Up-to-date Doppler techniques for breast tumor vascularity: superb microvascular imaging and contrast-enhanced ultrasound

Advanced Ultrasound Techniques for Neuroimaging in Pediatric Critical Care: A Review

Because of its portability, safety profile, and accessibility, ultrasound has been integral in pediatric neuroimaging. While conventional B-mode and Doppler ultrasound provide anatomic and limited flow information, new and developing advanced ultrasound techniques are facilitating real-time visualization of brain perfusion, microvascular flow, and changes in tissue stiffness in the brain. These techniques, which include contrast-enhanced ultrasound, microvascular imaging, and elastography, are providing new insights into and new methods of evaluating pathologies affecting children requiring critical care, including hypoxic-ischemic encephalopathy, stroke, and hydrocephalus. This review introduces advanced neurosonography techniques and their clinical applications in pediatric neurocritical care.

Ultrasonographic Detection of Vascularity of Focal Breast Lesions: Microvascular Imaging Versus Conventional Color and Power Doppler Imaging

To compare microvascular flow imaging (MVFI) to conventional Color-Doppler (CDI) and Power-Doppler (PDI) imaging in the detection of vascularity of Focal Breast Lesions (FBLs). A total of 180 solid FBLs (size: 3.5-45.2 mm) detected in 180 women (age: 21-87 years) were evaluated by means of CDI, PDI, and MVFI. Two blinded reviewers categorized lesion vascularity in absent or present, and vascularity pattern as (a) internal; (b) vessels in rim; (c) combined. The presence of a "penetrating vessel" was assessed separately. Differences in vascularization patterns (chi² test) and intra- and inter-observer agreement (Fleiss method) were calculated. ROC analysis was performed to assess performance of each technique in differentiating benign from malignant lesions. About 103/180 (57.2%) FBLs were benign and 77/180 (42.8%) were malignant. A statistically significant (p < .001) increase in blood flow detection was observed for both readers with MVFI in comparison to either CDI or PDI. Benign FBLs showed mainly absence of vascularity (p = .02 and p = .01 for each reader, respectively), rim pattern (p < .001 for both readers) or combined pattern (p = .01 and p = .04). Malignant lesions showed a statistically significant higher prevalence of internal flow pattern (p < .001 for both readers). The prevalence of penetrating vessels was significantly higher with MVFI in comparison to either CDI or PDI (p < .001 for both readers) and in the malignant FBLs (p < .001). ROC analysis showed MVFI (AUC = 0.70, 95%CI = [0.64-0.77]) more accurate than CDI (AUC = 0.67, 95%CI = [0.60-0.74]) and PDI (AUC = 0.67, 95%CI = [0.60-0.74]) though not significantly (p = .5436). Sensitivity/Specificity values for MVFI, PDI, and CDI were 76.6%/64.1%, 59.7%/73.8% and 58.4%/74.8%, respectively. Inter-reader agreement with MVFI was always very good (k-score 0.85-0.96), whereas with CDI and PDI evaluation ranged from good to very good. No differences in intra-observer agreement were noted. MVFI showed a statistically significant increase in the detection of the vascularization of FBLs in comparison to Color and Power-Doppler.

Qualitative Diagnosis of Solid Breast Mass by Blood Flow in Solid Breast Mass Based on Color Doppler Ultrasound

The incidence of breast cancer ranks first among female malignant tumor. With the increase of the sensitivity of color Doppler ultrasound blood flow, the blood flow distribution in and around the tumor can be clearly displayed, and the analysis of hemodynamic parameters is provided, which provides convenience for the study of tumor blood flow characteristics. Studies have shown that tumor cells can secrete a substance called angiogenesis factor, which makes the tumor site form a rich vascular network to promote tumor growth and metastasis. The tumor has many new blood vessels, abnormal structure, thin wall, lack of muscle layer, and is prone to form arteriovenous rash. These characteristics provide a pathological basis for color Doppler flow imaging (CDFI) for the diagnosis of breast cancer. This article discusses the role of two-dimensional sonographic features in the differential diagnosis of benign and malignant breast masses, CDFI was used to study the blood flow distribution and hemodynamic characteristics in benign and malignant breast masses; explore the value of blood flow characteristics and blood flow parameters in the differential diagnosis of breast masses. The experimental results show that the detection rate of blood flow signals and the classification of blood flow signals in the malignant group are higher than those in the benign group, mainly level II and III blood flow, and the irregular branched blood flow is more common, especially when the tumor appears penetrating blood flow supports the diagnosis of malignancy. PSV, RI and PI have a certain differential meaning in the diagnosis of benign and malignant breast masses. PSV, RI and PI of malignant masses are higher than benign masses. For tumors without obvious necrosis, the larger the tumor diameter, the richer the blood flow and the higher the blood flow grade is. The malignant tumors have more blood flow than the benign ones.

