Influence of the abdominal wall on the nonlinear propagation of focused therapeutic ultrasound

This article theoretically studies the influence of inhomogeneous abdominal walls on focused therapeutic ultrasound based on the phase screen model. An inhomogeneous tissue is considered as a combination of a homogeneous medium and a phase aberration screen. Variations of acoustic parameters such as peak positive pressure, peak negative pressure, and acoustic intensity are discussed with respect to the phase screen statistics of human abdominal walls. Results indicate that the abdominal wall can result in energy loss of the sound in the focal plane. For a typical human abdominal wall with correlation length of 7.9 mm and variance of 0.36, the peak acoustic intensity radiated from a 1MHz transmitter with a radius of 30 mm can be reduced by about 14% at the focal plane.

Different Effects of Therapeutic Ultrasound Parameters and Culture Conditions on Gene Transfection Efficiency

Objective： To investigate the effect of different therapeutic ultrasound （TUS） parameters and culture conditions on the cell viability and transfection efficiency of human cervical cancer cells （HeLa）. Methods： HeLa cells were cultured using two different protocols （in suspension or in monolayer）. Subsequently, cells were exposed to different TUS intensity （0.4 W/cm^2, 1.0 W/cm^2, 1.6 W/cm^2, 2.2 W/cm^2）, duty cycle （DC）（10%, 20%, 50%）, exposure time （1 min or 3 min）. Cell viability was analyzed by flow cytometry. Gene transfection of red fluorescent protein （DsRED） was detected. Results： TUS intensity and duty cycle had a great impact on the overall results （P〈0.01）. Cell injury were found to increase progressively with intensity （1.6 W/cm^2, 2.2 W/cm^2） and duty cycle （50%） and cell detachment was accompanied by ultrasound exposure in adherent cells Results of factorial design showed that the fashion of cell culture and the TUS parameters had interaction （P〈0.01）. The ideal conditions that cell viability above 80% producing maximum efficiency were noted to be at 1.0 W/cm^2 irradiated 3 min with a duty cycle of 20% in cell suspension. Conclusion： TUS parameters and transfection conditions have a great impact on the gene transfection and cell viability. Optimal parameters could enhance cell inembrane permeability, which facilitate to delivering the macromolecules into cells.

Practical approach to linear endoscopic ultrasound examination of the gallbladder

The gallbladder(GB)is a susceptible organ,prone to various pathologies that can be identified using different imaging techniques.Transabdominal ultrasound(TUS)is typically the initial diagnostic method due to its numerous well-established advantages.However,in cases of uncertainty or when a definitive diagnosis cannot be established,computed tomography(CT)or magnetic resonance imaging may be employed to provide more detailed information.Nevertheless,CT scans may sometimes offer inadequate spatial resolution,which can limit the differentiation of GB lesions,particularly when smaller yet clinically relevant abnormalities are involved.Conversely,endoscopic ultrasound(EUS)provides higher frequency compared to TUS,superior spatial resolution,and the option for contrast-enhanced harmonic imaging,enabling a more comprehensive examination.Thus,EUS can serve as a supplementary tool when conventional imaging methods are insufficient.This review will describe the standard EUS examination of the GB,focusing on its endosonographic characteristics in various GB path-ologies.

Therapeutic ultrasound cavitation and its free radical ESR determination

The formation of free radicals OH and H in a naturally air-saturated aqueous solution exposed to therapeutic CW ultrasound at a frequency of 820 kHz has been confirmed by using spin trapping 5, 5-dimethyl-1-pyrroline-1-oxide ( DMPO ) and electron spin resonance ( ESR) technique . It is suggested that these radicals are formed due to the high temperature and pressure produced by the ultrasonic transient cavitation. The transient cavitation threshold is found at 0. 537-0.632W/cm2 under a sonication time of 3 minutes .With increasing sound intensity the yield of free radicals OH raises rapidly at the intensity ranging from 1-2W/ cm2, and no longer increase is observed at above 3W/cm2. The sound intensity (Ⅰ) dependence of the yield of OH(D) can be approximately described by a regression equation: D = 8.1(I1/2 -Ic1/2 )1/2 where Ic=0. 667W/ cm2 . Under a fixing sound intensity the yield of OH increases monotonously with the sonication time.

Gastric cancer in 2022:Is there still a role for endoscopic ultrasound?

