Experimental study on high-frequency subharmonic scattering characteristics of ultrasound contrast agent microbubbles under low ambient pressure / 生物医学工程学杂志

Correlation between nonlinear subharmonic scattering of ultrasound contrast agent microbubbles and ambient pressure is expected to be used for local brain tissue pressure monitoring. Although high-frequency ultrasound has achieved high-resolution imaging of intracranial microvessels, the research on high-frequency subharmonic scattering characteristics of microbubbles is insufficient at present, which restricts the research progress of estimating local brain tissue pressure based on high-frequency subharmonic scattering of microbubbles. Therefore, under the excitation of 10 MHz high-frequency ultrasound, the effects of different acoustic pressures and ambient pressures on the high-frequency subharmonic scattering characteristics of three different ultrasound contrast agents including SonoVue, Sonazoid and Huashengxian were investigated in this in vitro study. Results showed that the subharmonic scattering amplitudes of the three microbubbles increased with the increase of ambient pressure at the peak negative acoustic pressures of 696, 766 and 817 kPa, and there was a favorable linear correlation between subharmonic amplitude and ambient pressure. Under the above three acoustic pressures, the highest correlation coefficient of SonoVue was 0.948 ( P = 0.03), the highest sensitivity of pressure measurement was 0.248 dB/mm Hg and the minimum root mean square error (RMSE) was 2.64 mm Hg. Sonazoid's highest correlation coefficient was 0.982 ( P < 0.01), the highest sensitivity of pressure measurement was 0.052 dB/mm Hg and the minimum RMSE was 1.51 mm Hg. The highest correlation coefficient of Huashengxian was 0.969 ( P = 0.02), the highest sensitivity of pressure measurement was 0.098 dB/mm Hg and the minimum RMSE was 2.00 mm Hg. The above in vitro experimental results indicate that by selecting ultrasound contrast agent microbubbles and optimizing acoustic pressure, the correlation between high-frequency subharmonic scattering of microbubbles and ambient pressure can be improved, the sensitivity of pressure measurement can be upgraded, and the measurement error can be reduced to meet the clinical demand for local brain tissue pressure measurement, which provided an important experimental basis for subsequent research in vivo.

Research Progress of Targeted Ultrasound Contrast Agent BR55 / 中国医学科学院学报

BR55 is an ultrasound contrast agent targeting vascular endothelial growth factor receptor 2,which can be used to detect tumor neovascularization and improve the diagnostic accuracy.Overseas researchers have used BR55 for human ultrasound molecular imaging,which showed good safety and tolerance.We reviewed the research progress on BR55 applied in the evaluation of tumor neovascularization from the composition,characteristics,animal experiments,and clinical studies of BR55.

Experiência inicial com ultrassom Doppler com contraste por microbolhas em adição ao ultrassom Doppler convencional para seguimento de correção endovascular de aneurisma de aorta abdominal / Initial experience with Duplex scan combined with contrast-enhanced ultrasound for follow-up of endovascular abdominal aortic aneurysm repair

Resumo Contexto O ultrassom contrastado por microbolhas (CMUS) é uma modalidade diagnóstica de acurácia bem demonstrada por estudos internacionais para seguimento de reparo endovascular do aneurisma de aorta abdominal (EVAR). Não existem, no entanto, estudos nacionais focados nesse método de seguimento. Objetivos O objetivo deste estudo foi relatar a experiência inicial com CMUS em um hospital terciário, traçando uma comparação dos achados do CMUS com o ultrassom Doppler convencional (USGD), com o intuito de verificar se a adição de contraste ao protocolo padrão de controle ultrassonográfico incorreu alteração nos achados. Métodos Entre 2015 e 2017, 21 pacientes em seguimento de EVAR foram submetidos ao USGD seguido de CMUS. Foram avaliados os achados de exame referentes à identificação de complicações, bem como à capacidade de identificação da origem da endofuga. Resultados Entre os 21 casos avaliados, 10 complicações foram evidenciadas no total: sete pacientes apresentaram endofuga (33,3%); dois pacientes apresentaram estenose em ramo de endoprótese (9,52%); e um paciente apresentou dissecção em artéria ilíaca externa (4,76%). Em 21 pacientes avaliados, o uso combinado dos métodos identificou 10 casos de complicações pós-EVAR. Em seis dos sete casos de endofugas (85,71%), o uso dos métodos combinados foi capaz de identificar a origem. O USGD isolado falhou na identificação da endofuga em dois casos (28,5%), identificando achados duvidosos em outros dois casos (28,5%), que obtiveram definição diagnóstica após associação do CMUS. Conclusões O CMUS é uma técnica de fácil execução, a qual adiciona subsídios ao seguimento de EVAR infrarrenal.

