The safety of deFinity and Optison for ultrasound image enhancement: a retrospective analysis of 78,383 administered contrast doses

Restoring microvascular circulation with diagnostic ultrasound and contrast agent: rationale and design of the REDUCE trial

OBJECTIVES

This study aims to evaluate the efficacy and cost-effectiveness of sonothrombolysis delivered pre and post primary percutaneous coronary intervention (pPCI) on infarct size assessed by cardiac MRI, in patients presenting with STEMI, when compared against sham procedure.

BACKGROUND

More than a half of patients with successful pPCI have significant microvascular obstruction and residual infarction. Sonothrombolysis is a therapeutic use of ultrasound with contrast enhancement that may improve microcirculation and infarct size. The benefits and real time physiological effects of sonothrombolysis in a multicentre setting are unclear.

METHODS

The REDUCE (Restoring microvascular circulation with diagnostic ultrasound and contrast agent) trial is a prospective, multicentre, patient and outcome blinded, sham-controlled trial. Patients presenting with STEMI will be randomized to one of 2 treatment arms, to receive either sonothrombolysis treatment or sham echocardiography before and after pPCI. This tailored design is based on preliminary pilot data from our centre, showing that sonothrombolysis can be safely delivered, without prolonging door to balloon time. Our primary endpoint will be infarct size assessed on day 4±2 on Cardiac Magnetic Resonance (CMR). Patients will be followed up for 6 months post pPCI to assess secondary endpoints. Sample size calculations indicate we will need 150 patients recruited in total.

CONCLUSIONS

This multicentre trial will test whether sonothrombolysis delivered pre and post primary PCI can improve patient outcomes and is cost-effective, when compared with sham ultrasound delivered with primary PCI. The results from this trial may provide evidence for the utilization of sonothrombolysis as an adjunct therapy to pPCI to improve cardiovascular outcomes in STEMI. ANZ Clinical Trial Registration number: ACTRN 12620000807954.

Radiation enhancement using focussed ultrasound-stimulated microbubbles for head and neck cancer: A phase 1 clinical trial

BACKGROUND AND PURPOSE

Preclinical research demonstrated that the exposure of microbubbles (intravascular gas microspheres) to focussed ultrasound within the targeted tumour upregulates pro-apoptotic pathways and enhances radiation-induced tumour cell death. This study aimed to assess the safety and efficacy of magnetic resonance (MR)-guided focussed ultrasound-stimulated microbubbles (MRgFUS-MB) for head and neck cancers (HN).

MATERIALS AND METHODS

This prospective phase 1 clinical trial included patients with newly diagnosed or recurrent HN cancer (except nasopharynx malignancies) for whom locoregional radiotherapy with radical- or palliative-intent as deemed appropriate. Patients with contraindications for microbubble administration or contrast-enhanced MR were excluded. MR-coupled focussed ultrasound sonicated intravenously administered microbubbles within the MR-guided target volume. Patients receiving 5-10 and 33-35 radiation fractions were planned for 2 and 3 MRgFUS-MB treatments, respectively. Primary endpoint was toxicity per CTCAEv5.0. Secondary endpoint was tumour response at 3 months per RECIST 1.1 criteria.

RESULTS

Twelve patients were enrolled between Jun/2020 and Nov/2023, but 1 withdrew consent. Eleven patients were included in safety analysis. Median follow-up was 7 months (range, 0.3-38). Most patients had oropharyngeal cancer (55 %) and received 20-30 Gy/5-10 fractions (63 %). No systemic toxicity or MRgFUS-MB-related adverse events occurred. The most severe acute adverse events were radiation-related grade 3 toxicities in 6 patients (55 %; dermatitis in 3, mucositis in 1, dysphagia in 6). No radiation necrosis or grade 4/5 toxicities were reported. 8 patients were included in the 3-month tumour response assessment: 4 had partial response (50 %), 3 had complete response (37.5 %), and 1 had progressive disease (12.5 %).

CONCLUSIONS

MRgFUS-MB treatment was safe and associated with high rates of tumour response at 3 months.

Advances in Imaging of Compressive Neuropathies

Ultrasound and magnetic resonance neurography are useful modalities to aid in the assessment of compressive neuropathies, although they are still limited in their resolution of nerve microstructure and their capacity to monitor postoperative nerve recovery. Optical coherence tomography, a preclinical imaging modality, is promising in its ability to better identify structural and potential physiologic changes to peripheral nerves, but requires additional testing and research prior to widespread clinical implementation. Further advances in nerve imaging may elucidate the ability to visualize the zone of nerve injury intraoperatively, monitor the progression of nerve regeneration, and localize problems during nerve recovery.

Sonothrombolysis Before and After Percutaneous Coronary Intervention Provides the Largest Myocardial Salvage in ST Segment Elevation Myocardial Infarction

BACKGROUND

Sonothrombolysis is a therapeutic application of ultrasound with ultrasound contrast for patients with ST elevation myocardial infarction (STEMI). Recent trials demonstrated that sonothrombolysis, delivered before and after primary percutaneous coronary intervention (pPCI), increases infarct vessel patency, improves microvascular flow, reduces infarct size, and improves ejection fraction. However, it is unclear whether pre-pPCI sonothrombolysis is essential for therapeutic benefit. We designed a parallel 3-arm sham-controlled randomized controlled trial to address this.

METHODS

Patients presenting with first STEMI undergoing pPCI within 6 hours of symptom onset were randomized 1:1:1 into 3 arms: sonothrombolysis pre-/post-pPCI (group 1), sham pre- sonothrombolysis post-pPCI (group 2), and sham pre-/post-pPCI (group 3). Our primary end point was infarct size (percentage of left ventricular mass) assessed by cardiac magnetic resonance imaging at day 4 ± 2. Secondary end points included myocardial salvage index (MSI) and echocardiographic parameters at day 4 ± 2 and 6 months.

RESULTS

Our trial was ceased early due to the COVID pandemic. From 122 patients screened between September 2020 and June 2021, 51 patients (age 60, male 82%) were included postrandomization. Median sonothrombolysis took 5 minutes pre-pPCI and 15 minutes post-, without significant door-to-balloon delay. There was a trend toward reduction in median infarct size between group 1 (8% [interquartile range, 4,11]), group 2 (11% [7, 19]), or group 3 (15% [9, 22]). Similarly there was a trend toward improved MSI in group 1 (79% [64, 85]) compared to groups 2 (51% [45, 70]) and 3 (48% [37, 73]) No major adverse cardiac events occurred during hospitalization.

CONCLUSIONS

Pre-pPCI sonothrombolysis may be key to improving MSI in STEMI. Multicenter trials and health economic analyses are required before clinical translation.

