Real-time qualitative ultrasound elastography of miscellaneous non-nodal neck masses: applications and limitations

Carotid body tumor imaging: MRI, ultrasound, and elastography with surgical management

A carotid body tumor is an uncommon tumor that develops from the carotid body. Carotid body tumor, also called paraganglioma, is often benign in nature and mostly found in the neck. They make up 0.5% of all body tumors and resemble glomus jugulare, glomus tympanicum, and pheochromocytoma, which are paragangliomas of the body. We present a case of a 22-year-old male patient who presented to the medical outpatient department with complaints of swelling in the left carotid triangle for 1 month. The patient had hoarseness of voice with odynophagia and dysphagia. We found out the diagnosis of carotid body tumor when the patient came for ultrasound, and the diagnosis was later confirmed on magnetic resonance imaging. The gold standard treatment for carotid body tumors is surgery. The surgical categorization by Shamblin et al. marks a turning point in the evaluation of these tumors' resectability and is still used to predict vascular morbidity, and according to it, our patient later underwent sub adventitial tumor excision.

Anterior deltoid muscle tension quantified with shear wave ultrasound elastography correlates with pain level after reverse shoulder arthroplasty

INTRODUCTION

Reverse shoulder arthroplasty (RSA) leads to medialization and distalization of the centre of rotation of the shoulder joint resulting in lengthening of the deltoid muscle. Shear wave ultrasound elastography (SWE) is a reliable method for quantifying tissue stiffness. The purpose of this study was to analyse if deltoid muscle tension after RSA correlates with the patients' pain level. We hypothesized that higher deltoid muscle tension would be associated with increased pain.

MATERIAL AND METHODS

Eighteen patients treated with RSA were included. Constant score (CS) and pain level on the visual analogue scale (VAS) were analysed and SWE was performed on both shoulders. All three regions of the deltoid muscle were examined in resting position and under standardized isometric loading.

RESULTS

Average patient age was 76 (range 64-84) years and average follow-up was 15 months (range 4-48). The average CS was 66 points (range 35-89) and the average pain level on the VAS was 1.8 (range 0.5-4.7). SWE revealed statistically significant higher muscle tension in the anterior and middle deltoid muscle region in patients after RSA compared to the contralateral non-operated side. There was a statistically significant correlation between pain level and anterior deltoid muscle tension.

CONCLUSION

SWE revealed increased tension in the anterior and middle portion of the deltoid muscle after RSA in a clinical setting. Increased tension of the anterior deltoid muscle portion significantly correlated with an increased pain level. SWE is a powerful, cost-effective, quick, dynamic, non-invasive, and radiation-free imaging technique to evaluate tissue elasticity in the shoulder with a wide range of applications.

LEVEL OF EVIDENCE

Diagnostic study, Level III.

Expression of human papillomavirus oncoproteins E6 and E7 inhibits invadopodia activity but promotes cell migration in HPV-positive head and neck squamous cell carcinoma cells

Background

The rapid increase in the incidence of head and neck squamous cell carcinoma (HNSCC) is caused by high‐risk human papillomavirus (HPV) infections. The HPV oncogenes E6 and E7 promote carcinogenesis by disrupting signaling pathways that control survival and proliferation. Although these cancers are often diagnosed with metastases, the mechanisms that regulate their dissemination are unknown.

Aims

The aim of this study was to determine whether the HPV‐16 E6 and E7 oncogenes affected the invasive and migratory properties of HNSCC cells which promote their spread and metastasis.

Methods and results

Invasiveness was determined using invadopodia assays which allow for quantitation of extracellular matrix (ECM) degradation by invadopodia which are proteolytic membrane protrusions that facilitate invasion. Using cell lines and genetic manipulations, we found that HPV inhibited invadopodia activity in aggressive cell lines which was mediated by the E6 and E7 oncogenes. Given these findings, we also tested whether HPV caused differences in the migratory ability of HNSCC cells using Transwell assays. In contrast to our invadopodia results, we found no correlation between HPV status and cell migration; however, blocking the expression of the E6 and E7 oncoproteins in a HPV‐positive (HPV⁺) HNSCC cell line resulted in decreased migration.

