Preoperative sentinel node identification with ultrasound using microbubbles in patients with breast cancer. AJR Am J Roentgenol. 2011;196:251-256. [PMID: 21257873 DOI: 10.2214/ajr.10.4865]

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.

Predicting axillary metastasis in breast cancer using lymphatic contrast-enhanced ultrasound-guided fine-needle aspiration of one lymph node

OBJECTIVES

Fine-needle aspiration (FNA) is a microinvasive method to diagnose lymph nodes. This study aims to determine the capability of lymphatic contrast-enhanced ultrasound (LCEUS)-guided FNA in predicting the axillary metastasis with the target of one lymph node (LN) in patients with breast cancer.

METHODS

LCEUS was prospectively performed in 105 patients with breast cancer. The most suspicious LN was targeted based on the characters of LCEUS. FNA was performed in the LN, followed by localization using a guide wire. The detection of lymph cells and/or tumour cells was recognized as a puncture success. Cytologic diagnosis was compared with histologic diagnosis of wire-marked LN for diagnosing accuracy and compared with histologic diagnosis of axillary LNs for predicting accuracy.

RESULTS

LCEUS-guided FNA was performed in all 105 female patients who underwent axillary dissection. The puncture success rates were 74.3%, 91.4%, and 97.1% for three sequential groups (P = .010). In diagnosing LN metastasis, the sensitivity, specificity, and accuracy values of LCEUS-guided FNA were 89.7%, 100%, and 95.7%, respectively. In predicting axillary metastasis, the sensitivity, specificity, and accuracy values of LCEUS-guided FNA were 81.4%, 100%, and 91.3%, respectively.

CONCLUSIONS

The microinvasive LCEUS-guided FNA of one lymph node can be an accurate method and may help predict axillary metastasis in patients with breast cancer.

ADVANCES IN KNOWLEDGE

This study presented that LCEUS combined with FNA would be practical in clinic. The characters of LCEUS could indicate the suspicious LNs and promote the accuracy in predicting axillary metastasis.

MR Lymphangiography in Lymphatic Disorders: Clinical Applications, Institutional Experience, and Practice Development

Lymphatic flow and anatomy can be challenging to study, owing to variable lymphatic anatomy in patients with diverse primary or secondary lymphatic pathologic conditions and the fact that lymphatic imaging is rarely performed in healthy individuals. The primary components of the lymphatic system outside the head and neck are the peripheral, retroperitoneal, mesenteric, hepatic, and pulmonary lymphatic systems and the thoracic duct. Multiple techniques have been developed for imaging components of the lymphatic system over the past century, with trade-offs in spatial, temporal, and contrast resolution; invasiveness; exposure to ionizing radiation; and the ability to obtain information on dynamic lymphatic flow. More recently, dynamic contrast-enhanced (DCE) MR lymphangiography (MRL) has emerged as a valuable tool for imaging both lymphatic flow and anatomy in a variety of congenital and acquired primary or secondary lymphatic disorders. The authors provide a brief overview of lymphatic physiology, anatomy, and imaging techniques. Next, an overview of DCE MRL and the development of an MRL practice and workflow in a hybrid interventional MRI suite incorporating cart-based in-room US is provided, with an emphasis on multidisciplinary collaboration. The spectrum of congenital and acquired lymphatic disorders encountered early in an MRL practice is provided, with emphasis on the diversity of imaging findings and how DCE MRL can aid in diagnosis and treatment of these patients. Methods such as DCE MRL for assessing the hepatic and mesenteric lymphatic systems and emerging technologies that may further expand DCE MRL use such as three-dimensional printing are introduced. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Lymphatic Mapping with Contrast-enhanced Ultrasound for Lymphaticovenous Anastomosis Surgery: How We Do It

Lymphaticovenous anastomosis (LVA) surgery is an effective surgery for the treatment of lymphedema in the extremities. Indocyanine green lymphography is the reference standard for visualizing lymphatics for LVA surgery, but it has several limitations; most notably, superficial dermal congestion can mask deeper lymphatic vessels. To overcome the limitations, we add contrast-enhanced ultrasound (CEUS) lymphography. We have previously reported that CEUS lymphography can identify lymphatic vessels for LVA surgery that indocyanine green lymphography does not. Here, we describe how we perform CEUS lymphography, including workflow, technique, and documentation. Before informed consent, the patient must be screened for possible adverse reactions to microbubbles. The procedure involves multiple intradermal injections of the microbubble agent at various sites along the extremity. After each injection, imaging for microbubble uptake by lymphatic vessels is performed using an ultrasound scanner with contrast-specific software. We use sulfur hexafluoride lipid-type A microspheres (Lumason/SonoVue; Bracco Suisse SA), but we are investigating the performance of other Food & Drug Administration-approved microbubble agents for CEUS lymphography. Having a systematic approach to marking the skin can mitigate the hindrance of marking over ultrasound coupling gel. Another benefit of CEUS lymphography is the rapid identification of neighboring veins compatible in size and location for anastomosis. We hold regular scheduled multidisciplinary meetings for coordination of care, discussion of outcomes, quality assurance, and ongoing innovation.

Sentinel lymph node identification using contrast-enhanced ultrasound in breast cancer: review of the literature

Before breast cancer surgery, sentinel lymph node (SLN) identification and biopsy using blue dye, radioisotope (RI) with a gamma probe, or a combination of the two are mainly performed. The dye-guided method requires skilled technique to make an incision in the skin and identify SLNs without damaging the lymphatic vessels. In addition, dye-induced anaphylactic shock has been reported. To use the γ-probe-guided method, the facility must be able to handle RI. However, to overcome the drawbacks of these methods, Omoto et al. developed a new identification modality using contrast-enhanced ultrasound with an ultrasound contrast agent (UCA) in 2002. Since then, many basic experiments and clinical studies using various UCA have been reported. In particular, a number of studies in SLN detection using Sonazoid have been reported and are herein reviewed.

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.

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.