Comparison of the Effectiveness of Shear Wave Elastography and Superb Microvascular Imaging in the Evaluation of Breast Masses

ABSTRACT

This study aims to determine the diagnostic performance of superb microvascular imaging (SMI) and shear wave elastography methods in evaluating breast lesions. We will also compare the effectiveness of the stiffness, velocity, and vascular index (VI) parameters in distinguishing malignancy.From January to June 2019, 121 patients with 121 solid breast masses (category 4 and 5 lesions according to the Breast Imaging-Reporting and Data System) detected during the routine grayscale sonographic examination were included in the study. Stiffness and velocity values were obtained using shear wave elastography for all lesions, and VI was obtained using SMI. The receiver operating characteristic curves were obtained to set the best cutoff values for the stiffness, velocity, and VI to differentiate patients with malignant breast lesions.All 121 lesions were pathologically verified by US-guided core needle biopsy. Forty-seven (38.9%) of the lesions were malignant, and 74 (61.1%) were benign. Median stiffness, velocity, and VI values were significantly lower in benign masses compared with malignant masses (P < 0.001). The optimum cutoff values for the stiffness, velocity, and VI were determined to be 58.3 kPa, 4.5 m/s, and 1.1%, respectively. The areas under the curves were 0.897 for stiffness, 0.884 for velocity, and 0.687 for VI.Shear wave elastography and SMI are noninvasive methods that may be used to evaluate breast masses. Although both methods' quantitative data are beneficial in differentiating malignant from benign masses, stiffness is the best parameter to be used.

Median Nerve's Microcirculation in Carpal Tunnel Syndrome: Superb Microvascular Imaging

BACKGROUND

The objectivity of physical and electrodiagnostic tests is limited in detecting carpal tunnel syndrome and its recurrence. Predicting the median nerve blood supply using superb microvascular imaging will allow exact diagnosis and a good follow-up system. The aims of this study include using superb microvascular imaging to correlate with electromyographic diagnosis, and to determine the impact of surgery on improvement in superb microvascular imaging.

METHODS

Between July of 2019 and January of 2020, 32 wrists of 21 patients were evaluated prospectively. After preoperative electrodiagnostic studies and vascular index measurement with superb microvascular imaging, open carpal tunnel release was performed by a single surgeon, and 3 months later standardized superb microvascular imaging was performed. Preoperative vascular indexes were compared with the mild, moderate, and severe electrodiagnostic study results. Preoperative and postoperative vascular index results were compared.

RESULTS

The average of the preoperative and postoperative imaging groups was 2.77 and 1.48, respectively, and there was a statistically significant difference between the two groups (p < 0.05). Although no significant difference was found between preoperative and postoperative vascular index values in patients presenting with mild carpal tunnel syndrome (p > 0.05), there was a significant decrease in vascular index values in patients presenting with moderate and severe carpal tunnel syndrome after surgical decompression.

CONCLUSIONS

Superb microvascular imaging is emerging as a groundbreaking, new, and reliable technique. Evaluation of the median nerve blood supply is a reliable method that would be helpful for early diagnosis, planning treatment, determining the severity of carpal tunnel syndrome, and postoperative follow-up.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, IV.

Clinical Applications of Superb Microvascular Imaging in the Superficial Tissues and Organs: A Systematic Review

Superb microvascular imaging (SMI) is an innovative Doppler technique for vascular examination. It uses an intelligent algorithm that efficiently separates low-speed flow signals from motion artifacts so that it can assess microvessels and the vessel distribution in detail. This article reviews the clinical applications of SMI in the disorders of superficial tissues and organs including thyroid nodules, breast tumors and lymph node diseases etc. More information of diseases that are closely associated with angiogenesis can be shown by SMI than other noninvasive examinations. Although some limitations exist, this safe and convenient technique is becoming acceptable and would play a more important role in disease diagnosis and therapeutic responses evaluation.

An advanced ultrasound application used to assess peripheral vascular diseases: superb microvascular imaging

Over the past several years, a novel ultrasound imaging modality termed superb microvascular imaging (SMI) has enabled visualization of microvessels. SMI ultrasound studies of peripheral artery diseases have significantly extended our knowledge of tissue microcirculation and the arterial microenvironments of atherosclerotic lesions. We here present an overview of current knowledge on the utility of SMI assessment of vascular diseases and highlight certain peripheral microcirculation disorders for which SMI is particularly valuable. The evidence indicates that SMI can detect intraplaque neovascularization and usefully assess carotid plaque vulnerability; vascularization of the carotid arterial wall detected by SMI is a potential marker of disease activity in patients with Takayasu arteritis; SMI reveals the foot microcirculation and yields a quantitative vascular index (in line with the angiosome concept); and, SMI may serve as an auxiliary diagnostic modality for hereditary hemorrhagic telangiectasia and Raynaud syndrome. In general, microcirculatory evaluation by SMI is an attractive field for future research on therapeutic strategies for peripheral vascular diseases.

Musculoskeletal ultrasound using superb microvascular imaging documents treatment response to biosimilar infliximab in rheumatoid arthritis

A 60-year-old woman with rheumatoid arthritis consulted for acute flare. She had elevated disease activity score 28 - erythrocyte sedimentation rate (DAS 28-ESR) of 6.88 and clinical disease activity index (CDAI) of 32. Her 12-joint ultrasound revealed widespread joint effusion. Synovial vascularity scores measured through superb microvascular imaging (SMI) and power Doppler were universally increased. We documented her treatment response 2 weeks after she received a single dose of biosimilar infliximab using clinical and sonographic data. Her DAS 28-ESR and CDAI scores decreased to 4.21 and 7.0, respectively. Reduction in synovial vascularity scores was demonstrated using SMI. While there was near total resolution in joint effusion and tenosynovitis, SMI was able to demonstrate synovial vascularity in joints with no clinical swelling nor tenderness. Musculoskeletal ultrasound and superb microvascular imaging are useful adjuncts in evaluating synovitis in rheumatoid arthritis and documenting treatment response through documentation of synovial vascularity, effusion and tenosynovitis.