Conclusions

Our data suggest that the E6 and E7 oncoproteins are negative regulators of invadopodia activity but may promote migration in HPV⁺ HNSCC cells. Despite the need for ECM proteolysis to penetrate most tissues, the unique structure of the head and neck tissues in which these cancers arise may facilitate the spread of migratory cancer cells without significant proteolytic ability.

Ultrasonographic elastography in the evaluation of normal and pathological skin - a review

The aim of this review article is to discuss the role of ultrasonographic elastography, a technique used to quantify tissue stiffness, in the evaluation of normal and pathological skin. A growing body of evidence suggests that elastography may be used for the diagnosis and monitoring of skin pathologies, in particular tumors, and fibrotic and sclerotic processes. Our knowledge about the elastographic parameters of normal skin is sparse, which together with the lack of reference values for cutaneous stiffness constitutes a serious limitation to the use of elastography in some medical disciplines, including aesthetic medicine.

Motorizing and Optimizing Ultrasound Strain Elastography for Detection of Intrauterine Growth Restriction Pregnancies

Intrauterine growth restriction is a prevalent disease in pregnancy in which placental insufficiency leads to 5 to 10 times higher mortality and lifelong morbidities. The current detection rate is poor, and recently, ultrasound strain elastography (USEL) was proposed as a new diagnostic technique. Currently, placental USEL uses maternal subcutaneous fat as the reference layer, but this is not ideal as fat tissue stiffness can vary widely between subjects. Current USEL also uses manual palpation, and under different compression depths and rates, viscoelastic tissues such as placenta can yield different stiffness results. In the study described here, we strove to improve placental USEL by (i) using an external polymeric pad of known stiffness as the reference layer and (ii) adopting motorized control of the transducer during USEL to standardize palpation motion. Results indicated that motorized USEL reduced measurement variability by 67% compared with freehand USEL. Satisfactory and statistically significant correlations between USEL measurements and mechanical testing validation results were obtained for our new USEL protocol. Placental tissues were found to be non-linear and viscoelastic in nature and, thus, differed in stiffness at different compression rates and depths. Our study also revealed that there was a specific compression depth and rate during USEL that provided better correlation to mechanical testing, and should be considered in clinical placental USEL.

The feasibility of shear wave elastography for diagnosing superficial benign soft tissue masses

PURPOSE

The purpose of this study was to investigate the feasibility of shear wave ultrasound elastography for differentiating superficial benign soft tissue masses through a comparison of their shear moduli.

METHODS

We retrospectively analyzed 48 masses from 46 patients from February 2014 to May 2016. Surgical excision, fine-needle aspiration, and clinical findings were used for the differential diagnosis. The ultrasonographic examinations were conducted by a single musculoskeletal radiologist, and the ultrasonographic findings were reviewed by two other radiologists who were blinded to the final diagnosis. Conventional ultrasonographic features and the median shear modulus were evaluated. We compared the median shear moduli of epidermoid cysts, ganglion cysts, and lipomatous tumors using the Kruskal-Wallis test. Additionally, the Mann-Whitney U test was used to compare two distinct groups.

RESULTS

Significant differences were found in the median shear moduli of epidermoid cysts, ganglion cysts, and lipomatous tumors (23.7, 5.8, and 9.2 kPa, respectively; P=0.019). Epidermoid cysts showed a greater median shear modulus than ganglion cysts (P=0.014) and lipomatous tumors (P=0.049).

CONCLUSION

Shear wave elastography may contribute to the differential diagnosis of superficial benign soft tissue masses through a direct quantitative analysis.

