Superb microvascular imaging technology for ultrasound examinations: Initial experiences for hepatic tumors

Role of Superb Microvascular Imaging (SMI) vascularity index values and vascularity patterns in the differential diagnosis of malignant liver lesions

PURPOSE

To evaluate the Superb Microvascular Imaging (SMI) vascular patterns and vascularity index (VI) values of malignant focal liver lesions (FLLs), assess their role in differential diagnosis, and examine interobserver agreement.

MATERIALS AND METHODS

A total of 107 patients (52 males, 55 females; mean age 62 ± 12.8 years, range 25-87) referred to the interventional radiology clinic for FLL biopsy between April 2022 and April 2023 were analyzed. Two radiologists independently assessed the SMI vascular patterns and calculated VI values. Differences among three lesion groups - hepatocellular carcinoma (HCC, n = 16), non-HCC primary liver malignancies (n = 16), and metastases (n = 75) - were evaluated, and interobserver agreement was assessed.

RESULTS

Most metastases (88%) demonstrated hypovascular patterns, while HCCs predominantly exhibited hypervascular patterns (68.7-81.3%). Non-HCC primary malignancies showed no dominant vascular pattern. Significant differences in SMI patterns were observed among lesion types (p = 0.001-0.035). VI values for HCCs (7.53-7.73) were significantly higher than those for non-HCC malignancies (2.73-2.93) and metastases (1.35-1.36) (p = 0.0001). ROC analysis based on VI values yielded AUCs of 0.886-0.887, with a cutoff of 2.92 providing 81.3% sensitivity and 79.1-80.2% specificity for HCC diagnosis. The inter-reader agreement for SMI patterns had a kappa score of 0.634, while the intraclass correlation coefficient (ICC) for VI values was 0.959.

CONCLUSION

HCCs displayed more hypervascular SMI patterns and significantly higher VI values compared to other malignant FLLs, emphasizing the diagnostic potential of VI in distinguishing HCC from non-HCC tumors. Although metastases primarily exhibited hypovascular patterns and low VI values, no dominant vascular pattern was identified in non-HCC primary liver malignancies. Assessing VI values provided higher interobserver agreement compared to SMI patterns, enhancing objectivity and reproducibility.

Intraoperative superb microvascular ultrasound imaging in glioma: novel quantitative analysis correlates with tumour grade

BACKGROUND

Accurate grading of gliomas is critical to guide therapy and predict prognosis. The presence of microvascular proliferation is a hallmark feature of high grade gliomas which to directly visualise traditionally requires targeted surgical biopsy of representative tissue. Superb microvascular imaging (SMI) is a novel high resolution Doppler ultrasound technique which can uniquely define the microvascular architecture of whole tumours.

METHODS

We examined both qualitative and quantitative vascular features of 32 gliomas captured with SMI, analysing flow signal density, vessel number, branching points, curvature, vessel angle deviation, fractal dimension, and entropy.

RESULTS

High-grade gliomas exhibit significantly greater vascular complexity and disorganisation, with increased fractal dimension and entropy, correlating with known histopathological markers of aggressive angiogenesis. The integrated ROC model achieved high accuracy (AUC = 0.95).

CONCLUSIONS

This study leveraged SMI to provide further insights into the microvascular architecture of gliomas which is not resolvable by magnetic resonance imaging. Applying novel quantitative analysis the study demonstrated that there are quantifiable differences in vascular morphology between high grade and low-grade gliomas. This unique in vivo imaging of glioma vascularity and quantification warrants further exploration as a potential new diagnostic and prognostic tool that may support glioma management, intraoperative decision-making and informing future prognosis.

The Role of Monochromatic Superb Microvascular Index to Predict Malignancy of Solid Focal Lesions: Correlation Between Vascular Index and Histological Bioptic Findings

OBJECTIVES

This study aims to assess the potential role of the ultrasound (US) monochromatic Superb Microvascular Index (mSMI) to predict malignancy of solid focal lesions, correlating the vascular index (VI) with bioptic histological results.

METHODS

In this single-center retrospective analysis, patients undergoing percutaneous US-guided biopsy of solid lesions were considered. Biopsy indication was given by a multidisciplinary team evaluation based on clinical radiological data. Exclusion criteria were: unfeasible SMI evaluations due to poor respiratory compliance, locations not appreciable with the SMI, previous antiangiogenetic chemo/immunotherapies, and inconclusive histological reports. The mSMI examination was conducted in order to visualize extremely low-velocity flows with a high resolution and high frame rate; the VI was semi-automatically calculated. All bioptic procedures were performed under sole US guidance using 16G or 18G needles, immediately after mSMI assessment.

RESULTS

Forty-four patients were included (mean age: 64 years; 27 males, 17 females). Liver (15/43), kidneys (9/43), and lymph nodes (6/43) were the most frequent targets. At histopathological analysis, 7 lesions were benign and 37 malignant, metastasis being the most represented. The VI calculated in malignant lesions was statistically higher compared to benign lesions (35.45% and 11% in malignant and benign, respectively; p-value 0.013). A threshold VI value of 15.4% was identified to differentiate malignant lesions. The overall diagnostic accuracy of the VI with the mSMI was 0.878, demonstrating a high level of diagnostic accuracy.

CONCLUSIONS

In this study, the mSMI analysis of solid focal lesions undergoing percutaneous biopsy significantly correlated with histological findings in terms of malignant/benign predictive value, reflecting histological vascular changes in malignant lesions.

Ultrasound innovations in abdominal radiology: techniques and clinical applications in pediatric imaging

Contrast-enhanced ultrasound, microvascular imaging, elastography, and fat quantification have varying degrees of utility, with some applications in the pediatric setting mirroring that in adults and having unique uses when applied to children in others. This review will present novel ultrasound technologies and the clinical context in which they are applied to the pediatric abdomen. New ultrasound technologies have a broad range of applications in clinical practice and represent a powerful diagnostic tool with the potential to replace other imaging modalities, such as magnetic resonance imaging and computed tomography, in specific cases.

Evaluation of in-stent restenosis after carotid artery stenting with superb microvascular imaging: initial findings

BackgroundCarotid artery stenting (CAS) is an interventional management in preventing ischemic stroke caused by carotid artery stenosis. After the treatment with CAS, in-stent restenosis caused by neointimal hyperplasia may develop.PurposeThis study aims to obtain a better determination of neointimal hyperplasia using superb microvascular imaging (SMI), which provides a high-quality visualization of the endoluminal lesions, and to compare these results with B-mode and Doppler ultrasound (US).Material and MethodsA total of 106 patients who underwent CAS in our interventional radiology unit between 2018 and 2020 were retrospectively analyzed. In total, 44 patients whose procedure images and post-procedural follow-up Doppler US and SMI data could be accessed were included.ResultsThere were nine patients who had in-stent restenosis. One patient had no velocity increase; however, on SMI the measurements showed in-stent restenosis both in area and diameter. The other eight patients had a stenosis degree in the range of 50%-79% on Doppler US. Five patients had in-stent restenosis, both in Doppler US and SMI, by area and diameter measurements. Two patients underwent digital subtraction angiography (DSA).ConclusionWe suggest that using SMI with duplex sonography improves detecting neointimal hyperplasia and in-stent restenosis. With SMI, better visualization of the stent lumen may improve the patient selection for DSA.

Identification of vascular hotspots and analysis of micro-vessel flow velocity waveforms in high-grade squamous intraepithelial lesions of the cervix

OBJECTIVES

To assess hotspot micro-vessel flow velocity waveforms in human papillomavirus (HPV) cervical infections using transvaginal power Doppler ultrasound (TV-PDU) and explore associations with high-grade squamous intraepithelial lesions (HSIL, cervical intraepithelial neoplasia [CIN] II and III).

METHODS

In all, 62 patients with confirmed HPV-HSIL (14 CIN II, 48 CIN III) and 65 age- and parity-matched women with neither HPV infection nor CIN were compared. Seven parameters by TV-PDU were used to assess vascular classification and micro-vessel flow velocity, including vascular grading (class I, II, III), lowest pulsatility index (PI), resistance index (RI), peak systolic velocity (PS), end-diastolic velocity (ED), time average maximum velocity (TAMV), and the vascular index (VI = PS/ED).

