Subdermal Ultrasound Contrast Agent Injection for Sentinel Lymph Node Identification: An Analysis of Safety and Contrast Agent Dose in Healthy Volunteers

Review of Clinical Applications of Sonazoid Ultrasound Contrast for Liver Evaluation

ABSTRACT

Sonazoid is a new ultrasound contrast agent with unique Kupffer phase imaging advantages and high mechanical index stability. This paper introduces the basic theories and advantages of Sonazoid ultrasound. Then, the application and latest advances of Sonazoid in the diagnosis and treatment of liver diseases are reviewed in detail. In addition, the advantages and disadvantages of Sonazoid ultrasound and its future directions are discussed. Sonazoid is expected to become an important tool for clinical ultrasound diagnosis and treatment.

Characterizing Sentinel Lymph Node Status in Breast Cancer Patients Using a Deep-Learning Model Compared With Radiologists' Analysis of Grayscale Ultrasound and Lymphosonography

ABSTRACT

The objective of the study was to use a deep learning model to differentiate between benign and malignant sentinel lymph nodes (SLNs) in patients with breast cancer compared to radiologists' assessments.Seventy-nine women with breast cancer were enrolled and underwent lymphosonography and contrast-enhanced ultrasound (CEUS) examination after subcutaneous injection of ultrasound contrast agent around their tumor to identify SLNs. Google AutoML was used to develop image classification model. Grayscale and CEUS images acquired during the ultrasound examination were uploaded with a data distribution of 80% for training/20% for testing. The performance metric used was area under precision/recall curve (AuPRC). In addition, 3 radiologists assessed SLNs as normal or abnormal based on a clinical established classification. Two-hundred seventeen SLNs were divided in 2 for model development; model 1 included all SLNs and model 2 had an equal number of benign and malignant SLNs. Validation results model 1 AuPRC 0.84 (grayscale)/0.91 (CEUS) and model 2 AuPRC 0.91 (grayscale)/0.87 (CEUS). The comparison between artificial intelligence (AI) and readers' showed statistical significant differences between all models and ultrasound modes; model 1 grayscale AI versus readers, P = 0.047, and model 1 CEUS AI versus readers, P < 0.001. Model 2 r grayscale AI versus readers, P = 0.032, and model 2 CEUS AI versus readers, P = 0.041.The interreader agreement overall result showed κ values of 0.20 for grayscale and 0.17 for CEUS.In conclusion, AutoML showed improved diagnostic performance in balance volume datasets. Radiologist performance was not influenced by the dataset's distribution.

Evaluation of Uterine Fibroid Vascularity Using Contrast-Enhanced Ultrasound in Comparison with Contrast-Enhanced Magnetic Resonance Imaging

OBJECTIVE

The aim of the work described here was to assess uterine fibroid vascularity using contrast-enhanced ultrasound (CEUS) as compared with magnetic resonance imaging (MRI).

METHODS

Forty women diagnosed with symptomatic uterine fibroids scheduled for uterine artery embolization (UAE) were enrolled in this institutional review board-approved study. Before UAE, participants underwent CEUS examination with an Aplio i800 scanner (Canon Medical Systems, Tustin, CA, USA) with curvilinear array (8C1). CEUS was performed using 2.0 mL of the ultrasound contrast agent Lumason (Bracco, Milan, Italy) administered intravenously. Digital CEUS clips were acquired and randomized offline, and fibroids were characterized as hyper- or hypovascular. MRI was used as reference standard for fibroid vascularity and compared with CEUS. Results were analyzed using McNemar's test.

RESULTS

Forty participants were enrolled in the trial. One patient did not proceed with the UAE procedure and one patient refused pre-procedure MRI because of claustrophobia. Therefore, 38 participants underwent CEUS and MRI examinations before UAE. Hypervascular fibroids were seen on MRI and CEUS in 24 and 26 participants, respectively. Hypovascular fibroids were seen with MRI and CEUS in 14 and 12 participants, respectively. Fibroids characterized as hypovascular in two participants by MRI were characterized as hypervascular by CEUS. CEUS and MRI findings were similar in 36 of 38 participants, corresponding to an accuracy of 95% (p = 0.62).

CONCLUSION

Contrast-enhanced ultrasound can accurately assess uterine fibroid vascularity, serving as a potential alternative to MRI in determination of the vascularity of uterine fibroids.