The application of ultrasound elastography in the shoulder

Ultrasound elastography (EUS) is a recently developed method for the assessment of tissue elasticity by applying mechanical stress and subsequently analyzing tissue displacement with ultrasound. To date, mainly two different techniques are used in clinical practice: strain (compression) EUS and shear wave EUS. However, shear wave EUS has been shown to be more examiner independent and more reliable as this technique allows a quantitative measurement of tissue elasticity. There is increasing evidence that EUS can be used to evaluate mechanical properties of musculoskeletal tissue. Thus, it might be a powerful tool to detect and to monitor pathologic processes affecting the shoulder girdle. As ultrasound is an essential clinical tool for the examination of the shoulder, this review describes the two most important EUS techniques available for clinical use, presenting the published evidence on the applications of EUS for the evaluation of pathologic processes affecting the shoulder joint. In addition, technical issues, limitations, and future perspectives of these methods for the assessment of the shoulder are outlined.

Performances and Limitations of Several Ultrasound-Based Elastography Techniques: A Phantom Study

The objective of this study is to assess strain and shear wave (SW) elastography performance in terms of accuracy by performing in vitro measurements on a calibrated elastography phantom. Acquisitions were done on a phantom containing 4 inclusions (12-74 kPa) embedded in a homogeneous background material (30 kPa). We performed qualitative assessment on elastograms, semiquantitative assessment with strain or elasticity ratios between each inclusion and the background and quantitative evaluation with SW acquisitions. Ratio and elasticity estimations were compared with expected values. Biases, relative errors and 95% confidence intervals (95% CI) were calculated. All techniques adequately classified inclusions as harder or softer than the background. For stiffness ratio estimation, SW methods were more precise than strain methods and had significantly higher percentages of correctly classified measurements (p = 0.008). Quantitative stiffness measurements were reproducible despite constant biases. SW elastography methods provide more reproducible estimations of tissue stiffness ratio than strain methods, as well as reproducible quantitative tissue stiffness despite constant biases.

WFUMB Guidelines and Recommendations on the Clinical Use of Ultrasound Elastography: Part 4. Thyroid

The World Federation for Ultrasound in Medicine and Biology (WFUMB) has produced guidelines for the use of elastography techniques including basic science, breast and liver. Here we present elastography in thyroid diseases. For each available technique, procedure, reproducibility, results and limitations are analyzed and recommendations are given. Finally, recommendations are given based on the level of evidence of the published literature and on the WFUMB expert group's consensus. The document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of thyroid diseases.

Evaluation of healthy muscle tissue by strain and shear wave elastography - Dependency on depth and ROI position in relation to underlying bone

PURPOSE

The aim of this study was to evaluate the influence of depth and underlying bone on strain ratios and shear wave speeds for three different muscles in healthy volunteers. For strain ratios the influence from different reference region-of-interest positions was also evaluated.

MATERIAL AND METHODS

Ten healthy volunteers (five males and five females) had their biceps brachii, gastrocnemius, and quadriceps muscle examined with strain- and shear wave elastography at three different depths and in regions located above bone and beside bone. Strain ratios were averaged from cine-loops of 10s length, and shear wave speeds were measured 10 times at each target point. The distance from the skin surface to the centre of each region-of-interest was measured. Measurements were evaluated with descriptive statistics and linear regression.

RESULTS

Linear regression showed a significant influence on strain ratio measurements from the reference region-of-interest position, i.e. being above the same structures as the target region-of-interest or not (means: 1.65 and 0.78; (P<0.001)). For shear wave speeds, there was a significant influence from depth and location above or beside bone (P=0.011 and P=0.031).

CONCLUSION

Strain ratio values depend significantly on reference and target region-of-interest being above the same tissue, for instance bone. Strain ratios were not influenced by depth in this study. Shear wave speeds decreased with increasing scanning depth and if there was bone below the region-of-interest.

Therapeutic value of ultrasound-guided percutaneous transhepatic cholangiographic drainage in malignant obstructive jaundice

AIM: To assess the value of ultrasound-guided percutaneous transhepatic biliary drainage (PTCD) in the treatment of malignant obstructive jaundice.

METHODS: From August 2015 to March 2016, 78 patients underwent ultrasound-guided PTCD at our hospital, including 46 patients with cholangiocarcinoma, 18 patients with pancreatic cancer, 8 patients with bile duct stones and suppurative cholangitis, and 6 patients with ampullary tumor. Right hepatic duct puncture was performed in 48 cases, left hepatic duct puncture in 20 cases, and bilateral liver puncture in 10 cases. Surgical efficacy was observed.