Radiation enhancement using focussed ultrasound-stimulated microbubbles for breast cancer: A Phase 1 clinical trial

BACKGROUND

Preclinical studies have demonstrated that tumour cell death can be enhanced 10- to 40-fold when radiotherapy is combined with focussed ultrasound-stimulated microbubble (FUS-MB) treatment. The acoustic exposure of microbubbles (intravascular gas microspheres) within the target volume causes bubble cavitation, which induces perturbation of tumour vasculature and activates endothelial cell apoptotic pathways responsible for the ablative effect of stereotactic body radiotherapy. Subsequent irradiation of a microbubble-sensitised tumour causes rapid increased tumour death. The study here presents the mature safety and efficacy outcomes of magnetic resonance (MR)-guided FUS-MB (MRgFUS-MB) treatment, a radioenhancement therapy for breast cancer.

METHODS AND FINDINGS

This prospective, single-center, single-arm Phase 1 clinical trial included patients with stages I-IV breast cancer with in situ tumours for whom breast or chest wall radiotherapy was deemed adequate by a multidisciplinary team (clinicaltrials.gov identifier: NCT04431674). Patients were excluded if they had contraindications for contrast-enhanced MR or microbubble administration. Patients underwent 2 to 3 MRgFUS-MB treatments throughout radiotherapy. An MR-coupled focussed ultrasound device operating at 800 kHz and 570 kPa peak negative pressure was used to sonicate intravenously administrated microbubbles within the MR-guided target volume. The primary outcome was acute toxicity per Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Secondary outcomes were tumour response at 3 months and local control (LC). A total of 21 female patients presenting with 23 primary breast tumours were enrolled and allocated to intervention between August/2020 and November/2022. Three patients subsequently withdrew consent and, therefore, 18 patients with 20 tumours were included in the safety and LC analyses. Two patients died due to progressive metastatic disease before 3 months following treatment completion and were excluded from the tumour response analysis. The prescribed radiation doses were 20 Gy/5 fractions (40%, n = 8/20), 30 to 35 Gy/5 fractions (35%, n = 7/20), 30 to 40 Gy/10 fractions (15%, n = 3/20), and 66 Gy/33 fractions (10%, n = 2/20). The median follow-up was 9 months (range, 0.3 to 29). Radiation dermatitis was the most common acute toxicity (Grade 1 in 16/20, Grade 2 in 1/20, and Grade 3 in 2/20). One patient developed grade 1 allergic reaction possibly related to microbubbles administration. At 3 months, 18 tumours were evaluated for response: 9 exhibited complete response (50%, n = 9/18), 6 partial response (33%, n = 6/18), 2 stable disease (11%, n = 2/18), and 1 progressive disease (6%, n = 1/18). Further follow-up of responses indicated that the 6-, 12-, and 24-month LC rates were 94% (95% confidence interval [CI] [84%, 100%]), 88% (95% CI [75%, 100%]), and 76% (95% CI [54%, 100%]), respectively. The study's limitations include variable tumour sizes and dose fractionation regimens and the anticipated small sample size typical for a Phase 1 clinical trial.

CONCLUSIONS

MRgFUS-MB is an innovative radioenhancement therapy associated with a safe profile, potentially promising responses, and durable LC. These results warrant validation in Phase 2 clinical trials.

TRIAL REGISTRATION

clinicaltrials.gov, identifier NCT04431674.

Pulmonary Transit Time Assessment by CEUS in Healthy Rabbits: Feasibility, and the Effects of UCAs Dilution Concentration

To evaluate the inter-observer variability and the intra-observer repeatability of pulmonary transit time (PTT) measurement using contrast-enhanced ultrasound (CEUS) in healthy rabbits, and assess the effects of dilution concentration of ultrasound contrast agents (UCAs) on PTT. Thirteen healthy rabbits were selected, and five concentrations UCAs of 1:200, 1:100, 1:50, 1:10, and 1:1 were injected into the right ear vein. Five digital loops were obtained from the apical 4-chamber view. Four sonographers obtained PTT by plotting the TIC of right atrium (RA) and left atrium (LA) at two time points (T1 and T2). The frame counts of the first appearance of UCAs in RA and LA had excellent inter-observer agreement, with intra-class correlations (ICC) of 0.996, 0.988, respectively. The agreement of PTT among four observers was all good at five different concentrations, with an ICC of 0.758-0.873. The reproducibility of PTT obtained by four observers at T1 and T2 was performed well, with ICC of 0.888-0.961. The median inter-observer variability across 13 rabbits was 6.5% and the median variability within 14 days for 4 observers was 1.9%, 1.7%, 2.2%, 1.9%, respectively; The PTT of 13 healthy rabbits is 1.01 ± 0.18 second. The difference of PTT between five concentrations is statistically significant. The PTT obtained by a concentration of 1:200 and 1:100 were higher than that of 1:1, while there were no significantly differences in PTT of a concentration of 1:1, 1:10, and 1:50. PTT measured by CEUS in rabbits is feasible, with excellent inter-observer and intra-observer reliability and reproducibility, and dilution concentration of UCAs influences PTT results.

Ultrasound-responsive microbubbles and nanodroplets: A pathway to targeted drug delivery

Ultrasound-responsive agents have shown great potential as targeted drug delivery agents, effectively augmenting cell permeability and facilitating drug absorption. This review focuses on two specific agents, microbubbles and nanodroplets, and provides a sequential overview of their drug delivery process. Particular emphasis is given to the mechanical response of the agents under ultrasound, and the subsequent physical and biological effects on the cells. Finally, the state-of-the-art in their pre-clinical and clinical implementation are discussed. Throughout the review, major challenges that need to be overcome in order to accelerate their clinical translation are highlighted.

Incidence of Severe Adverse Drug Reactions to Ultrasound Enhancement Agents in a Contemporary Echocardiography Practice

OBJECTIVES

Prior data indicate a very rare risk of serious adverse drug reaction (ADR) to ultrasound enhancement agents (UEAs). We sought to evaluate the frequency of ADR to UEA administration in contemporary practice.

METHODS

We retrospectively reviewed 4 US health systems to characterize the frequency and severity of ADR to UEA. Adverse drug reactions were considered severe when cardiopulmonary involvement was present and critical when there was loss of consciousness, loss of pulse, or ST-segment elevation. Rates of isolated back pain and headache were derived from the Mayo Clinic Rochester stress echocardiography database where systematic prospective reporting of ADR was performed.