Abstract Background Microbubble contrast enhanced ultrasound (CEUS) is an accurate diagnostic method for follow-up after endovascular abdominal aortic aneurysm repair (EVAR) that has been well-established in international studies. However, there are no Brazilian studies that focus on this follow-up method. Objectives The objective of this study was to report initial experience with CEUS at a tertiary hospital, comparing the findings of CEUS with those of conventional Doppler ultrasound (DUS), with the aim of determining whether addition of contrast to the standard ultrasonographic control protocol resulted in different findings. Methods From 2015 to 2017, 21 patients in follow-up after EVAR underwent DUS followed by CEUS. The findings of these examinations were analyzed in terms of identification of complications and their capacity to identify the origin of endoleaks. Results There was evidence of complications in 10 of the 21 cases examined: seven patients exhibited endoleaks (33.3%); two patients exhibited stenosis of a branch of the endograft (9.52%); and one patient exhibited a dissection involving the external iliac artery (4.76%). In the 21 patients assessed, combined use of both methods identified 10 cases of post-EVAR complications. In six of the seven cases of endoleaks (85.71%), use of the methods in combination was capable of identifying the origin of endoleakage. DUS alone failed to identify endoleaks in two cases (28.5%) and identified doubtful findings in another two cases (28.5%), in which diagnostic definition was achieved after employing CEUS. Conclusions CEUS is a technique that is easy to perform and provides additional support for follow-up of infrarenal EVAR.

Synergistic Anti-tumor Mechanisms of Low-frequency Ultrasound-targeted Microbubble Destruction:Mechanisms and Application / 中国医学科学院学报

Ultrasound contrast agent microbubbles combined with low frequency ultrasound named as low-frequency ultrasound-targeted microbubble destruction technology has become an effective and non-invasive anti-tumor therapy for deep tumors.It can enhance the efficacies of chemotherapy,gene therapy,immunotherapy,and anti-angiogenic therapy by improving cell membrane permeability and destroying tumor neovasculature.It can be applied to sonodynamic therapy and realize multimodal synergistic therapy on the basis of nanoparticles,which increases the anti-tumor efficiency and offers a promising target therapy for tumors.

Assessment of neovascularization during bone healing using contrast-enhanced ultrasonography in a canine tibial osteotomy model: a preliminary study

Value of Contrast Transesophageal Echocardiography in the Detection of Intrapulmonary Vascular Dilatations in Hepatosplenic Schistosomiasis / Valor do Ecocardiograma Transesofágico com Contraste no Diagnóstico da Dilatação Vascular Intrapulmonar na Esquistossomose Hepatoesplênica