RESULTS: All patients had successful surgery, and the success rate was 100%. No bile peritonitis, abdominal bleeding or other complications occurred. Serum total bilirubin, direct bilirubin, alkaline phosphatase, alanine aminotransferase, and γ-glutamyl transferase were significantly reduced after surgery (P < 0.05). The above indices were all significantly lower on 45 d compared to 10 d after surgery (P < 0.05).

CONCLUSION: Ultrasound-guided PTCD is simple and highly effective in the management of malignant obstructive jaundice, with a high success rate and few complications.

Use of Ultrasound Elastography in the Assessment of the Musculoskeletal System

This article presents possible applications of ultrasound elastography in musculoskeletal imaging based on the available literature, as well as the possibility of extending indications for the use of elastography in the future. Ultrasound elastography (EUS) is a new method that shows structural changes in tissues following application of physical stress. Elastography techniques have been widely used to assess muscles and tendons in vitro since the early parts of the twentieth century. Only recently with the advent of new technology and creation of highly specialized ultrasound devices, has elastography gained widespread use in numerous applications.

The authors performed a search of the Medline/PubMed databases for original research and reviewed publications on the application of ultrasound elastography for musculoskeletal imaging.

All publications demonstrate possible uses of ultrasound elastography in examinations of the musculoskeletal system. The most widely studied areas include the muscles, tendons and rheumatic diseases. There are also reports on the employment in vessel imaging.

The main limitation of elastography as a technique is above all the variability of applied pressure during imaging, which is operator-dependent. It would therefore be reasonable to provide clear guidelines on the technique applied, as well as clear indications for performing the test. It is important to develop methods for creating artifact-free, closed-loop, compression-decompression cycles.

The main advantages include cost-effectiveness, short duration of the study, non-invasive nature of the procedure, as well as a potentially broader clinical availability. There are no clear guidelines with regard to indications as well as examination techniques.

Ultrasound elastography is a new and still poorly researched method. We conclude, however, that it can be widely used in the examinations of musculoskeletal system. Therefore, it is necessary to conduct large, multi-center studies to determine the methodology, indications and technique of examination.

Shear Wave Elastography in Head and Neck Lymph Node Assessment: Image Quality and Diagnostic Impact Compared with B-Mode and Doppler Ultrasonography

The aim of this study was to assess the diagnostic performance of shear wave elastography (SWE) in comparison to B-mode and Doppler ultrasonography in differentiating benign from malignant head and neck lymph nodes (HNLNs). Sixty-two HNLNs from 56 patients were prospectively examined using B-mode, Doppler and SWE. The standard of reference was histopathology or cytology and follow-up. Qualitative malignant criteria (hilum infiltration, cortical hypo-echogenicity, irregular margins, abnormal vessels) were assessed on a five-point scale. Four quantitative parameters were obtained: long axis length, short axis length, short axis/long axis ratio, resistive index and maximum shear elasticity modulus (μmax). Diagnostic performance was analyzed with special emphasis on the sub-centimeter HNLN subgroup. Thirty HNLNs were malignant (48%). μmax intra-observer reproducibility was 0.899 (0.728 in sub-centimeter subgroup). Malignant HNLNs were stiffer (μmax = 72.4 ± 59.0 kPa) compared with benign nodes (μmax = 23.3 ± 25.3 kPa) (p < 0.001). Among the quantitative criteria, μmax had the highest diagnostic accuracy (area under the curve = 0.903 ± 0.042), especially in the sub-centimeter subgroup (area under the curve = 0.929 ± 0.045; p < 0.001) in which the area under the curve was significantly higher compared with the other quantitative criteria (p < 0.05). The additional use of SWE combined with B-mode tended to improve diagnostic accuracy (p > 0.05). SWE is a promising reproducible quantitative tool with which to predict malignant HNLNs, especially sub-centimeter nodes.