Contrast enhanced magneto-motive ultrasound in lymph nodes - modelling and pre-clinical imaging using magnetic microbubbles

Despite advances in MRI, the detection and characterisation of lymph nodes in rectal cancer remains complex, especially when assessing the response to neo-adjuvant treatment. An alternative approach is functional imaging, previously shown to aid characterization of cancer tissues. We report proof-of-concept of the novel technique Contrast-Enhanced Magneto-Motive Ultrasound (CE-MMUS) to recover information relating to local perfusion and lymphatic drainage, and interrogate tissue mechanical properties through magnetically induced tissue deformations. The feasibility of the proposed application was explored using a combination of pre-clinical ultrasound imaging and finite element analysis. First, contrast enhanced ultrasound imaging on one wild type mouse recorded lymphatic drainage of magnetic microbubbles after bolus injection. Second, preliminary CE-MMUS data were acquired as a proof of concept. Third, the magneto-mechanical interactions of a magnetic microbubble with an elastic solid were simulated using finite element software. Accumulation of magnetic microbubbles in the inguinal lymph node was verified using contrast enhanced ultrasound, with peak enhancement occurring 3.7 s post-injection. Preliminary CE-MMUS indicates the presence of magnetic contrast agent in the lymph node. The finite element analysis explores how the magnetic force is transferred to motion of the solid, which depends on elasticity and bubble radius, indicating an inverse relation with displacement. Combining magnetic microbubbles with MMUS could harness the advantages of both techniques, to provide perfusion information, robust lymph node delineation and characterisation based on mechanical properties. Clinical Relevance- Robust detection and characterisation of lymph nodes could be aided by visualising lymphatic drainage of magnetic microbubbles using contrast enhanced ultrasound imaging and magneto-motion, which is dependent on tissue mechanical properties.

Modelling of magnetic microbubbles to evaluate contrast enhanced magnetomotive ultrasound in lymph nodes - a pre-clinical study

OBJECTIVES

Despite advances in MRI the detection and characterisation of lymph nodes in rectal cancer remains complex, especially when assessing the response to neoadjuvant treatment. An alternative approach is functional imaging, previously shown to aid characterisation of cancer tissues. We report proof of concept of the novel technique Contrast-Enhanced Magneto-Motive Ultrasound (CE-MMUS) to recover information relating to local perfusion and lymphatic drainage, and interrogate tissue mechanical properties through magnetically induced deformations.

METHODS

The feasibility of the proposed application was explored using a combination of experimental animal and phantom ultrasound imaging, along with finite element analysis. First, contrast-enhanced ultrasound imaging on one wild type mouse recorded lymphatic drainage of magnetic microbubbles after bolus injection. Second, tissue phantoms were imaged using MMUS to illustrate the force- and elasticity dependence of the magnetomotion. Third, the magnetomechanical interactions of a magnetic microbubble with an elastic solid were simulated using finite element software.

RESULTS

Accumulation of magnetic microbubbles in the inguinal lymph node was verified using contrast enhanced ultrasound, with peak enhancement occurring 3.7 s post-injection. The magnetic microbubble gave rise to displacements depending on force, elasticity, and bubble radius, indicating an inverse relation between displacement and the latter two.

CONCLUSION

Combining magnetic microbubbles with MMUS could harness the advantages of both techniques, to provide perfusion information, robust lymph node delineation and characterisation based on mechanical properties.

ADVANCES IN KNOWLEDGE

(a) Lymphatic drainage of magnetic microbubbles visualised using contrast-enhanced ultrasound imaging and (b) magnetomechanical interactions between such bubbles and surrounding tissue could both contribute to (c) robust detection and characterisation of lymph nodes.

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.

The value of contrast-enhanced ultrasound enhancement patterns for the diagnosis of sentinel lymph node status in breast cancer: systematic review and meta-analysis

BACKGROUND

The sentinel lymph node (SLN) can represent the metastasis status of axillary lymph nodes and is a prognostic factor of breast cancer. Preoperative imaging provides information for axillary surgery decision-making, and this meta-analysis evaluated the diagnostic value of contrast-enhanced ultrasound (CEUS) for SLN status in breast cancer patients.

METHODS

The PubMed, Embase, Medline, Google Scholar, Clinical Trails gov. and Cochrane Library databases were searched from inception until 31 March 2020. Two review authors independently screened and selected the relevant studies and extracted data, and the assessment of the methodological quality of studies was according to the QUADAS-2 tool. The diagnostic value of CEUS was assessed by calculating the pooled sensitivity, specificity, area under the curve, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio, and a summary receiver operating characteristic curve and hierarchical modeling method was used to conduct the meta-analysis.

RESULTS

Five studies with 771 breast cancer patients were included, and the results showed CEUS could provide additional information for SLN preoperative diagnosis. A homogeneous or uniform enhancement pattern suggested a benign lymph node, and a heterogeneous, no pattern, or weak enhancement pattern suggested a node was malignant, demonstrating high sensitivity of 0.960 (95% CI: 0.856, 0.989) and moderate specificity of 0.807 (0.581, 0.926). The pooled positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 4.987 (2.104, 11.822) and 0.049 (0.014, 0.168), and 101.294 (31.202, 328.837), respectively.

CONCLUSIONS

A homogeneous enhancement pattern was highly suggestive of benign lymph nodes with high sensitivity. CEUS could effectively identify the SLN, and facilitate the diagnosis of its metastatic status.

REGISTRATION NUMBER

PROSPERO protocol CRD42020176828.

Preoperative localization of sentinel lymph nodes using percutaneous contrast-enhanced ultrasonography in patients with breast cancer

BACKGROUND

This study aimed to investigate the feasibility of preoperative identification of sentinel lymph nodes (SLNs) by contrast-enhanced ultrasound (CEUS) for patients with breast cancer.

METHODS

The patients with T1-T2N0M0 breast cancer who were scheduled for primary surgical treatment were recruited. All the patients had received a periareolar intradermal injection of an ultrasonic contrast agent (SonoVue, Bracco, Milan, Italy) followed by an ultrasound to identify contrast-enhanced SLNs. A guidewire was deployed to localize the SLN. Methylene blue stain was used to help trace SLNs during the operation. The identification rate and accuracy rate were recorded. The number of SLNs labeled by two methods was counted and compared using Wilcoxon testing.

RESULTS

A total of 366 SLNs were detected in 72 patients by methylene blue intraoperatively, with a median of 5 lymph nodes [interquartile range (IQR), 4-6] per patient. A total of 95 SLNs were detected in 63 patients (87.5%) by CEUS, with a median of 1 lymph node (IQR, 1-2) per patient. The number of SLNs detected by CEUS was significantly less than that labeled by the methylene blue staining method (Z=-7.362, P=0000). Pathology confirmed 12 single metastases in all the lymph nodes examined, 10 of which were the only lymph node identified by CEUS.