RESULTS

HSIL was primarily associated with vascular class I (75.8%), followed by class II (14.5%) and class III (9.7%). PI, RI, and VI in HSIL were significantly lower than the control group (P < 0.0001). Mean PI, RI, and VI values decreased progressively from the normal cervix to CIN II-III. At a PI cutoff of 1.03, sensitivity was 88.7%, specificity was 83.8%, and area under the curve (AUC) was 95.0. At an RI cutoff of 0.68, sensitivity was 96.8%, specificity 61.5%, and AUC 84.0. At a VI cutoff of 2.84, sensitivity was 85.5%, specificity 78.5%, and AUC 85.0.

CONCLUSION

Based on different patterns of hotspot vascular classification and micro-vessel flow velocity waveforms, particularly PI between HSIL and the normal cervix, TV-PDU may offer a potential role for aiding the planning for patients with suspicious HSIL. Further studies are needed to validate the findings.

Intraoperative superb microvascular ultrasound imaging in glioma: novel quantitative analysis correlates with tumour grade

Accurate grading of gliomas is critical to guide therapy and predict prognosis. The presence of microvascular proliferation is a hallmark feature of high grade gliomas which traditionally requires targeted surgical biopsy of representative tissue. Superb microvascular imaging (SMI) is a novel high resolution Doppler ultrasound technique which can uniquely define the microvascular architecture of whole tumours. We examined both qualitative and quantitative vascular features of gliomas captured with SMI, analysing flow signal density, vessel number, branching points, curvature, vessel angle deviation, fractal dimension, and entropy. Results indicate that high-grade gliomas exhibit significantly greater vascular complexity and disorganisation, with increased fractal dimension and entropy, correlating with known histopathological markers of aggressive angiogenesis. The integrated ROC model achieved high accuracy (AUC = 0.95), highlighting SMI's potential as a non-invasive diagnostic and prognostic tool. While further validation with larger datasets is required, this study opens avenues for SMI in glioma management, supporting intraoperative decision-making and informing future prognosis.

Non-contrast ultrasound assessment of blood flow in clinical practice

Since the first clinical use of ultrasound in the 1940s, significant advancements have been made in its applications. Color Doppler imaging and power Doppler imaging are considered the first and second generations of flow ultrasound assessment tools, respectively. Subsequently, the introduction of contrastenhanced ultrasound has significantly improved the assessment of arterial and venous vascular patterns in lesions and vessels. 'Blood flow brightness-mode imaging' or 'B-flow', a non-Doppler ultrasound flow assessment mode introduced more recently, provides even more information for ultrasound users in flow assessment. Microvascular imaging, introduced about a decade ago, is the third generation of Doppler non-contrast ultrasound flow modes, and is growing in popularity. Using a special wall filter, microvascular imaging overcomes the limitations of color Doppler imaging and power Doppler imaging in the detection of slow flowing signals. Advanced dynamic flow is a third-generation non-contrast Doppler flow technology that has so far gained popularity in obstetric ultrasound, commonly used to evaluate fetal umbilical vessels and heart chambers. This review article presents some recent updates on the various non-contrast ultrasound flow modalities available in clinical practice. It focuses on the design principles of individual flow modalities, discussing their strengths, limitations, and clinical applications, along with a review of the relevant literature.

Application of superb microvascular imaging technology in clinical disease activity of rheumatoid arthritis

OBJECTIVES

Detection of synovitis is essential for assessing the activity and predicting the prognosis of rheumatoid arthritis (RA). The aim of this study was to investigate the diagnostic performance of superb microvascular imaging (SMI) in RA patients with high, moderate, and low activity.

METHODS

One hundred four patients with active RA were selected from the hospital between May 2022 and August 2023. The study observed the correlation between bone erosion of the carpal joint, joint cavity effusion, thickness of synovial hyperplasia of the carpal joint, positivity rate of synovial blood vessels, and their semiquantitative scores with the clinical disease activity of RA using SMI examination.

RESULTS

The detection of synovial hyperplasia thickness and joint effusion in the high-activity group was higher than that in the low-activity group, and the difference was statistically significant (P < 0.05). The quantitative SMI test demonstrated that the synovial blood flow grading and semiquantitative grade increased gradually with activity level (P<0.05). During the high, moderate, and low-activity groups, the vascular index (VI) value of the hyperplastic synovial membrane decreased gradually, showing statistical significance both between and within the groups (P<0.05).

CONCLUSION

SMI technology exhibited high sensitivity and accuracy in assessing disease activity in RA. It holds significant clinical application value as a reliable auxiliary tool for assessing disease activity in RA and treatment. Key Points • Super micro-vascular imaging (SMI) demonstrated higher detection rates of microvessels in RA patients with high disease activity compared to those with low activity, showing statistical significance. • The quantitative SMI test revealed a clear correlation between synovial blood flow grading and disease activity levels in RA patients, highlighting the potential of SMI as a valuable tool for disease activity and treatment of rheumatoid arthritis.

Superb microvascular imaging for evaluating the activity of juvenile localised scleroderma: a preliminary study

OBJECTIVES

To investigate microvascular changes in juvenile localised scleroderma (JLS) lesions using superb microvascular imaging (SMI) and assess SMI's utility in evaluating disease activity.

METHODS

This prospective study enroled 16 children (7 males) with pathologically diagnosed JLS between January 2021 and June 2023. Lesions were assessed using Localised Scleroderma Cutaneous Assessment Tools, including the localised scleroderma skin activity index (LoSAI) and localised scleroderma skin damage index (LoSDI). Lesions with LoSAI scores > 0 were classified as active. The thickness and blood flow of the lesions and healthy skin layers of the contralateral site were evaluated using ultrasound. SMI was used to detect microvascular blood flow in the lesions and healthy skin, and the vascular index (VI) was calculated. The difference in VI between active lesions and healthy skin was correlated with LoSAI and total scores.

RESULTS

Of 46 lesions, 23 were active and 23 inactive. The skin thickness of the lesion was 0.094 ± 0.024 cm, and that of the healthy site was 0.108 ± 0.026 cm (p < 0.001). The VI of the active lesions and healthy skin were 7.60 (3.60, 12.80)% and 1.10 (0.50, 2.10)%, respectively (p < 0.001). The VI of the inactive lesions and the healthy skin were 0.85 (0.00, 2.20)% and 1.60 (1.00, 3.10)%, respectively (p = 0.011). VI differences between active lesions and healthy skin positively correlated with the LoSAI clinical score (r = 0.625, p = 0.001) and total score (r = 0.842, p < 0.001).

CONCLUSION

SMI can quantitatively detect microvascular blood flow changes in JLS skin, indicating lesion activity and severity.

CLINICAL RELEVANCE STATEMENT

SMI is a convenient, non-invasive, technique for detecting active JLS lesions and can provide valuable information to guide treatment options.

KEY POINTS

Current grading systems of juvenile localised scleroderma rely on subjective clinical information. Superb Microvascular Imaging identified that vascular indexes between active lesions and healthy skin positively correlated with clinical scores. Superb Microvascular Imaging effectively assesses microvascular blood flow, aiding juvenile localised scleroderma lesion activity evaluation.

Comment on, "Superb microvascular ultrasound is a promising non-invasive diagnostic tool to assess a ventriculoperitoneal shunt system function: a feasibility study"

This study by Brawanski et al. (2024) contributes significantly to neurosurgery by assessing ventriculoperitoneal shunt (VPS) function using superb microvascular ultrasound (SMI). The authors provide a thorough evaluation of SMI as a novel, non-invasive diagnostic tool, demonstrating its effectiveness in detecting cerebrospinal fluid (CSF) flow within VPS systems. By focusing on asymptomatic hydrocephalus patients, the study offers a less invasive alternative to traditional diagnostic methods, potentially reducing the need for exploratory surgeries. However, the study could have been strengthened by exploring the variability of SMI measurements under different physiological conditions and including symptomatic patients. Additionally, further analysis of the long-term reliability of SMI is needed. Future research should expand the study's scope to assess SMI's diagnostic capabilities across varied conditions and explore its integration with other non-invasive techniques, thereby enhancing its clinical utility in managing hydrocephalus and VPS functionality.