Usefulness of strain elastography of the musculoskeletal system

Ultrasound elastography is a widely used technique for assessing the mechanical characteristics of tissues. Although there are several ultrasound elastography techniques, strain elastography (SE) is currently the most widely used technique for visualizing an elastographic map in real time. Among its various indications, SE is especially useful in evaluating the musculoskeletal system. In this article, we review the SE techniques for clinical practice and describe the images produced by these techniques in the context of the musculoskeletal system. SE provides information about tissue stiffness and allows real-time visualization of the image; however, SE cannot completely replace gray-scale, color, or power Doppler ultrasonography. SE can increase diagnostic accuracy and may be useful for the follow-up of benign lesions.

Paediatric neck masses at a University teaching hospital in northwestern Tanzania: a prospective analysis of 148 cases

Background

Pediatric neck masses are one of the common surgical conditions presenting to the pediatric surgical wards and clinics in many centers worldwide. There is paucity of published information regarding pediatric neck masses in Tanzania and the study area in particular. This study determines the etiology, clinico-histopathological patterns and treatment outcome of pediatric neck masses and to identify predictors of outcome in our local setting.

Methods

This was a prospective cross-sectional hospital based study done in children aged ten years and below with neck masses for a five months period. Statistical data analysis was done using SPSS version 17.0.

Results

A total of 148 patients were studied. Their ages ranged from 2 months to 10 years (median 3 years). The male to female ratio was 2.5:1. Inflammatory lesions were the most frequent cause of neck masses accounting for 43.9% of cases. The median duration of illness was 2 years. Except for the neck mass, 72 (48.6%) of the children had clinically stable health condition on presentation. The posterior triangle was commonly involved in 118 (79.7%) patients. eight (5.4%) were HIV positive. The majority of patients (95.9%) were treated surgically. Postoperative complication rate was 30.4% and surgical site infection was the most frequent complication in 37.5% of cases. The median length of hospital stay was 10 days and was significantly longer in patients with malignant masses and those with surgical site infection (p <0.001). The overall mortality rate in this study was 8.1% and it was significantly associated with malignant masses, associated pre-existing illness, late presentation, HIV positivity, low CD 4 count, high ASA class and presence of surgical site infections (p <0.001). The outcome of patients on discharge was excellent as more than 90% of patients were successfully treated and discharged well.

Conclusion

Pediatric neck masses are among the most common causes of paediatric surgical admissions and pose a diagnostic and therapeutic challenge in our setting. We advocate early surgical consultation and thorough and timely histopathological examination of neck masses in children.

Sonoelastography: musculoskeletal applications

All participants for image samplings provided written informed consent. Conventional B-mode ultrasonography (US) has been widely utilized for musculoskeletal problems as a first-line approach because of the advantages of real-time access and the relatively low cost. The biomechanical properties of soft tissues reflect to some degree the pathophysiology of the musculoskeletal disorder. Sonoelastography is an in situ method that can be used to assess the mechanical properties of soft tissue qualitatively and quantitatively through US imaging techniques. Sonoelastography has demonstrated feasibility in the diagnosis of cancers of the breast and liver, and in some preliminary work, in several musculoskeletal disorders. The main types of sonoelastography are compression elastography, shear-wave elastography, and transient elastography. In this article, the current knowledge of sonoelastographic techniques and their use in musculoskeletal imaging will be reviewed.

Assessment of neuromuscular conditions using ultrasound

Upper extremity pain in persons with spinal cord injury is a common cause of morbidity. Ultrasound of nerve, muscle, and tendon has the potential to become a valuable modality in assessing this population, and has the advantage of reduced health care costs, portability, and use in populations that cannot tolerate MRI. It has the potential to detect issues before the onset of significant morbidity, and preserve patient independence. Upper extremity ultrasound already has many studies showing its utility in diagnosis, and newer techniques have the potential to enhance its use in the diagnosis and management of musculoskeletal conditions.