RESULTS

Among 26,539 Definity and 11,579 Lumason administrations in the Mayo Clinic Rochester stress echocardiography database, isolated back pain or headache was more frequent with Definity (0.49% vs 0.04%, P < .0001) but less common with Definity infusion versus bolus (0.08% vs 0.53%, P = .007). Among all sites there were 201,834 Definity and 84,943 Lumason administrations. Severe and critical ADR were more frequent with Lumason than with Definity (0.0848% vs 0.0114% and 0.0330% vs 0.0010%, respectively; P < .001 for each). Among the 3 health systems with >2,000 Lumason administrations, the frequency of severe ADR with Lumason ranged from 0.0755% to 0.1093% and the frequency of critical ADR ranged from 0.0293% to 0.0525%. Severe ADR rates with Definity were stable over time but increased in more recent years with Lumason (P = .02). Patients with an ADR to Lumason since the beginning of 2021 were more likely to have received a COVID-19 vaccination compared with matched controls (88% vs 75%; P = .05) and more likely to have received Moderna than Pfizer-Biotech (71% vs 26%, P < .001).

CONCLUSION

Severe and critical ADR, while rare, were more frequent with Lumason, and the frequency has increased in more recent years. Additional work is needed to better understand factors, including associations with recently developed mRNA vaccines, which may be contributing to the increased rates of ADR to UEA since 2021.

Efficacy and safety of use of ultrasound enhancing agent in patients hospitalized with COVID-19

PURPOSE

The efficacy and safety of ultrasound enhancing agent (UEA) was unknown in the COVID-19 hospitalized patients. We set out to establish the utility of UEA and its safety profile.

METHODS

A retrospective observational study of prospectively assessed hospitalized patients referred for transthoracic echocardiography (TTE) for suspected cardiac pathology due to COVID-19. The indications and subsequent ability to answer the indications for all TTE were reviewed, as well as impact on diagnosis and management. UEA safety was considered through 48 h mortality.

RESULTS

From a total of 364 patients (mean age 64.8yrs, 64% males) hospitalized with COVID-19 with TTE requested, an indication could be identified in 363, and 61 required administration of UEA. Standard TTE was able to answer the original indication in 275 (75.8%) patients. This was increased to 322 (88.7%) patients, a relative increase of 17.1%, with the use of UEA (p < 0.001). There was subsequent change in diagnosis in 22 out of 61 (36%) patients receiving UEA and change in management in 13 out of 61 (21.3%). There was no significant increase in 48 h (p = 0.14) mortality with UEA use. The patient population of TTE with UEA versus TTE without UEA differed in having a higher incidence of left ventricular systolic dysfunction, right ventricular dilatation, and self-defined white ethnicity.

CONCLUSION

The use of UEA in COVID-19 hospitalized patients, including those who were critically ill, provided incremental information when compared to TTE without UEA resulting in both changes in diagnosis and management plan and appears to be safe.

Safety of Ultrasound Contrast Agents in Pediatric Patients With Sickle Cell Disease and Trait

Ultrasound contrast agent (UCA) use is increasing. Recent isolated reports observed a rise in pain-related adverse events with the intravenous administration of the UCA Definity in adults with sickle cell disease. To date, no studies have investigated the incidence of similar adverse events with UCA Lumason or Optison. We describe our experience regarding the safety of Lumason and Optison in children with sickle cell disease and trait who underwent contrast-enhanced ultrasound exams in our department with intravenous, intravesical, and other intracavitary routes. No pain-related or other adverse events were observed in this pediatric population with any route of UCA administration.

Contrast echocardiography: a practical guideline from the British Society of Echocardiography

Ultrasound contrast agents (UCAs) have a well-established role in clinical cardiology. Contrast echocardiography has evolved into a routine technique through the establishment of contrast protocols, an excellent safety profile, and clinical guidelines which highlight the incremental prognostic utility of contrast enhanced echocardiography. This document aims to provide practical guidance on the safe and effective use of contrast; reviews the role of individual staff groups; and training requirements to facilitate its routine use in the echocardiography laboratory.

Contrast Echocardiography for Assessing Myocardial Perfusion

PURPOSE OF REVIEW

Improvements in ultrasound methods for detecting microbubble ultrasound enhancing agents have led to an increase in the use of perfusion imaging with myocardial contrast echocardiography (MCE). This technique is now beginning to play an important role in specific clinical scenarios, which is the focus of this review.

RECENT FINDINGS

MCE was originally conceived as a technique for detecting resting perfusion abnormalities related to ischemia at rest or during stress from coronary artery disease. More recently, MCE has increasingly been used in circumstances where the technique's ability to provide rapid, quantitative, or bedside assessment of perfusion is advantageous. Quantitative MCE is also increasingly being used as a research technique for evaluating pathobiology and therapy that involve changes in the myocardial microcirculation. While MCE was developed and validated decades ago, it is only now beginning to be used by an increasing number of clinicians due to improvements in imaging technology and recognition of specific situations where the technique is impactful.

Imaging in inflammatory arthritis: progress towards precision medicine

Imaging techniques such as ultrasonography and MRI have gained ground in the diagnosis and management of inflammatory arthritis, as these imaging modalities allow a sensitive assessment of musculoskeletal inflammation and damage. However, these techniques cannot discriminate between disease subsets and are currently unable to deliver an accurate prediction of disease progression and therapeutic response in individual patients. This major shortcoming of today's technology hinders a targeted and personalized patient management approach. Technological advances in the areas of high-resolution imaging (for example, high-resolution peripheral quantitative computed tomography and ultra-high field MRI), functional and molecular-based imaging (such as chemical exchange saturation transfer MRI, positron emission tomography, fluorescence optical imaging, optoacoustic imaging and contrast-enhanced ultrasonography) and artificial intelligence-based data analysis could help to tackle these challenges. These new imaging approaches offer detailed anatomical delineation and an in vivo and non-invasive evaluation of the immunometabolic status of inflammatory reactions, thereby facilitating an in-depth characterization of inflammation. By means of these developments, the aim of earlier diagnosis, enhanced monitoring and, ultimately, a personalized treatment strategy looms closer.

Contrast-Enhanced Ultrasound for Image-Guided Procedures

Contrast-enhanced ultrasound (CEUS) uses intravenously injected gas microbubbles as a pure blood pool contrast agent to demonstrate blood flow and tissue perfusion at a much higher sensitivity than color Doppler and power Doppler ultrasound. CEUS has gained traction in abdominal diagnostic imaging for improved lesion detection and characterization and a complementary problem-solving tool to CT and MRI. In addition to its diagnostic applications, CEUS has also proven useful for pre-procedure planning, procedure guidance, and post-procedure evaluation. This review provides a practical overview and guides to the application of CEUS in percutaneous, ultrasound-guided, needle-driven procedures, focusing on 2 common procedures, which illustrate the many benefits of CEUS- core needle biopsy (CNB) and percutaneous hepatic lesion ablation.