Abstract Background: Hepatopulmonary syndrome (HPS), found in cirrhotic patients, has been little studied in hepatosplenic schistosomiasis (HSS) and includes the occurrence of intrapulmonary vascular dilatations (IPVD). Contrast transesophageal echocardiography (cTEE) with microbubbles is more sensitive than contrast transthoracic echocardiography (cTTE) with microbubbles in the detection of IPVD in cirrhosis. Objective: To assess the performance of the cTEE, compared with that of cTTE, in detecting IPVD for the diagnosis of HPS in patients with HSS. Methods: cTEE and cTTE for investigation of IPVD and laboratory tests were performed in 22 patients with HSS. Agitated saline solution was injected in peripheral vein during the cTEE and cTTE procedures. Late appearance of the microbubbles in the left chambers indicated the presence of IPVD. Results of the two methods were compared by the Student's t-test and the chi-square test (p < 0.05). Results: cTEE was performed in all patients without complications. Three patients were excluded due to the presence of patent foramen ovale (PFO). The presence of IPVD was confirmed in 13 (68%) of 19 patients according to the cTEE and in only six (32%, p < 0.01) according to the cTTE. No significant differences in clinical or laboratory data were found between the groups with and without IPVD, including the alveolar-arterial gradient. The diagnosis of HPS (presence of IPVD with changes in the arterial blood gas analysis) was made in five patients by the cTEE and in only one by the cTTE (p = 0.09). Conclusion: In HSS patients, cTEE was safe and superior to cTTE in detecting IPVD and allowed the exclusion of PFO.

Resumo Fundamento: A síndrome hepatopulmonar (SHP), presente em pacientes cirróticos, é pouco estudada na esquistossomose hepatoesplênica (EHE) e inclui a ocorrência de dilatações vasculares intrapulmonares (DVP). O ecocardiograma transesofágico com contraste (ETEc) de microbolhas é mais sensível que o ecocardiograma transtorácico com contraste (ETTc) de microbolhas na identificação de DVP na cirrose. Objetivo: Avaliar o desempenho do ETEc comparado ao ETTc na identificação de DVP para diagnóstico de SHP em pacientes com EHE. Métodos: Incluímos 22 pacientes com EHE submetidos a ETEc e ETTc para pesquisa de DVP, além de exames laboratoriais. Os ETEc e ETTc foram realizados empregando-se solução salina agitada, injetada em veia periférica. A visualização tardia das microbolhas em câmaras esquerdas indicava presença de DVP. Os resultados foram comparados entre os dois métodos pelos testes t de Stu dent e qui-quadrado (significância p < 0,05). Resultados: Todos os 22 pacientes realizaram ETEc sem intercorrências. Foram excluídos três pela presença de forame oval patente (FOP), e a análise final foi realizada nos outros 19. A DVP esteve presente ao ETEc em 13 pacientes (68%) e em apenas seis ao ETTc (32%, p < 0,01). Não houve diferenças significativas nos dados clínicos e laboratoriais entre os grupos com e sem DVP, incluindo a diferença alveoloarterial de oxigênio. O diagnóstico de SHP (presença de DVP com alterações gasométricas) ocorreu em cinco pacientes pelo ETEc e em apenas um pelo ETTc (p = 0,09). Conclusão: Em pacientes com EHE, o ETEc foi seguro e superior ao ETTc na detecção de DVP não identificada ao ETTc, o que possibilitou adicionalmente excluir FOP.

Rapid diagnosis of respiratory distress syndrome by oral aspirate in premature newborns / Diagnóstico rápido da síndrome do desconforto respiratório por aspirado bucal em recém-nascidos prematuros

Abstract Objective: The stable microbubble test on gastric aspirate and on amniotic fluid has been used for the diagnosis of respiratory distress syndrome in the newborn. However, no study has performed this test on oral aspirates from premature infants. The objective of this study was to evaluate the performance of the stable microbubble test on oral aspirates from preterm newborns to predict respiratory distress syndrome. Method: This study included infants with gestational age <34 weeks. Oral fluids were obtained immediately after birth and gastric fluids were collected within the first 30 minutes of life. The samples were frozen and tested within 72 hours. Results: The sample was composed of paired aspirates from 64 newborns, who were divided into two groups: respiratory distress syndrome group (n = 21) and control group (n = 43). The median (interquartile range) of the stable microbubble count in the oral samples of infants with respiratory distress syndrome was significantly lower than that of infants who did not develop respiratory symptoms: respiratory distress syndrome group = 12 (8 -22) stable microbubbles/mm2; control group = 100 (48 -230) microbubbles/mm2 (p < 0.001). The correlation between microbubble count in gastric and oral aspirates was 0.90 (95% confidence interval = 0.85 -0.95; p < 0.001). Considering a cut-off point of 25 microbubbles/mm2, the sensitivity and the specificity of the stable microbubble test were 81.4% and 85.7%, respectively. Conclusion: The study suggests that the stable microbubble test performed on oral aspirate is a reliable alternative to that performed on gastric fluid for the prediction of respiratory distress syndrome in the newborn.