CONCLUSIONS

Periareolar intradermal injection of an ultrasonic contrast agent was an effective and convenient supplementary to localize SLNs. The technique was expected to improve the accuracy of axillary staging with minor surgical trauma and postoperative complications.

Sentinel lymph node detection by combining nonradioactive techniques with contrast agents: State of the art and prospects

The status of sentinel lymph nodes (SLNs) has a substantial prognostic value because these nodes are the first place where cancer cells accumulate along their spreading route. Routine SLN biopsy ("gold standard") involves peritumoral injections of radiopharmaceuticals, such as technetium-99m, which has obvious disadvantages. This review examines the methods used as "gold standard" analogs to diagnose SLNs. Nonradioactive preoperative and intraoperative methods of SLN detection are analyzed. Promising photonic tools for SLNs detection are reviewed, including NIR-I/NIR-II fluorescence imaging, photoswitching dyes for SLN detection, in vivo photoacoustic detection, imaging and biopsy of SLNs. Also are discussed methods of SLN detection by magnetic resonance imaging, ultrasonic imaging systems including as combined with photoacoustic imaging, and methods based on the magnetometer-aided detection of superparamagnetic nanoparticles. The advantages and disadvantages of nonradioactive SLN-detection methods are shown. The review concludes with prospects for the use of conservative diagnostic methods in combination with photonic tools.

Emerging contrast-enhanced ultrasound applications in children

Ultrasound contrast agent (UCA) use in radiology is expanding beyond traditional applications such as evaluation of liver lesions, vesicoureteral reflux and echocardiography. Among emerging techniques, 3-D and 4-D contrast-enhanced ultrasound (CEUS) imaging have demonstrated potential in enhancing the accuracy of voiding urosonography and are ready for wider clinical adoption. US contrast-based lymphatic imaging has been implemented for guiding needle placement in MR lymphangiography in children. In adults, intraoperative CEUS imaging has improved diagnosis and assisted surgical management in tumor resection, and its translation to pediatric brain tumor surgery is imminent. Because of growing interest in precision medicine, targeted US molecular imaging is a topic of active preclinical research and early stage clinical translation. Finally, an exciting new development in the application of UCA is in the field of localized drug delivery and release, with a particular emphasis on treating aggressive brain tumors. Under the appropriate acoustic settings, UCA can reversibly open the blood-brain barrier, allowing drug delivery into the brain. The aim of this article is to review the emerging CEUS applications and provide evidence regarding the feasibility of these applications for clinical implementation.

Evaluation of whole axillary status with lymphatic contrast-enhanced ultrasound in patients with breast cancer

OBJECTIVES

This study aims to evaluate the whole axillary status of patients with breast cancer by lymphatic contrast-enhanced ultrasound (LCEUS).

METHODS

LCEUS was applied for 169 patients with suspected breast cancer. Abnormal patterns in lymphatic channels, sentinel lymph nodes (SLNs), and non-enhanced but abnormal lymph nodes were investigated. The signs of distorted, attenuated, netted, or interrupted lymphatic channels, defective-filling or no-filling SLNs, and the appearance of non-enhanced but abnormal lymph nodes were designated as features of axillary metastasis. A positive outcome was given when any of the abnormal patterns was found in the LCEUS. The diagnostic efficiencies were calculated to differentiate the axillary lymphatic status using LCEUS for the whole axilla, compared with conventional ultrasound (US) and LCEUS for SLNs.

RESULTS

The LCEUS procedure was successfully performed for 157 breast cancer patients with axillary dissection. Compared to normal axillae, abnormal patterns had a significantly higher frequency in metastatic axillae (p = 0.000). Using conventional US to evaluate the whole axillae, the diagnostic sensitivity, specificity, and accuracy were 69.1%, 71.9%, and 70.7%, respectively. When LCEUS was used for SLN evaluation to predict the whole axilla, the diagnostic sensitivity, specificity, and accuracy were 66.2%, 89.9%, and 79.6%, respectively. When LCEUS was used as the whole axillary evaluation method, the diagnostic sensitivity, specificity, and accuracy were 76.5%, 86.5%, and 82.2%, respectively.

CONCLUSION

LCEUS can be an accurate method to observe the whole axillae in breast cancer patients. Lymphatic channels, SLNs, and non-enhanced but abnormal lymph nodes constitute the LCEUS for whole axillary evaluation.

KEY POINTS

• LCEUS can be an accurate method to observe the whole axillae in breast cancer patients. • Three aspects in the LCEUS for whole axillary evaluation are the lymphatic channels, sentinel lymph nodes (SLNs), and non-enhanced but abnormal lymph nodes. • Signs of distorted, attenuated, netted, or interrupted lymphatic channels, defective-filling or no-filling SLNs, and the appearance of non-enhanced but abnormal lymph nodes were considered as features of axillary metastasis.

Contrast-Enhanced Ultrasound in Locating Axillary Sentinel Lymph Nodes in Patients with Breast Cancer: A Prospective Study

The objective was to explore the clinical value of contrast-enhanced ultrasound (CEUS) in locating the sentinel lymph node (SLN) in patients with early breast cancer. We screened 143 consecutive patients with breast cancer between July 2017 and August 2019. The number of SLNs identified by CEUS and dual labeling (blue dye and radiolabeled colloid) were recorded. The accuracy of CEUS plus fine-needle aspiration cytology (FNAC) was assessed. The rate of identification of SLNs with CEUS was 84.0% (121/144), and that of dual labeling was 97.92% (141/144). There was no significant association between non-enhancement (p = 0.060) or inhomogeneous enhancement (p = 0.468) and lymph node metastasis. The sensitivity and specificity of CEUS-SLNs plus FNAC was 78.38% and 100%, respectively. The technique of CEUS is a promising method for locating the axillary SLN. But it is hard to identify lymph node metastasis with CEUS alone. CEUS-SLNs plus FNAC is a sound technique for diagnosis of the metastasis of SLN.

Preoperative Contrast-Enhanced Ultrasound (CEUS) Combined with 125I Seeds Localization in Sentinel Lymph Node Biopsy for Breast Cancer

Objective

To assess the clinical value of contrast-enhanced ultrasound (CEUS) technology in predicting axillary lymph nodes status before surgery, and to explore the feasibility of sentinel lymph nodes (SLNs) localization guided by CEUS combined with ¹²⁵I implantation for breast cancer.