Decreased Size of Mammary Tumors Caused by Preoperative Treatment with Aglepristone in Female Domestic Dogs (Canis familiaris) Do Not Influence the Density of the Benign Neoplastic Tissue Measured Using Shear Wave Elastography Technique

Shear wave elastography (SWE) can be useful to discriminate between malignant and benign mammary tumors. In dogs with elevated progesterone levels compared to the baseline and fast-growing tumors, treatment with the use of aglepristone allows for tumor size reduction, which facilitates surgery. This study aimed to evaluate the influence of the preoperative treatment of benign mammary tumors (BMTs), performed with the use of aglepristone, on the density of the tumor tissue measured by SWE. Twelve female dogs with diagnosed BMTs and increased levels of progesterone were treated with aglepristone (Alizine, Virbac, France) at 10 mg/kg s.c. (Subcutaneous injection). twice, with a 24 h interval. The density of the tumor was evaluated by SWE before and after the treatment. The type of tumor was evaluated by fine needle aspiration cytology before treatment, and a histopathological examination was made after surgical removal, performed after the aglepristone treatment. In all the cases, a significant reduction in the mammary tumor's size was observed following treatment, with no influence on the density of the tumor's tissue measured by SWE. Similar studies on malignant mammary tumors are warranted to verify if in these cases, density will also be a constant parameter that is not dependent on the tumor size.

Superb microvascular imaging technology of ultrasound examinations for the evaluation of tumor vascularity in hepatic hemangiomas

Purpose

This study aimed to investigate and categorize the diverse features of hepatic hemangiomas on superb microvascular imaging (SMI) in a relatively large prospective study.

Methods

In this prospective study, 70 patients with 92 hepatic hemangiomas were consecutively enrolled. All nodules were radiologically confirmed with the typical imaging features of hepatic hemangiomas on dynamic computed tomography (CT) or magnetic resonance imaging (MRI). Using SMI, all lesions were evaluated and categorized into subgroups according to the flow pattern on SMI. Differences in the frequencies of SMI patterns according to lesion size and enhancement patterns on dynamic CT or MRI were also compared.

Results

In 67.4% (62/92) of hemangiomas, tumor vascularity was detected using SMI, while 32.6% (30/92) did not show any signal on the SMI examination, and the absence of an SMI signal was not shown in rapidly enhancing hemangiomas (0% [0/30] vs. 100% [30/30], P=0.002) and was more frequent in lesions <2 cm than in lesions ≥2 cm (44.0% [22/50] vs. 2.7% [8/42], P=0.011). In hepatic hemangiomas in which vascularity was detected (n=62), the strip rim pattern was the most common SMI pattern of hepatic hemangiomas (48.4%, 30/62), followed by the nodular rim pattern involving spotty dot-like engorged vessels (37.1%, 23/62).

Conclusion

The evaluation of the inner vascularity of hepatic hemangiomas with SMI was feasible for most hemangiomas, especially in larger (≥2 cm) or rapidly enhancing hemangiomas. The most frequent SMI patterns of hepatic hemangiomas were the strip rim pattern and nodular rim pattern.

Breast Ultrasound Microvascular Imaging and Radiogenomics

Microvascular ultrasound (US) techniques are advanced Doppler techniques that provide high sensitivity and spatial resolution for detailed visualization of low-flow vessels. Microvascular US imaging can be applied to breast lesion evaluation with or without US contrast agents. Microvascular US imaging without a contrast agent uses a sophisticated wall filtering system to selectively obtain low-flow Doppler signals from overlapped artifacts. Microvascular US imaging with second-generation contrast agents amplifies flow signals and makes them last longer, which facilitates hemodynamic evaluation of breast lesions. In this review article, we will introduce various microvascular US techniques, explain their clinical applications in breast cancer diagnosis and radiologic-histopathologic correlation, and provide a summary of a recent radiogenomic study using microvascular US.

Vascular imaging of atherosclerosis: Strengths and weaknesses

Atherosclerosis is an inflammatory disease that can lead to several complications such as ischemic heart disease, stroke, and peripheral vascular disease. Therefore, researchers and clinicians rely heavily on the use of imaging modalities to identify, and more recently, quantify the burden of atherosclerosis in the aorta, carotid arteries, coronary arteries, and peripheral vasculature. These imaging techniques vary in invasiveness, cost, resolution, radiation exposure, and presence of artifacts. Consequently, a detailed understanding of the risks and benefits of each technique is crucial prior to their introduction into routine cardiovascular screening. Additionally, recent research in the field of microvascular imaging has proven to be important in the field of atherosclerosis. Using techniques such as contrast-enhanced ultrasound and superb microvascular imaging, researchers have been able to detect blood vessels within a plaque lesion that may contribute to vulnerability and rupture. This paper will review the strengths and weaknesses of the various imaging techniques used to measure atherosclerotic burden. Furthermore, it will discuss the future of advanced imaging modalities as potential biomarkers for atherosclerosis.

Combination of Quantitative Parameters of Shear Wave Elastography and Superb Microvascular Imaging to Evaluate Breast Masses

Objective

This study aimed to evaluate the diagnostic value of combining the quantitative parameters of shear wave elastography (SWE) and superb microvascular imaging (SMI) to breast ultrasound (US) to differentiate between benign and malignant breast masses.