Advantages of contrast-enhanced ultrasound in the localization and diagnostics of sentinel lymph nodes in breast cancer

Sentinel lymph nodes (SLNs) are the first station of lymph nodes that extend from the breast tumor to the axillary lymphatic drainage. The pathological status of these LNs can predict that of the entire axillary lymph node. Therefore, the accurate identification of SLNs is necessary for sentinel lymph node biopsy (SLNB) to replace axillary lymph node dissection (ALND). The quality of life and prognosis of breast cancer patients are related to proper surgical treatment after the precise identification of SLNs. Some of the SLN tracers that have been identified include radioisotope, nano-carbon, indocyanine green (ICG), and methylene blue (MB). However, these tracers have certain limitations, such as pigmentation, radiation dangers, and the requirement for costly detection equipment. Ultrasound contrast agents (UCAs) have good specificity and sensitivity, and thus can compensate for some shortcomings of the mentioned tracers. This technique is also being applied to SLNB in patients with breast cancer, and can even provide an initial judgment on SLN status. Contrast-enhanced ultrasound (CEUS) has the advantages of high distinguishability, simple operation, no radiation harm, low cost, and accurate localization; therefore, it is expected to replace the traditional biopsy methods. In addition, it can significantly enhance the accuracy of SLN localization and shorten the operation time.

A review of contrast-enhanced ultrasound using SonoVue® and Sonazoid™ in non-hepatic organs

Contrast-enhanced ultrasound (CEUS) is a dependable modality for the diagnosis of various clinical conditions. A judicious selection of ultrasound contrast agent (UCA) is imperative for optimizing imaging and improving diagnosis. Approved UCAs for imaging the majority of organs include SonoVue, a pure blood agent, and Sonazoid, which exhibits an additional Kupffer phase. Despite the fact that the two UCAs are increasingly being employed, there is a lack of comparative reviews between the two agents in different organs diseases. This review represents the first attempt to compare the two UCAs in non-hepatic organs, primarily including breast, thyroid, pancreas, and spleen diseases. Through comparative analysis, this review provides a comprehensive and objective evaluation of the performance characteristics of SonoVue and Sonazoid, with the aim of offering valuable guidance for the clinical application of CEUS. Overall, further clinical evidences are required to compare and contrast the dissimilarities between the two UCAs in non-hepatic organs, enabling clinicians to make an appropriate selection based on actual clinical applications.

Lymphography using microbubbles and contrast-enhanced ultrasound (CEUS) before lymphatic supermicrosurgery for severe lymphorrhea of lower extremity

Lymphaticovenous anastomosis (LVA) is an effective surgical treatment for lymphorrhea. However, the traditional indocyanine green (ICG) fluorescent lymphography mapping for lymphatic vessels has limitations, it can only depict the initial capillary lymphatic network localized in the dermis of the skin, which cannot visualize lymphatics deeper than 1.5 cm. A new mapping technique, microbubbles and contrast-enhanced ultrasound (CEUS) can address the problem. In one case of lymphocutaneous fistula, for the first time, we used microbubbles and CEUS technique for preoperative localization for LVAs. Microbubbles and CEUS can identify deep lymphatic vessels and better evaluate the function of lymphatic vessels. The patient's symptoms of edema and lymphorrhea improved clinically. Microbubbles and CEUS is an effective methods for identifying lymphatic vessels in lower limbs.

Identification of sentinel lymph nodes in esophageal cancer patients using contrast-enhanced EUS with peritumoral injections

Objectives

The objective of this pilot study was to compare the performance of contrast-enhanced EUS (CE-EUS)-guided fine-needle aspiration (FNA) with EUS-FNA for lymph node (LN) staging in esophageal cancer.

Methods

Thirty-seven subjects with esophageal cancer undergoing EUS staging were enrolled, and 30 completed this institutional review board-approved study. A Prosound F75 US system (Hitachi Medical Systems, Tokyo, Japan) with harmonic contrast imaging software and GF-UCT180 curvilinear endoscope (Olympus, Tokyo, Japan) was utilized. All LNs identified by standard EUS were first noted. Sonazoid (dose: 1 mL; GE Healthcare, Oslo, Norway) was administered peritumorally, and all enhanced LNs were recorded. Fine-needle aspiration was performed on LNs considered suspicious by EUS alone, as well as LNs enhanced on CE-EUS. Performance of each modality was compared using FNA cytology as reference standard.