Methods

From August 2017 to February 2019, 115 patients were included in this prospective study. Before surgery, a microbubble (SonoVue) was injected intradermally next to the areola. The enhancement patterns of SLNs were recorded and ¹²⁵I seeds were deployed into the enhanced nodes. Then, all patients underwent standard sentinel lymph node biopsy (SLNB) and all ¹²⁵I seeds were found out guided by a gamma detector in surgery. The localization was considered successful if ¹²⁵I seeds were implanted in/beside the nodes.

Results

SLNs in 103 cases were successfully identified, the success rate was 89.6% (103/115), 118 SLNs were detected in total. ¹²⁵I seeds were deployed successfully in 99 cases, and all of the ¹²⁵I-labeled SLNs were then successfully detected by combined method (radionuclides and blue dye). The accuracy of ¹²⁵I seeds localization was 96.1% (99/103). Based on the enhancement patterns recorded, 34 cases were predicted to have SLNs metastasis (metastasis in 27 cases and no metastasis in 7 cases confirmed by postoperative pathology) and 65 cases were predicted to have no SLNs metastasis (metastasis in 5 cases and no metastasis in 60 cases by pathology). The positive predictive value and negtive predictive value of CEUS in assessing axillary status were 79.4% (27/34) and 92.3% (60/65), respectively. The axillary metastasis rate in CEUS combined with ¹²⁵I seeds localization was 27.3% (27/99), while the metastasis rate in the combined method of SLNB was 32.3% (32/99). The sensitivity of ¹²⁵I seeds localization was 84.4% (27/32), the false-negative rate was 15.6% (5/32), and the consistency evaluation was excellent (Kappa value=0.880, P<0.001).

Conclusion

CEUS combined with ¹²⁵I seeds implantation can locate SLNs accurately and has excellent consistency with the combined method. The enhancement patterns can provide helpful predicting information of axillary status preoperatively. However, more studies are needed to be carried out to verify our outcomes and explore the feasibility of applying CEUS technology in clinical work.

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.

Contrast-enhanced ultrasound for sentinel lymph node mapping in the routine staging of canine mast cell tumours: A feasibility study

Canine mast cell tumours (MCTs) typically spread to lymph nodes (LNs) before reaching distant sites, and LN assessment is an important part of MCT staging. Sentinel LN (SLN) mapping techniques to identify draining LNs are being developed and could improve the accuracy of MCT staging. The primary objective of this feasibility study was to determine the safety and effectiveness of contrast-enhanced ultrasound (CEUS) to identify SLNs. Secondary objectives were to determine if the SLNs identified by CEUS coincided with the regional LN predicted by the anatomical lymphosomes, if previous MCT excision altered CEUS SLN findings, and if CEUS could identify MCT nodal metastases. Between June 2017 and March 2019, 59 dogs with 62 MCTs were enrolled. No adverse events related to CEUS were reported. CEUS detected at least 1 SLN in 59/62 MCTs (95.2%, 95% CI: 86.5-99.0%). In only 32/59 (54.2%) MCTs, clinicians would have correctly predicted the SLN(s) identified by CEUS. Among the 35 MCTs that had histological examination of the SLN(s), the prevalence of metastasis was 60% (95% CI: 42.1-76.1%). Additional staging procedures did not reveal any metastases in dogs with histologically non-metastatic SLNs. Integration of CEUS SLN mapping into the routine staging of MCTs is promising, but future studies are required to refine this procedure and to investigate if it would translate into a clinical benefit.

Contrast-enhanced ultrasonography and blue dye methods in detection of sentinel lymph nodes following neoadjuvant chemotherapy in initially node positive breast cancer

BACKGROUND

Recent studies show that contrast-enhanced ultrasonography (CEUS) using SonoVue has the potential to improve the performance of sentinel lymph node biopsy (SLNB) in patients with early breast cancer. However, the evidence of SLNB using CEUS in patients converting from cN1 to cN0 after neoadjuvant chemotherapy (NAC) is lacking. The aim of this prospective study is to evaluate the feasibility of CEUS using SonoVue for the identification of sentinel lymph node (SLN) and the value of the combination of CEUS and blue dye (BD) for SLNB in patients converting from cN1 to cN0 following NAC.

METHODS

Patients with cytology-proven node positive breast cancer at the initial diagnosis (stage T1-T3N1M0) from January 2018 to January 2019, underwent NAC. Patients converting from cN1 to cN0 following NAC were enrolled and randomized into two groups for SLNB: the combination method group using CEUS and BD together, and the single BD method group. Then all patients underwent complete axillary lymph node dissection (ALND) and primary breast surgery. Compared with the final pathological results, the identification rate, sensitivity, specificity, accuracy, false negative rate, negative predictive value, positive predictive value were recorded and compared between two methods.

RESULTS

A total of 400 patients with stage T1-T3N1M0 disease underwent NAC between January 2018 to January 2019, among which 134 (33.5%) patients had clinically negative node confirmed by imaging after NAC and randomized into two groups. Each group included 67 cases. In the combination method group, contrast-enhanced lymphatic vessels in 66 cases of 67 were clearly visualized by US soon after the periareolar injection of SonoVue and the SLNs were accurately localized. The identification rate of the combination method was 98.5%%, which was significantly higher than 83.6% (56/67) using the single BD method. The mean numbers of SLNs identified by the combination method was higher than that by the single BD method. Compared with pathological diagnosis, sensitivity, specificity, accuracy, the positive predictive value, the negative predictive value, and the FNR of the combingation method were 84.4%, 100%, 89.4%, 100%, 75%, and 15.6%, respectively. In contrast, sensitivity, specificity, accuracy, the positive predictive value, the negative predictive value, and the FNR using single blue dye were 73.9%, 100%, 89.3%, 100%, 84.6%, and 26.1%, respectively. The FNR using the combination method was significantly lower than that using single BD.

CONCLUSION

Identification of SLNs in patients converting from cN1 to cN0 following NAC by CEUS is a technically feasible. The combination of CEUS and BD is more effective than BD alone for SLNB in patients converting from cN1 to cN0 following NAC.

Accuracy of CEUS-guided sentinel lymph node biopsy in early-stage breast cancer: a study review and meta-analysis

Objective

To investigate whether preoperative localization of sentinel lymph node (SLN) by contrast-enhanced ultrasound (CEUS) can further improve the accuracy of sentinel lymph node biopsy (SLNB).