Resumo Objetivo: O teste das microbolhas estáveis no aspirado gástrico e no líquido amniótico foi usado no diagnóstico da síndrome do desconforto respiratório do recém-nascido. Contudo, nenhum estudo fez esse teste nos aspirados bucais de neonatos prematuros. O objetivo deste estudo foi avaliar o desempenho do teste das microbolhas estáveis em aspirados bucais de recém-nascidos prematuros para prever síndrome do desconforto respiratório. Método: Este estudo incluiu neonatos com idade gestacional < 34 semanas. Os fluidos orais foram obtidos imediatamente após o nascimento e os fluidos gástricos foram coletados nos primeiros 30 minutos de vida. As amostras foram congeladas e testadas em 72 horas. Resultados: A amostra foi composta de aspirados pareados de 64 recém-nascidos, divididos em dois grupos: grupo de síndrome do desconforto respiratório (n = 21) e grupo de controle (n = 43). A mediana (intervalo interquartil) da contagem das microbolhas estáveis nas amostras de fluido oral dos neonatos com síndrome do desconforto respiratório foi significativamente menor que a dos neonatos que não desenvolveram sintomas respiratórios: grupo de síndrome do desconforto respiratório = 12 (8-22) microbolhas estáveis/mm2; grupo de controle = 100 (48-230) microbolhas/mm2 (p < 0,001). A correlação entre a contagem das microbolhas nos aspirados gástricos e bucais foi 0,90 (intervalo de confiança de 95% = 0,85-0,95; p < 0,001). Considerando um ponto de corte de 25 microbolhas/mm2, a sensibilidade e a especificidade do teste das microbolhas estáveis foram 81,4% e 85,7%, respectivamente. Conclusão: O estudo sugere que o teste das microbolhas estáveis feito no aspirado bucal é uma opção confiável ao fluido gástrico para a predição da síndrome do desconforto respiratório do recém-nascido.

Magnetic Resonance-Guided Focused Ultrasound : Current Status and Future Perspectives in Thermal Ablation and Blood-Brain Barrier Opening

Magnetic resonance-guided focused ultrasound (MRgFUS) is an emerging new technology with considerable potential to treat various neurological diseases. With refinement of ultrasound transducer technology and integration with magnetic resonance imaging guidance, transcranial sonication of precise cerebral targets has become a therapeutic option. Intensity is a key determinant of ultrasound effects. High-intensity focused ultrasound can produce targeted lesions via thermal ablation of tissue. MRgFUS-mediated stereotactic ablation is non-invasive, incision-free, and confers immediate therapeutic effects. Since the US Food and Drug Administration approval of MRgFUS in 2016 for unilateral thalamotomy in medication-refractory essential tremor, studies on novel indications such as Parkinson's disease, psychiatric disease, and brain tumors are underway. MRgFUS is also used in the context of blood-brain barrier (BBB) opening at low intensities, in combination with intravenously-administered microbubbles. Preclinical studies show that MRgFUS-mediated BBB opening safely enhances the delivery of targeted chemotherapeutic agents to the brain and improves tumor control as well as survival. In addition, BBB opening has been shown to activate the innate immune system in animal models of Alzheimer’s disease. Amyloid plaque clearance and promotion of neurogenesis in these studies suggest that MRgFUS-mediated BBB opening may be a new paradigm for neurodegenerative disease treatment in the future. Here, we review the current status of preclinical and clinical trials of MRgFUS-mediated thermal ablation and BBB opening, described their mechanisms of action, and discuss future prospects.

