Efficacy and safety of endoscopic resection in treatment of small gastric stromal tumors: A state-of-the-art review

Gastrointestinal stromal tumors can occur in any part of the gastrointestinal tract,but gastric stromal tumors(GSTs)are the most common.All GSTs have the potential to become malignant,and these can be divided into four different grades by risk from low to high:Very low risk,low risk,medium risk,and high risk.Current guidelines all recommend early complete excision of GSTs larger than 2 cm in diameter.However,it is not clear whether small GSTs(sGSTs,i.e.,those smaller than 2 cm in diameter)should be treated as early as possible.The National Comprehensive Cancer Network recommends that endoscopic ultrasonographyguided(EUS-guided)fine-needle aspiration biopsy and imaging(computed tomography or magnetic-resonance imaging)be used to assess cancer risk for sGSTs detected by gastroscopy to determine treatment.When EUS indicates a higher risk of tumor,surgical resection is recommended.There are some questions on whether sGSTs also require early treatment.Many studies have shown that endoscopic treatment of GSTs with diameters of 2-5 cm is very effective.We here address whether endoscopic therapy is also suitable for sGSTs.In this paper,we try to explain three questions:(1)Does sGST require treatment?(2)Is digestive endoscopy a safe and effective means of treating sGST?and(3)When sGSTs are at different sites and depths,which endoscopic treatment method is more suitable?

Effect of aluminum phosphate gel on prevention of early rebleeding after ligation of esophageal variceal hemorrhage

BACKGROUND Liver cirrhosis is the main cause of portal hypertension.The leading cause of death in patients with liver cirrhosis is its most common complication,esophageal variceal bleeding(EVB).Endoscopic variceal ligation(EVL)is recommended by many guidelines to treat EVB and prevent rebleeding;however,esophageal ulcers occur after treatment.Delayed healing of ulcers and unhealed ulcers lead to high rebleeding and mortality rates.Thus,the prevention of early postoperative rebleeding is of great significance in improving the quality of life and prognosis of patients.AIM To evaluate the efficacy of aluminum phosphate gel(APG)plus a proton pump inhibitor(PPI)in the prevention of early rebleeding after EVL in patients with EVB.METHODS The medical records of 792 patients who were diagnosed with EVB and in whom bleeding was successfully stopped by EVL at Shenzhen People’s Hospital,Guangdong Province,China from January 2015 to December 2020 were collected.According to the study inclusion and exclusion criteria,401 cases were included in a PPI-monotherapy group(PPI group),and 377 cases were included in a PPI and APG combination therapy(PPI+APG)group.We compared the incidence rates of early rebleeding and other complications within 6 wk after treatment between the two groups.The two-sample t-test,Wilcoxon rank-sum test,and chisquared test were adopted for statistical analyses.RESULTS No significant differences in age,sex,model for end-stage liver disease score,coagulation function,serum albumin level,or hemoglobin level were found between the two groups.The incidence of early rebleeding in the PPI+APG group(9/337;2.39%)was significantly lower than that in the PPI group(30/401;7.48%)(P=0.001).Causes of early rebleeding in the PPI group were esophageal ulcer(3.99%,16/401)and esophageal varices(3.49%,14/401),while those in the PPI+APG group were also esophageal ulcers(5/377;1.33%)and esophageal varices(4/377;1.06%);such causes were significantly less frequent in the PPI+APG group than in the PPI group(P=0.022 and 0.024,respectively).The early mortality rate within 6 wk in both groups was 0%,which was correlated with the timely rehospitalization of all patients with rebleeding and the conduct of emergency endoscopic therapy.The incidence of adverse events other than early bleeding in the PPI+APG group(28/377;7.43%)was significantly lower than that in the PPI group(63/401;15.71%)(P<0.001).The incidence of chest pain in the PPI+APG group(9/377;2.39%)was significantly lower than that in the PPI group(56/401;13.97%)(P<0.001).The incidence of constipation in the PPI+APG group(16/377;4.24%)was significantly higher than that in the PPI group(3/401;0.75%)(P=0.002)but constipation was relieved after patients drank more water or took lactulose.In the PPI and PPI+APG groups,the incidence rates of spontaneous peritonitis within 6 wk after discharge were 0.50%(2/401)and 0.53%(2/377),respectively,and those of hepatic encephalopathy were 0.50%(2/401)and 0.27%(1/377),respectively,presenting no significant difference(P>0.999).CONCLUSION PPI+APG combination therapy significantly reduces the incidence of early rebleeding and chest pain in patients with EVB after EVL.

Meta-objective with sub-micrometer resolution for microendoscopes

Microendoscopes are vital for disease detection and clinical diagnosis. The essential issue for microendoscopes is to achieve minimally invasive and high-resolution observations of soft tissue structures inside deep body cavities.Obviously, the microscope objective is a must with the capabilities of both high lateral resolution in a wide field of view(FOV) and miniaturization in size. Here, we propose a meta-objective, i.e., microscope objective based on cascaded metalenses. The two metalenses, with the optical diameters of 400 μm and 180 μm, respectively, are mounted on both sides of a 500-μm-thick silica film. Sub-micrometer lateral resolution reaches as high as 775 nm in such a naked meta-objective, with monochromatic aberration correction in a 125 μm full FOV and near diffraction limit imaging. Combined with a fiber bundle microscope system, the single cell contour of biological tissue(e.g., water lily leaf) can be clearly observed, compared to the indistinguishable features in other conventional lens-based fiber bundle systems, such as plano–convex and gradient refractive index(GRIN) cases.

Phase characterisation of metalenses

Metalenses have emerged as a new optical element or system in recent years,showing superior performance and abundant applications.However,the phase distribution of a metalens has not been measured directly up to now,hindering further quantitative evaluation of its performance.We have developed an interferometric imaging phase measurement system to measure the phase distribution of a metalens by taking only one photo of the interference pattern.Based on the measured phase distribution,we analyse the negative chromatic aberration effect of monochromatic metalenses and propose a feature size of metalenses.Different sensitivities of the phase response to wavelength between the Pancharatnam-Berry phase-based metalens and propagation phase-reliant metalens are directly observed in the experiment.Furthermore,through phase distribution analysis,it is found that the distance between the measured metalens and the brightest spot of focusing will deviate from the focal length when the metalens has a low nominal numerical aperture,even though the metalens is ideal without any fabrication error.We also use the measured phase distribution to quantitatively characterise the imaging performance of the metalens.Our phase measurement system will help not only designers optimise the designs of metalenses but also fabricants distinguish defects to improve the fabrication process,which will pave the way for metalenses in industrial applications.

Ideal nodal rings of one-dimensional photonic crystals in the visible region

Three-dimensional(3D)artificial metacrystals host rich topological phases,such as Weyl points,nodal rings,and 3D photonic topological insulators.These topological states enable a wide range of applications,including 3D robust waveguides,one-way fiber,and negative refraction of the surface wave.However,these carefully designed metacrystals are usually very complex,hindering their extension to nanoscale photonic systems.Here,we theoretically proposed and experimentally realized an ideal nodal ring in the visible region using a simple 1D photonic crystal.The TT-Berrry phase around the ring is manifested by a 2π reflection phase's winding and the resultant drumhead surface states.By breaking the inversion symmetry,the nodal ring can be gapped and the n-Berry phase would diffuse into a toroidal-shaped Berry flux,resulting in photonic ridge states(the 3D extension of quantum valley Hall states).Our results provide a simple and feasible platform for exploring 3D topological physics and its potential applications in nanophotonics.