Materials and Methods

A total of 200 pathologically confirmed breast lesions in 192 patients were retrospectively reviewed using breast US with B-mode imaging, SWE, and SMI. Breast masses were assessed based on the breast imaging reporting and data system (BI-RADS) and quantitative parameters using the maximum elasticity (Emax) and ratio (Eratio) in SWE and the vascular index in SMI (SMI_VI). The area under the receiver operating characteristic curve (AUC) value, sensitivity, specificity, accuracy, negative predictive value, and positive predictive value of B-mode alone versus the combination of B-mode US with SWE or SMI of both parameters in differentiating between benign and malignant breast masses was compared, respectively. Hypothetical performances of selective downgrading of BI-RADS category 4a (set 1) and both upgrading of category 3 and downgrading of category 4a (set 2) were calculated.

Results

Emax with a cutoff value of 86.45 kPa had the highest AUC value compared to Eratio of 3.57 or SMI_VI of 3.35%. In set 1, the combination of B-mode with Emax or SMI_VI had a significantly higher AUC value (0.829 and 0.778, respectively) than B-mode alone (0.719) (p < 0.001 and p = 0.047, respectively). B-mode US with the addition of Emax, Eratio, and SMI_VI had the best diagnostic performance of AUC value (0.849). The accuracy and specificity increased significantly from 68.0% to 84.0% (p < 0.001) and from 46.1% to 79.1% (p < 0.001), respectively, and the sensitivity decreased from 97.6% to 90.6% without statistical loss (p = 0.199).

Conclusion

Combining all quantitative values of SWE and SMI with B-mode US improved the diagnostic performance in differentiating between benign and malignant breast lesions.

Reproducibility and diagnostic performance of the vascular index of superb microvascular imaging in real-time breast ultrasonography for evaluating breast masses

Purpose

This study aimed to evaluate the reproducibility and diagnostic performance of a quantitative parameter of superb microvascular imaging (SMI) in real-time breast ultrasonography (US) for differentiating benign from malignant breast masses.

Methods

Eighty-seven breast masses in 75 patients who underwent both B-mode US and SMI before US-guided core needle biopsy were included in this study. Two radiologists performed B-mode US and measured the vascular index (VI) of SMI respectively for each lesion in real time. Intraobserver and interobserver agreements were analyzed for the VI of SMI. The diagnostic performance of B-mode US using the Breast Imaging Reporting and Database System lexicon and combined use with the VI of SMI was evaluated compared to pathology.

Results

The median VI of malignant masses (n=32) was significantly higher than that of benign masses (n=55) (7.6% and 2.6%, respectively; P<0.001). The intraobserver agreement for VI was excellent regardless of the pathology, size, or depth of the lesion. The interobserver agreement for VI was excellent regardless of the presence of a measurement interval. The interobserver agreement for the final diagnostic decision was improved by combining B-mode US and VI (κ=0.883) in comparison with B-mode US only (κ=0.617). Adding VI led to significant improvements in the specificity (87.2% vs. 52.7%, 83.6% vs. 49.0%), accuracy (89.7% vs. 69.3%, 84.0% vs. 65.9%) and positive predictive value (81.5% vs. 55.1%, 75.6% vs. 52.6%) of B-mode US for both observers compared with B-mode US alone (all, P=0.001).

Conclusion

The VI of SMI for real-time breast US is highly reproducible and leads to improved diagnostic performance for differentiating between benign and malignant breast lesions in combination with B-mode US.

Quantitative Musculoskeletal Ultrasound

Ultrasound (US) imaging plays a crucial role in the assessment of musculoskeletal (MSK) disorders. Several quantitative tools are offered by US systems and add information to conventional US imaging. This article reviews the quantitative US imaging tools currently available in MSK radiology, specifically focusing on the evaluation of elasticity with shear-wave elastography, perfusion with contrast-enhanced US and noncontrast superb microvascular imaging, and bone and muscle mass with quantitative US methods. Some of them are well established and already of clinical value, such as elasticity and contrast-enhanced perfusion assessment in muscles and tendons. MSK radiologists should be aware of the potential of quantitative US tools and take advantage of their use in everyday practice, both for clinical and research purposes.

The diagnostic value of Superb Microvascular Imaging in identifying benign tumors of parotid gland

BACKGROUND

We compared the ultrasound features, superb microvascular imaging (SMI) and micro vessel density (MVD) of pleomorphic adenoma (PA), Warthin's tumor (WT) and basal cell adenoma (BCA) to explore the clinic value of SMI in differential diagnosis of benign tumors of parotid gland.

METHODS

The vascular distributions and grade by color doppler flow imaging (CDFI) and SMI, as well as vascular index (VI) of 249 parotid gland masses from 217 patients were analyzed.

RESULTS

The internal echogenicity of BCA are more homogeneous in comparing with WT and PA(P < 0.05). By SMI, the vascular distribution and vascular grade in PA were mainly peripheral (33.1%) and avascular (25.7%), Grade 1 (27.8%) and Grade 0 (25.7%). WT were mainly central (31.3%) and mixed distribution (34.9%), in Grade 3 (37.3%) and Grade 2 (36.2%). BCA was mainly peripheral (33.3%) and mixed distribution (33.3%), in Grade 2 (33.3%) and Grade 3 (33.3%). The overall detection rate of SMI for vascular Grade 2 and 3 was significantly higher than that of CDFI (P < 0.05). Both VI and MVD were lowest in PA, highest in WT (P < 0.001). The VI by SMI was correlated with MVD (P < 0.001). The correlation index between vascular distribution and grade by SMI and MVD were significantly higher than CDFI.