Contrast-enhanced ultrasound approach to the diagnosis of focal liver lesions: the importance of washout

Contrast-enhanced ultrasound (CEUS) is a powerful technique for differentiating focal liver lesions (FLLs) without the risks of potential nephrotoxicity or ionizing radiation. In the diagnostic algorithm for FLLs on CEUS, washout is an important feature, as its presence is highly suggestive of malignancy and its characteristics are useful in distinguishing hepatocellular from non-hepatocellular malignancies. Interpreting washout on CEUS requires an understanding that microbubble contrast agents are strictly intravascular, unlike computed tomography or magnetic resonance imaging contrast agents. This review explains the definition and types of washout on CEUS in accordance with the 2017 version of the CEUS Liver Imaging Reporting and Data System and presents their applications to differential diagnosis with illustrative examples. Additionally, we propose potential mechanisms of rapid washout and describe the washout phenomenon in benign entities.

Contrast-enhanced Ultrasonography: The Third Modality for Differentiation of Liver Mass

Contrast-enhanced ultrasonography (CEUS) using microbubble ultrasonography contrast agent can show the vascular structure and unique contrast enhancement patterns of focal liver lesions, including hepatocellular carcinoma (HCC). CEUS shows three phases, similar to a vascular pattern on computer tomography (CT), and typical arterial enhancement and portal or late phase washout in HCC. CEUS can show real-time images without nephrotoxicity or radiation hazard and can be used as guidance for loco-regional treatment and estimation of treatment response of HCC. In addition, some data recently revealed the usefulness of CEUS in the early estimation of response to anti-cancer pharmacological (i.e., sorafenib) therapy in advanced HCC. Although CEUS has limitations in clinical practice and more investigation is needed for its validation, it is recommended as a main diagnostic modality in a few major clinical practice guidelines for HCC. Thus, greater understanding of CEUS is necessary to extend its application in real practice for diagnosis and management of diseases.

Magnetic Resonance-Guided Focused Ultrasound : Current Status and Future Perspectives in Thermal Ablation and Blood-Brain Barrier Opening

Magnetic resonance-guided focused ultrasound (MRgFUS) is an emerging new technology with considerable potential to treat various neurological diseases. With refinement of ultrasound transducer technology and integration with magnetic resonance imaging guidance, transcranial sonication of precise cerebral targets has become a therapeutic option. Intensity is a key determinant of ultrasound effects. High-intensity focused ultrasound can produce targeted lesions via thermal ablation of tissue. MRgFUS-mediated stereotactic ablation is non-invasive, incision-free, and confers immediate therapeutic effects. Since the US Food and Drug Administration approval of MRgFUS in 2016 for unilateral thalamotomy in medication-refractory essential tremor, studies on novel indications such as Parkinson's disease, psychiatric disease, and brain tumors are underway. MRgFUS is also used in the context of blood-brain barrier (BBB) opening at low intensities, in combination with intravenously-administered microbubbles. Preclinical studies show that MRgFUS-mediated BBB opening safely enhances the delivery of targeted chemotherapeutic agents to the brain and improves tumor control as well as survival. In addition, BBB opening has been shown to activate the innate immune system in animal models of Alzheimer’s disease. Amyloid plaque clearance and promotion of neurogenesis in these studies suggest that MRgFUS-mediated BBB opening may be a new paradigm for neurodegenerative disease treatment in the future. Here, we review the current status of preclinical and clinical trials of MRgFUS-mediated thermal ablation and BBB opening, described their mechanisms of action, and discuss future prospects.

Advances in low-frequency ultrasound combined with microbubbles in targeted tumor therapy / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

The development of low-frequency ultrasound imaging technology and the improvement of ultrasound contrast agent production technology mean that they play an increasingly important role in tumor therapy. The interaction between ultrasound and microbubbles and their biological effects can transfer and release microbubbles carrying genes and drugs to target tissues, mediate the apoptosis of tumor cells, and block the embolization of tumor microvasculature. With the optimization of ultrasound parameters, the development of targeted microbubbles, and the emergence of various composite probes with both diagnostic and therapeutic functions, low-frequency ultrasound combined with microbubble contrast agents will bring new hope for clinical tumor treatment.

