elasticity in the stiffest portion of mass, Emax and Emean; lesion-to-fat elasticity ratio, Erat) were measured with both 2D and 3D SWE. The area under the receiver operating characteristic curve (AUC), sensitivity and specificity of B-mode, 2D, 3D SWE and combined data of B-mode and SWE were compared.

RESULTS

Sixty-seven of the 144 breast masses (47 %) were malignant. Overall, higher elasticity values of 3D SWE than 2D SWE were noted for both benign and malignant masses. The AUC for 2D and 3D SWE were not significantly different: Emean, 0.938 vs 0.928; Emax, 0.939 vs 0.930; Erat, 0.907 vs 0.871. Either 2D or 3D SWE significantly improved the specificity of B-mode ultrasound from 29.9 % (23 of 77) up to 71.4 % (55 of 77) and 63.6 % (49 of 77) without a significant change in sensitivity.

CONCLUSION

Two-dimensional and 3D SWE performed equally in distinguishing benign from malignant masses and both techniques improved the specificity of B-mode ultrasound.

Quantification of cervical elastography: a reproducibility study

OBJECTIVES

To assess a new method for numerical quantification of cervical elastography during pregnancy and to evaluate the repeatability of the measurements.

METHODS

Cervical elastography was carried out twice by a single operator in 112 singleton pregnancies at a median of 21 (range, 12-40) weeks' gestation. In 50 of the cases a second operator performed another elastography measurement. The intraobserver and interobserver repeatability of measurements in different parts of the cervix were assessed using intraclass correlation coefficients with 95% CI and by Bland-Altman analysis.

RESULTS

There were no statistically significant differences in the elastography measurements made by the same and by two different observers in each area measured, except in the area that receives the force of the transducer directly. The distribution of elastographic measurements obtained in different regions of the cervix demonstrated that the external and superior parts were significantly softer than the internal and inferior parts.

CONCLUSION

It is possible to provide an objective quantification of elastographic colors in the cervix. The measurements obtained by elastography may be a mere reflection of the force being applied by the transducer to different parts of the cervix. It is too premature to suggest that the measurements of rate-of-change in tissue displacement reflect histological changes that could provide a measure of cervical ripening.

Non-mass-like lesions on breast ultrasonography: a systematic review

This article reviews various non-mass-like ultrasonography (US) findings of the breast and the sonographic-pathologic correlation with Doppler techniques, elastography, and MRI. High-resolution US allows for identification of small, clinically occult non-mass-like US findings. Ductal carcinoma in situ and invasive lobular carcinoma usually manifest as a non-mass-like lesion on US. It is useful to classify non-mass-like lesions on US in a similar manner to the classification of non-mass-like enhancement on MRI.