Identifying Functional Lymph Nodes in Lower Extremity Lymphedema Patients: The Role of High-frequency Ultrasound

BACKGROUND

 Lymph nodes may play a potential role in lymphedema surgery. Radiologic evaluation of nodes may reveal the status of pathologic conditions but with limited accuracy. This study is the first to evaluate the efficacy of ultrasound in detecting functioning nodes in lymphedema patients and presents a criterion for determining the functionality of the lymph nodes.

METHODS

 This retrospective study reviews 30 lower extremity lymphedema cases which were candidates for lymph node to vein anastomosis. Lymphoscintigraphy and magnetic resonant lymphangiography (MRL) imaging were compared with ultrasound features which were correlated to intraoperative indocyanine green (ICG) nodal uptake as an indication of functionality.

RESULTS

 Majority were International Society of Lymphology stage 2 late (50.0%) and stage 3 (26.7%). ICG positive uptake (functioning nodes) was noted in 22 (73.3%), while 8 patients (26.6%) had negative uptake (nonfunctioning). Ultrasound had significantly the highest specificity (100%) for identifying functional nodes followed by lymphoscintigraphy (55%) and MRL (36%; p = 0.002, p < 0.001, respectively). This was associated with 100% positive predictive value compared against lymphoscintigraphy (44%) and MRL (36%; p < 0.001 for both). The identified ultrasound imaging criteria for functioning lymph node were oval lymph node shape (Solbiati Index), morphology, vascularity pattern, and vascularity quantification.

CONCLUSION

 The use of ultrasound in nodal evaluation was proven effective in different pathologic conditions and demonstrated the best prediction for functionality of the lymph node based on the new evaluation criteria.

Fetal Hepatic Hemangioma Diagnosed in Utero Using Doppler Microvascular Imaging

A 35-year-old pregnant woman was referred to our institution at 33 weeks' gestation for evaluation of a fetal abdominal tumor. B-mode ultrasonography demonstrated a massive lesion. Bidirectional power Doppler mode showed abundant blood flow surrounding the tumor. On superb micro-vascular imaging, various Doppler signal patterns were observed within the tumor, including diffuse fine dotted-like signals, linear flow, and internal shunt flow. Sequential observations of the tumor and cardiac cycles also revealed pulsatile flow beneath the edges of the tumor and continuous fine flow in the central area, resembling a 'centripetal fill-in' appearance on contrast computed tomography. Therefore, we assumed the fetal tumor to be a hepatic hemangioma. Fetal heart failure was detected at 37 weeks' gestation, and a 2,484-g female infant was delivered with 1- and 5-min Apgar scores of 7 and 8, respectively. A postnatal contrast computed tomography examination showed a progressive centripetal fill-in appearance, leading to a diagnosis of hepatic hemangioma. Kasabach-Merritt syndrome was also noted. Intensive treatment was performed, and the infant was discharged at 3 months after birth. In summary, we experienced a case of hepatic hemangioma diagnosed in utero using superb micro-vascular imaging. And basing seamless postnatal treatments on prenatal imaging findings may help to reduce the perinatal mortality.

Transabdominal ultrasound evaluation of vascularity of gallbladder lesions: particularly those with wall thickening

Gallbladder wall thickening is relatively common in clinical settings, and for appropriate diagnosis, the size, shape, internal structure, surface contour, and vascularity of the gallbladder wall must be evaluated. Morphological evaluation is the most important; however, some gallbladder lesions resemble gallbladder cancer in imaging studies, making differential diagnosis challenging. Vascular evaluation is indispensable for a precise diagnosis in these cases. In this review, we present the current status of vascular evaluation using US and diagnosis using vascular imaging for gallbladder lesions, including those presenting with wall thickening. To date, several ultrasound imaging techniques have been developed to assess vascularity, including Doppler imaging with high sensitivity, use of contrast agents, and microvascular imaging using a novel filter for Doppler imaging. Although conventional color Doppler imaging is rarely used for the diagnosis of gallbladder lesions, the efficacy of contrast-enhanced ultrasound in assessing the vascularity, enhancement pattern, or timing of enhancement/washout has been reported. Presence of multiple irregular microvessels has been speculated to indicate malignancy. However, few reports on microvessels have been published, and further studies are required for the precise diagnosis of gallbladder lesions with microvascular evaluation.

[Contrast-enhanced ultrasound (CEUS) for characterisation of focal liver lesions]

Due to the trend towards increased use of imaging and rising awareness among high-risk patients, gastroenterologists and hepatologists are more frequently confronted with patients with focal liver lesions. In the differentiation of these lesions, CT and MRI have increasingly found their way into primary diagnostic steps in everyday clinical practice. Contrast-enhanced sonography, on the other hand, is a very effective and cost-efficient method for assessing focal liver lesions. The success of the method is not only based on the visualisation of microvascularisation in real time. If sonography is performed by the treating physician, he can use the exact knowledge of history and clinical findings to specifically adapt the examination procedure and to interpret the sonographic findings with greater accuracy ("clinical sonography"). At the same time, the method enables the practitioner to combine diagnostics and management decisions in his or her own hands. To achieve excellent results with contrast-enhanced sonography-as with any other imaging method-it is necessary that the examiner is sufficiently qualified.This article systematically presents the sonographic characteristics of the most common liver lesions and clearly shows their contrast patterns using videos (available via QR code). The article illustrates that CEUS could-and from the authors' point of view, should-have an even greater significance in the future.

Assessment of renal congestion in a rat model with congestive heart failure using superb microvascular imaging

PURPOSE

Renal congestion is a therapeutic target in congestive heart failure. However, its detailed evaluation in a clinical setting is challenging. This study sought to assess renal congestion impairment using superb microvascular imaging (SMI), a simple and accessible method.

METHODS

Dahl salt-sensitive rats, used as a model for congestive heart failure, underwent central venous pressure (CVP) measurements. Renal congestion was evaluated through measurements of renal medullary pressure (RMP) and assessment of renal perfusion using contrast-enhanced ultrasonography at both the early (control group) and heart failure phases (HF group). All rats were assessed with SMI. The region of interest (ROI) was set in interlobular vessels, interlobar vessels, and a combination of these areas. The area ratio was calculated from the color pixel count in the ROI divided by the total pixel count in the ROI. Intrarenal perfusion index (IRPI) was defined as (maximum area ratio-minimum area ratio) / maximum area ratio.

RESULTS

There were no significant differences in renal function and left ventricular ejection fraction between the two groups. CVP, time-to-peak (TTP) in the medulla, and RMP were higher in the HF group than in the control group. In the HF group, IRPI, evaluated in the interlobular vessels, was significantly higher than in the control group. IRPI was positively correlated with TTP in the medulla (p = 0.028, R = 0.60) and RMP (p < 0.001, R = 0.84), indicating that IRPI reflected renal congestion.

CONCLUSIONS

IRPI is a useful tool for assessing renal congestion in rats with congestive heart failure.

Superb Microvascular Imaging in Pediatric Focal Nodular Hyperplasia

OBJECTIVE

To investigate superb microvascular imaging (SMI), a novel Doppler ultrasound technique that can visualize low-velocity microvascular flow, for assessing pediatric focal nodular hyperplasia (FNH).

PATIENTS AND METHODS

Nine FNH lesions in 6 patients were enrolled. On SMI and color Doppler imaging (CDI), intralesional vascularity was assessed visually and categorized as typical spoke-wheel pattern (central vessel radiating from the center to the periphery), multifocal spoke-wheel pattern, and nonspecific pattern. We compared the vascular features of the lesions between SMI and CDI and evaluated vascular patterns according to lesion size.

RESULTS

In terms of vascularity pattern, the typical spoke-wheel pattern of FNH was noted more frequently on SMI (67%) than on CDI (11%; P < 0.05). In addition, a multifocal spoke-wheel pattern was noted in all remaining lesions (33%) on SMI. On the contrary, a nonspecific vascular pattern was detected in the majority (78%) of CDI. Regarding the lesion size and vascularity on SMI, the typical spoke-wheel pattern was seen more frequently in the small FNH group than in the large FNH group. The intralesional vascular signal was detected more frequently on SMI (100%) than on CDI (89%).

CONCLUSION

SMI is feasible in evaluating FNH in children and has a greater ability to demonstrate the spoke-wheel pattern than CDI.