Measuring Intrahepatic Vascular Changes Using Contrast-Enhanced Ultrasonography to Predict the Prognosis of Alcoholic Hepatitis Combined with Cirrhosis: A Prospective Pilot Study

BACKGROUND/AIMS: Acute hepatic dysfunction combined with alcoholic hepatitis (AH) in alcoholic cirrhosis is related to hepatic hypo-perfusion secondary to intrahepatic necroinflammation, neoangiogenesis, and shunt. The hepatic vein arrival time (HVAT) assessed by microbubble contrast-enhanced ultrasonography (CEUS) is closely correlated with the severity of intrahepatic changes. We investigated the usefulness of HVAT to predict short-term mortality of AH in cirrhosis. METHODS: Thirty-nine patients with alcoholic cirrhosis (27 males) and AH were prospectively enrolled. HVAT study was performed within 3 days after admission using ultrasonic contrast (SonoVue®). The primary outcome was 12-week mortality. RESULTS: Twelve-week mortality developed in nine patients. HVAT was significantly different between the mortality and survival groups (9.3±2.0 seconds vs 12.6±3.5 seconds, p=0.002). The odds ratio of a shortened HVAT for 12-week mortality was 1.481 (95% confidence interval, 1.050–2.090; p=0.025). The area under the receiver operating characteristic curve of HVAT for 12-week mortality was 0.787 (p=0.010). The combination of MDF and HVAT ≥11.0 seconds resulted in an 87.5% survival rate even if the MDF score ≥32; however, HVAT < 11.0 seconds was related with mortality despite a MDF score < 32. CONCLUSIONS: HVAT using microbubble CEUS could be a useful additional index to predict short-term mortality in patients with AH and cirrhosis.

Effect of RNA Interference Targeting Gene Combined with Ultrasonic Irradiation and SonoVue Microbubbles on Proliferation and Apoptosis in Keratinocytes of Psoriatic Lesions / 中华医学杂志(英文版)

Background@#Signal transducer and activator of transcription 3 (STAT3) was strongly expressed and activated in psoriatic keratinocytes (KCs) and correlated with the severity of psoriasis. The study aimed to investigate the effects of STAT3 small interfering RNA (siRNA) combined with ultrasonic irradiation and SonoVue microbubbles on the proliferation and apoptosis in KCs of psoriatic lesions and the relative mechanisms.@*Methods@#Psoriatic KCs were transfected under four experimental conditions: (1) STAT3 siRNA carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (LUS group); (2) STAT3 siRNA only carried by Lipofectamine 3000 (L group); (3) the negative control of siRNA carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (siRNA-NC); (4) not treated as Blank. Cell Counting Kit-8 assay was used to evaluate the cell proliferation. Cell cycle analysis was detected with cycle test Plus DNA reagent kit associated with flow cytometer. FITC Annexin V apoptosis detection kit associated with flow cytometer was applied for apoptosis analysis. Fluo calcium indicator associated with flow cytometer was used to analyze intracellular free calcium concentration ([Ca]). The expressions of cyclin D1 and Bcl-xL were detected both at the mRNA level by real-time reverse transcription-polymerase chain reaction (RT-PCR) and at the protein level by Western blotting. The obtained data were statistically evaluated by two-way analysis of variance.@*Results@#STAT3 siRNA inhibited the growth of KCs in a time-dependent manner showing the highest proliferation inhibition in LUS group with proliferation ratio of 45.38% ± 5.85% at 72h (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced an altered cell cycle distribution of KCs showing the highest increases in G2/M-phase population up to 18.06% ± 0.36% in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced late apoptosis of KCs with the highest late apoptosis percentage of 22.87% ± 1.28% in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced the elevation of [Ca]of KCs with the highest calcium fluorescence intensity mean of 1213.67 ± 60.51 in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced the downregulation of cyclin D1 and Bcl-xL expressions of KCs at mRNA and protein levels with the lowest expressions in LUS group with cyclin D1 expression of 51.81% ± 9.58% and 70.17% ± 4.22% at mRNA level and at protein level, respectively, and with Bcl-xL expression of 37.58% ± 4.92% and 64.06% ± 7.78% at mRNA level and at protein level, respectively (P < 0.05 vs. L group, siRNA-NC, or Blank).@*Conclusions@#STAT3 siRNA inhibited the growth and induced the apoptosis in psoriatic KCs likely partly through altering cell cycle distribution, elevating [Ca], and downregulating cyclin D1 and Bcl-xL expressions. Silencing the target gene STAT3 in psoriatic KCs with siRNA combined with ultrasonic irradiation and microbubbles would contribute to a significant innovation as a new clinical therapy for psoriasis.