Results

A total of 132 LNs were detected with EUS, of which 59 showed enhancement on CE-EUS. Fifty-three LNs underwent FNA, and 22 LNs were determined to be malignant. Among the latter, 10 were considered suspicious by EUS, whereas the other 12 LNs underwent FNA only because of CE-EUS enhancement. Contrast-enhanced EUS showed enhancement in 19 of the 22 malignant LNs. The rate of metastatic node identification from EUS was 45% (10/22), and it was 86% (19/22; P = 0.008) for CE-EUS. Eight subjects (8/30 [27% of study total]) had nodal status upgraded by the addition of CE-EUS, which influenced LN staging and clinical management.

Conclusions

Fine-needle aspiration of LNs identified by CE-EUS may increase metastasis positive rate by ruling out LNs not associated with the tumor drainage pattern. In addition, CE-EUS seems to identify more metastatic LNs that would not be biopsied under the standard EUS criteria.

Sentinel Lymph Node Identification in Post Neoadjuvant Chemotherapy Breast Cancer Patients Undergoing Surgical Excision Using Lymphosonography

OBJECTIVES

This study evaluated the efficacy of lymphosonography in the identification of sentinel lymph nodes (SLNs) in post neoadjuvant chemotherapy patients with breast cancer scheduled to undergo surgical excision.

METHODS

Seventy-nine subjects scheduled for breast cancer surgery with SLN excision completed this IRB-approved study, out of which 18 (23%) underwent neoadjuvant chemotherapy before surgery. Subjects underwent percutaneous Sonazoid (GE Healthcare) injections around the tumor area for a total of 1.0 mL. Lymphosonography was performed using CPS on an S3000 HELX scanner (Siemens Healthineers) with a linear probe. Subjects received blue dye and radioactive tracer as part of their standard of care. Excised SLNs were classified as positive or negative for the presence of blue dye, radioactive tracer and Sonazoid. The results were compared between methods and pathology findings.

RESULTS

Seventy-two SLNs were surgically excised from 18 subjects, 29 were positive for blue dye, 63 were positive for radioactive tracer and 57 were positive for Sonazoid. Comparison with blue dye showed that both radioactive tracer and lymphosonography achieved an accuracy of 53% (P > .50). Comparison with radioactive tracer showed that blue dye had an accuracy of 53%, while lymphosonography achieved an accuracy of 67% (P < .01). Of the 72 SLNs, 15 were determined malignant by pathology; the detection rate was 47% for blue dye (7/15), 67% for radioactive tracer (10/15) and 100% for lymphosonography (15/15) (P < .001).

CONCLUSIONS

Lymphosonography achieved similar accuracy as radioactive tracer and higher accuracy than blue dye for identifying SLNs. The 15 SLNs positive for malignancy were all identified by lymphosonography.

Anatomy Versus Physiology: Is Breast Lymphatic Drainage to the Internal Thoracic (Internal Mammary) Lymphatic System Clinically Relevant?

Approximately 15%-25% of breast lymphatic drainage passes through the internal thoracic (internal mammary) lymphatic system, draining the inner quadrants of the breast. This study aimed to use lymphosonography to identify sentinel lymph nodes (SLNs) in the axillary and internal thoracic lymphatic systems in patients with breast cancer. Seventy-nine patients received subcutaneous ultrasound contrast agent injections around the tumor. Lymphosonography was used to identify SLNs. In 14 of the 79 patients (17.7%), the tumor was located in the inner quadrant of the breast. Lymphosonography identified 217 SLNs in 79 patients, averaging 2.7 SLNs per patient. The 217 identified SLNs in the 79 patients were located in the axillary lymphatic system; none were located in the internal thoracic (internal mammary) lymphatic system, although it was expected in two to four patients (i.e., 4-11 SLNs). These results implied that SLNs associated with breast cancer are predominantly located in the axillary lymphatic system.

Sentinel Lymph Node Identification in Patients With Breast Cancer Using Lymphosonography

The objective of the work described here was to evaluate the efficacy of lymphosonography in identifying sentinel lymph nodes (SLNs) in patients with breast cancer undergoing surgical excision. Of the 86 individuals enrolled, 79 completed this institutional review board-approved study. Participants received subcutaneous 1.0-mL injections of ultrasound contrast agent (UCA) around the tumor. An ultrasound scanner with contrast-enhanced ultrasound (CEUS) capabilities was used to identify SLNs. Participants were administered with blue dye and radioactive tracer to guide SLN excision as standard-of-care. Excised SLNs were classified as positive or negative for the presence of blue dye, radioactive tracer and UCA, and sent for pathology. Two hundred fifty-two SLNs were excised; 158 were positive for blue dye, 222 were positive for radioactive tracer and 223 were positive for UCA. Comparison with blue dye revealed accuracies of 96.2% for radioactive tracer and 99.4% for lymphosonography (p > 0.15). Relative to radioactive tracer, blue dye had an accuracy of 68.5%, and lymphosonography achieved 86.5% (p < 0.0001). Of 252 SLNs excised, 34 were determined to be malignant by pathology; 18 were positive for blue dye (detection rate = 53%), 23 for radioactive tracer (detection rate = 68%) and 34 for UCA (detection rate = 100%) (p < 0.0001). Lymphosonography was similar in accuracy to radioactive tracer and higher in accuracy than blue dye in identifying SLNs. All 34 malignant SLNs were identified by lymphosonography.