Method

Collect published literatures or conference reports by searching electronic databases. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) evaluation method is used to evaluate the quality of the screened literatures. The pooled risk ratio of cancer metastasis of SLN identified by CEUS (CE-SLN) compared with SLN not identified by CEUS (nonCE-SLN) is calculated, and the pooled diagnostic accuracy of CE-SLN for pathological status of all SLNs is also evaluated.

Result

Through search and screening, a total of 16 studies were included, of which five and seven studies, respectively, entered the meta-analysis of metastatic risk ratio and diagnostic accuracy. The localization rate of preoperative CEUS for sentinel lymph nodes was 70 to 100%. The meta-analysis shows that the risk of metastasis of SLN identified by CEUS is significantly higher than that not identified by CEUS, 26.0% vs 4.6%, and risk ratio (RR) is 6.08 (95% CI 4.17–8.85). In early-stage breast cancer, the pathological status of CE-SLN is a good representative of all SLNs, with a pooled sensitivity of 98% (95% CI 0.94–1.00), pooled specificity of 100% (95% CI 0.99–1.00), diagnostic odds ratio (DOR) of 2153.18 (95% CI 476.53–9729.06), and area under the subject receiver operating characteristic (SROC) curve of 0.9968.

Conclusion

In early-stage breast cancer, preoperative localization of SLN by CEUS is expected to further improve the accuracy of sentinel lymph node biopsy (SLNB).

Two Non-gadolinium-based, Innovative Approaches to Preoperative Lymphangiography

Most magnetic resonance lymphangiography techniques employ intravenous gadolinium-based contrast agents, which carry a US Food and Drug Administration warning about gadolinium retention in the body when used intravenously. Because of this, there may be reluctance to perform intradermal injections of gadolinium-based contrast agents in patients with obstructed lymphatic drainage due to concerns about gadolinium retention in the skin and soft tissues and potential-related toxicity. The aim of this study was to show proof of concept of 2 preoperative lymphangiographic techniques that do not use gadolinium-based contrast agents. One technique used contrast-enhanced ultrasound with intradermal injections of microbubbles (Lumason) in a patient with stage 3, nonpitting left upper extremity edema. Another technique used magnetic resonance imaging with intradermal injections of 0.03 mg/mL or 0.003% ferumoxytol (Feraheme) in a patient with stage 3, nonpitting right lower extremity edema. Both contrast-enhanced ultrasound with microbubbles and magnetic resonance lymphangiogram with ferumoxytol were able to identify candidates for lymphovenous bypass surgery. These candidates were not identified by conventional indocyanine green injections. The authors conclude that (1) low-dose ferumoxytol is a potentially effective non-gadolinium–based contrast alternative to gadolinium-based contrast agent in magnetic resonance lymphangiography and (2) contrast-enhanced ultrasound can identify candidate lymphatic vessels for anastomosis.

Ribonucleic Acid Engineering of Dendritic Cells for Therapeutic Vaccination: Ready 'N Able to Improve Clinical Outcome?

Targeting and exploiting the immune system has become a valid alternative to conventional options for treating cancer and infectious disease. Dendritic cells (DCs) take a central place given their role as key orchestrators of immunity. Therapeutic vaccination with autologous DCs aims to stimulate the patient's own immune system to specifically target his/her disease and has proven to be an effective form of immunotherapy with very little toxicity. A great amount of research in this field has concentrated on engineering these DCs through ribonucleic acid (RNA) to improve vaccine efficacy and thereby the historically low response rates. We reviewed in depth the 52 clinical trials that have been published on RNA-engineered DC vaccination, spanning from 2001 to date and reporting on 696 different vaccinated patients. While ambiguity prevents reliable quantification of effects, these trials do provide evidence that RNA-modified DC vaccination can induce objective clinical responses and survival benefit in cancer patients through stimulation of anti-cancer immunity, without significant toxicity. Succinct background knowledge of RNA engineering strategies and concise conclusions from available clinical and recent preclinical evidence will help guide future research in the larger domain of DC immunotherapy.

Preliminary study of real-time three-dimensional contrast-enhanced ultrasound of sentinel lymph nodes in breast cancer

PURPOSE

To investigate the clinical value of real-time three-dimensional contrast-enhanced ultrasound (3D-CEUS) in the detection of sentinel lymph nodes (SLNs) and drainage lymphatics in breast cancer patients.

METHOD

The prospective study was performed in women with pathology-confirmed T1/2 breast cancer between June 2016 and December 2017 who underwent sentinel lymph node biopsy and 3D-CEUS. The number, size, location, enhancement pattern of SLNs, and the lymphatic drainage patterns were reviewed. The routes, location of SLNs, and lymph channels (LCs) on the surface were marked. All patients underwent blue dye-guided sentinel lymph node biopsy (SLNB) finally.

RESULTS

According to the postoperative pathology findings and the blue dye staining of the lymphatic drainage routes, there are six patterns of lymphatic drainage routes and the coincidence rate of the 3D-CEUS was 97.4%; the sensitivity, specificity, positive predictive value, negative predictive value, the LN detection rate, and the correct diagnosis rate of the 3D-CEUS were 75%, 93.0%, 81.8%, 89.9%, 95.3%, and 87.7%, respectively.

CONCLUSION

3D-CEUS is a new feasible and useful approach to detect the SLNs and LCs. 3D-CEUS can accurately localize the LCs and SLNs and estimate the presence of metastatic lymph nodes.

KEY POINTS

• The three-dimensional contrast-enhanced ultrasound can detect the sentinel lymph nodes. • The three-dimensional contrast-enhanced ultrasound can show the stereo direction of sentinel lymph nodes and lymph drainage routes. • The three-dimensional contrast-enhanced ultrasound can accurately localize the LCs and SLNs and estimate the presence of metastatic lymph nodes.

Preliminary study of contrast-enhanced ultrasound in combination with blue dye vs. indocyanine green fluorescence, in combination with blue dye for sentinel lymph node biopsy in breast cancer

Background

This preliminary study aimed to examine the feasibility of sentinel lymph node biopsy (SLNB) using contrast-enhanced ultrasound (CEUS) vs. indocyanine green fluorescence (ICG), combined with blue dye in patients with breast cancer.

Methods

This was a retrospective study of consecutive female patients with invasive stage I-III (based on pre-operative physical examination and imaging) primary breast cancer at the Peking Union Medical College Hospital between 01/2013 and 01/2015 who underwent preoperative SLNB by ICG + blue dye or CEUS + blue dye. The numbers of detected SLNs, detection rates, and recurrence-free survival (RFS) rates were compared between the two groups.