The Role of Superb Microvascular Imaging and Shear Wave Elastography in the Prediction of Hemorrhage Complications After Renal Parenchyma Biopsy

OBJECTIVES

The aim of study was to evaluate the diagnostic utility of the renal parenchyma elasticity with the shear wave elastography (SWE) and microvascularization with the superb microvascular imaging (SMI) technique before kidney biopsy and to predict the complication of hemorrhage before kidney biopsy.

METHODS

A total of 75 patients were included in the prospective study. Before the biopsy, vascularity features of the kidney parenchyma in the area to be biopsied were assessed by SMI and parenchymal stiffness by SWE and were examined by 2 independent radiologists.

RESULTS

A statistically significant difference was found in the SMI and SWE values between the groups with and without hematoma and hematuria when compared with the Student t test and Mann-Whitney U test ( P < 0.05). The SWE hardness cutoff value, which maximizes the prediction of the development of hematuria, was found to be 18.40 kPa, and the sensitivity and specificity values were 84.4% and 62.8%, respectively. In SMI vascularity index values, the cutoff value was found to be 0.247410800 kPa, and sensitivity and specificity values were 81.3% and 83.7%, respectively. The cutoff value of the SMI vascularity index values that maximized the prediction of hematoma development was 0.297009650, and the sensitivity and specificity values were 87% and 87%, respectively.

CONCLUSIONS

We believe that evaluating and standardizing the microvascularization and elasticity of the kidney parenchyma before a percutaneous kidney biopsy will be potentially useful as a guiding method in the prediction of postbiopsy hemorrhage development.

New microvascular ultrasound techniques: abdominal applications

Microvascular ultrasound (MVUS) is a new ultrasound technique that allows the detection of slow-velocity flow, providing the visualization of the blood flow in small vessels without the need of intravenous contrast agent administration. This technology has been integrated in the most recent ultrasound equipment and applied for the assessment of vascularization. Compared to conventional color Doppler and power Doppler imaging, MVUS provides higher capability to detect intralesional flow. A growing number of studies explored the potential applications in hepatobiliary, genitourinary, and vascular pathologies. Different flow patterns can be observed in hepatic and renal focal lesions providing information on tumor vascularity and improving the differential diagnosis. This article aims to provide a detailed review on the current evidences and applications of MVUS in abdominal imaging.

Potential diagnostic value of quantitative superb microvascular imaging in premalignant and malignant cervical lesions

Objective

The purpose of this study was to assess the diagnostic efficacy of the vascular index (VI) on superb microvascular imaging (SMI) in distinguishing normal uterine cervical epithelium, high-grade cervical intraepithelial neoplasia (CIN), and cervical cancer.

Methods

The retrospective study included women with pathology-confirmed CIN or cervical cancer, who underwent transvaginal ultrasound and SMI between April 2021 and October 2022. The SIM manifestations of normal cervix and cervical lesions were reviewed. SIM were measured and converted into vascular index (VI) which compared between cervical lesions and control groups. We have retrospectively compared ultrasound features of cervical lesions and characteristics of patients. Measurement reliability was evaluated by intra class correlation coefficient (ICC).

Results

A total of 235 consecutive females were enrolled, comprising 38 with high-grade CIN, 96 with cervical cancer, and 101 with a normal uterine cervix. The microvascular architecture exhibited significant variations between premalignant and malignant cervical lesions. Branch-like patterns were predominantly observed in high-grade CIN, while crab claw-like and fireball-like patterns were more commonly associated with cervical cancer. The median VI of cervical cancer (34.7 ± 10.3) was significantly higher than that of high-grade CIN (17.6 ± 4.2) (P < 0.001). Moreover, the VI values of cervical cancer differed significantly among different FIGO stages and pathological types (P < 0.001 and P = 0.003, respectively). The VI demonstrated superior diagnostic performance for cervical lesions compared to vascular patterns (AUC = 0.974 and 0.969, respectively). Using a cut-off value of 25.5, the VI yielded a sensitivity of 82.3% and a specificity of 99.3% for cervical lesion detection.

Conclusions

The SMI parameter (VI) exhibited a significantly higher value in cervical cancer compared to high-grade CIN, with a high level of agreement among observers. These findings suggest that quantitative SMI holds promise as an imaging technique for the detection and characterization of cervical lesions.

Usefulness of contrast-enhanced ultrasonography for biliary tract disease

Conventional ultrasonography (US) for biliary tract disease shows high time and spatial resolution. In addition, it is simple and minimally invasive, and is selected as a first-choice examination procedure for biliary tract disease. Currently, contrast-enhanced US (CEUS), which facilitates the more accurate assessment of lesion blood flow in comparison with color and power Doppler US, is performed using a second-generation ultrasonic contrast agent. Such agents are stable and provide a timeline for CEUS diagnosis. Gallbladder lesions are classified into three types: gallbladder biliary lesion (GBL), gallbladder polypoid lesion (GPL), and gallbladder wall thickening (GWT). Bile duct lesions can also be classified into three types: bile duct biliary lesion (BBL), bile duct polypoid lesion (BDPL), and bile duct wall thickening (BDWT). CEUS facilitates the differentiation of GBL/BBL from tumorous lesions based on the presence or absence of blood vessels. In the case of GPL, it is important to identify a vascular stalk attached to the lesion. In the case of GWT, the presence or absence of a non-contrast-enhanced area, the Rokitansky-Aschoff sinus, and continuity of a contrast-enhanced gallbladder wall layer are important for differentiation from gallbladder cancer. In the case of BDWT, it is useful to evaluate the contour of the contrast-enhanced medial layer of the bile duct wall for differentiating IgG4-related sclerosing cholangitis from primary sclerosing cholangitis. CEUS for ampullary carcinoma accurately reflects histopathological findings of the lesion. Evaluating blood flow in the lesion, continuity of the gallbladder wall, and contour of the bile duct wall via CEUS provides useful information for the diagnosis of biliary tract disease.

The feasibility of early response evaluation using superb microvascular imaging one day after transcatheter arterial chemoembolization for hepatocellular carcinoma

PURPOSE

The purpose of this study was to determine the feasibility of early Superb microvascular imaging (SMI) for prediction of the effect of HCC treatment after transcatheter arterial chemoembolization (TACE).

MATERIALS AND METHODS

A total of 96 HCCs (70 patients) treated with TACE between September 2021 and May 2022 were included in this study. SMI, Color Doppler imaging (CDI), and Power Doppler imaging (PDI) were performed the day after TACE for evaluation of intratumoral vascularity of the lesion using an Aplio500 ultrasound scanner (Toshiba Medical Systems, Corporation, Tochigi, Japan). Grading of the vascular presence was performed using a five-point scale. A dynamic CT image taken after 29-42 days was used for comparison of sensitivity, specificity, and accuracy for detection of tumor vascularity between SMI, CDI, and PDI. Univariate and multivariate analysis were performed for assessment of factors affecting intratumoral vascularity.

RESULTS

Fifty-eight lesions (60%) showed complete remission (CR) and 38 lesions (40%) showed partial response (PR) or no response at 29-42 days on Multi-detector Computed Tomography (MDCT) after TACE. SMI showed sensitivity of 86.84% for detection of intratumoral flow, which was significantly higher compared with that of CDI (10.53%, p < 0.001) and PDI (36.84%, p < 0.001). The results of multivariate analysis indicated that tumor size was a significant factor in detection of blood flow using the SMI technique.

CONCLUSION

Early SMI may be utilized as an adjunctive diagnostic test for evaluation of treated lesions after TACE, particularly when the location of the tumor is in an area of the liver where a suitable sonic window can be identified.

Quantitative ultrasound for non-invasive evaluation of subclinical rejection in renal transplantation

OBJECTIVES

This study aimed to investigate the predictive efficacy of shear-wave elastography, superb microvascular imaging (SMI), and CEUS for allograft rejection in kidney transplants without graft dysfunction.

METHODS

From January 2021 to November 2021, 72 consecutive patients who underwent both allograft biopsy and ultrasound were evaluated. Blood test results were obtained within a week of the ultrasound examinations, which were performed before the protocol biopsy. Resistive index (RI), tissue viscoelasticity, vascular index, and quantitative CEUS parameters were measured. Patients were divided based on biopsy results into the rejection and non-rejection groups.