Safety of Lumason® (SonoVue®) in special populations and critically ill patients

Evidence for the safe use of Lumason® (SonoVue®), an ultrasound enhancing agent (UEA), in special patient populations is critical to enable healthcare professionals to make informed decisions concerning its use in such patients. Herein, we provide insight on the safety and tolerability of Lumason® in special patient populations. Findings are presented from clinical pharmacology studies conducted in patients with compromised cardiopulmonary conditions, from a retrospective study performed in critically ill patients, and from post-marketing surveillance data from over 20 years of market use of Lumason® (SonoVue®). No detrimental effects of Lumason® on cardiac electrophysiology were observed in patients with coronary artery disease (CAD), and no significant effects on pulmonary hemodynamics were noted in patients with pulmonary hypertension or congestive heart failure. Similarly, no effects on several assessments of pulmonary function (e.g., FVC) were observed in patients with chronic obstructive pulmonary disease (COPD), and no clinically meaningful changes in O2 saturation or other safety parameters were observed after administration of Lumason® to patients with diffuse interstitial pulmonary fibrosis (DIPF). The retrospective study of critically ill patients revealed no significant difference for in-hospital mortality between patients administered Lumason® for echocardiography versus those who had undergone echocardiography without contrast agent. Post-marketing surveillance revealed very low reporting rates (RR) for non-serious and serious adverse events and that serious hypersensitivity reactions were rare. These findings confirm that Lumason® is a safe and well tolerated UEA for use in special populations and critically ill patients.

Contrast-Enhanced Ultrasonography for Acute Kidney Injury: A Systematic Review and Meta-Analysis

OBJECTIVE

The aim of the work described here was to provide an evidence-based evaluation of contrast-enhanced ultrasonography (CEUS) in acute kidney injury (AKI) and assess variations in renal microperfusion with CEUS quantitative parameters in patients at a high risk of developing AKI.

METHODS

A meta-analysis and systematic review were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the Embase, MEDLINE, Web of Science and the Cochrane Library databases were used to search the relevant articles systematically (2000-2022). Studies using CEUS to assess renal cortical microcirculation in AKI were included.

RESULTS

Six prospective studies (374 patients) were included. The overall quality of included studies was moderate to high. CEUS measures, maximum intensity (standard mean difference [SMD]: -1.37, 95% confidence interval [CI]: -1.64 to -1.09) and wash-in rate (SMD: -0.77, 95% CI: -1.09 to -0.45) were lower in the AKI+ group than in the AKI- group, and mean transit time (SMD: 0.76, 95% CI: 0.11-1.40) and time to peak (SMD: 1.63, 95% CI: 0.99-2.27) were higher in the AKI+ group. Moreover, maximum intensity and wash-in rate values changed before creatinine changed in the AKI+ group.

CONCLUSION

Patients with AKI had reduced microcirculatory perfusion, prolonged perfusion time and a reduced rising slope in the renal cortex, which occurred before serum creatinine changes. And they could be measured using CEUS, indicating that CEUS could help in the diagnosis of AKI.

[Contrast-enhanced ultrasound: history, application and perspectives]

The article discusses the stages of formation and development of ultrasound diagnostics, including those with contrast enhancement. The main types of contrast agents and their mechanism of action are presented. Examples of the use of contrast-enhanced ultrasound in various fields of medicine are given. The prospects of the method and its place in clinical practice are discussed.

Photoacoustic/ultrasound-guided gene silencing: Multifunctional microbubbles for treating adjuvant-induced arthritis

AIMS

To effectively deliver small interfering RNA (siRNA) to inflammatory tissues for treating rheumatoid arthritis (RA), we developed the multifunctional microbubbles (MBs) to perform photoacoustic/ultrasound-guided gene silencing.

METHODS

Fluorescein amidite (FAM)-labelled tumour necrosis factor-α (TNF-α)-siRNA and cationic MBs were mixed to fabricate FAM-TNF-α-siRNA-cMBs. The cell transfection efficacy of FAM-TNF-α-siRNA-cMBs was evaluated in vitro on RAW264.7 cells. Subsequently, wistar rats with adjuvant-induced arthritis (AIA) were injected intravenously with MBs and simultaneously subjected to low-frequency ultrasound for ultrasound-targeted microbubble destruction (UTMD). Photoacoustic imaging (PAI) was utilized to visualize the distribution of siRNA. And the clinical and pathological changes of AIA rats was estimated.

RESULTS

FAM-TNF-α-siRNA-cMBs were evenly distributed within the RAW264.7 cells and significantly reduced TNF-α mRNA levels of the cells. For AIA rats, the entering and collapsing of MBs was visualized by contrast-enhanced ultrasound (CEUS). Photoacoustic imaging showed markedly enhanced signals following injection, indicating localization of the FAM-labelled siRNA. The articular tissues of the AIA rats treated with TNF-α-siRNA-cMBs and UTMD showed decreased TNF-α expression levels.

CONCLUSIONS

The theranostic MBs exhibited a TNF-α gene silencing effect under the guidance of CEUS and PAI. The theranostic MBs served as vehicles for delivering siRNA as well as contrast agents for CEUS and PAI.

Increased Susceptibility for Adverse Reactions to Ultrasound Enhancing Agents in Sickle Cell Disease

BACKGROUND

Pain-related adverse events (AEs) to ultrasound enhancing agents (UEAs) have been reported in patients with sickle cell disease (SCD). The aims of this study were to characterize the scope of these AEs in the SCD population and to investigate potential mechanisms on the basis of pathways involved in SCD vaso-occlusive crisis (VOC) and pain.

METHODS

The prevalence and classification of AEs were analyzed from two clinical trials in which high-dose Definity infusions were used in patients with SCD (n = 55) or matched control subjects (n = 43) to study muscle or myocardial microvascular perfusion. Because complement (C') activation can trigger VOC in SCD, C' activation and surface adhesion of C' proteins on lipid UEAs were studied in vitro. C'-mediated UEA attachment to bone marrow immune cells was assessed using flow cytometry in a murine SCD model (Townes mice). Blood from patients receiving Definity was obtained to measure specific lysophospholipid metabolites of lipids in Definity thought to mediate SCD pain.

RESULTS

Moderate or greater AEs, all of which were nociceptive (back or bone pain), occurred in one control subject and nine SCD subjects (2% vs 16%, P = .02). Patients with SCD who had AEs tended to have more severe manifestations of SCD. Three of the subjects with SCD had previously received Definity without complications. In patients with SCD, four AEs were classified as severe in intensity and as serious AEs on the basis of need for medical intervention. AEs were described to be similar to SCD-related pain, but there was no evidence for VOC, hemolysis, hypotension, or hypoxemia. At baseline, markers of C' activation were greater in patients with SCD than control subjects. However, after administration of lipid UEAs, SCD and control subjects were similar with regard to C' activation response, anaphylatoxin production, bone marrow microbubble retention, and production of lysophospholipids. There was a trend toward increased deposition of C3b and C3bi on lipid UEAs exposed to serum from patients with SCD.