CONCLUSION

SMI can provide low-velocity blood flow information, which is helpful for the differential diagnosis of common benign tumors of parotid gland, and is expected to be more widely used.

Ultrasonographic Demonstration of the Tissue Microvasculature in Children: Microvascular Ultrasonography Versus Conventional Color Doppler Ultrasonography

Microvascular ultrasonographic imaging is the most recent and unique Doppler ultrasound technique. It uses an advanced clutter filter that can remove clutter artifacts and preserve the low-velocity microvascular flow signal. The potential advantages of microvascular ultrasonography are its superiority in detection and visualization of the small blood vessels in tissues, providing radiologists with more information on the vascular structures. Therefore, it has shown particular value in the clinical fields. The aim of this study was to provide microvascular ultrasonographic images for the tissue microvasculature, including the brain, thyroid gland, kidney, urinary bladder, small bowel, ovary, testis, lymph node, and hemangiomas in children, focusing on the comparison with conventional color Doppler ultrasonographic images.

Clinical applications of Doppler ultrasonography for thyroid disease: consensus statement by the Korean Society of Thyroid Radiology

Doppler ultrasonography (US) is widely used for the differential diagnosis of thyroid nodules, metastatic cervical lymph nodes in patients with thyroid cancer, and diffuse parenchymal disease, as well as for guidance in various US-guided procedures, including biopsy and ablation. However, controversies remain regarding the appropriate use and interpretation of Doppler US. Therefore, the Korean Society of Thyroid Radiology organized a taskforce to develop a consensus statement on the clinical use of Doppler US for thyroid disease. The review and recommendations in this article are based on a comprehensive analysis of the current literature and the consensus of experts.

Neurosurgical intraoperative ultrasonography using contrast enhanced superb microvascular imaging -vessel density and appearance time of the contrast agent

Background: Ultrasonography (US) provides real-time information on structures within the skull during neurosurgical operations. Superb microvascular imaging (SMI) is the latest imaging technique for detecting very low-velocity flow with minimal motion artifacts, and we have reported on this technique for intraoperative US monitoring. We combined SMI with administration of contrast agent to obtain detailed information during neurosurgical operations.Materials and methods: Twenty patients diagnosed with brain tumor (10 meningiomas, 5 glioblastomas, 2 hemangioblastomas, 1 schwannoma, 1 malignant lymphoma, 1 brain abscess) underwent neurosurgery under US with SMI and contrast agent techniques. Vessel density and appearance time following contrast administration were analyzed.Results: Flow in numerous vessels was not visualized by SMI alone, but appeared following injection of contrast agent in all cases. Flow in tumors was drastically enhanced by contrast agent in schwannoma, hemangioblastoma and meningioma, compared to normal brain tissue. Flows in the dilated and bent vessels of glioblastoma were also enhanced, although flow in hypoechoic lymphoma remained inconspicuous. The characteristics of tumor vessels were clearly visualized and tumor borders were demonstrated by the difference between tumor flow and brain flow, by the increased tumor vessel density and decreased appearance time of contrast agent compared to normal brain vessels.Conclusions: The combination of SMI and contrast agent techniques for intraoperative US monitoring could provide innovative flow images of tumor and normal brain. The neurosurgeon obtains information about tumor flow and tumor borderline before tumor resection.

Microvascular Flow Imaging of Residual or Recurrent Hepatocellular Carcinoma after Transarterial Chemoembolization: Comparison with Color/Power Doppler Imaging

Objective

To determine the feasibility of microvascular flow imaging (MVFI) in comparison with color/power Doppler imaging (CDI/PDI) for detection of intratumoral vascularity in suspected post-transarterial chemoembolization (TACE) residual or recurrent hepatocellular carcinomas (HCCs) by using contrast-enhanced ultrasonography (CEUS) or hepatic angiography (HA) findings as the reference standard.

Materials and Methods

One hundred HCCs (mean size, 2.2 cm) in 100 patients treated with TACE were included in this prospective study. CDI, PDI, and MVFI were performed in tandem for evaluating intratumoral vascularity of the lesions by using an RS85 ultrasound scanner (Samsung Medison Co., Ltd.). Intratumoral vascularity in each technique was assessed by two radiologists in consensus by using a 5-point scale. Then, one of the two radiologists and another radiologist performed additional image review in the reverse order (MVFI-PDI-CDI) for evaluation of intra- and interobserver agreements. Results were then compared with those of either HA or CEUS as the reference. The McNemar test, logistic regression analysis, and intraclass correlation coefficient (ICC) were used.

Results

CEUS or HA revealed intratumoral vascularity in 87% (87/100) of the tumors. Sensitivity (79.3%, 69/87) and accuracy (80.0%, 80/100) of MVFI were significantly higher than those of CDI (sensitivity, 27.6% [24/87]; accuracy, 37.0% [37/100]) or PDI (sensitivity, 36.8% [32/87]; accuracy, 44.0% [44/100]) (all p < 0.05). CDI, PDI, and MVFI presented excellent intraobserver (ICCs > 0.9) and good interobserver agreements (ICCs > 0.6).

Conclusion

MVFI demonstrated significantly higher sensitivity and accuracy than did CDI and PDI for the detection of intratumoral vascularity in suspected residual or recurrent HCCs after TACE.