Prediction Model and Nomogram of Early Recurrence of Hepatocellular Carcinoma after Radiofrequency Ablation Based on Logistic Regression Analysis

The purpose of this study was to screen for high-risk factors leading to the early recurrence of hepatocellular carcinoma (HCC) after radiofrequency ablation (RFA) and to construct a prediction model and nomogram. This retrospective study included 108 patients with primary HCC who underwent RFA treatment at the Harbin Medical University Cancer Hospital between January 2018 and June 2019. Four risk factors were screened for using univariate and multivariate logistic regression analyses: number of tumors (hazard ratio [HR] = 14.684, 95% confidence interval [CI]: 1.099-196.215, p = 0.042), neutrophil-to-lymphocyte ratio (NLR) (HR = 2.178, 95% CI: 1.003-4.730, p = 0.049), contrast-enhanced ultrasound (CEUS) performance (HR = 6.482, 95% CI: 1.161-36.184, p = 0.033) and α-fetoprotein (AFP) level (HR = 1.001, 95% CI: 1.000-1.003, p = 0.040). We established a prediction model: Logit(p) = -3.096 + 2.827 × (number of tumors >1 = 1) + 1.851 × (CEUS revealing rapid enhancement of blood flow signal in the arterial phase and clearance in the portal phase = 1) + 1.941 × (NLR >1.55 = 1) + 0.257 × (AFP >32.545 = 1). Through clinical decision curve analysis, the model's threshold was 0.043-0.873, indicating a high clinical value. Patients with a high AFP level, typical CEUS enhancement pattern, multiple tumors and elevated NLR are more likely to relapse early.

Evaluation of contrast-enhanced ultrasonography with Sonazoid® in visualization of local anesthetic distribution in rectus sheath block: a prospective, clinical study

PURPOSE

Clear visualization of ultrasound (US) images is crucial for successful US-guided nerve block. However, accurate determination of local anesthetic (LA) distribution from US images remains difficult. Sonazoid^®, which comprises perflubutane microbubbles, is used to diagnose hepatic and breast tumors. This study aimed to investigate the visibility of Sonazoid^® in perioperative US-guided nerve block.

METHODS

We performed rectus sheath block (RSB) in patients scheduled for laparoscopic abdominal surgery (n = 10). 10 mL of a mixture containing equal amounts of 0.75% ropivacaine and iohexol with the addition of Sonazoid^® diluted 100-fold was administered. We investigated the correlation and agreement between Sonazoid^® and iohexol distributions. The brightness of the solution and tissues was calculated: a grayscale value between 0 (dark) and 255 (bright) was measured in all pixels of the region of interest. Adverse events were also investigated.

RESULTS

Sonazoid^® was clearly visualized and distinguished from the surrounding tissues both during and after RSB. The spread of Sonazoid® and iohexol was significantly correlated (spearman's ρ = 0.53, p = 0.0004). Bland-Altman analyses revealed significant mean difference between two methods (15.6 mm; 95% confidence interval [CI]: 10.6, 20.6; standard deviation (SD) 15.65; p < 0.0001). Limits of agreement were - 14.94 to 46.24 mm. Sonazoid^® significantly increased the mean grayscale values at the posterior rectus sheath (93.7 vs. 201.9, p < 0.0001). There were no complications.

CONCLUSION

Sonazoid diluted 100-fold^® was clearly visualized real-time, and the enhancement was sustained and measurable after RSB. Sonazoid^® could potentially be used for the contrast agent of US-guided nerve block.

Contrast-enhanced ultrasound: a new tool for imaging the superficial lymphatic vessels of the upper limb

Background

Despite the new lymphatic imaging methods, there is still a need for a straightforward method of detecting lymphatic abnormalities. Our goal was to investigate the feasibility of applying a contrast enhanced ultrasound (CEUS) procedure as a new approach for visualising the superficial lymphatic vessels of the upper limb.