RESULTS

Among the 72 patients, 21 patients had pathological characteristics of acute rejection. RI of allograft was significantly higher in the rejection group (p = 0.007), compared to the non-rejection group. There were no significant between-group differences in vascular indices of SMI, mean elasticity, and mean viscosity. Meanwhile, among the parameters obtained by the time-intensity curve on CEUS, the cortical and medullary ratios of average contrast signal intensity, peak enhancement, wash-in area AUC, wash-in perfusion index, wash-out AUC, and wash-in and wash-out AUC were significantly different between the two groups (p < 0.05). In the receiver operating characteristic curve analysis for predicting allograft rejection, the AUC was 0.853 for the combination of six CEUS parameters, RI, and blood urea nitrogen.

CONCLUSIONS

Among non-invasive quantitative ultrasound measurements, CEUS parameters are the most useful for diagnosing subclinical allograft rejection. Furthermore, the combination of CEUS parameters, RI, and blood urea nitrogen may be helpful for the early detection of renal allograft rejection.

KEY POINTS

• Among non-invasive quantitative ultrasound measurements, CEUS parameters are the most useful for the diagnosis of subclinical allograft rejection. • On CEUS, the C/M ratios of MeanLin, PE, WiAUC, WiPI, WoAUC, and WiWoAUC are significantly lower in the rejection group; the combination of these showed reliable predictive performance for rejection. • The combination of CEUS parameters, RI, and BUN has a high predictive capability for subclinical allograft rejection.

[Phenotyping the sheep tail - Presentation of characterization methods in the context of breeding for short-tailedness]

OBJECTIVE

In order to establish targeted breeding for short-tailedness, a suitable method must initially be found that allows phenotyping of the sheep tail beyond tail length. In this study, in addition to assessing body measurements, more advanced studies such as ultrasonography and radiology were performed on the caudal spine of sheep for the first time. The objective of this work was to analyze the physiological variation of tail lengths and vertebrae within a merino sheep population. It also aimed to validate the use of sonographic gray scale analysis and perfusion measurement on the sheep tail.

MATERIAL AND METHOD

Tail length and circumference in centimeters were measured in 256 Merino lambs on the first or second day of life. At 14 weeks of age the caudal spine of these animals was examined radiographically. Sonographic gray scale analysis and measurement of the perfusion velocity of the caudal artery mediana were also performed in a portion of the animals.

RESULTS

The tested method of measurement showed a standard error of 0,08 cm and a coefficient of variation of 0,23% for tail length and 0,78% for tail circumference. The animals had a mean tail length of 22,5±2,32 cm and a mean tail circumference of 6,53±0,49 cm. The mean caudal vertebrae count for this population was 20,4±1,6. The use of a mobile radiographic unit is well suited for imaging the caudal spine in sheep. It was demonstrated that the caudal median artery could be imaged for measurement of perfusion velocity (cm/s), and sonographic gray-scale analysis also showed good feasibility. The mean gray scale value is 19,74±4,5 and the modal value for the most commonly found gray scale pixels is 191,53±120,2. The mean perfusion velocity for the caudal artery mediana is 5,83±3,04 cm/s.

CONCLUSION

The results show that the methods presented are well suited for further characterization of the ovine tail. For the first time, gray values for the tail tissue and the perfusion velocity of the caudal artery mediana were determined.

Quantitative analysis of superb microvascular imaging for monitoring tumor response to chemoradiotherapy in locally advanced cervical cancer

Objectives

As an ultrasound (US) image processing method, superb microvascular imaging (SMI) extracts and visualizes flow signals from vessels through advanced clutter suppression technology. We investigated the feasibility of SMI in monitoring treatment response in patients with locally advanced cervical cancer (LACC) undergoing chemoradiotherapy (CRT).

Methods

Forty-nine patients underwent CRT and received SMI examination at 3 time points: before therapy (baseline), 3 weeks during, and 1 month after CRT. The maximum tumor diameter (Dmax), vascularity index (VI), and their percentage changes (ΔDmax and ΔVI) were calculated. ΔDmax was compared with MRI results as the reference standard.

Results

Based on the MRI findings, 44 were classified as complete response (CR) group and 5 as partial response (PR) group. The Dmax and ΔDmax showed decrease in CR and PR groups at 3 weeks during CRT (P< 0.05), but no significant difference between the two groups (P > 0.05). Compared to the baseline, significant decrease in VI and ΔVI were observed at during and after treatment in the two groups (P< 0.05). Moreover, there were significant differences in VI and ΔVI at 3 weeks during CRT between the CR and PR groups (P< 0.05). ΔVI at 3 weeks during CRT showed a better predictive performance for responder prognosis than VI (AUC = 0.964, AUC = 0.950, respectively, P = 0.001), with a cut-off value of 41.6% yielding 100% sensitivity and 86.4% specificity.

Conclusions

The SMI parameters (VI and ΔVI) have potential for monitoring treatment response in LACC.

Microvascular flow imaging to differentiate focal hepatic lesions: the spoke-wheel pattern as a specific sign of focal nodular hyperplasia

Microvascular flow imaging (MVFI) is an advanced Doppler ultrasound technique designed to detect slow-velocity blood flow in small-caliber microvessels. This technique is capable of realtime, highly detailed visualization of tumor vessels without using a contrast agent. MVFI has been recently applied for the characterization of focal liver lesions and has revealed typical vascularity distributions in multiple types thereof. Focal nodular hyperplasia (FNH) constitutes an important differential diagnosis of malignant liver tumors. In this essay, we provide iconographic documentation of the MVFI appearance of FNH and other common solid liver lesions. Identifying the typical patterns of vascularity, including the spoke-wheel pattern with MVFI, can expedite the diagnosis, spare patients from unnecessary procedures, and save costs.

Non-invasive evaluation of vascular architecture of focal liver lesions by micro vascular imaging

OBJECTIVE

To explore the value of vascular architecture detected by micro vascular imaging (MVI) in preoperative diagnosis of focal liver lesions (FLLs).

METHODS

In this retrospective study, patients with surgery and histopathologically proved or radiologically confirmed FLLs were included. Vascular architecture of FLLs were acquired by color Doppler flow imaging (CDFI) and MVI on LOGIQ™ E20 ultrasound machine (C1-6 convex array probes). Alder semiquantitative analysis (grade 0-3) and morphologic features of blood vessels (pattern a-f) were used to assess the blood flow within the FLLs. Interobserver agreement for evaluating blood flow of FLLs was analyzed. Using Adler's grading or morphologic patterns as diagnostic criteria for malignant FLLs, the diagnostic efficiency was analyzed and compared.

RESULTS

From October 2021 and February 2022, 50 patients diagnosed with 40 malignant FLLs and 10 benign FLLs were finally included. The Kappa value within two observers for evaluating the blood flow of FLLs was 0.78 for MVI and 0.55 for CDFI. According to Alder semiquantitative analysis, more high-level blood flow signals (grade 2-3) were detected by MVI than CDFI (P < 0.05). Based on high-level blood flow signals (grade 2-3) and hypervascular supply patterns (pattern e and f), the diagnostic accuracy for malignant FLLs were 76% and 68% for MVI, 56% and 38% for CDFI, respectively.

CONCLUSION

MVI is superior to CDFI in evaluating vascular architecture of FLLs. The high-level flow signals and hypervascular pattern detected by MVI have a useful and complementary value in preoperative non-invasive identification of malignant FLLs.

Morphometric analysis of tumor microvessels for detection of hepatocellular carcinoma using contrast-free ultrasound imaging: A feasibility study

Introduction

A contrast-free ultrasound microvasculature imaging technique was evaluated in this study to determine whether extracting morphological features of the vascular networks in hepatic lesions can be beneficial in differentiating benign and malignant tumors (hepatocellular carcinoma (HCC) in particular).

Methods

A total of 29 lesions from 22 patients were included in this work. A post-processing algorithm consisting of clutter filtering, denoising, and vessel enhancement steps was implemented on ultrasound data to visualize microvessel structures. These structures were then further characterized and quantified through additional image processing. A total of nine morphological metrics were examined to compare different groups of lesions. A two-sided Wilcoxon rank sum test was used for statistical analysis.

Results

In the malignant versus benign comparison, six of the metrics manifested statistical significance. Comparing only HCC cases with the benign, only three of the metrics were significantly different. No statistically significant distinction was observed between different malignancies (HCC versus cholangiocarcinoma and metastatic adenocarcinoma) for any of the metrics.

Discussion

Obtained results suggest that designing predictive models based on such morphological characteristics on a larger sample size may prove helpful in differentiating benign from malignant liver masses.

