After the production of the gradient coil of the magnetic resonance imaging system, electromagnetic field testing is required to verify whether the assembly accuracy meets the electromagnetic field requirements. Since the passive magnetic field B _z satisfies the Laplace ^,s equation and is a harmonic function, and according to the extreme value principle of harmonic function, the maximum or minimum values of B _z can only appear on the boundaries, so the observation points of the magnetic field are generally selected on the surface of the spherical imaging area. For superconducting magnets used for human body magnetic resonance imaging, a spherical area with a center diameter of 40~50 cm is generally selected as the shimming target area. Only the field value of the target area needs to be measured, and the spherical harmonic coefficients obtained after data processing are used to determine the magnetic field performance of the gradient coil. There are many testing principles and methods for electromagnetic fields, so there is no unified way and method in the field of commercial applications. This article is based on the Gauss-Legendre numerical integration, measures and analyzes the magnetic field performance of gradient coils by building a data acquisition system, and this article applies numerical analysis methods to calculate the spherical harmonic coefficients of the magnetic field using discrete test data, providing a feasible method for the production and testing of gradient coils.
Magnetic Resonance Imaging/methods* ; Magnetic Fields ; Electromagnetic Fields ; Equipment Design

Objective:To document the effectiveness of ultrasound-guided genicular nerve block (GNB) in treating knee osteoarthritis (KOA).Methods:A total of 92 KOA patients were randomly divided into an observation group and a control group with 46 in each. Those in both groups were treated conventionally, including with non-steroidal anti-inflammatory drugs, acupuncture, ultrasound, laser irradiation and manipulation therapy. The observation group additionally underwent ultrasound-guided genicular nerve block treatment, once a week for 2 weeks. Pain scoring on a visual analog scale (VAS), the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and a 6-minute walk test (6MWT) were used to evaluate everyone before and after the treatment, and then 8 weeks later.Results:In the observation group the average VAS rating [(3.54±2.00) at week 2 and (4.13±2.04) at week 8] and the average WOMAC subscale and total scores [(36.91±16.91) at week 8] had improved significantly right after the experiment and 8 weeks later. But in the control group this was true only right after the treatment. The observation group also demonstrated superior improvements in 6MWT distance at week 2 [(434.22±125.19)m] and week 8 [(446.35±126.45)m] compared to both its own baseline and the control group.Conclusions:Ultrasound-guided genicular nerve block is a rapid, precise, effective, and long-lasting intervention for alleviating pain, improving knee function and enhancing walking endurance in KOA patients.

Objective:To investigate a novel coating technology for artificial blood vessel pipelines, conducting preliminary tests on the mechanical stability, hemocompatibility, and biocompatibility of the coating.Methods:The polyester braided artificial blood vessels produced by Terumo Corporation were subjected to three different experimental treatments and divided into three groups. Model group: The uncoated artificial blood vessels were thoroughly cleaned and freeze-dried. Experimental group: The artificial blood vessels were first immersed in a dopamine solution to form a polydopamine(PDA) coating on their surface, and then further immersed in an earthworm active protein/gelatin(EWAP/GT) solution to create PDA/GT/EWAP-modified artificial blood vessels. Collagen group: The untreated polyester woven artificial blood vessels served as the control. The study detailed the characterization, porosity, water permeability, degradation rate, blood compatibility, and cytotoxicity of the PDA/GT/EWAP-coated artificial blood vessels. Additionally, a 2-week in vivo study was conducted to evaluate the biocompatibility of the PDA/GT/EWAP-coated artificial blood vessels implanted subcutaneously in SD rats.Results:The PDA/GT/EWAP-coated artificial vascular grafts were successfully fabricated. The artificial blood vessels in the PDA/GT/EWAP group exhibited a porosityof(50.53±1.10)%, with water permeability showing a gradual decreasing trend over time. The overall in vitro degradation rate at 4 weeks was(1.83±0.08)%, and the PDA/GT/EWAP group demonstrated favorable mechanical stability. The activated partial thromboplastin time(APTT) of the PDA/GT/EWAP group was(26.30±0.46)s, the thrombin time(TT) was(18.83±0.49)s, the hemolysis rate was(2.15±0.09)%, and the plasma recalcification time(PRT) was(191.00±10.54)s, indicating excellent blood compatibility and anticoagulant properties. MTT assay evaluation of the PDA/GT/EWAP group revealed no significant cytotoxicity. After subcutaneous implantation of vascular samples in rats for 2 weeks, analysis of blood immune parameters and hematoxylin-eosin(HE) staining of the artificial vascular samples showed that the immune response in the PDA/GT/EWAP group exhibited no significant difference compared to the collagen group and was superior to the model group. Conclusion.Conclusion:The PDA/GT/EWAP composite-coated artificial blood vessel demonstrates excellent mechanical properties, good hemocompatibility, biocompatibility, and low cytotoxicity. It also shows remarkable stability. This research offers a new approach for domestic technological breakthroughs in related fields.