Results

A total of 443 patients were included. The detection rates of SLNs in the CEUS + blue dye and ICG + blue dye groups were 98.4 and 98.1%, respectively (P = 0.814). The average numbers of SLNs detected per patient showed no significant difference between the two groups (3.06 ± 1.33 and 3.12 ± 1.31 in the CEUS + blue dye and ICG + blue dye groups, respectively; P = 0.659). After a median follow-up of 46 months, five patients in the CEUS + blue dye group and 15 in the ICG + blue dye group had recurrence. RFS rates showed no significant difference (P = 0.55).

Conclusion

This preliminary study suggests that CEUS + blue dye and ICG + blue dye are both feasible for SLN detection in breast cancer.

Perinodal fibrosis developed after ultrasonography-guided core-needle biopsy of a contrast-enhanced ultrasound-detected sentinel axillary node interferes with subsequent surgical sentinel node dissection

OBJECTIVE

To evaluate perinodal fibrosis after 14-gauge staging core-needle biopsy (CNB) of the axillary sentinel lymph node (SLN) identified using contrast-enhanced ultrasonography (CEUS) and its interference with subsequent surgical SLN dissection in breast cancer patients.

METHODS

Frequencies or means of main clinical, sonographic, pathological, and surgical characteristics were calculated. We also compared patient groups with and without perinodal pathological fibrosis.

RESULTS

Forty-eight patients who underwent CEUS + CNB and axillary surgery were eligible for this cross-sectional study. Axillary surgical specimens showed perinodal fibrosis in 9/48 (18.7%) patients. Interference with SLN dissection was reported in 4/48 (8.3%) patients (two hematomas, three abnormal palpation findings, and four difficult dissections). The overall surgical detection rate of SLN was 43/48 (89.6%). In the majority of cases, perinodal fibrosis was described as moderate (4/9 [44.4%]) or severe (4/9 [44.4%]). The mean time elapsed between CEUS + CNB and axillary dissection was shorter in patients with perinodal fibrosis (P = .04). Interference with SLN dissection was only reported in patients with perinodal fibrosis (P < .001). Surgical SLN detection was successful in all nine cases in which perinodal pathological fibrosis or interference with SLN dissection was reported.

CONCLUSION

Perinodal fibrosis may impair the surgical SLN dissection in early stage breast cancer patients who were staged using CEUS + CNB using a14-gauge needle.

High Frame Rate Contrast-Enhanced Ultrasound Imaging for Slow Lymphatic Flow: Influence of Ultrasound Pressure and Flow Rate on Bubble Disruption and Image Persistence

Contrast-enhanced ultrasound (CEUS) utilising microbubbles shows great potential for visualising lymphatic vessels and identifying sentinel lymph nodes (SLNs) which are valuable for axillary staging in breast cancer patients. However, current CEUS imaging techniques have limitations that affect the accurate visualisation and tracking of lymphatic vessels and SLN. (i) Tissue artefacts and bubble disruption can reduce the image contrast. (ii) Limited spatial and temporal resolution diminishes the amount of information that can be captured by CEUS. (iii) The slow lymph flow makes Doppler-based approaches less effective. This work evaluates on a lymphatic vessel phantom the use of high frame rate (HFR) CEUS for the detection of lymphatic vessels where flow is slow. Specifically, the work particularly investigates the impact of key factors in lymphatic imaging, including ultrasound pressure and flow velocity as well as probe motion during vessel tracking, on bubble disruption and image contrast. Experiments were also conducted to apply HFR CEUS imaging on vasculature in a rabbit popliteal lymph node (LN). Our results show that (i) HFR imaging and singular value decomposition (SVD) filtering can significantly reduce tissue artefacts in the phantom at high clinical frequencies; (ii) the slow flow rate within the phantom makes image contrast and signal persistence more susceptible to changes in ultrasound amplitude or mechanical index (MI), and an MI value can be chosen to reach a compromise between images contrast and bubble disruption under slow flow condition; (iii) probe motion significantly decreases image contrast of the vessel, which can be improved by applying motion correction before SVD filtering; (iv) the optical observation of the impact of ultrasound pressure on HFR CEUS further confirms the importance of optimising ultrasound amplitude and (v) vessels inside rabbit LN with blood flow less than 3 mm/s are clearly visualised.

[Capabilities of contrast-enhanced ultrasound for preoperative assessment of regional lymphatic basin in patients with early oral cavity squamous cell cancer]

This review paper describes the possibilities of visualization of regional lymph nodes using contrast-enhanced ultrasound. Discussed is the experience of contrast-enhanced ultrasound implication for differential diagnosis of regional metastases of squamous cell carcinoma of the oral mucosa. The basics of the technique of contrast-enhanced ultrasound examination of the neck lymphatic basin are described.

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

CLINICAL/METHODICAL ISSUE

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

STANDARD RADIOLOGICAL METHODS

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

METHODICAL INNOVATIONS

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

PERFORMANCE

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

ACHIEVEMENTS

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

PRACTICAL RECOMMENDATIONS

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

Ultrasound multiple scattering with microbubbles can differentiate between tumor and healthy tissue in vivo

Most solid tumors are characterized by highly dense, isotropic vessel networks. Characterization of such features has shown promise for early cancer diagnosis. Ultrasound diffusion has been used to characterize the micro-architecture of complex media, such as bone and the lungs. In this work, we examine a non-invasive diffusion-based ultrasound technique to assess neo-vascularization. Because the diffusion constant reflects the density of scatterers in heterogeneous media, we hypothesize that by injecting microbubbles into the vasculature, ultrasound diffusivity can reflect vascular density (VD), thus differentiating the microvascular patterns between tumors and healthy tissue. The diffusion constant and its anisotropy are shown to be significantly different between fibrosarcoma tumors (n  =  16) and control tissue (n  =  18) in a rat animal model in vivo. The diffusion constant values for control and tumor were found to be 1.38  ±  0.51 mm2 µs-1 and 0.65  ±  0.27 mm2 µs-1, respectively. These results are corroborated with VD from acoustic angiography (AA) data, confirming increased vessel density in tumors compared to controls. The diffusion constant offers a promising way to quantitatively assess vascular networks when combined with contrast agents, which may allow early tumor detection and characterization.