CONCLUSIONS

Patients with SCD are particularly susceptible to nociceptive AEs when given Definity at high doses. The mechanism for these AEs remains unclear but most are not related to the triggering of classic VOC.

Noninvasive Evaluation of Cardiac Chamber Pressures Using Subharmonic-Aided Pressure Estimation With Definity Microbubbles

BACKGROUND

Noninvasive and accurate assessment of intracardiac pressures has remained an elusive goal of noninvasive cardiac imaging.

OBJECTIVES

The purpose of this study was to investigate if errors in intracardiac pressures obtained noninvasively using contrast microbubbles and the subharmonic-aided pressure estimation (SHAPE) technique are <5 mm Hg.

METHODS

In a nonrandomized institutional review board-approved clinical trial (NCT03243942), patients scheduled for a left-sided and/or right-sided heart catheterization procedure and providing written informed consent were included. A standard-of-care catheterization procedure was performed advancing clinically used pressure catheters into the left and/or right ventricles and/or the aorta. After pressure catheter placement, patients received an infusion of Definity microbubbles (n = 56; 2 vials diluted in 50 mL of saline; infusion rate: 4-10 mL/min) (Lantheus Medical Imaging). Then SHAPE data was acquired using a validated interface developed on a SonixTablet scanner (BK Medical Systems) synchronously with the pressure catheter data. A conversion factor (mm Hg/dB) was derived from SHAPE data and measurements with a SphygmoCor XCEL PWA device (ATCOR Medical) and was combined with SHAPE data from the left and/or the right ventricles to obtain clinically relevant systolic and diastolic ventricular pressures.

RESULTS

The mean value of absolute errors for left ventricular minimum and end diastolic pressures were 2.9 ± 2.0 and 1.7 ± 1.2 mm Hg (n = 26), respectively, and for right ventricular systolic pressures was 2.2 ± 1.5 mm Hg (n = 11). Two adverse events occurred during Definity infusion; both were resolved.

CONCLUSIONS

These results indicate that the SHAPE technique with Definity microbubbles is encouragingly efficacious for obtaining intracardiac pressures noninvasively and accurately. (Noninvasive, Subharmonic Intra-Cardiac Pressure Measurement; NCT03243942).

Future Considerations in the Diagnosis and Treatment of Compressive Neuropathies of the Upper Extremity

Compressive neuropathies of the upper extremity are among the most common conditions seen by hand surgeons. The diagnoses of carpal tunnel syndrome and cubital tunnel syndrome have traditionally been made by a combination of history, physical examination, and electrodiagnostic testing. However, findings can be nonspecific and electrodiagnostic testing is invasive for the patient. The diagnosis of compressive neuropathies continues to evolve as technology advances, and newer diagnostic modalities predominantly focus on preoperative diagnostic imaging with ultrasound and magnetic resonance imaging/neurography. With the advent of cheaper, faster, and less invasive imaging, the future may bring a paradigm shift away from electrophysiology as the gold standard for the preoperative diagnosis of compressive neuropathies. Intraoperative imaging of nerve health is an emerging concept that warrants further investigation, whereas postoperative imaging of nerve recovery with ultrasound and magnetic resonance imaging currently has a limited role because of nonspecific findings and potential for misinterpretation. Advances in surgical treatment of compressive neuropathies appear to center around the use of imaging for less invasive neurolysis techniques and other adjunctive treatments with nerve decompression. The management of failed peripheral nerve decompressions and recurrent compressive neuropathies remains challenging.

How promising are HIV-1-based virus-like particles for medical applications

New approaches aimed at identifying patient-specific drug targets and addressing unmet clinical needs in the framework of precision medicine are a strong motivation for researchers worldwide. As scientists learn more about proteins that drive known diseases, they are better able to design promising therapeutic approaches to target those proteins. The field of nanotechnology has been extensively explored in the past years, and nanoparticles (NPs) have emerged as promising systems for target-specific delivery of drugs. Virus-like particles (VLPs) arise as auspicious NPs due to their intrinsic properties. The lack of viral genetic material and the inability to replicate, together with tropism conservation and antigenicity characteristic of the native virus prompted extensive interest in their use as vaccines or as delivery systems for therapeutic and/or imaging agents. Owing to its simplicity and non-complex structure, one of the viruses currently under study for the construction of VLPs is the human immunodeficiency virus type 1 (HIV-1). Typically, HIV-1-based VLPs are used for antibody discovery, vaccines, diagnostic reagent development and protein-based assays. This review will be centered on the use of HIV-1-based VLPs and their potential biomedical applications.

CEUS cardiac exam protocols International Contrast Ultrasound Society (ICUS) recommendations

The present CEUS Cardiac Exam Protocols represent the first effort to promulgate a standard set of protocols for optimal administration of ultrasound enhancing agents (UEAs) in echocardiography, based on more than two decades of experience in the use of UEAs for cardiac imaging. The protocols reflect current clinical CEUS practice in many modern echocardiography laboratories throughout the world. Specific attention is given to preparation and dosing of three UEAs that have been approved by the United States Food and Drug Administration (FDA) and additional regulatory bodies in Europe, the Americas and Asia–Pacific. Consistent with professional society guidelines (J Am Soc Echocardiogr 31:241–274, 2018; J Am Soc Echocardiogr 27:797–810, 2014; Eur Heart J Cardiovasc Imaging 18:1205, 2017), these protocols cover unapproved “off-label” uses of UEAs—including stress echocardiography and myocardial perfusion imaging—in addition to approved uses. Accordingly, these protocols may differ from information provided in product labels, which are generally based on studies performed prior to product approval and may not always reflect state of the art clinical practice or guidelines.

The benefit of contrast-enhanced ultrasound in biopsies for focal liver lesions: a retrospective study of 820 cases

OBJECTIVE

This study compared the performance between ultrasound (US)- and contrast-enhanced US (CEUS)-guided liver biopsies and evaluated the benefit of CEUS in percutaneous biopsy for focal liver lesions (FLLs).

METHODS

We performed a retrospective study of 820 patients with FLLs, who underwent percutaneous liver biopsy in our center between 2017 and 2019. The patients were divided into two groups based on whether US (n = 362) or CEUS (n = 458) used before a biopsy. The two groups were compared based on specimen adequacy for pathological diagnosis and diagnostic accuracy of liver biopsy. Stratification analysis was performed based on lesion and protocol characteristics to provide detailed information for selecting the imaging guidance for biopsy.