Application value of shear-wave elastography combined with monochrome superb microvascular imaging in renal allograft chronic rejection

BACKGROUND

Conventional ultrasound (US), which include gray scale US and Doppler US, is the first-line imaging modality for the evaluation of renal allograft; however, conventional US indicators have limitations.

OBJECTIVE

To explore the application value of shear-wave elastography (SWE) combined with monochrome superb microvascular imaging (mSMI) in renal allograft chronic rejection (CR).

METHODS

From November 2021 to February 2022 in the Lanzhou University Second Hospital, the US features of 54 patients with renal allograft were retrospectively analyzed. Patients were categorized into two groups: stable group(n = 44) and CR group(n = 10), with clinical diagnosis as reference standard. The vascular index (VI) on mSMI and parenchymal stiffness were measured in the middle cortex of all renal allografts and receiver operating characteristic (ROC) curves were drawn to evaluate the feasibility of differentiation. Statistically significant US features and biochemical indicators such as creatinine were scored, and the results of the scores were analyzed by ROC curve.

RESULTS

The VI on mSMI of the stable group (49.5±2.0) was significantly greater than that of the CR group (33.8±5.9) (P = 0.028). There was a statistically significant difference in parenchymal stiffness between stable group (16.2kPa±1.2) and CR group (33.9kPa±6.6) (P = 0.027). The sensitivity was 90% and specificity was 81.8% of the scores in the differentiation of stable group from CR group (cut-off value, 2; P = 0.000).

CONCLUSION

SWE combined with mSMI may help differentiate stable renal allograft from renal allograft CR and have the potential application value in the diagnosis of renal allograft CR.

Microvascular Flow Imaging: A State-of-the-Art Review of Clinical Use and Promise

Vascular imaging with color and power Doppler is a useful tool in the assessment of various disease processes. Assessment of blood flow, from infarction and ischemia to hyperemia, in organs, neoplasms, and vessels, is used in nearly every US investigation. Recent developments in this area are sensitive to small-vessel low velocity flow without use of intravenous contrast agents, known as microvascular flow imaging (MVFI). MVFI is more sensitive in detection of small vessels than color, power, and spectral Doppler, reducing the need for follow-up contrast-enhanced US (CEUS), CT, and MRI, except when arterial and venous wash-in and washout characteristics would be helpful in diagnosis. Varying clinical applications of MVFI are reviewed in adult and pediatric populations, including its technical underpinnings. MVFI shows promise in assessment of several conditions including benign and malignant lesions in the liver and kidney, acute pathologic abnormalities in the gallbladder and testes, and superficial lymph nodes. Future potential of MVFI in different conditions (eg, endovascular repair) is discussed. Finally, clinical cases in which MVFI correlated and potentially obviated additional CEUS, CT, or MRI are shown.

The clinical application of ultrasonography with superb microvascular imaging-a review

Superb microvascular imaging (SMI) is among the latest doppler ultrasound methods. It uses an advanced clutter filter to eliminate artifacts caused by breathing, movement and retains the low-speed blood signals in microvessels. The great advantage of SMI is that it can intuitively detect very slow blood signals in microvessels, providing clinicians with more significant information about flow distribution in the target area. Therefore, it is speculated that SMI has important application value. The purpose of this article is to outline the application of SMI in different parts of the body.

An Innovative Ultrasound Technique for Early Detection of Kidney Dysfunction: Superb Microvascular Imaging as a Reference Standard

Background: Superb microvascular imaging (SMI) is an innovative ultrasound image processing technique that provides greater detail and better visualization of small branching vessels. We assume that SMI will provide sufficient information regarding the severity of chronic kidney disease (CKD) and reflecting histological changes. Aims: The aims was to assess the capabilities of SMI imaging regarding the early detection of kidney dysfunction and renal fibrosis in comparison to the reference standard renal biopsy for the early diagnosis of kidney fibrosis. Methods: SMI was performed in patients (n = 52) with CKD stage 2–5, where some of them underwent biopsy proven CKD and fibrosis as part of the diagnosis. In addition, biochemical tests were performed, including kidney function tests, urine collection for proteinuria, and the estimation of GFR by MDRD or CKD-EPI eGFR in CKD patients and healthy controls (n = 17). All subjects underwent SMI, where vascularity is expressed as the SMI index (a low index reflects low vascularity/fibrosis and vice versa). Results: The SMI vascular index was significantly lower in CKD patients as compared with healthy controls (72.2 ± 12.9 vs. 49.9 ± 16.7%, p < 0.01). Notably, a moderate correlation between the SMI index and eGFR was found among the CKD patients (r = 0.56, p < 0.001). Similarly, a strong correlation was found between SCr and the SMI index of the diseased subjects (r = −0.54, p < 0.001). In patients who underwent renal biopsy, the SMI index corresponded with the histological alterations and CKD staging. Conclusions: This study demonstrated that SMI imaging may be utilized in CKD patients of various stages for the evaluation of chronic renal morphological changes and for differentiation between CKD grades.

Contrast-enhanced and microvascular ultrasound imaging features of testicular lymphoma: report of five cases and review literature

Background

To retrospectively investigate the grey-scale, Doppler, contrast-enhanced and microvascular ultrasound of five patients with primary testicular lymphoma of our institute through review literature analysis.

Methods

From January to November 2020, five patients with primary testicular lymphoma confirmed by histology were preoperatively investigated with a standardized sonographic protocol including contrast-enhanced and microvascular ultrasound.

Results

Conventional ultrasound showed localized hypoechogenicity represented with solitary (2 of 5), multiple lesions (2 of 5), or entire testicular involvement (1 of 5). Increased blood flow appeared in color Doppler ultrasound with straight vascular sign (4 of 5). In contrast-enhanced ultrasound images confirmed this pattern (4 of 5) and presented hyper enhancement with enlarged range. On microvascular ultrasound imagings, all lesions were presented with straight and parallel course of intralesional vessels (5 of 5).

Conclusions

Here, we identified an increased vascularity with enlarged range on contrast-enhanced ultrasound along with a linear nonbranching pattern by vascular sign on microvascular ultrasonographic of testicular lymphoma.

Analysis of vascularization in thyroid gland nodes with superb microvascular imaging (SMI) and CD34 expression histology: a pilot study

Background

The Doppler sonography technique known as "superb microvascular imaging" (SMI) is advancing sonographic micro vascularization imaging in various disciplines. In this study, we aimed to determine whether SMI could reliably reproduce the blood flow in thyroid nodes and whether malignancy could be diagnosed, based on vascularization properties. Immunhistochemical staining by CD34 and SMI where used to determine the vascularization of nodes in terms of quantified vascularization parameters gained by computational evaluation.

Methods

We used image analysis programs to investigate whether the quantitative value for vascularization strength in the thyroid node, measured with SMI, was correlated with the actual degree of vascularization, determined microscopically. We included 16 patients that underwent thyroid resections. We prepared thyroid gland tissue slices for immunohistochemistry and labelled endothelial cells with CD34 to visualize blood vessels microscopically. We used image analysis programs, ImageJ, to quantify SMI Doppler sonographic measurements and CellProfiler to quantify CD34 expression in histological sections. We evaluated the numeric values for diagnostic value in node differentiation. Furthermore, we compared these values to check for correlations.

Results

Among the 16 nodes studied, three harboured malignant tumours (18.75%): two papillary and one follicular carcinoma. Among the 13 benign lesions (81.25%), four harboured follicular adenomas. Malignant and benign nodes were not significantly different in sonographic (0.88 ± 0.89 vs. 1.13 ± 0.19; p = 0.2790) or immunohistochemical measurements of vascularization strength (0.05 ± 0.05 vs. 0.08 ± 0.06; p = 0.2260).

Conclusion

We found a positive, significant correlation (r = 0.55588; p = 0.0254) between SMI (quantitative values for vascularization strength) and immunohistochemistry (CD34 staining) evaluations of thyroid nodes.