Sentinel lymph node mapping by near-infrared fluorescence imaging and contrast-enhanced ultrasound in healthy dogs

Sentinel lymph node (SLN) mapping is a valuable and crucial diagnostic procedure in staging malignancies. We compared two non-invasive techniques, near-infrared (NIR) fluorescence imaging and contrast-enhanced ultrasound (CEUS), to identify the SLNs in three superficial anatomical regions in an animal model. Six healthy laboratory dogs were included in a proof-of-concept trial. A NIR fluorescent dye (Indocyanine Green) and microbubbles (Sonovue) were consecutively injected subdermally in the Inguinal, axillary and popliteal region to map the SLNs. Transcutaneous NIR fluorescence imaging identified SLNs in 17 out of a total of 18 occasions. CEUS identified SLNs in all regions (18/18). Whereas NIR fluorescence imaging performed better in the visualization of the afferent lymphatic tract, CEUS demonstrated different filling patterns of the SLNs, a feature potentially critical for the concept of SLN mapping in cancer patients. Both NIR fluorescence imaging and CEUS are safe, non-invasive, practical and accurate methods to perform real-time transcutaneous SLN mapping with potential in a clinical setting.

Contrast-enhanced ultrasonography in interventional oncology

Contrast-enhanced ultrasound (CEUS) has evolved from the use of agitated saline to second generation bioengineered microbubbles designed to withstand insonation with limited destruction. While only one of these newer agents is approved by the Food and Drug Administration for use outside echocardiography, interventional radiologists are increasingly finding off-label uses for ultrasound contrast agents. Notably, these agents have an extremely benign safety profile with no hepatic or renal toxicities and no radiation exposure. Alongside diagnostic applications, CEUS has begun to develop its own niche within the realm of interventional oncology. Certainly, the characterization of focal solid organ lesions (such as hepatic and renal lesions) by CEUS has been an important development. However, interventional oncologists are finding that the dynamic and real-time information afforded by CEUS can improve biopsy guidance, ablation therapy, and provide early evidence of tumor viability after locoregional therapy. Even more novel uses of CEUS include lymph node mapping and sentinel lymph node localization. Critical areas of research still exist. The purpose of this article is to provide a narrative review of the emerging roles of CEUS in interventional oncology.

New Technologies for Sentinel Lymph Node Detection

The 'standard of care' method for sentinel node mapping is the combination technique using radioisotope and blue dye although some centres use radioisotope or blue dye alone. Radioisotope usage requires licensing, has regulatory issues around handling and disposal of waste, and logistically may be unavailable or difficult to implement in some centres or less developed country. This has led to the development of alternative methods such as superparamagnetic iron oxide (SPIO), fluorescence techniques using indocyanine green (ICG) or fluorescein, computed tomography lymphography, and contrast-enhanced ultrasound scan (CEUS) using microbubbles. The newer techniques will potentially enable a more widespread adoption of this procedure; however, a common barrier for these techniques is the lack of standardisation and no randomised trials to evaluate their effectiveness against the current standard of care. Furthermore, many of these techniques are more costly and may become redundant in node-negative patients with small tumours if ongoing trials show that sentinel node biopsy offers no additional benefit to grey-scale axillary ultrasound. This review discusses the new techniques for sentinel node mapping that have emerged including their pros and cons.

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

OBJECTIVES

Mapping of the lymphatic chain for identification of the sentinel lymph node (SLN) is an important aspect of predicting outcomes for patients with breast cancer, and it is usually performed as an intraoperative procedure using blue dye and/or radiopharmaceutical agents. Recently, the use of contrast-enhanced ultrasound (CEUS) has been proposed as an alternative imaging technique for this mapping. The objective of this study was to evaluate the use of subdermal administration of the ultrasound (US) contrast agent Sonazoid (GE Healthcare, Oslo, Norway) in terms of patient safety and to select the dose to be used for lymphatic applications in humans.

METHODS

This study was performed in 12 female volunteers who received bilateral subdermal injections of Sonazoid (1 or 2 mL dose) in the mid-upper outer quadrant of their breasts at 2 different time points. Contrast-enhanced US examinations were performed 0, 0.25, 0.5, 1, 2, 4, 6, and 24 hours after injection to identify SLNs.

RESULTS

Sentinel lymph nodes were identified within the first hour after injection as enhanced structures, and there was no significant difference by dose in the number of SLNs identified (P = .74). The volunteers only had minor adverse experiences (AEs) that resolved completely without intervention by study completion.

CONCLUSIONS

The subdermal use of Sonazoid in this study showed only minor local and nonsignificant AEs that were completely resolved without any intervention. Two different doses were compared with no significant differences observed between them. Hence, the lower dose studied (1 mL) was selected for use in future clinical studies.

[Imaging diagnostic methods for identification of sentinel lymph nodes in patients with early squamous cell carcinoma of the oral cavity mucosa: a literature review]

The paper describes properties of clinical visualization approaches which are applied for detection of sentinel lymph nodes in patients suffering from oral cavity squamous cell cancer. Diagnostic efficiency results and technological features of different imaging techniques are discussed.

Variation of sentinel lymphatic channels (SLCs) and sentinel lymph nodes (SLNs) assessed by contrast-enhanced ultrasound (CEUS) in breast cancer patients

BACKGROUND

The objective of this study was to assess the feasibility of detecting the variation of sentinel lymphatic channels (SLCs) and sentinel lymph nodes (SLNs) in breast cancer patients using contrast-enhanced ultrasound (CEUS).

METHODS

A total of 46 breast cancer patients were prospectively recruited in the study. All the participants received intradermal and peritumoral injection of microbubbles as contrast agent, and SLCs and SLNs were assessed preoperatively. Blue dye was injected subareolarly and peritumorally during the surgery. The SLNs detected by CEUS and blue dye were sent to the pathology laboratory for histopathological analysis.

RESULTS

At least one SLC and SLN were detected by CEUS in all 46 cases. Three types of SLCs were detected, including superficial sentinel lymphatic channels (SSLCs), penetrating sentinel lymphatic channels (PSLCs), and deep sentinel lymphatic channels (DSLCs). Five lymphatic drainage patterns (LDPs) were found, including SSLC, PSLC, SSLC + PSLC, SSLC + DSLC, and SSLC + PSLC + DSLC. Only SSLC was detected on CEUS in 24 cases; only PSLC was detected in 3 cases; both SSLC and PSLC were detected in 8 cases; both SSLC and DSLC were detected in 7 cases; SSLC, PSLC, and DSLC were all detected in the remaining 4 cases. An actual LDP was defined on the combination of CEUS and dissection of the specimen. The accuracy rate of CEUS was 43/46. Interestingly, a bifurcated SLC was found in 8 patients. In 3 patients, a discontinuous SLC and non-enhanced SLN were found by CEUS. Also, no dyed SLNs were detected during the surgery. The axillary lymph nodes turned out tumor involved histologically.