Methods

Thirty healthy volunteers were examined with CEUS after bilateral intradermal injection of Sonazoid® contrast agent in distal antebrachium. We registered factors affecting intradermal injections, imaging of the superficial lymphatic vessels and the enhancement time of contrast agent reaching the levels of elbow and axilla.

Results

CEUS imaging of superficial lymphatic vessels was successful in 59 of 60 upper limbs (98.3%). Median [interquartile ranges] enhancement times of contrast agent to reach the elbow (right 18 s [11–25], left 15 s [12–25]) and axilla (right 77 s [33–118], left 66 s [42–115]) were equally fast. Successful intradermal injections were found to result in two types of contrast enhancement (strong or moderate), while the enhancement time depended on the type of the successful injection. No major differences in enhancement times were observed related to sex, body mass index, age, or side of the arm.

Conclusions

The superficial lymphatic pathways of the upper limb can be visualised with CEUS imaging. Since enhancement time is dependent on the success of intradermal injections, one must pay attention to the injection technique. Further studies are needed to evaluate the method in patients with lymphatic function disorders such as breast cancer therapy related lymphoedema.

Lymphatic Mapping Using US Microbubbles before Lymphaticovenous Anastomosis Surgery for Lymphedema

Background Lymphaticovenous anastomosis (LVA) surgery is an effective surgical treatment of secondary lymphedema in the extremities, but indocyanine green (ICG) fluorescent lymphography, the reference standard for imaging target lymphatic vessels, has several limitations. More effective methods are needed for preoperative planning. Purpose To evaluate whether contrast-enhanced US (CEUS) can be used to identify target lymphatic vessels for LVA surgery in patients with secondary upper extremity lymphedema and compare the results with those from ICG fluorescent lymphography. Materials and Methods In this single-center retrospective review, CEUS with intradermal injection of microbubbles was performed in patients before LVA surgery in the upper extremities between October 2019 and September 2021. All patients had secondary upper extremity lymphedema from breast cancer treatment. Technical success rate was defined as lymphatic vessels identified with use of CEUS that led to successful LVAs. Descriptive statistics were used. Results All 11 patients were women (mean age, 56 years ± 8 [SD]). The median number of microbubble injection sites was 11 (range, 8-14). CEUS helped identify lymphatic vessels in all 11 women, including in six women in whom ICG fluorescent lymphography could not be performed or failed to help identify any targets. Thirty-five explorations (median, three per patient; range, two to four) were performed, and 24 LVAs (median, three per patient; range, zero to four) were created. Of the anastomoses, 33% (eight of 24) were mapped with use of both CEUS and ICG fluorescent lymphography, 58% (14 of 24) with CEUS only, and 8% (two of 24) with ICG fluorescent lymphography only. Among the 33 explorations on targets mapped with CEUS, an anastomosis could be made at 22 sites, for a technical success rate of 67%. Seven women had at least one additional LVA created from the use of CEUS. Conclusion Contrast-enhanced US is a promising tool for identifying lymphatic vessels in the upper extremities, especially when indocyanine green fluorescent lymphography fails to depict targets or cannot be used. Published under a CC BY 4.0 license.

Advanced diagnostic imaging of sentinel lymph node in early stage breast cancer

Sentinel lymph node biopsy has been regarded as the standard procedure for early staging breast cancer. One of the key steps is to locate the sentinel lymph node (SLN). The recommended method is the joint use of blue dye and radioisotope. However, due to radionuclide radiation and high cost, it is urgent to develop more convenient and sensitive imaging methods to accurately locate SLN. This article discusses the advancement of accurately locating SLN by isotope tracer imaging, magnetic tracer method, computed tomographic lymphography, and trans-lymphatic contrast-enhanced ultrasound, as well as proposing new propose for clinical diagnosis.