Use of cationic microbubbles targeted to P-selectin to improve ultrasound-mediated gene transfection of hVEGF165 to the ischemic myocardium / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Gene therapies have been applied to the treatment of cardiovascular disease, but their use is limited by the need to deliver them to the right target. We have employed targeted contrast ultrasound-mediated gene transfection (TCUMGT) via ultrasound-targeted microbubble destruction (UTMD) to transfer therapeutic genes to specific anatomic and pathological targets. Phospholipid microbubbles (MBs) with pcDNA3.1-human vascular endothelial growth factor 165 (pcDNA3.1-hVEGF165) plasmids targeted to P-selectin (MB+P+VEGFp) were created by conjugating monoclonal antibodies against P-selectin to the lipid shell. These microbubbles were divided into four groups: microbubble only (MB), microbubble+P-selectin (MB+P), microbubble+pcDNA3.1-hVEGF165 plasmid (MB+VEGFp), and microbubble+ P-selectin+pcDNA3.1-hVEGF165 plasmid (MB+P+VEGFp). The reverse transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) results showed that the VEGF gene was successfully transfected by TCUMGT and the efficiency is increased with P-selectin targeting moiety. UTMD-mediated delivery of VEGF increased myocardial vascular density and improved cardiac function, and MB+P+VEGFp delivery showed greater improvement than MB+VEGFp. This study drew support from TCUGMT technology and took advantage of targeted ultrasound contrast agent to identify ischemic myocardium, release pcDNA3.1-hVEGF165 recombinant plasmid, and improve the myocardial microenvironment, so promoting the restoration of myocardial function.

Influence of ultrasound contrast agents on spectral Doppler analysis in recipients of liver transplantation

BACKGROUND/AIMS: Clinical validation is required to determine whether Doppler measurements are comparable before and after administering ultrasound contrast agent (USCA). The purpose of this study is to explore whether the use of USCA affects spectral Doppler analysis in recipients of liver transplantation (LT). METHODS: For this study, 36 patients were examined using Doppler ultrasonography (US) along with a contrast-enhanced US for surveillance of vascular complications after LT. The following spectral Doppler US parameters were measured before and after administration of USCA: peak systolic velocity, end-diastolic velocity, resistive index, and systolic acceleration time of the graft hepatic artery; peak flow velocity of the graft portal vein; and peak flow velocity and venous pulsatility index of the graft hepatic vein. RESULTS: The mean peak systolic and end-diastolic velocities of the hepatic artery and the peak flow velocity of the portal and hepatic veins were increased after intravenously administration of the USCA, ranging from 10% to 13%. However, the changes were not statistically significant (P=0.097, 0.103, 0.128, and 0.190, respectively). There were no significant differences in other measured parameters, including the resistive index (P=0.205) and systolic acceleration time (P=0.489) of the hepatic artery and venous pulsatility index (P=0.494) of the hepatic vein. CONCLUSIONS: The measured velocities of graft hepatic vessels tended to increase after administration of USCA, but without statistical significance. The comparison of serial Doppler parameters with or without injection of USCA is valid during Doppler surveillance in recipients of LT.