Gastric cancer(GC)represents the fourth leading cause of cancer death worldwide and many factors can influence its development(diet,geographic area,genetic,Helicobacter pylori or Epstein-Barr virus infections).High quality endoscopy represents the modality of choice for GC diagnosis.The correct morphologic classification during a high-resolution endoscopy is fundamental for oncologic diagnosis,staging and therapeutic decisions.Since its initial introduction in clinical practice the endoscopic ultrasound(EUS)has been considered a valuable tool for tumor(T-)and lymph nodes(N-)staging also in GC,in order to establish the best therapeutic strategy for the patient(e.g.,upfront surgery vs neoadjuvant treatments).EUS tools as elastography,Doppler and contrast administration can improve diagnosis mainly in case of malignant lymph node evaluation.EUS has a marginal role in disease staging but has a fundamental role in case of a pre-endoscopic resection management and in the new era of endoscopic mucosal resection or submucosal dissection as minimally invasive surgery.Diagnosis and locoregional staging of GC with EUS are a method of inarguable value for the assessment of gastric wall involvement and presence of infiltrated paragastric lymph nodes.EUS can also have a role in disease restaging in those patients who have undergone neoadjuvant treatment.EUS can also have a role in the advanced phases of the disease,in facilitating palliative,minimallyinvasive treatments,such as gastroenterostomy or biliary drainages.This review intends to discuss the modern role of EUS in GC topic.

High intensity focused ultrasound: A noninvasive therapy for locally advanced pancreatic cancer

The noninvasive ablation of pancreatic cancer with high intensity focused ultrasound(HIFU) energy is received increasingly widespread interest. With rapidly temperature rise to cytotoxic levels within the focal volume of ultrasound beams, HIFU can selectively ablate a targeted lesion of the pancreas without any damage to surrounding or overlying tissues. Preliminary studies suggest that this approach is technical safe and feasible, and can be used alone or in combination with systemic chemotherapy for the treatment of patients with locally advanced pancreatic cancer. It can effectively alleviate cancer-related abdominal pain, and may confer an additional survival benefit with few significant complications. This review provides a brief overview of HIFU, describes current clinical applications, summarizes characteristics of continuous and pulsed HIFU, and discusses future applications and challenges in the treatment of pancreatic cancer.

Noninvasive temperature estimation by detecting echo-strain change including thermal expansion

This article studies the feasibility of noninvasive temperature estimation by detecting echo-strain including thermal expansion in therapeutic ultrasound treatment. This technique evaluates distributions of echo-strain and temperature inside the tissue by detecting echo signals pre- and post-heating, in combination with the temperature dependence of sound speed and thermal expansion. In the computer simulation and experimental study, echo signals pre- and post- heating are acquired and then the temperature elevation is evaluated by correlation analysis. Results demonstrate that this technique can effectively extend the measured temperature range up to 75℃ with an accuracy of±2 ℃.

Endo-hepatology:An emerging field

Gastroenterologists have long been spearheading the care of patients with various forms of liver disease.The diagnosis and management of liver disease has traditionally been a combination of clinical,laboratory,and imaging findings coupled with percutaneous and intravascular procedures with endoscopy largely limited to screening for and therapy of esophageal and gastric varices.As the applications of diagnostic and therapeutic endoscopic ultrasound(EUS)have evolved,it has found a particular niche within hepatology now coined.Here we discuss several EUS-guided procedures such as liver biopsy,shear wave elastography,direct portal pressure measurement,paracentesis,as well as EUSguided therapies for variceal hemorrhage.

Impact of microbubble enhanced, pulsed, focused ultrasound on tumor circulation of subcutaneous VX2 cancer

Background Intravascular microbubble-enhanced acoustic cavitation is capable of disrupting the vascular walls of capillaries and small vessels. This study was designed to investigate the impact of microbubble-enhanced, pulsed and focused ultrasound （MEUS） on the blood perfusion of subcutaneous VX2 tumors in rabbits. Methods Subcutaneous VX2 cancers in twenty New Zealand rabbits were treated by combining high-pressure amplitude, pulsed and focused therapeutic ultrasound （TUS） and intravenous microbubble injections. The TUS transducer was operated with a peak negative pressure of 4.6 MPa and a duty cycle of 0.41%. Controls were subcutaneous VX2 cancers treated with TUS or microbubbles only. Contrast-enhanced ultrasound （CEUS） and intravenous Evans Blue （EB） perfusion were performed to assess the tumor circulation. The tumor microvascular disruption was assessed by histological examination. Results CEUS showed that the tumor circulation almost vanished after MEUS treatment. The average peak grayscale value （GSV） of tumor CEUS dropped significantly from 84.1±22.4 to 15.8±10.8 in the MEUS-treated tumors but no significant GSV changes were found in tumors in the two control groups. The mean tumor EB content of the MEUS-treated tumors was significantly lower than that of the controls. Histological examination found scattered tumor microvascular disruption with intercellular edema after MEUS treatment. Conclusion The tumor circulation of VX2 cancers can be arrested or significantly reduced by MEUS due to microvascular disruption. Chin M~.cl ,I 2014：127 （14）： 2605-2611