Dynamic Contrast-Enhanced Ultrasonography with Sonazoid for Diagnosis of Microvascular Invasion in Hepatocellular Carcinoma

The aim of the present study was to investigate the imaging features observed in pre-operative Sonazoid contrast-enhanced ultrasound (SZ-CEUS) and the correlations with the presence of microvascular invasion (MVI) in hepatocellular carcinoma (HCC) patients. In this single-center retrospective study, 31 patients with surgically and histopathologically confirmed HCC lesions were included. Patients were classified according to the presence of MVI into the MVI-positive group (n = 15) and MVI-negative group (n = 16). The CEUS examinations were performed within 2 or 3 d before surgery. Features, including tumor necrosis and ultrasound contrast agent (UCA) distribution characteristics in the arterial phase (AP), tumor types (single nodular [SN] or non-single nodular [non-SN]) in the post-vascular phase (PVP), wash-in time, wash-in slope, time to peak (TTP) and peak intensity (PI), were assessed. Univariate analysis revealed statistically significant differences between the two groups with respect to tumor necrosis (p = 0.002), inhomogeneous distribution of contrast agent in the AP (p = 0.001) and non-SN type in the PVP (p < 0.001). There was no significant difference in the quantitative parameters. Multivariate analysis revealed that non-SN type in the PVP was a significant independent risk factor for MVI of HCC (odds ratio = 30.51, 95% confidence interval [CI]: 2.335-398.731, p = 0.009). The area under the receiver operating characteristic (ROC) curve (AUC), sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 0.873, 93.3%, 81.3%, 82.4% and 92.9%, respectively. Thus, SZ-CEUS can provide useful information for the diagnosis of MVI in HCC.

Saphenous-sparing Ascending Video Endoscopic Inguinal Lymph Node Dissection Using a Leg Approach: Surgical Technique and Perioperative and Pathological Outcomes

Background

Open inguinal lymph node dissection (oILND) has high morbidity. Ascending saphenous-sparing video endoscopic ILND (VEILND-AS+) represents a minimally invasive alternative with potential benefits.

Objective

To describe our VEILND-AS+ technique and compare outcomes to oILND.

Design, setting, and participants

This was a retrospective cohort study of penile cancer patients.

Surgical procedure

VEILND-AS+ was performed according to the technique described in the supplementary video.

Measurements

We compared perioperative and pathological outcomes between the two procedures.

Results and limitations

In the study cohort of 206 men we performed 40 VEILND-AS+ and 251 oILND procedures. In comparison to oILND, VEILND-AS+ had a longer operation time (185 vs 120 min; p < 0.01) but a shorter hospital stay (2 vs 4 d; p < 0.01). A median of eight resected lymph nodes with a median of one affected node per groin was observed in both groups. Extranodal extension was found in 30% of cases after VEILND-AS+ and 35% after oILND. In both groups the median drainage time was 13 d. Wound infections were observed in 38% of cases after VEILND-AS+ and 27% after oILND (p = 0.19). Skin necrosis or wound breakdown occurred in 0% and 6% of cases after VEILND-AS+ and oILND (p < 0.01), while lymphoceles were drained in 18% and 7% of cases, respectively(p = 0.03). Following VEILND-AS+ and oILND, 20% and 14% of patients, respectively, were referred to a lymph oedema clinic (p < 0.01).

Conclusions

VEILND-AS+ is a safe procedure and offers shorter hospital stays and possibly a lower risk of skin necrosis and wound breakdown in comparison to oILND. Further improvements in the VEILND-AS+ technique are required to reduce complications associated with dead space and injury to lymphatic vessels.

Patient summary

For patients undergoing surgery on lymph nodes in the groin, a minimally invasive approach instead of open surgery led to discharge 2 days earlier and may have lower rates of severe wound complications.

Comparative study of two contrast agents for intraoperative identification of sentinel lymph nodes in patients with early breast cancer

Background

The use of contrast-enhanced ultrasound (CEUS) to locate sentinel lymph nodes (SLNs) in breast cancer has been studied more and more in recent years. This prospective study aimed to compare periareolar injection of two different contrast agents, SonoVue^® (SNV) and Sonazoid^® (SNZ), followed by CEUS to identify SLNs in breast cancer patients with clinically negative nodes.

Methods

A total of 205 patients with T1-2N0M0 breast cancer were divided into the SNV group and SNZ group. All were administered a periareolar injection of SNV or SNZ and underwent US to identify contrast-enhanced SLNs. Each contrast-enhanced SLN underwent a biopsy with blue dye and examined again by CEUS in vitro.

Results

In all cases, contrast-enhanced lymphatic vessels were clearly visualized using US soon after the periareolar injection of SNZ, and the SLNs were easily identified. The SLN identification rates were 75.27% (210/279) for SNV and 93.58% (102/109) for SNZ. Although the accuracy of detecting SLN metastasis was slightly different between the two groups, there was no statistically significant difference between those groups (P=0.615). Moreover, it was possible to identify SLNs in vitro in the SNZ group, and these could be compared with the lymph nodes (LNs) located using SNZ during the preoperative stage and with blue dye during the procedure. This helped in determining the resection requirements.