Quantifying fibrosis in head and neck cancer treatment: An overview

BACKGROUND

Fibrosis is a common late complication of radiotherapy and/or surgical treatment for head and neck cancers. Fibrosis is difficult to quantify and formal methods of measure are not well recognized. The purpose of this review was to summarize the methods available to quantify neck fibrosis.

METHODS

A PubMed search of articles was carried out using key words "neck" and "fibrosis."

RESULTS

Many methods have been used to assess fibrosis, however, there is no preferred methodology. Specific to neck fibrosis, most studies have relied upon hand palpation rating scales. Indentation and suction techniques have been used to mechanically quantify neck fibrosis. There is scope to develop applications of ultrasound, dielectric, bioimpedance, and MRI techniques for use in the neck region.

CONCLUSION

Quantitative assessment of neck fibrosis is sought after in order to compare treatment regimens and improve quality of life outcomes in patients with head and neck cancer.

Averaging improves strain images of the biceps brachii using quasi-static ultrasound elastography

OBJECTIVE

Quasi-static ultrasound elastography is a technique for measuring tissue deformation (strain) under externally applied loading and can be used to identify the presence of abnormalities. The objective of this study was to demonstrate the efficacy of averaging strain images from repeated compression cycles in mitigating user-induced error using quasi-static ultrasound elastography.

METHODS

Freehand compressions were performed with an ultrasound transducer on the biceps brachii of nine participants (five males and four females), as well as with a custom automated compression system. Sets of strain images from the freehand techniques were averaged to create single representative images and compared against strain images from the automated compressions using both qualitative and quantitative metrics.

RESULTS

Significant improvements in intra-operator repeatability and interoperator reproducibility can be achieved by averaging strain images from four to eight repeated compressions. The resulting strain images did not lose significant image data compared with strain images from single automated compressions.

CONCLUSION

Averaging is introduced as a feasible and appropriate technique to improve strain image quality without sacrificing important image data.

ADVANCES IN KNOWLEDGE

Simple averaging of multiple freehand elastography measures can achieve a similar degree of accuracy, repeatability and reproducibility as that of more awkward and expensive automated methods. The resulting elastograms can be used to obtain a more accurate and complete diagnosis without additional cost to the doctor or the patient.

The tactile sensation imaging system for embedded lesion characterization

Elasticity is an important indicator of tissue health, with increased stiffness pointing to an increased risk of cancer. We investigated a tissue inclusion characterization method for the application of early breast tumor identification. A tactile sensation imaging system (TSIS) is developed to capture images of the embedded lesions using total internal reflection principle. From tactile images, we developed a novel method to estimate that size, depth, and elasticity of the embedded lesion using 3-D finite-element-model-based forward algorithm, and neural-network-based inversion algorithm are employed. The proposed characterization method was validated by the realistic tissue phantom with inclusions to emulate the tumors. The experimental results showed that, the proposed characterization method estimated the size, depth, and Young's modulus of a tissue inclusion with 6.98%, 7.17%, and 5.07% relative errors, respectively. A pilot clinical study was also performed to characterize the lesion of human breast cancer patients using TSIS.

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.

Effects of compression force on elasticity index and elasticity ratio in ultrasound elastography

OBJECTIVES

The purpose of this study was to investigate the relationship between compression force and hardness values in ultrasound elastography.

METHODS

Ultrasound elastography was performed using an elastography phantom, comprising inclusions with different elasticities and echogenicities. The compression force was set to approximately 100 gw (light force) and approximately 500 gw (heavy force). The elasticity index (EI) of the inclusion was measured. The EI was a relative hardness value of a structure within an elastographic image. Similarly, the EI of the background was measured as a reference. The elasticity ratio (ER) was calculated as the EI of the inclusion divided by the EI of the reference.

RESULTS

The hardness of the phantom could be discerned with both the EI and ER, regardless of the compression force. The EI and ER with heavy force tended to be higher than those with light force, but the difference was not significant. A strong correlation was observed between the EI and ER of soft structures, whereas the correlation between the EI and ER of hard structures was weak, and the ER values varied widely.