Psoriasis is a chronic,inflammatory,recurrent,and systemic disease mediated by immune dysregulation,which is often accompanied by psychological issues such as depression and anxiety.Recent research on the gut microbiota and depression and anxiety has made significant progress,with studies demonstrating that the gut microbiota plays a crucial role in the pathogenesis of psoriasis.Dysbiosis of the gut microbiota may be an important comorbidity mechanism linking psoriasis with depression and anxiety.This article summarizes the changes in the abundance of gut microbiota in patients with psoriasis and those with depression and anxiety,as well as how the gut microbiota influences this comorbidity through neural pathways and immune-endocrine pathways.It aims to provide novel perspectives for the study of the comorbidity mechanisms and clinical treatment of psoriasis and depression and anxiety.In the future,targeting the gut microbiota may enable the development of personalized treatments.

Objective Compare the tip perfusion index(TPI)with the disappearance of eyelash reflex in guiding the timing of intubation for painless gastroscopy,in order to find the optimal timing for painless gastroscopy.Methods 362 patients who underwent painless gastroscopy from January to June 2024 were selected.According to the random number table method,they were divided into group N(122 cases,direct endoscopic examination after the disappearance of eyelash reflex),group NS(121 cases,endoscopic examination 30 seconds after the disappearance of eyelash reflex),and group E[119 cases,endoscopic examination after continuous increase of TPI(newly measured value>previous measured value more than 3 times)].The changes in heart rate(HR),mean arterial pressure(MAP),and percutaneous arterial oxygen saturation(SpO2)before anesthesia induction(T0),before intubation(T1),through the throat(T2),and after examination(T3)were recorded and compared among the three groups.The intubation waiting time(from the completion of general anesthesia induction to the moment of intubation)and the incidence of adverse reaction were compared among the three groups.Results The waiting time for endoscopy in group N was(5.52±2.17)s,which was significantly shorter than that in group E[(18.60±3.89)s]and group NS[(35.74±2.17)s],and the differences were statistically significant(P<0.01).At T1 time point,the SpO2 of the group E was significantly higher than that of group N and group NS,the differences were statistically significant(P<0.01).There were no statistical difference of SpO2 at T0,T2 and T3 time points among the three groups(P>0.05).There were no statistical differences in HR and MAP at the T0,T1,T2 and T3 time points among the three groups(P>0.05);The MAP and HR of the three groups of patients at time point T0 were significantly higher than those at time points T1,T2 and T3,and the differences were statistically significant(P<0.05).The incidence of lower jaw support in group E was significantly lower than that in group NS and group N,the incidence of body movement and the rate of additional propofol administration were significantly lower than those in group N,the incidence of coughing was significantly lower than that in group NS,and the differences were statistically significant(P<0.05).Conclusion The TPI is a simple,non-invasive,objective,and real-time predictor of the timing of intubation for painless gastroscopy,which is significantly better than guiding the timing of intubation through the eyelash reflex.When the TPI continuously increases from a low point,it is a good time for painless gastroscopy intubation.