Acute scrotal pain in pediatric patients: diagnosis with an innovative Doppler technique (MicroV)

Acute scrotal pain is one of the most frequent symptoms in pediatric patients visited in the Emergency Department. Ultrasonography with color and power Doppler represents the first-line method that clinicians use to carry out the differential diagnosis between spermatic cord torsion and inflammation, but sensitivity and specificity are 63-100% and 97-100%, respectively; this variability may be related to operator's experience and testis vascular hemodynamics and also to machine performance and patient age. Recent technological innovations have made possible to create a new Doppler mode called ultrasound microvascular imaging. This technique exploits algorithms capable of separating low frequencies of static tissue artifacts from ones of very weak flows. It is known as MicroV (from Esaote) and Superb microvascular imaging (from Toshiba). It provides both macrocirculation vascular maps, as a typical Doppler feature, and microcirculation vascular maps. Furthermore, the use of background subtraction could improve the visibility of small vascular structures. We report a case of a pediatric patient suffering from acute scrotal pain assessed ultrasonographically with this innovative Doppler technique (MicroV) that may give more confidence in detecting testicular vascular signals if compared with traditional Doppler techniques.

Ultrasound Microflow Imaging Technology for Diagnosis of Adhesive Capsulitis of the Shoulder

OBJECTIVES

To assess the diagnostic accuracy of Superb Microvascular Imaging (SMI; Canon Medical Systems, Otawara, Japan) at the subcoracoid triangle for adhesive capsulitis of the shoulder, to compare the diagnostic value of SMI with that of conventional ultrasound (US) and power Doppler ultrasound (PDUS) findings, and to investigate the correlation between vascular flow on SMI with clinical features.

METHODS

Our study included 39 patients with a diagnosis of adhesive capsulitis and 35 healthy patients as a control group. The echogenicity in the rotator interval and coracohumeral ligament thickness were assessed with conventional US. Vascular flow in the subcoracoid fat triangle was evaluated with SMI and PDUS (SMI and PDUS areas). A receiver operating characteristic curve analysis was performed to evaluate diagnostic accuracy. The correlation between US findings and the range of motion, pain intensity, and duration of symptoms was also evaluated.

RESULTS

The SMI area was higher in the adhesive capsulitis group than in the control group (2.95 versus 0 mm² ; P < .01). The visualization of vascular flow at the subcoracoid fat triangle was superior with SMI compared with PDUS (P < .01). In the receiver operating characteristic analysis, the SMI area showed higher diagnostic performance, with an area under the curve of 0.90 compared with other US findings. The area of SMI vascular flow was also negatively correlated with external rotation and forward flexion (P < .05) in the adhesive capsulitis group.

CONCLUSIONS

Measurement of vascular flow at the subcoracoid fat triangle using SMI facilitated the diagnosis of adhesive capsulitis. Superb Microvascular Imaging was superior to PDUS in diagnostic performance. Vascular flow was negatively correlated with the range of motion of external rotation and forward flexion.

The Vascular Index of Superb Microvascular Imaging Can Improve the Diagnostic Accuracy for Breast Imaging Reporting and Data System Category 4 Breast Lesions

PURPOSE

To investigate whether the vascular index (VI) of superb microvascular imaging (SMI) could improve the diagnostic efficiency for BI-RADS 4 breast lesions and reduce the number of unnecessary biopsies.

PATIENTS AND METHODS

For this study, we selected 222 consecutive BI-RADS 4 breast lesions detected by ultrasound and confirmed by pathology from January 2016 to October 2018. A VI of 4.0 was set as the cutoff value to degrade BI-RADS classification. We calculated the accuracy, sensitivity and PPV of a BI-RADS diagnosis alone and the combination of BI-RADS and the VI.

RESULTS

Pathologically, of the 222 lesions, 129 were confirmed to be benign, and 93 were found to be malignant. A VI of 4.0 was set as the cutoff value; when the VI≤4.0, those BI-RADS 4 masses were downgraded one level (4C-4B, 4B-4A, 4A-3) to an integral BI-RADS grade, while the others maintained the conventional grade. A total of 54 BI-RADS 4 lesions were degraded to BI-RADS 3, including 53 benign lesions and 1 malignant lesion. The diagnostic accuracy (65.3% vs 41.9%) and PPV (54.8% vs 41.9%) were significantly improved. The sensitivity decreased slightly (98.9% vs 100%) because 1 of the 54 downgraded BI-RADS 4 lesions, which had a pathological type of invasive ductal carcinoma, was incorrectly downgraded.

CONCLUSION

SMI is a noninvasive tool for visualizing the vascular structure with high-resolution microvascular images. As a quantitative index, the VI can be used to appropriately downgrade benign lesions classified as BI-RADS 4, which can improve the diagnostic accuracy and PPV and reduce unnecessary biopsies.