CONCLUSIONS

The EI offers potential as a good indicator for assessing the hardness.

Ultrasound elastography in the head and neck. Part II. Accuracy for malignancy

Ultrasound elastography (USE) describes a variety of ultrasound-based imaging techniques that measure tissue stiffness properties, and is currently under intense investigation for tissue characterization in several anatomic sites. This article summarizes the evidence regarding the accuracy of USE for malignancy in the head and neck. Currently, most published data pertains to small pilot studies with varied methodologies. Encouragingly, most studies have documented promising results for USE in terms of high accuracy for malignancy in thyroid nodules and cervical lymph nodes, which have surpassed conventional sonographic criteria. However, a minority of studies have documented opposite findings. USE seems to be suboptimal for salivary malignancies, and some evidence suggests that USE does not provide useful diagnostic information compared with conventional ultrasonography for miscellaneous neck masses. Further larger studies are required to validate these findings although, in view of the predominance of highly optimistic results for thyroid nodules and cervical lymph nodes, USE may become a useful ancillary technique in the routine diagnostic work-up of lesions in these tissues in the near future.

Sonographic findings of axillary masses: what can be imaged in this space?

The diagnosis of axillary masses can be challenging because various tumors can develop in parts of the axilla other than lymph nodes, even though we frequently encounter axillary masses in daily practice. These lesions include soft tissue masses associated with nontumorous conditions (accessory breast tissue and chronic granulomatous inflammation) and benign and malignant tumorous conditions (lipomas, epidermal inclusion cysts, lymphangiomas, fibroadenomas, schwannomas, malignant neuroendocrine tumors, and lymph node-associated diseases). In this pictorial essay, we display commonly encountered sonographic findings of various axillary lesions to assist in the differential diagnosis of axillary masses.

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.

Ultrasound elastography for musculoskeletal applications

Ultrasound elastography (EUS) is a method to assess the mechanical properties of tissue, by applying stress and detecting tissue displacement using ultrasound. There are several EUS techniques used in clinical practice; strain (compression) EUS is the most common technique that allows real-time visualisation of the elastographic map on the screen. There is increasing evidence that EUS can be used to measure the mechanical properties of musculoskeletal tissue in clinical practice, with the future potential for early diagnosis to both guide and monitor therapy. This review describes the various EUS techniques available for clinical use, presents the published evidence on musculoskeletal applications of EUS and discusses the technical issues, limitations and future perspectives of this method in the assessment of the musculoskeletal system.

Is sonoelastography a helpful method for evaluation of parotid tumors?

Sonoelastography is a novel technique, useful in a noninvasive assessment of lesions in multiple organs. The aim of the study was to examine whether the combination of conventional ultrasonography (US) with sonoelastography might improve the reliability of parotid tumor evaluation. Fourty-three consecutive patients with parotid tumors were surgically treated at a single tertiary center at the Department of Otolaryngology, Head and Neck Surgery. The sample included 27 women and 16 men, aged 15–80 (the mean age = 54 years). The reference group constituted of 54 healthy volunteers. High resolution grayscale ultrasonography (US) was performed preoperatively using a 15 MHz linear array transducer. Elastograms (ES) were scored by the conventional Ueno 5-point scale from ES1 (blue-soft) to ES5 (the entire lesion and surrounding area shaded red-stiff). In addition, detailed stiffness values in kPa were collected. The group consisted of 33 patients with benign and 10 patients with malignant tumors. The mean stiffness value was 146.6 kPa in 10 malignant tumors (mostly ES4) and 88.7 kPa in 33 benign tumors (mostly ES2 and ES3). The differences in tissue stiffness between normal parotid parenchyma in the reference group and the mean value for all tumors in the examined group were statistically significant (p < 0.001), and so was the case with the differences between the benign and malignant tumors (p < 0.001). Low stiffness scores (ES1,2) were found in 2 malignant and 15 benign tumors while high scores (ES3,4) were found in 8 malignancies and 18 benign tumors. Sonoelastography overlapping elasticity to the grayscale images supports additional informations. Preferential selection of the lesions characterized by high stiffness (ES4) improves the differential diagnosis of parotid tumors but the large degree of uncertainty of this method should also be pointed out.