Conclusions

When comparing the subdermal use of SNV and SNZ, no significant differences in the number of detected SLNs and the diagnosis of metastatic LNs were observed. Because SLNs can be detected for a longer time in living tissues with SNZ, this contrast agent may provide more intraoperative information for complete resection of all preoperative localization of SLN.

Combination of Lymphatic and Intravenous Contrast-Enhanced Ultrasound for Evaluation of Cervical Lymph Node Metastasis from Papillary Thyroid Carcinoma: A Preliminary Study

The aim of this prospective study was to evaluate the value of the combination of lymphatic contrast-enhanced ultrasound (LCEUS) and intravenous contrast-enhanced ultrasound (IVCEUS) for the identification of cervical lymph node metastasis (CLNM) from papillary thyroid carcinoma (PTC). From November 2018 to March 2019, 24 consecutive patients with PTC were evaluated. All patients underwent routine US, LCEUS and IVCEUS. Pathology was used as the gold standard. After injection of a contrast agent into the thyroid parenchyma, lymphatic vessels and lymph nodes (LNs) could be exclusively displayed as hyper-enhancement on LCEUS. Benign LNs displayed a complete bright ring (100%) and homogeneous perfusion (88.9%) on LCEUS, while displaying centrifugal perfusion (66.7%) and homogenous enhancement (88.9%) on IVCEUS. Perfusion defects (94.9%) and interruption of the bright ring (71.8%) were the two characteristic LCEUS signs for diagnosing CLNM. On IVCEUS, CLNM appeared as centripetal perfusion (59.0%) and heterogeneous enhancement (59.0%). After comparison with pathology, perfusion defect was correlated to the metastatic foci in the medulla and interruption of the bright ring to the tumor seeding in the marginal sinus (all p values <0.05). LCEUS had more value (area under the receiver operating characteristic curve [AUC] = 0.850, 95% confidence interval [CI]: 0.682-1.000) in diagnosing CLNM than IVCEUS (AUC = 0.692, 95% CI: 0.494-0.890) and routine US (AUC = 0.581, 95% CI: 0.367-0.796). The combination of LCEUS and IVCEUS has the highest diagnostic value (AUC = 0.863, 95% CI: 0.696-1.000). LCEUS had higher diagnostic value than IVCEUS and US for CLNM from PTC. The combination of LCEUS and IVCEUS has the highest diagnostic value for CLNM.

Percutaneous Sonazoid-enhanced ultrasonography combined with in vitro verification for detection and characterization of sentinel lymph nodes in early breast cancer

Objectives

To assess the efficacy of percutaneous Sonazoid-enhanced ultrasound and in vitro verification for identification sentinel lymph nodes (SLNs) and diagnosis of metastatic SLNs in patients with early breast cancer (BC).

Methods

Sixty-eight patients with early BC were enrolled finally. After the induction of general anesthesia, 0.4 ml of Sonazoid (SNZ), a new second-generation tissue-specific ultrasound contrast agent (UCA), mixed with 0.6 ml of methylene blue, was injected intradermally. The lymphatic vessels and connected SLNs were immediately observed and marked. After being resected, these SLNs were soaked in saline water and examined still in the mode of contrast-enhanced ultrasound (CEUS) in vitro. This procedure could ensure that all the enhanced nodes had been removed as much as possible. The numbers of SLNs detected by UCA and blue dye were recorded. The enhancement patterns of SLNs were compared with the final pathological results.

Results

SLNs detection rate by SNZ-CEUS was 100%, which was higher than that by blue dye (95.59%). CEUS identified a median of 1.5 nodes, while blue dye identified a median of 1.9 nodes per case (p = 0.0012). When homogeneous high perfusion and complete annular high perfusion were regarded as negative nodes, the sensitivity and negative predictive value were 92.31% and 96.79% respectively, while the specificity was 84.21%.

Conclusions

Percutaneous SNZ-enhanced ultrasonography combined with in vitro verification is a feasible and reliable method for SLNs identification intraoperatively. Enhancement patterns can be helpful in determining the status of SLNs.

Key Points

• CEUS with percutaneous injection of Sonazoid can successfully identify SLNs with the rate of 100% in early breast cancer patients, higher than 95.59% of blue dye.

• Sonazoid, with high affinity with reticuloendothelial cells, increases the imaging time of SLNs and facilitates biopsy intraoperatively better than Sonovue as a lymphatic tracer.