Application of new ultrasound techniques for focal liver lesions

Ultrasonography (US) has the overwhelming advantages of not entailing radiation exposure and being a noninvasive, real-time, convenient, easy-to-perform, and relatively inexpensive imaging modality. It is used as the first-line imaging modality for screening, detection, and diagnosis of focal liver lesions (FLLs) [small hepatocellular carcinomas (HCCs), in particular]. However, with the increasing demand for accurate and early diagnosis of small HCCs, newer radiologic methods need to be explored to overcome certain limitations of US. For example, the imaging is easily negatively affected by the presence of gas, rib cage, and subcutaneous fat, and is insensitive for capturing the subtle but vital information on the blood flow. It was in response to this need that new promising technologies such as contrast-enhanced ultrasound and fusion imaging were introduced for the detection of liver lesions. This paper presents an overview of the epidemiology and mechanisms of the development of HCCs, with an emphasis on the application of US in the diagnosis and treatment of FLLs. The aim of this article is to provide the state-of-the-art developments in the imaging diagnosis of FLLs and evaluation of ablation treatment of early HCCs. By keeping abreast of these recent advances, we hope that doctors and researchers working in the field of diagnosis/treatment of liver diseases will be able to discriminate benign FLLs such as regenerative nodules and focal nodular hyperplasia from HCCs, so as to avoid unnecessary repeated tumor biopsies and overtreatment. In particular, we expect that small HCCs or precancerous nodules (such as dysplastic nodules) can be accurately diagnosed and appropriately treated even at an early stage.

Ultrasensitive Ultrasound Microvessel Imaging for Characterizing Benign and Malignant Breast Tumors

Tumor angiogenesis plays an important role during breast tumor growth. However, conventional Doppler has limited sensitivity to detect small blood vessels, resulting in a large overlap of Doppler features between benign and malignant tumors. An ultrasensitive ultrasound microvessel imaging (UMI) technique was recently developed. To evaluate the performance of UMI, we studied 44 patients with 51 breast masses. Tumor pathology served as the gold standard: 28 malignancies and 23 benignities. UMI provided a significant improvement in depicting smaller vessels compared with conventional Doppler. The microvessel morphologies observed on UMI were associated with tumor benign/malignant classification. The diagnostic accuracy of correct Breast Imaging Reporting and Data System (BI-RADS) classification rate (BI-RADS ≥4a: test positive; BI-RADS ≤3: test negative) as a fraction of total mass population was improved by 16% after combining conventional ultrasound with UMI compared with using conventional ultrasound alone. This improvement indicates the potential of UMI in reducing unnecessary benign biopsies and avoiding missed malignant biopsies.

Utilization of contrast-enhanced ultrasound in the evaluation of craniofacial osseous lesions: A case report

A 14-year-old boy undergoing brain MRI had an incidental avidly enhancing lobulated lesion in the left superolateral orbital rim with associated cortical erosion. Apart from Contrast-enhanced Magnetic Resonance Imaging (MRI), and Computed Tomography (CT), Contrast-Enhanced Ultrasound (CEUS) was obtained prior to a biopsy. It provided additional information about the microvasculature and an orbital biopsy was subsequently performed through an upper eyelid crease incision with minimal blood loss and no postoperative complications. Histopathological examination revealed features which were compatible with the diagnosis of LCH. The authors propose that CEUS may be considered as an adjunct and possibly alternative imaging modality for the evaluation of craniofacial osseous lesions, especially in the orbital region (due to the known radio-sensitivity of the eyes) and in pediatric patients, to minimize the risk of ionizing-radiation exposure.

Clinical Applications of Superb Microvascular Imaging in the Liver, Breast, Thyroid, Skeletal Muscle, and Carotid Plaques

This article reviews the clinical applications of Superb Microvascular Imaging (SMI; Canon Medical Systems, Otawara, Japan) in the liver, breast, thyroid, skeletal muscle, and carotid plaques. Diseases that are closely associated with angiogenesis can be diagnosed by SMI in a relatively early phase, and using SMI can prevent adverse reactions associated with the contrast agents used in contrast-enhanced ultrasound. Super Microvascular Imaging also shows particular value in grading disease activities and monitoring therapeutic responses. Although SMI has some limitations, such as a lack of clinical standards, it can add information to conventional ultrasound examinations and may become a noninvasive alternative to invasive diagnostic procedures for many clinical conditions.

Differentiation Between Malignant and Benign Lymph Nodes: Role of Superb Microvascular Imaging in the Evaluation of Cervical Lymph Nodes

OBJECTIVES

This study aimed to assess the value of Superb Microvascular Imaging (SMI; Canon Medical Systems, Otawara, Japan) for distinguishing between benign and malignant cervical lymph nodes (LNs) and to compare SMI with power Doppler ultrasound (PDUS).

METHODS

Power Doppler ultrasound and SMI examinations were performed for patients' cervical LNs. The distribution of feeding vessels, number, and appearance of internal vessels were analyzed by 2 readers, and the results of PDUS and SMI were compared. Interobserver agreement was assessed. A subgroup analysis was performed to assess differences in vascular patterns between metastasis and tuberculous lymphadenitis and between Kikuchi disease and lymphoma. The diagnostic performance for distinguishing between benign and malignant LNs was calculated.

RESULTS

In total, 147 patients with 147 cervical LNs (85 benign and 62 malignant) were assessed. Interobserver agreement was moderate to strong for SMI. There were significant differences in the vascular patterns between benign and malignant LNs on SMI (distribution, number, and appearance, all P < .001), but not on PDUS. In the subgroup analysis, SMI showed a significant difference in the vascular patterns observed between metastasis and tuberculous lymphadenitis (distribution, P = .012; number, P = .014; and appearance, P = .005). Superb Microvascular Imaging detected significantly greater numbers of vessels in lymphoma than in Kikuchi disease (P = .012). The sensitivity of SMI was significantly greater than that of PDUS in distinguishing malignant from benign LNs (86.9% versus 54.1%; P < .001).