RESULTS

Compared with the US group, the CEUS group yielded more acceptable samples (97.6% vs. 99.4%, p < 0.05) and improved diagnostic accuracy (92.6% vs. 96.4%, p < 0.05), and achieved better sensitivity (92.5% vs. 96.2%, p < 0.05) for liver biopsies, especially in FLLs ≥ 5 cm, heterogeneous hypoechoic FLLs, or FLLs with an obscure boundary. The CEUS group showed significantly higher accuracy compared with the US group pertaining to single-puncture biopsies (100% vs. 92.7%, p < 0.05) or biopsies with punctures ≤ 2 (97.6% vs. 94.3%, p < 0.05).

CONCLUSION

CEUS achieved an enhanced success rate for sampling and diagnostic accuracy of liver biopsies, especially in FLLs ≥ 5 cm, heterogeneous hypoechoic FLLs, or FLLs with an obscure boundary. CEUS can be used to decrease the number of punctures needed, which might increase the safety of liver biopsy.

KEY POINTS

• CEUS can help confirm an adequate biopsy site, increasing the sampling success rate and diagnostic accuracy of the liver biopsy. • CEUS can be used to decrease the number of punctures needed to improve the safety of liver biopsy. • It is recommended to use CEUS guidance for liver biopsies, especially with FLLs ≥ 5 cm, heterogeneous hypoechoic FLLs, or FLLs with an obscure boundary.

Microbubbles Stabilized by Protein Shell: From Pioneering Ultrasound Contrast Agents to Advanced Theranostic Systems

Ultrasound is a widely-used imaging modality in clinics as a low-cost, non-invasive, non-radiative procedure allowing therapists faster decision-making. Microbubbles have been used as ultrasound contrast agents for decades, while recent attention has been attracted to consider them as stimuli-responsive drug delivery systems. Pioneering microbubbles were Albunex with a protein shell composed of human serum albumin, which entered clinical practice in 1993. However, current research expanded the set of proteins for a microbubble shell beyond albumin and applications of protein microbubbles beyond ultrasound imaging. Hence, this review summarizes all-known protein microbubbles over decades with a critical evaluation of formulations and applications to optimize the safety (low toxicity and high biocompatibility) as well as imaging efficiency. We provide a comprehensive overview of (1) proteins involved in microbubble formulation, (2) peculiarities of preparation of protein stabilized microbubbles with consideration of large-scale production, (3) key chemical factors of stabilization and functionalization of protein-shelled microbubbles, and (4) biomedical applications beyond ultrasound imaging (multimodal imaging, drug/gene delivery with attention to anticancer treatment, antibacterial activity, biosensing). Presented critical evaluation of the current state-of-the-art for protein microbubbles should focus the field on relevant strategies in microbubble formulation and application for short-term clinical translation. Thus, a protein bubble-based platform is very perspective for theranostic application in clinics.

Advanced Echocardiography Techniques: The Future Stethoscope of Systemic Diseases

Cardiovascular disease (CVD) has been showing patterns of extensive rise in prevalence in the contemporary era, affecting the quality of life of millions of people and leading the causes of death worldwide. It has been a provocative challenge for modern medicine to diagnose CVD in its crib, owing to its etiological factors being attributed to a large array of systemic diseases, as well as its non-binary hideous nature that gradually leads to functional disability. Novel echocardiography techniques have enabled the cardiac ultrasound to provide a comprehensive analysis of the heart in an objective, feasible, time- and cost-effective manner. Speckle tracking echocardiography, contrast echocardiography, and 3D echocardiography have shown the highest potential for widespread use. The uses of novel modalities have been elaborately demonstrated in this study as a proof of concept that echocardiography has a place in routine general practice with supportive evidence being as recent as its role in the concurrent COVID-19 pandemic. Despite such evidence, many uses remain off-label and unexploited in practice. Generalization of echocardiography at the point of care can become a much-needed turning point in the clinical approach to case management. To actualize such aspirations, we recommend further prospective and interventional studies to examine the effect of implementing advanced techniques at the point of care on the decision-making process and evaluate their effectiveness in prevention of cardiovascular morbidities and mortalities.

Using Immersive Virtual Reality Simulation to Ensure Competence in Contrast-Enhanced Ultrasound

Contrast-enhanced ultrasound (CEUS) is used in various medical specialties as a diagnostic imaging tool and for procedural guidance. Experience in the procedure is currently attained via supervised clinical practice that is challenged by patient availability and risks. Prior simulation-based training and subsequent assessment could improve and ensure competence before performance on patients, but no simulator currently exists. Immersive virtual reality (IVR) is a new promising simulation tool that can replicate complex interactions and environments that are unfeasible to achieve by traditional simulators. This study was aimed at developing an IVR simulation-based test for core CEUS competencies and gathering validity evidence for the test in accordance with Messick's framework. The test was developed by IVR software specialists and clinical experts in CEUS and medical education and imitated a CEUS examination of a patient with a focal liver lesion with emphasis on the pre-contrast preparations. Twenty-five medical doctors with varying CEUS experience were recruited as test participants, and their results were used to analyze test quality and to establish a pass/fail standard. The final test of 23 test items had good internal reliability (Cronbach's α = 0.85) and discriminatory abilities. The risks of false positives and negatives (9.1% and 23.6%, respectively) were acceptable for the test to be used as a certification tool prior to supervised clinical training in CEUS.

Imaging of Benign and Malignant Breast Lesions Using Contrast-Enhanced Ultrasound: A Pictorial Essay

ABSTRACT

Contrast-enhanced ultrasound is a promising noninvasive imaging technique for evaluating benign and malignant breast lesions, as contrast provides information about perfusion and microvasculature. Contrast-enhanced ultrasound is currently off-label use in the breast in the United States, but its clinical and investigational use in breast imaging is gaining popularity. It is important for radiologists to be familiar with the imaging appearances of benign and malignant breast masses using contrast-enhanced ultrasound. This pictorial essay illustrates enhancement patterns of various breast masses from our own experience. Pathologies include subtypes of invasive breast cancer, fibroadenomas, papillary lesions, fibrocystic change, and inflammatory processes. Contrast-enhanced ultrasound pitfalls and limitations are discussed.