MR elastography of the head and neck: driver design and initial results

PURPOSE

The purpose was to describe the design and fabrication of a driver suitable for magnetic resonance elastography (MRE) of the head and neck and to assess its performance in evaluating human parotid gland, lymph nodes and thyroid at 3.0 T.

MATERIALS AND METHODS

A head and neck driver was fabricated using a commercial transducer, headrest mould and piston extension. Driver performance was tested using a motion-sensitized spin-echo MRE pulse sequence. Six healthy volunteers and three patients (two metastatic nodes and one papillary carcinoma) were evaluated using MRE. Viscoelastic maps were computed to obtain storage modulus (G') and loss modulus (G") of the normal parotid and thyroid, metastatic node and thyroid cancer. Reproducibility was assessed by coefficient of variation.

RESULTS

All subjects completed MRE examination without discomfort. Initial G' and G" values were as follows: normal parotid gland, 1.12 kPa and 0.48 kPa; thyroid, 0.58 kPa and 0.42 kPa; metastatic node, 0.66 kPa and 0.58 kPa; and thyroid cancer, 0.17 kPa and 0.28 kPa. Based on parotid data, the coefficient of variation for G' and G" was 4.7% and 9.8%.

CONCLUSION

A new MRE driver for head and neck was successfully implemented, and our initial results suggested the device was suitable for the mechanical assessment of tissues in the head and neck.

A pilot study evaluating real-time shear wave ultrasound elastography of miscellaneous non-nodal neck masses in a routine head and neck ultrasound clinic

A pilot study was performed to evaluate shear wave ultrasound elastography (SWE) for miscellaneous non-nodal/salivary/thyroid neck lesions. Forty-six lesions undergoing conventional sonography also underwent SWE. Elastic moduli from the stiffest areas in lesions were correlated with diagnosis. Forty lesions were benign (9 lipomas, 8 lymphatic/venous vascular malformations, 7 thyroglossal duct cysts, 4 branchial cleft cysts, 4 abscesses/phlegmons, 3 neurogenic tumors and 1 each of paraganglioma, sebaceous cyst, pseudotumor, hypertrophic scar, ranula) and 6 were malignant (1 malignant fibrous histiocytoma, 2 primary squamous cell carcinomas and 3 intramuscular metastases [2 squamous cell carcinomas, 1 malignant melanoma]).Median stiffness of malignant lesions (226.4 kPa, range 55.6 to 300.0) was higher than benign lesions (28.3 kPa, range 4.0 to 300.0) (p < 0.001). SWE cut-off with highest accuracy (174.4 kPa) achieved 83.3% sensitivity and 97.5% specificity, and the cut-off with 100% sensitivity (55.6 kPa) achieved 75% specificity. All malignant lesions were suspected on conventional sonography. The preliminary data indicate that SWE is feasible for miscellaneous neck lesions. SWE would not have altered management in terms of detecting undisclosed malignancies, although as a quantitative technique, it may increase the diagnostic confidence of less experienced operators performing head and neck ultrasound.

Inclusion mechanical property estimation using tactile images, finite element method, and artificial neural network

In this paper, we developed a methodology for estimating three parameters of tissue inclusion: size, depth, and Young's modulus from the tactile data obtained at the tissue surface with the tactile sensation imaging system. The estimation method consists of the forward algorithm using finite element method, and inversion algorithm using artificial neural network. The forward algorithm is designed to comprehensively predict the tactile data based on the mechanical properties of the tissue inclusion. This forward information is used to develop an inversion algorithm that will be used to extract the size, depth, and Young's modulus of a tissue inclusion from the tactile image. The proposed method is then validated with custom made tissue phantoms with matching elasticities of typical human breast tissues. The experimental results showed that the proposed estimation method estimates the size, depth, and Young's modulus of tissue inclusions with root mean squared errors of 1.25 mm, 2.09 mm, and 28.65 kPa, respectively.