CONCLUSIONS

Superb Microvascular Imaging yields more detailed information about nodal vessels than does PDUS by enabling visualization of small nodal vessels. Superb Microvascular Imaging is useful and feasible for differentiating between malignant and benign cervical LNs.

[Contrast-enhanced ultrasound in the diagnostic workup of lymph nodes]

CLINICAL/METHODICAL ISSUE

Daily tasks in sonographic diagnostics include detection and characterization of peripheral and abdominal lymph nodes.

STANDARD RADIOLOGICAL METHODS

In addition to the B‑mode methods, color-coded Doppler sonography (CCDS) plays an important role in the evaluation of lymph nodes.

METHODICAL INNOVATIONS

Contrast-enhanced ultrasound (CEUS) has become a standard procedure in vascular and organ diagnostics. Tissue perfusion can be recorded visually and retrospectively in real time using time-dependent intensity analysis. The contrast agent dosage depends primarily on the location of the lymph nodes and the type and frequency of the transducer. Vascular and tumor cell density, intranodal pressure due to increased vascular permeability and preservation or destruction of the capsule must be taken into account when interpreting the findings.

PERFORMANCE

The indication for CEUS results from the B‑mode and CCDS findings and plays an important role especially in the verification of vitality before and after therapy. Uneven or apparently non-perfused areas allow a targeted puncture of vital tumor tissue.

ACHIEVEMENTS

Especially in abdominal lymph nodes, CEUS has a high diagnostic reliability. It is not always possible to differentiate between inflamed lymph nodes and lymph nodes altered by lymphoma filtration.

PRACTICAL RECOMMENDATIONS

CEUS helps to better assess the dignity of lymph nodes by visualizing their micro- and macrovascularization. After frustrated puncture, vital areas can be specifically biopsied. CEUS is particularly valuable in assessing the success of therapy.

Microvascular imaging of the skin

Despite our understanding that the microvasculature plays a multifaceted role in the development and progression of various conditions, we know little about the extent of this involvement. A need exists for non-invasive, clinically meaningful imaging modalities capable of elucidating microvascular information to aid in our understanding of disease, and to aid in the diagnosis/monitoring of disease for more patient-specific care. In this review article, a number of imaging techniques are summarized that have been utilized to investigate the microvasculature of skin, along with their advantages, disadvantages and future perspectives in preclinical and clinical settings. These techniques include dermoscopy, capillaroscopy, Doppler sonography, laser Doppler flowmetry (LDF) and perfusion imaging, laser speckle contrast imaging (LSCI), optical coherence tomography (OCT), including its Doppler and dynamic variant and the more recently developed OCT angiography (OCTA), photoacoustic imaging, and spatial frequency domain imaging (SFDI). Attention is largely, but not exclusively, placed on optical imaging modalities that use intrinsic optical signals to contrast the microvasculature. We conclude that whilst each imaging modality has been successful in filling a particular niche, there is no one, all-encompassing modality without inherent flaws. Therefore, the future of cutaneous microvascular imaging may lie in utilizing a multi-modal approach that will counter the disadvantages of individual systems to synergistically augment our imaging capabilities.

Superb Microvascular Imaging Compared with Contrast-Enhanced Ultrasound for Assessing Laser Ablation Treatment of Benign Thyroid Nodules

Purpose

To compare superb microvascular imaging (SMI) with contrast-enhanced ultrasonography (CEUS) for evaluating the ablation of benign thyroid nodules.

Methods

225 Patients with 256 benign thyroid nodules underwent conventional ultrasound, color Doppler flow imaging (CDFI), CEUS, and SMI before and after laser ablation. They were routinely followed up at 1, 3, 6, and 12 months. The volume and volume reduction rate of the ablated nodules was calculated.

Results

On SMI, the complete ablated nodules had no microvascular perfusion, while the incompletely ablated nodules had microvascular perfusion at the edge of the nodule. The percentages of the detected incompletely ablated nodules of SMI (37/256, 14.45%) and CEUS (41/256, 16.02%) were comparable, and both were significantly higher than CDFI (P< 0.001). CEUS was used as the criterion to determine whether the nodules were completely ablated. The sensitivity, specificity, and accuracy of SMI for detecting incompletely ablated nodules were 90.2, 98.2, and 100%, respectively. The volume of ablated nodules, as measured on ultrasound, was greater than that on CEUS or SMI (both P< 0.001), while CEUS and SMI were similar. The average volume reduction rate of nodules at 1, 3, 6, and 12 months was 40.25, 54.98, 76.83, and 95.43%, respectively.

Conclusion

SMI sensitively detected the capillaries within residual thyroid nodules after laser ablation. The lesion size and detection rate of incompletely ablated nodules via SMI was consistent with that of CEUS. SMI may replace CEUS in certain cases for monitoring the curative effect of laser ablation for benign thyroid nodules.

Application of contrast-enhanced ultrasound for evaluation of thyroid nodules

Contrast-enhanced ultrasound (CEUS) is widely used to evaluate tumor microcirculation, which is useful in the differential diagnosis between benignity and malignancy. In the last 10 years, the applicability of CEUS to thyroid nodules has greatly improved due to technological refinements and the development of second-generation contrast agents. In this review, we summarize the applications of CEUS for thyroid nodules, focusing on the imaging findings of malignant and benign nodules in the existing literature and the use of those findings to predict malignancies, with an additional brief description of the utilization of CEUS for other thyroid-related diseases.