• Homogenous high and complete annular high perfusions have a sensitivity of 92.31% and a negative predictive value of 96.79% in the prediction of uninvolved SLNs.

New Developments in Imaging for Sentinel Lymph Node Biopsy in Early-Stage Oral Cavity Squamous Cell Carcinoma

Sentinel lymph node biopsy (SLNB) is a diagnostic staging procedure that aims to identify the first draining lymph node(s) from the primary tumor, the sentinel lymph nodes (SLN), as their histopathological status reflects the histopathological status of the rest of the nodal basin. The routine SLNB procedure consists of peritumoral injections with a technetium-99m [^99mTc]-labelled radiotracer followed by lymphoscintigraphy and SPECT-CT imaging. Based on these imaging results, the identified SLNs are marked for surgical extirpation and are subjected to histopathological assessment. The routine SLNB procedure has proven to reliably stage the clinically negative neck in early-stage oral squamous cell carcinoma (OSCC). However, an infamous limitation arises in situations where SLNs are located in close vicinity of the tracer injection site. In these cases, the hotspot of the injection site can hide adjacent SLNs and hamper the discrimination between tracer injection site and SLNs (shine-through phenomenon). Therefore, technical developments are needed to bring the diagnostic accuracy of SLNB for early-stage OSCC to a higher level. This review evaluates novel SLNB imaging techniques for early-stage OSCC: MR lymphography, CT lymphography, PET lymphoscintigraphy and contrast-enhanced lymphosonography. Furthermore, their reported diagnostic accuracy is described and their relative merits, disadvantages and potential applications are outlined.

Real-Time Visualization of Lymphatic Flow to Sentinel Lymph Nodes by Contrast-Enhanced Ultrasonography with Sonazoid in Patients with Breast Cancer

Contrast-enhanced ultrasonography with Sonazoid (SNZ) enables real-time visualization, resulting in more precise identification of lymphatic flow to sentinel lymph nodes (SLNs). This study aimed to classify lymphatic drainage patterns to SLNs. Patients (n = 75) with T1-2 N0 M0 breast cancer received a periareolar injection of SNZ to identify SNZ-enhanced SLNs (SNZ-SLNs), followed by SLN biopsy with blue dye. The lymphatic drainage patterns were classified into four types: type A, single lymphatic route/single SLN; type B, multiple lymphatic routes/single SLN; type C, single lymphatic route/multiple SLNs; and type D, multiple lymphatic routes/multiple SLNs. SLNs were successfully identified in all patients using both blue dye and SNZ. The drainage lymphatic pathways identified were as follows: type A in 53 cases (70.7%), type B in seven (9.3%), type C in eight cases (10.7%) and type D in seven (9.3%). SNZ-SLN biopsy is a technically simple method with a 100% identification rate, enabling the real-time visualization of lymphatic flow to SNZ-SLNs.

How Pre-operative Sentinel Lymph Node Contrast-Enhanced Ultrasound Helps Intra-operative Sentinel Lymph Node Biopsy in Breast Cancer: Initial Experience

We aimed to evaluate the value of sentinel lymph node contrast-enhanced ultrasound (SLN-CEUS) and surface tracing for the biopsy of intra-operative sentinel lymph nodes (SLNs). Between June 2015 and December 2017, a total of 453 patients with early invasive breast cancer were recruited. Patients received an intradermal injection of microbubble contrast agent around the areola on the day before surgery. The locations and sizes of lymphatic channels (LCs) and SLNs were marked on the body surface using gentian violet. Then, injection of double blue dye was performed half an hour before surgery. We compared the pathway of LCs and the location of SLNs obtained from SLN-CEUS and blue dye during surgery. Among the 453 patients, the mean numbers of LCs and SLNs detected by SLN-CEUS were 1.42 and 1.72, respectively, and the coincidence rate was 98.2% compared with blue dye during surgery. The median distance from the SLN to skin measured by pre-operative CEUS and blue dye was 1.95 ± 0.69 and 2.03 ± 0.87 cm (p = 0.35). There were three SLN enhancement in our research, including homogeneous enhancement, inhomogeneous enhancement and no enhancement, with the sensitivity, specificity, positive predictive value and negative predictive value of SLN-CEUS for the diagnosis of SLNs being 96.82%, 91.91%, 87.54% and 98.01%, respectively. SLN-CEUS with skin marking can identify the pathway of LCs and the location of the SLN before surgery, measure the distance from the SLN to skin and determine if the SLN is metastatic. SLN-CEUS can be used as an effective complement to the blue dye method.