Microbubbles used for contrast enhanced ultrasound and theragnosis: a review of principles to applications

Ultrasound was developed several decades ago as a useful imaging modality, and it became the second most popular diagnostic tool due to its non-invasiveness, real-time capabilities, and safety. Additionally, ultrasound has been used as a therapeutic tool with several therapeutic agents and in nanomedicine. Ultrasound imaging is often used to diagnose many types of cancers, including breast, stomach, and thyroid cancers. In addition, ultrasound-mediated therapy is used in cases of joint inflammation, rheumatoid arthritis, and osteoarthritis. Microbubbles, when used as ultrasound contrast agents, can act as echo-enhancers and therapeutic agents, and they can play an essential role in ultrasound imaging and ultrasound-mediated therapy. Recently, various types of ultrasound contrast agents made of lipid, polymer, and protein shells have been used. Air, nitrogen, and perfluorocarbon are usually included in the core of the microbubbles to enhance ultrasound imaging, and therapeutic drugs are conjugated and loaded onto the surface or into the core of the microbubbles, depending on the purpose and properties of the substance. Many research groups have utilized ultrasound contrast agents to enhance the imaging signal in blood vessels or tissues and to overcome the blood–brain barrier or blood-retina barrier. These agents are also used to help treat diseases in various regions or systems of the body, such as the cardiovascular system, or as a cancer treatment. In addition, with the introduction of targeted moiety and multiple functional groups, ultrasound contrast agents are expected to have a potential future in ultrasound imaging and therapy. In this paper, we briefly review the principles of ultrasound and introduce the underlying theory, applications, limitations, and future perspectives of ultrasound contrast agents.

Biological effects of blood–brain barrier disruption using a focused ultrasound

With focused ultrasound (FUS) and microbubbles, BBB can be transiently disrupted with a localized and non-invasive approach. BBB disruption induced by FUS has made progressions to move forward on delivery of therapeutic agents into a brain in a specific area of brain for better treatment of neurological diseases. In addition to be used as an improvement of drug delivery, BBB disruption has been found to induce biological effects such as a clearance of protein aggregation which cause Alzheimer's disease, regulation of proteins which facilitate drug uptake, and modulation of neuronal function and neurogenesis. In this review, we discuss overview about the principles of BBB opening with FUS and milestones in these biological effects of FUS-induced BBB disruption.

Ultrasound-guided drug delivery in cancer

Recent advancements in ultrasound and microbubble (USMB) mediated drug delivery technology has shown that this approach can improve spatially confined delivery of drugs and genes to target tissues while reducing systemic dose and toxicity. The mechanism behind enhanced delivery of therapeutics is sonoporation, the formation of openings in the vasculature, induced by ultrasound-triggered oscillations and destruction of microbubbles. In this review, progress and challenges of USMB mediated drug delivery are summarized, with special focus on cancer therapy.

Synthesis of ultrasound contrast agents: characteristics and size distribution analysis (secondary publication)

PURPOSE: The purpose of this study was to establish a method for ultrasound (US) contrast agent synthesis and to evaluate the characteristics of the synthesized US contrast agent. METHODS: A US contrast agent, composed of liposome and sulfur hexafluoride (SF₆), was synthesized by dissolving 21 μmol 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine (DPPC, C₄₀H₈₀NO₈P), 9 μmol cholesterol, and 1.9 μmol of dihexadecylphosphate (DCP, [CH₃(CH₂)15O]₂P(O)OH) in chloroform. After evaporation in a warm water bath and drying for 12-24 hours, the contrast agent was synthesized using the sonication process by the addition of a buffer and SF₆ gas. The size distribution of the bubbles was analyzed using dynamic light scattering measurement methods. The degradation curve was evaluated by assessing the change in the number of contrast agent bubbles using light microscopy immediately, 12, 24, 36, 48, 60, 72, and 84 hours after synthesis. The echogenicity of the synthesized microbubbles was compared with commercially available microbubbles (SonoVue, Bracco). RESULTS: contrast agent was synthesized successfully using an evaporation-drying-sonication method. Most bubbles had a mean diameter of 154.2 nm and showed marked degradation 24 hours after synthesis. Although no statistically significant differences were observed between SonoVue and the synthesized contrast agent, a difference in echogenicity was observed between the synthesized contrast agent and saline (P<0.01). CONCLUSION: We successfully synthesized a US contrast agent using an evaporation-dryingsonication method. These results may help future research in the fields of anticancer drug delivery, gene delivery, targeted molecular imaging, and targeted therapy.