Objective Compare the tip perfusion index(TPI)with the disappearance of eyelash reflex in guiding the timing of intubation for painless gastroscopy,in order to find the optimal timing for painless gastroscopy.Methods 362 patients who underwent painless gastroscopy from January to June 2024 were selected.According to the random number table method,they were divided into group N(122 cases,direct endoscopic examination after the disappearance of eyelash reflex),group NS(121 cases,endoscopic examination 30 seconds after the disappearance of eyelash reflex),and group E[119 cases,endoscopic examination after continuous increase of TPI(newly measured value>previous measured value more than 3 times)].The changes in heart rate(HR),mean arterial pressure(MAP),and percutaneous arterial oxygen saturation(SpO2)before anesthesia induction(T0),before intubation(T1),through the throat(T2),and after examination(T3)were recorded and compared among the three groups.The intubation waiting time(from the completion of general anesthesia induction to the moment of intubation)and the incidence of adverse reaction were compared among the three groups.Results The waiting time for endoscopy in group N was(5.52±2.17)s,which was significantly shorter than that in group E[(18.60±3.89)s]and group NS[(35.74±2.17)s],and the differences were statistically significant(P<0.01).At T1 time point,the SpO2 of the group E was significantly higher than that of group N and group NS,the differences were statistically significant(P<0.01).There were no statistical difference of SpO2 at T0,T2 and T3 time points among the three groups(P>0.05).There were no statistical differences in HR and MAP at the T0,T1,T2 and T3 time points among the three groups(P>0.05);The MAP and HR of the three groups of patients at time point T0 were significantly higher than those at time points T1,T2 and T3,and the differences were statistically significant(P<0.05).The incidence of lower jaw support in group E was significantly lower than that in group NS and group N,the incidence of body movement and the rate of additional propofol administration were significantly lower than those in group N,the incidence of coughing was significantly lower than that in group NS,and the differences were statistically significant(P<0.05).Conclusion The TPI is a simple,non-invasive,objective,and real-time predictor of the timing of intubation for painless gastroscopy,which is significantly better than guiding the timing of intubation through the eyelash reflex.When the TPI continuously increases from a low point,it is a good time for painless gastroscopy intubation.

Psoriasis is a chronic,inflammatory,recurrent,and systemic disease mediated by immune dysregulation,which is often accompanied by psychological issues such as depression and anxiety.Recent research on the gut microbiota and depression and anxiety has made significant progress,with studies demonstrating that the gut microbiota plays a crucial role in the pathogenesis of psoriasis.Dysbiosis of the gut microbiota may be an important comorbidity mechanism linking psoriasis with depression and anxiety.This article summarizes the changes in the abundance of gut microbiota in patients with psoriasis and those with depression and anxiety,as well as how the gut microbiota influences this comorbidity through neural pathways and immune-endocrine pathways.It aims to provide novel perspectives for the study of the comorbidity mechanisms and clinical treatment of psoriasis and depression and anxiety.In the future,targeting the gut microbiota may enable the development of personalized treatments.

Objective:To document the effectiveness of ultrasound-guided genicular nerve block (GNB) in treating knee osteoarthritis (KOA).Methods:A total of 92 KOA patients were randomly divided into an observation group and a control group with 46 in each. Those in both groups were treated conventionally, including with non-steroidal anti-inflammatory drugs, acupuncture, ultrasound, laser irradiation and manipulation therapy. The observation group additionally underwent ultrasound-guided genicular nerve block treatment, once a week for 2 weeks. Pain scoring on a visual analog scale (VAS), the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and a 6-minute walk test (6MWT) were used to evaluate everyone before and after the treatment, and then 8 weeks later.Results:In the observation group the average VAS rating [(3.54±2.00) at week 2 and (4.13±2.04) at week 8] and the average WOMAC subscale and total scores [(36.91±16.91) at week 8] had improved significantly right after the experiment and 8 weeks later. But in the control group this was true only right after the treatment. The observation group also demonstrated superior improvements in 6MWT distance at week 2 [(434.22±125.19)m] and week 8 [(446.35±126.45)m] compared to both its own baseline and the control group.Conclusions:Ultrasound-guided genicular nerve block is a rapid, precise, effective, and long-lasting intervention for alleviating pain, improving knee function and enhancing walking endurance in KOA patients.