New frontiers in liver ultrasound: From mono to multi parametricity

Modern liver ultrasonography (US) has become a "one-stop shop" able to provide not only anatomic and morphologic but also functional information about vascularity, stiffness and other various liver tissue properties. Modern US techniques allow a quantitative assessment of various liver diseases. US scanning is no more limited to the visualized plane, but three-dimensional, volumetric acquisition and consequent post-processing are also possible. Further, US scan can be consistently merged and visualized in real time with Computed Tomography and Magnetic Resonance Imaging examinations. Effective and safe microbubble-based contrast agents allow a real time, dynamic study of contrast kinetic for the detection and characterization of focal liver lesions. Ultrasound can be used to guide loco-regional treatment of liver malignancies and to assess tumoral response either to interventional procedures or medical therapies. Microbubbles may also carry and deliver drugs under ultrasound exposure. US plays a crucial role in diagnosing, treating and monitoring focal and diffuse liver disease. On the basis of personal experience and literature data, this paper is aimed to review the main topics involving recent advances in the field of liver ultrasound.

Evaluation of Multimode Color Doppler Flow Imaging in the Diagnosis of Solid Renal Tumor

Background

Renal cell carcinoma is one of the most common malignant tumors in urinary system, seriously affecting people's health and life. This study aimed to evaluate the clinical value of multi-mode color Doppler flow imaging for diagnosis of solid renal tumor.

Methods

Sixty-six renal solid tumors from 63 patients were examined by color Doppler flow imaging (CDFI), power Doppler flow imaging (PDFI), superb microvascular imaging (SMI), and contrast-enhanced ultrasound (CEUS) before surgery. The diagnostic efficacy of the four methods was compared by determining blood flow grade and ring-like blood flow with Adler's method. Chi-square test and Fisher's test were performed to compare the results of sensitivity and specificity among four methods.

Results

Statistically significant differences in blood flow grade and ring-like blood flow were observed between benign and malignant renal tumors as detected by SMI and CEUS (P < 0.05), whereas no difference was found as detected by CDFI and PDFI (P > 0.05). The results indicated that the sensitivity and specificity of SMI (82.46%, 88.89%) and CEUS (84.21%, 88.89%) were higher than those of CDFI (42.11%, 66.67%) and PDFI (47.37%, 77.78%). Compared with the abilities of CDFI and PDFI, SMI and CEUS can better display the micro-blood flow in the tumors and evaluate the blood flow grading, which indicated that SMI and CEUS may have high values in the differential diagnosis of benign and malignant solid renal tumors.

Conclusion

SMI and CEUS can improve the sensitivity and specificity of the diagnosis of benign and malignant renal tumors and have a high application value.

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.

Diagnostic accuracy of ultrasound superb microvascular imaging for focal liver lesions: A protocol for systematic review and meta-analysis

BACKGROUND

Superb microvascular imaging (SMI) is a new ultrasound vascular imaging technology, which uses a new Doppler algorithm, it has the characteristics of high sensitivity and high resolution to detect low velocity blood flow; it is easier to detect microvessels with low-velocity flow compared with color Doppler flow imaging in theory; and it can image the microvessels of the lesion without angiography.[1] Previous studies showed that SMI can detect tumor neovascularization to differentiate benign from malignant focal liver lessions (FLLs). However, the results of these studies have been contradictory with low sample sizes. This meta-analysis tested the hypothesis that SMI is accurate in distinguishing benign and malignant FLLs.

METHODS

We will search PubMed, Web of Science, Cochrane Library, and Chinese biomedical databases from their inceptions to the November 30, 2020, without language restrictions. Two authors will independently carry out searching literature records, scanning titles and abstracts, full texts, collecting data, and assessing risk of bias. Review Manager 5.2 and Stata14.0 software will be used for data analysis.

RESULTS

This systematic review will determine the accuracy of SMI in the differential diagnosis between benign and malignant FLLs.

CONCLUSION

Its findings will provide helpful evidence for the accuracy of SMI in the differential diagnosis between benign and malignant FLLs.

SYSTEMATIC REVIEW REGISTRATION

INPLASY2020120081.

Imaging based flowchart for gallbladder polyp evaluation

BACKGROUND

Preoperative differentiation between neoplastic and nonneoplastic gallbladder polyps, and the subsequent indication for cholecystectomy remains a clinical dilemma. The current 1 cm size threshold for neoplasia is unspecific. The aim of this study was to improve diagnostic work-up for gallbladder polyps using sonographic and MRI characteristics of neoplastic and nonneoplastic polyps.

METHODS

A prospective, exploratory study including patients undergoing cholecystectomy for gallbladder polyp(s) was conducted. Patients underwent targeted transabdominal ultrasound (TAUS) and MRI. Outcomes were sensitivity and specificity for polyp diagnosis, and the radiological characteristics of neoplastic and nonneoplastic polyp types. Histopathology after cholecystectomy was used as reference standard.

RESULTS

Histopathology demonstrated gallbladder polyps in 20/27 patients (74%): 14 cholesterol polyps, three adenomyomatosis, two adenomas and one gastric heterotopia. Sensitivity of polyp identification were 72% (routine TAUS) and 86% (targeted TAUS and MRI). Both adenomas were identified as neoplastic on targeted TAUS and MRI. Sonographic presentation as multiple, pedunculated polyps, either heterogeneous or with hyperechoic foci, or as single polyps containing cysts were limited to nonneoplastic polyps. On MRI hyperintense polyps on T1-weighted image were cholesterol polyps. An adenoma with high-grade dysplasia showed foci of decreased ADC values. We propose a checklist for polyp evaluation by targeted TAUS and a flowchart for radiological work-up of gallbladder polyps.

CONCLUSIONS

The presented checklist and flowchart could aid diagnostic work-up for gallbladder polyps compared to current routine ultrasound, by elimination of nonneoplastic polyps and ultimately improve treatment decision for patients with gallbladder polyps.

Comparison of Super-Resolution US and Contrast Material-enhanced US in Detection of the Spoke Wheel Sign in Patients with Focal Nodular Hyperplasia

Background Diagnosis of focal nodular hyperplasia (FNH) with US generally requires the use of contrast material. The effect of the super-resolution US technique on the diagnosis of FNH is unknown. Purpose To investigate the equivalence between super-resolution US and contrast material-enhanced US in the detection of spoke wheel sign in patients with FNH by comparing patterns of tumor vascularity. Materials and Methods This is a secondary analysis of a prospective trial (NCT02737865) that enrolled participants diagnosed with FNH between May 2016 and March 2019. These patients underwent super-resolution US and subsequent contrast-enhanced US with perfluorobutane microbubbles on the same day. The primary outcome was the confidence score of detecting spoke wheel sign in patients with FNH at US. Two radiologists used a four-point scale to score their confidence in the presence of the spoke wheel sign based on super-resolution US and contrast-enhanced US findings. Two one-sided tests were used to test the equivalence between super-resolution US and contrast-enhanced US in terms of the score for the confidence level of the spoke wheel sign. Interobserver agreement for both techniques between the two radiologists, using the recorded images, was analyzed by using an intraclass correlation coefficient. Results In 62 patients (mean age, 37 years; range, 20-69 years; 41 women) with FNH, the majority of patients showed a spoke wheel sign at super-resolution US and contrast-enhanced US (63% [39 of 62] and 71% [44 of 62], respectively; P = .36). There was no significant difference between the super-resolution US and contrast-enhanced US techniques regarding the confidence score for the spoke wheel sign (mean score, 1.8 vs 2.0; P = .03 for equivalence test). The intraclass correlation coefficients of super-resolution US and contrast-enhanced US regarding the presence of the spoke wheel sign were 0.82 (95% confidence interval: 0.73, 0.96) and 0.58 (95% confidence interval: 0.41, 0.73), respectively. Conclusion In comparison with contrast-enhanced US, super-resolution US provided a reliable rate of detection of the spoke wheel sign in patients with focal nodular hyperplasia. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Fetzer in this issue.

Efficacy of superb microvascular imaging of ultrasound for diagnosis of gallbladder lesion

BACKGROUND/PURPOSE

The diagnosis of gallbladder (GB) lesions is occasionally difficult. Recently, superb microvascular imaging (SMI) of ultrasound has been developed as a novel microvascular imaging technique. We evaluated the feasibility of SMI for the diagnosis of GB lesions and compared microvascular imaging between benign and malignant GB lesions.

METHODS

Twenty patients with GB-protruded lesions or wall thickening who underwent SMI from August 2015 to July 2017 were included in this retrospective study. The measured outcomes were the quality of microvascular imaging when compared between normal SMI (N-SMI) and contrast-enhanced SMI (CE-SMI), and the microvascular findings (vascularity, vascular morphology, presence of branching, and presence of caliber change) when compared between benign and malignant GB lesions.