Contrast Ultrasound, Sonothrombolysis and Sonoperfusion in Cardiovascular Disease: Shifting to Theragnostic Clinical Trials

Contrast ultrasound has a variety of applications in cardiovascular medicine, both in diagnosing cardiovascular disease as well as providing prognostic information. Visualization of intravascular contrast microbubbles is based on acoustic cavitation, the characteristic oscillation that results in changes in the reflected ultrasound waves. At high power, this acoustic response generates sufficient shear that is capable of enhancing endothelium-dependent perfusion in atherothrombotic cardiovascular disease (sonoperfusion). The oscillation and collapse of microbubbles in response to ultrasound also induces microstreaming and jetting that can fragment thrombus (sonothrombolysis). Several preclinical studies have focused on identifying optimal diagnostic ultrasound settings and treatment regimens. Clinical trials have been performed in acute myocardial infarction, stroke, and peripheral arterial disease often with improved outcome. In the coming years, results of ongoing clinical trials along with innovation and improvements in sonothrombolysis and sonoperfusion will determine whether this theragnostic technique will become a valuable addition to reperfusion therapy.

Feasibility of contrast-enhanced ultrasound and flank position during percutaneous nephrolithotomy in patients with no apparent hydronephrosis: a randomized controlled trial

Purpose

To investigate the puncture accuracy and feasibility of contrast-enhanced ultrasound (CEUS) guided percutaneous nephrolithotomy (PCNL) in flank position for patients with no apparent hydronephrosis.

Methods

Between May 2018 and June 2020, 72 kidney stone patients with no or mild hydronephrosis were randomized into two groups: a CEUS-guided PCNL group and a conventional ultrasound (US)-guided group. Patients’ demographics and perioperative outcomes were compared, including the success rate of puncture via calyceal fornix, the success rate of a single-needle puncture, puncture time, operative time, postoperative hemoglobin loss, stone-free rate, incidence of complications and postoperative stay.

Results

The success rate of puncture via calyceal fornix for CEUS-guided group was significantly higher than that for conventional US-guided group (86.1 vs. 47.2%, p = 0.002). Patients performed with CEUS-guided PCNL required shorter renal puncture time than those guided with conventional US (36.5 s vs. 61.0 s, p < 0.001). The median postoperative hemoglobin loss in the CEUS-guided group was significantly lower than that in conventional US-guided group (2.5 vs. 14.5 g/L, p < 0.01). There was no statistically significant difference in the success rate of a single-needle puncture, operative time, stone-free rate, incidence of complications and postoperative stay between the two groups.

Conclusion

CEUS guidance facilitates identification of the renal calyx fornix, and benefits more precise renal puncture and less hemoglobin loss in PCNL. CEUS-guided PCNL in flank position is a feasible approach to the treatment of kidney stone patients with no apparent hydronephrosis.

Trial registration number: ChiCTR1800015417.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-022-03933-4.

Safety of SF6(SonoVue®) Contrast Agent on Pharmacological Stress Echocardiogram

Fundamento

Em 2007, a Food and Drug Administration (FDA) determinou revisões sobre segurança dos agentes de contraste ecocardiográfico (ACE) disponíveis no mercado após relatos de mortes. Ao longo desses anos, diversos estudos comprovaram a segurança dos ACE, porém com poucos estudos relacionados ao SonoVue^®.

Objetivos

Avaliar a segurança do SonoVue^® durante o ecocardiograma sob estresse farmacológico (EEF) por meio da análise da incidência de reações alérgicas e da comparação entre os grupos quanto ao surgimento de arritmia, efeitos colaterais menores e eventos adversos.

Métodos

Estudo observacional, prospectivo, no qual 2.346 pacientes foram submetidos ao EEF e divididos em dois grupos: grupo 1 com ACE (n=1.099) e grupo 2 sem ACE (n=1.247). Os pacientes foram avaliados durante o EEF – 24 horas e 30 dias. Foi definido p significativo quando <0,05.

Resultados

O grupo 1 apresentou efeitos colaterais mais leves, como cefaleia (5/0,5% vs. 19/1,5%, p=0,012) e hipertensão reativa (3/0,3% vs . 19/1,5%, p=0,002), menos arritmias como extrassístoles ventriculares (180/16,4% vs . 247/19,8%, p=0,032) e taquicardia paroxística supraventricular (2/0,2% vs . 15/1,2%, p=0,003), assim como nenhum evento adverso como infarto agudo do miocárdio (IAM) e óbito. No grupo 2, um paciente apresentou IAM <24h (1/01%) e dois óbitos <30 dias (2/0,1%). Urticária relacionada ao SonoVue^® foi observada em 3 (0,3%) pacientes sem reação anafilática.

Conclusão

SonoVue^® demonstrou segurança durante o EEF, não sendo observados morte, IAM ou reação anafilática. Observou-se menor incidência de efeitos colaterais mais leves e arritmias no grupo que utilizou o ACE, assim como baixa incidência de reações alérgicas leves.

Effects of Copaiba Oil in Peripheral Markers of Oxidative Stress in a Model of Cor Pulmonale in Rats

Fundamento

Até o presente momento, os efeitos sistêmicos do óleo de copaíba jamais foram documentados no Cor pulmonale induzido por monocrotalina.

Objetivos

Investigar os efeitos do óleo de copaíba nos marcadores periféricos de stress oxidativo em ratos com Cor pulmonale.

Métodos

Ratos Wistar machos (170±20g, n=7/grupo) foram divididos em quatro grupos: controle (CO), monocrotalina (MCT), óleo de copaíba (O), e monocrotalina + óleo de copaíba (MCT-O). Foi administrada a MCT (60 mg/kg i.p.) e, depois de uma semana, foi iniciado o tratamento com óleo de copaíba (400 mg/kg/day-gavagem-14 dias). Foi realizado o ecocardiograma e, depois disso, foi coletado sangue do tronco para a realização de avaliações de stress oxidativo. Análise estatística: ANOVA de duas vias com teste Student-Newman-Keuls post hoc. P-valores <0,05 foram considerados significativos.

Resultados

O óleo de copaíba reduziu a resistência vascular pulmonar e a hipertrofia do ventrículo direito (VD) hipertrofia (Índice de Fulton (mg/mg)): MCT-O= 0,39±0,03; MCT= 0,49±0,01), e função sistólica melhorada (fração de encurtamento do VD, %) no grupo MCT-O (17,8±8,2) em comparação com o grupo de MCT (9,4±3,1; p<0,05). Além disso, no grupo MCT-O, espécies reativas do oxigênio e os níveis de carbonila foram reduzidos, e os parâmetros antioxidantes aumentaram no sangue periférico (p <0,05).

Conclusões

Os resultados deste estudo sugerem que o óleo de copaíba tem um efeito antioxidante sistêmico interessante, que se reflete na melhoria da função e na morfometria do VD nesse modelo de Cor pulmonale . A atenuação do Cor pulmonale promovida pelo óleo de copaíba coincidiu com uma redução no stress oxidativo sistêmico.