CONCLUSION

CEUS is feasible to assess the variation of SLCs and SLNs preoperatively in breast cancer patients. SLNB is not suggested when a discontinuous SLC and non-enhanced SLN were detected by CEUS.

Contrast-enhanced ultrasound imaging in vivo with laser-activated nanodroplets

PURPOSE

This study introduces a real-time contrast-enhanced ultrasound imaging method with recently developed laser-activated nanodroplets (LANDs), a new class of phase-change nanometer-scale contrast agents that provides perceptible, sustained high-contrast with ultrasound.

METHODS

In response to pulsed laser irradiation, the LANDs-, which contain liquid perfluorohexane and optical fuses-blink (vaporize and recondense). That is, they change their state from liquid nanodroplets to gas microbubbles, and then back to liquid nanodroplets. In their gaseous microbubble state, the LANDs provide high-contrast ultrasound, but the microbubbles formed in situ typically recondense in tens of milliseconds. As a result, LAND visualization by standard, real-time ultrasound is limited. However, the periodic optical triggering of LANDs allows us to observe corresponding transient, periodic changes in ultrasound contrast. This study formulates a probability function that measures how ultrasound temporal signals vary in periodicity. Then, the estimated probability is mapped onto a B-scan image to construct a LAND-localized, contrast-enhanced image. We verified our method through phantom and in vivo experiments using an ultrasound system (Vevo 2100, FUJIFILM VisualSonics, Inc., Toronto, ON, Canada) operating with a 40-MHz linear array and interfaced with a 10 Hz Nd:YAG laser (Phocus, Opotek Inc., Carlsbad, CA, USA) operating at the fundamental 1064 nm wavelength.

RESULTS

From the phantom study, the results showed improvements in the contrast-to-noise ratio of our approach over conventional ultrasound ranging from 129% to 267%, with corresponding execution times of 0.10 to 0.29 s, meaning that the developed method is computationally efficient while yielding high-contrast ultrasound. Furthermore, in vivo sentinel lymph node (SLN) imaging results demonstrated that our technique could accurately identify the SLN.

CONCLUSIONS

The results indicate that our approach enables efficient and robust LAND localization in real time with substantially improved contrast, which is essential for the successful translation of this contrast agent platform to clinical settings.

Identification of Sentinel Lymph Nodes Using Contrast-Enhanced Ultrasound in Breast Cancer

Sentinel lymph node (SLN) biopsy has become the standard of care in axillary staging of breast cancer patients who are clinically node negative as it reduces the morbidity of axillary nodal dissection. SLN biopsy using blue dye and radioisotopes have high identification rates but its limitations include anaphylaxis, disposal of radioactive waste, and potential second surgery in up to 35% of patients who show nodal metastases on SLN biopsy. Contrast-enhanced ultrasound (CEUS) has the potential for SLNs to be identified without the aforementioned risks. CEUS involves the administration of intravenous contrast agents containing microbubbles of perfluorocarbon or nitrogen gas. The bubbles greatly affect ultrasound backscatter and increase vascular contrast in a similar manner to intravenous contrast agents used in CT and MRI. It is safe and easily performed with no requirement for ionizing radiation and no risk of nephrotoxicity. Microbubbles are taken up by lymph nodes when injected directly into tissues, including sub-areolar injection in the breast cancer patient. This method may prove valuable in patients with ductal carcinoma in situ, where operative SLN biopsy remains controversial, and in women undergoing prophylactic mastectomies for high risk. This technique may also have a role after neoadjuvant chemotherapy where frequently there is fibrosis in the treated SLNs.

Contrast-enhanced ultrasound mapping of sentinel lymph nodes in oral tongue cancer-a pilot study

OBJECTIVES

To assess the usefulness of contrast-enhanced ultrasound (CEUS) with peritumoral injection of microbubble contrast agent for detecting the sentinel lymph nodes for oral tongue carcinoma.

METHODS

The study was carried out on 12 patients with T1-2cN0 oral tongue cancer. A radical resection of the primary disease was planned; a modified radical supraomohyoid neck dissection was reserved for patients with larger lesions (T2, n = 8). The treatment plan and execution were not influenced by sentinel node mapping outcome. The Sonovue^™ contrast agent (Bracco Imaging, Milan, Italy) was utilized. After detection, the position and radiologic features of the sentinel nodes were recorded.

RESULTS

The identification rate of the sentinel nodes was 91.7%; one patient failed to demonstrate any enhanced areas. A total of 15 sentinel nodes were found in the rest of the 11 cases, with a mean of 1.4 nodes for each patient. The sentinel nodes were localized in: Level IA-1 (6.7%) node; Level IB-11 (73.3%) nodes; Level IIA-3 (20.0%) nodes. No contrast-related adverse effects were observed.

CONCLUSIONS

For oral tongue tumours, CEUS is a feasible and potentially widely available approach of sentinel node mapping. Further clinical research is required to establish the position of CEUS detection of the sentinel nodes in oral cavity cancers.

Indocyanine-green-loaded microbubbles for localization of sentinel lymph node using near-infrared fluorescence/ultrasound imaging: a feasibility study

Current strategies for sentinel lymph node (SLN) biopsy to detect cancer metastasis have some limitations such as the associated radiation exposure and high false-negative rates due to dye particles through the true SLNs to contiguous LNs.

[Focus on methods for detection of sentinel nodes in breast cancer]

The sentinel node procedure (GS) is the recommended technique for axillary surgical exploration in localized breast cancer with no clinical or radiological lymph node involvement. This surgical technique is based on a dual isotope and colorimetric detection. Although it allows a significant reduction in morbidity compared to axillary dissection (CA), this procedure induces a number of organizational constraints, in particular for the radioisotope injection. Specially for this reason, other GS methods have emerged in recent years, some of which appear promising (detection by fluorescence and magnetic iron). The objective of this paper was to carry out a synthesis of the reference method of detection (radioisotope) GS and analyze the recent literature on new detection methods.