Objective:To investigate a novel coating technology for artificial blood vessel pipelines, conducting preliminary tests on the mechanical stability, hemocompatibility, and biocompatibility of the coating.Methods:The polyester braided artificial blood vessels produced by Terumo Corporation were subjected to three different experimental treatments and divided into three groups. Model group: The uncoated artificial blood vessels were thoroughly cleaned and freeze-dried. Experimental group: The artificial blood vessels were first immersed in a dopamine solution to form a polydopamine(PDA) coating on their surface, and then further immersed in an earthworm active protein/gelatin(EWAP/GT) solution to create PDA/GT/EWAP-modified artificial blood vessels. Collagen group: The untreated polyester woven artificial blood vessels served as the control. The study detailed the characterization, porosity, water permeability, degradation rate, blood compatibility, and cytotoxicity of the PDA/GT/EWAP-coated artificial blood vessels. Additionally, a 2-week in vivo study was conducted to evaluate the biocompatibility of the PDA/GT/EWAP-coated artificial blood vessels implanted subcutaneously in SD rats.Results:The PDA/GT/EWAP-coated artificial vascular grafts were successfully fabricated. The artificial blood vessels in the PDA/GT/EWAP group exhibited a porosityof(50.53±1.10)%, with water permeability showing a gradual decreasing trend over time. The overall in vitro degradation rate at 4 weeks was(1.83±0.08)%, and the PDA/GT/EWAP group demonstrated favorable mechanical stability. The activated partial thromboplastin time(APTT) of the PDA/GT/EWAP group was(26.30±0.46)s, the thrombin time(TT) was(18.83±0.49)s, the hemolysis rate was(2.15±0.09)%, and the plasma recalcification time(PRT) was(191.00±10.54)s, indicating excellent blood compatibility and anticoagulant properties. MTT assay evaluation of the PDA/GT/EWAP group revealed no significant cytotoxicity. After subcutaneous implantation of vascular samples in rats for 2 weeks, analysis of blood immune parameters and hematoxylin-eosin(HE) staining of the artificial vascular samples showed that the immune response in the PDA/GT/EWAP group exhibited no significant difference compared to the collagen group and was superior to the model group. Conclusion.Conclusion:The PDA/GT/EWAP composite-coated artificial blood vessel demonstrates excellent mechanical properties, good hemocompatibility, biocompatibility, and low cytotoxicity. It also shows remarkable stability. This research offers a new approach for domestic technological breakthroughs in related fields.

Objective:To explore the impact of intradialytic hypotension (IDH) on brain component volume, as well as its relationship with depression and cognitive function changes in maintenance hemodialysis patients.Method:It was a cross-sectional observational study. Clinical data of 119 patients under maintenance hemodialysis in Peking Union Medical College Hospital from July 2013 to July 2014 were collected, retrospectively. Patients were divided into IDH group and non-IDH group. 3.0T Magnetic resonance imaging examination of the head for all patients was completed and the results of volume analysis of each component of the brain were extracted. Cognitive function was assessed by the Chinese version of the simplified mental state examination scale (C-MMSE) and the Chinese version of the Montreal cognitive assessment scale (C-MoCA). Depressive status was assessed by the Hamilton depression scale 17 (HAMD_17) and living ability was assessed by the Alzheimer's disease collaborative study-daily living ability assessment questionnaire. In addition, the Philadelphia word learning test was used to measure memory, the Boston naming test to measure language, the connection test A and B to measure executive ability, and the Stroup test C to measure attention. The differences in brain component volume, cognitive function, emotion, and life ability between two groups of patients were compared, and the correlation between IDH and brain component volume was explored by regression analysis.Result:A total of 119 patients were included in this study, of whom 22 (18.5%) had hypotension during dialysis. The volumes of amygdala, cuneiform lobe, and posterior cingulate gyrus in IDH group were significantly smaller than those in the non-hypotension group [ (1.6±0.2) mm 3vs. (1.7±0.2) mm 3, t=2.674, P=0.009; (6.9±0.8) mm 3vs. (7.4±1.0) mm 3, t=2.187, P=0.031; (6.9±0.8) mm 3vs. (7.4±0.9) mm 3, t=2.252, P=0.024]. The differences of gray matter, white matter volume between the two groups showed a similar trend but did not reach statistical significance. And lacunar infarction and cerebral microbleeds were more common in IDH group. The daily living ability scores of the two groups were similar (65.51±11.52 vs. 65.71±11.53, Z=-0.456, P=0.648). The proportion of patients with cognitive abnormalities was higher in the IDH group, without statistical significance. The proportion of depression was similar. Univariate linear regression analysis showed that IDH was significantly negatively correlated with the volume of amygdala, cuneiform cortex, and posterior cingulate gyrus, which control emotions in the brain ( B=-0.117, 95% CI -0.203--0.030, P=0.009; B=-0.484, 95% CI -0.923--0.046, P=0.031; B=-0.485, 95% CI -0.911--0.058, P=0.026). After multivariate adjustment, decreased amygdala volume was still correlated with IDH ( B=-0.111, 95% CI -0.198--0.025, P=0.026). Conclusion:Recurrent IDH may lead to atrophy of various brain components, which may be one of the reasons for cognitive and emotional changes in maintenance hemodialysis patients.