The promising shadow of microbubble over medical sciences: from fighting wide scope of prevalence disease to cancer eradication

Microbubbles are typically 0.5-10 μm in size. Their size tends to make it easier for medication delivery mechanisms to navigate the body by allowing them to be swallowed more easily. The gas included in the microbubble is surrounded by a membrane that may consist of biocompatible biopolymers, polymers, surfactants, proteins, lipids, or a combination thereof. One of the most effective implementation techniques for tiny bubbles is to apply them as a drug carrier that has the potential to activate ultrasound (US); this allows the drug to be released by US. Microbubbles are often designed to preserve and secure medicines or substances before they have reached a certain area of concern and, finally, US is used to disintegrate microbubbles, triggering site-specific leakage/release of biologically active drugs. They have excellent therapeutic potential in a wide range of common diseases. In this article, we discussed microbubbles and their advantageous medicinal uses in the treatment of certain prevalent disorders, including Parkinson's disease, Alzheimer's disease, cardiovascular disease, diabetic condition, renal defects, and finally, their use in the treatment of various forms of cancer as well as their incorporation with nanoparticles. Using microbubble technology as a novel carrier, the ability to prevent and eradicate prevalent diseases has strengthened the promise of effective care to improve patient well-being and life expectancy.

Definity, echo contrast, induced cardiac arrest: brief review of the literature

Definity is a contrast media used to enhance the endocardium during echocardiography. Cardiac arrest as an adverse reaction to Definity is still a debate. We are presenting a rare case of a 69-year-old male patient who developed cardiopulmonary arrest immediately after Definity injection during resting echocardiography.

Identification of micro-channels within chronic total occlusions using contrast-enhanced ultrasound

BACKGROUND

Vascular micro-channels within chronic total occlusions (CTO) have been identified in histopathology and animal studies. They have been proposed as a potential path for achieving endovascular crossing via the lumen. There are currently no noninvasive means of imaging these structures. The aim of this study was to investigate whether contrast-enhanced ultrasound (CEUS) examination can identify micro-channels within CTO in humans.

METHODS

CTO within the femoropopliteal arteries were imaged with CEUS examination in 38 patients. Segments containing micro-channels were identified and their length measured. The proportion of occlusion length containing micro-channels was assessed for each case. Micro-channel appearances including linear or tortuous configuration, crossing of occlusion caps, and connections to vasa vasorum were recorded.

RESULTS

The median CTO length was 17.0 cm (interquartile range [IQR], 6.9-27.9 cm) and median age of CTO was 12 months (IQR, 6-16 months). Micro-channels were identified in 92.1% of cases (35/38). The median length within a lesion containing micro-channels was 6.4 cm (IQR, 2.4-14.3 cm) and median proportion of CTO containing micro-channels was 47.9% (IQR, 1.7%-28.5%). A linear micro-channel configuration was seen in 84.2% of cases and a tortuous configuration was seen in 57.9% of cases. Micro-channel connections through the cap were seen in 50% (19/38 cases) and connections to the vasa vasorum in 71.1% (27/38 cases). No association was found between the proportion of each lesion containing micro-channels and CTO age, lesion length or calcification severity. There were no adverse effects related to contrast use.

CONCLUSIONS

CEUS can be used to detect micro-channels in CTO in human femoropopliteal arteries. This imaging technique is safe and minimally invasive and may represent a practical method for selection of occlusion crossing method. Further work is required to determine whether identification of micro-channels can be used to improve treatment decision-making and provide a better understanding of the natural history of femoropopliteal CTO.

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.

Contrast echocardiography: current status and future directions

Contrast echocardiography is a family of ultrasound-based procedures, whereby acoustic enhancing agents, usually microbubbles, are administered by intravenous route and detected in order to improve diagnostic performance. This review describes: (1) the agents that have been designed for diagnostic imaging, (2) current clinical applications where either left ventricular opacification or microvascular perfusion imaging with myocardial contrast echocardiography have been demonstrated to provide incremental information to non-contrast echocardiography and (3) future diagnostic and therapeutic applications of contrast ultrasound that rely on unique compositional design of ultrasound-enhancing agents.

Review of ultrasound contrast agents in current clinical practice with special focus on DEFINITY® in cardiac imaging

Echocardiography is the most widely used noninvasive modality to evaluate the structure and function of the cardiac muscle in daily practice. However, up to 15-20% of echocardiograms are considered suboptimal. To enable accurate assessment of cardiac function and wall motion abnormality, the use of ultrasound microbubble contrast has shown substantial benefits in cases of salvaging nondiagnostic studies and enhancing the diagnostic accuracy in daily practice. DEFINITY^® is a perflutren based, lipid shelled microbubble contrast agent, which is US FDA approved for left ventricular opacification. The basis of ultrasound microbubbles, its development, and the clinical role of DEFINITY (characteristics, indications and case examples, side effect profile and existing evidence) is the subject of discussion in this review.

Contrast-enhanced ultrasound for the assessment of placental development and function

The use of contrast agents as signal enhancers during ultrasound improves visualization and the diagnostic utility of this technology in medical imaging. Although widely used in many disciplines, contrast ultrasound is not routinely implemented in obstetrics, largely due to safety concerns of administered agents for pregnant women and the limited number of studies that address this issue. Here the microbubble characteristics that make them beneficial for enhancement of the blood pool and the quantification of real-time imaging are reviewed. Literature from pregnant animal model studies and safety assessments are detailed, and the potential for contrast-enhanced ultrasound to provide clinically relevant data and benefit our understanding of early placental development and detection of placental dysfunction is discussed.

A review of ultrasound-mediated microbubbles technology for cancer therapy: a vehicle for chemotherapeutic drug delivery

Background:

The unique behaviour of microbubbles under ultrasound acoustic pressure makes them useful agents for drug and gene delivery. Several studies have demonstrated the potential application of microbubbles as a non-invasive, safe and effective technique for targeted delivery of drugs and genes. The drugs can be incorporated into the microbubbles in several different approaches and then carried to the site of interest where it can be released by destruction of the microbubbles using ultrasound to achieve the required therapeutic effect.

Methods:

The objective of this article is to report on a review of the recent advances of ultrasound-mediated microbubbles as a vehicle for delivering drugs and genes and its potential application for the treatment of cancer.

Conclusion:

Ultrasound-mediated microbubble technology has the potential to significantly improve chemotherapy drug delivery to treatment sites with minimal side effects. Moreover, the technology can induce temporary and reversible changes in the permeability of cells and vessels, thereby allowing for drug delivery in a spatially localised region which can improve the efficiency of drugs with poor bioavailability due to their poor absorption, rapid metabolism and rapid systemic elimination.