RESULTS

The quality of microvascular imaging of CE-SMI was evaluated as better than that of N-SMI, showing a significant difference (P < .001). From the CE-SMI microvascular findings, the evaluation of vascular morphology and the presence of caliber change showed a significant difference between benign and malignant GB lesions (P = .005, P < .001).

CONCLUSIONS

The evaluation of GB lesions using SMI was feasible with a contrast agent. Vascular morphology and the presence of caliber change may help in the differential diagnosis of GB lesions.

Superb Microvascular Imaging Improves Detection of Vascularity in Indeterminate Renal Masses

OBJECTIVES

Vascular assessment of indeterminate renal masses (iRMs) remains a crucial element of diagnostic imaging, as the presence of blood flow within renal lesions suggests malignancy. We compared the utility of Superb Microvascular Imaging (SMI; Canon Medical Systems, Tustin, CA), a novel Doppler technique, to standard color Doppler imaging (CDI) and power Doppler imaging (PDI) for the detection of vascularity within iRMs.

METHODS

Patients undergoing contrast-enhanced ultrasound (CEUS) evaluations for iRMs first underwent a renal ultrasound examination with the following modes: CDI, PDI, color Superb Microvascular Imaging (cSMI), and monochrome Superb Microvascular Imaging (mSMI), using an Aplio i800 scanner with an i8CX1 transducer (Canon Medical Systems). After image randomization, each mode was assessed for iRM vascularity by 4 blinded readers on a diagnostic confidence scale of 1 to 5 (5 = most confident). The results were compared to CEUS as the reference standard.

RESULTS

Forty-one patients with 50 lesions met inclusion criteria. Relative to the other 3 modalities, mSMI had the highest sensitivity (63.3%), whereas cSMI had the highest specificity (62.1%). Both cSMI and mSMI also had the highest diagnostic accuracy (0.678 and 0.680, respectively; both P < 0.001) compared to CDI (0.568) and PDI (0.555). Although the reader-reported confidence interval of mSMI (mean ± SD, 3.6 ± 1.1) was significantly lower than CDI (4.1 ± 1.0) and PDI (4.0 ± 1.0; P < 0.001), the confidence level of cSMI (4.1 ± 0.9) was not (P > 0.173).

CONCLUSIONS

Preliminary data suggest that SMI is a potentially useful modality in detecting microvasculature in iRMs compared to standard Doppler techniques. Future studies should aim to compare the efficacy of both SMI and CEUS and to assess the ability of SMI to characterize malignancy in iRMs.

Role of Superb Microvascular Imaging in Differentiating Between Malignant and Benign Solid Breast Masses

INTRODUCTION

The purpose of this study was to evaluate the diagnostic performance of superb microvascular imaging (SMI) in breast lesions.

MATERIALS AND METHODS

Eighty-five solid breast lesions were studied with color Doppler flow imaging (CDFI), power Doppler imaging (PDI), monochromatic SMI (mSMI), and contrast-enhanced ultrasonography (CEUS). The penetrating vessels (PVs) and microvascular morphologic and distribution features of the breast tumors were evaluated for each modality.

RESULTS

The diagnostic accuracies of CDFI, PDI, mSMI, and CEUS were calculated and compared. Surgical pathologic analysis showed 47 benign and 38 malignant lesions. Compared with CDFI and PDI, mSMI and CEUS detected more PVs in breast lesions. The microvascular architecture showed significant differences between benign and malignant lesions. Benign lesions mainly displayed avascular, line-like, and branch-like patterns, and malignant lesions tended to display root hair-like and crab claw-like patterns. mSMI and CEUS identified more root hair-like and crab claw-like patterns in malignant lesions than CDFI and PDI. The sensitivity, negative predictive value, and accuracy of mSMI findings in diagnosing malignancy based on PVs and vascular patterns were both higher than those of CDFI and PDI.

CONCLUSIONS

mSMI is equal to CEUS and superior to CDFI and PDI in identifying microvascular and discriminating malignant and benign breast masses.

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.

Diagnostic Value of Superb Microvascular Imaging in Parotid Tumors

Background

The aim of this study was to evaluate the clinical diagnostic value of superb microvascular imaging (SMI) in assessing vascular distribution, vascularity, and vessel morphology of parotid tumors (PTs).

Material/Methods

PT patients confirmed by postoperative histopathological detection and who underwent color Doppler flow imaging (CDFI), microvascular imaging (MVI), and SMI examination were recruited. PTs were classified into 3 groups: pleomorphic adenoma (PA), Warthin tumor (WT), and malignant PT (MT). The tumor vascular distribution, vascularity, and vessel morphology recorded by CDFI, MVI, and SMI were compared among PA, WT, and MT group. PT diagnosis was performed using histopathological detection. Fisher’s exact test was used to compare the diagnostic sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and accuracy between SMI and MVI examination in PTs.

Results

We enrolled 198 PTs consisting of 114 PAs, 56 WTs, and 28 MTs into our study. CDFI examination found no significant differences in vascular distribution and vascularity among the PA, WT, and WT groups. SMI examination found significant differences in vascular distribution and vascularity among the 3 groups. MVI found significant differences in vessel morphology, including uneven distribution of blood flow, arborization, and irregular blood flow among the PA, WT, and MT groups. SMI found significant differences in arborization and irregular blood flow, but none of the differences in uneven distribution of blood flow among the 3 groups were significant. The diagnostic sensitivity, specificity, and accuracy of SMI and MVI in PTs showed no significant differences.

Conclusions

SMI more accurately evaluated the vascular distribution and vascularity of PTs than CDFI. SMI might be a potential non-invasive diagnostic method for PTs in clinical practice.

Superb Microvascular Imaging in the Evaluation of Pediatric Graves Disease and Hashimoto Thyroiditis

OBJECTIVES

We aimed to investigate the differences between spectral Doppler and Superb Microvascular Imaging (SMI; Canon Medical Systems, Tokyo, Japan) findings in children with Hashimoto thyroiditis (HT) and Graves disease (GD) compared to healthy control participants.

METHODS

The study included 34 patients with GD, 37 patients with HT, and 22 healthy volunteers. All patients with HT and 11 patients with GD were euthyroid; 23 patients with GD had symptoms of hyperthyroidism and had thyrotropin values of less than 0.5 mIU/L. Thyroid volumes, mean resistive indices, and peak systolic velocities along with vascularity indices (VIs) on Superb Microvascular Imaging were measured.

RESULTS

Patients with GD had a significantly higher mean thyroid volume (P < .001; right lobe, 11.80 mL; left lobe, 9.10 mL) and peak systolic velocity (right, 32.5 cm/s; left, 30 cm/s) with a lower resistive index (right, 0.48%; left, 0.48%) compared to patients with HT (right, 8.78 mL, 20 cm/s, 0.55%; left, 7.41 mL, 20 cm/s, 0.55%, respectively) and also control participants (right, 4.59 mL, 15 cm/s, 0.56%; left, 3.52 mL, 15 cm/s, 0.54%). Patients with GD had a significantly higher median VI (right, 25%; left, 26%) compared to patients with HT (right, 11%; left, 13%) and control participants (right, 8%; left, 8%). When patients with GD were categorized as euthyroid and hyperthyroid based on thyrotropin levels and clinical symptoms, both euthyroid and hyperthyroid patients with GD had significantly higher thyroid volumes compared to patients with HT (P < .001). Hyperthyroid patients with GD had higher thyroid volumes compared to euthyroid patients with GD; however, the difference failed to reach statistical significance. A significant strong positive correlation with the VI and thyrotropin receptor autoantibody levels (r = 0.696) was found. The highest area under the curve was obtained for the right lobe VI (0.885), followed by the left lobe VI (0.872), right lobe volume (0.828), and peak systolic velocity (0.810). The optimal cutoff VI value for distinguishing between HT and GD was 17.35% with sensitivity, specificity, and diagnostic accuracy of 85.3%, 78.4%, and 81.7%, respectively.

CONCLUSIONS

Superb Microvascular Imaging is a new method that can detect subtle vascularity changes with higher accuracy compared to spectral Doppler parameters in distinguishing between HT and GD.

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.