A Comparative Study between Landmark Based and Real Time Ultrasound Guided Sub Arachnoid Block

Background: Sub arachnoid block (SAB) performed by traditional landmark palpation technique can be inaccurate. This problem is exacerbated by altered patient anatomy due to obesity and age-related changes. A pre-procedural ultrasound scan of the lumbar spine has been shown to be of benefit in guiding lumbar epidural insertion in obstetric patients. Information on the use of real-time ultrasound (RUS) guided SAB, to date, been limited. This study compared RUS guided SAB to traditional landmark guided technique in patients undergoing spinal anesthesia for different surgical procedures. Methods: This was a prospective, single center, comparative observational study conducted in the department of anesthesiology at our center. 560 patients who underwent spinal anesthesia either by landmark based technique or real-time ultrasound-guided methods. The primary outcome was the first attempt success rate of dural puncture when employing the two methods. Results: Baseline characteristics were similar in the two study groups. The first attempt success rate of dural puncture in landmark guided group was 64.3% compared to 72.6% in the ultrasound guided group. This difference was not statistically significant. The procedure performance time was significantly shorter with landmark palpation compared to use of real-time ultrasound guided method. Conclusion: Use of RUS-guided technique does not significantly improve the first attempt success rate of SAB dural puncture during spinal anesthesia compared to the traditional landmark-guided technique.

Transit time ultrasound perivascular flow probe technology is superior to MR imaging on hepatic blood flow measurement in a porcine model

Background: The hepatic hemodynamics is an essential parameter in surgical planning as well as in various disease processes. The transit time ultrasound(TTUS) perivascular flow probe technology is widely used in clinical practice to evaluate the hepatic inflow, yet invasive. The phase-contrast-MRI(PC-MRI) is not invasive and potentially applicable in assessing the hepatic blood flow. In the present study, we compared the hepatic inflow rates using the PC-MRI and the TTUS probe, and evaluated their predictive value of post-hepatectomy adverse events. Methods: Eighteen large white pigs were anaesthetized for PC-MRI and approximately 75% hepatic resection was performed under a unified protocol. The blood flow was measured in the hepatic artery(Qha), the portal vein(Qpv), and the aorta above the celiac trunk(Qca) using PC-MRI, and was compared to the TTUS probe. The Bland-Altman method was conducted and a partial least squares regression(PLS) model was implemented. Results: The mean Qpv measured in PC-MRI was 0.55 ± 0.12 L/min, and in the TTUS probe was 0.74 ± 0.17 L/min. Qca was 1.40 ± 0.47 L/min in the PC-MRI and 2.00 ± 0.60 L/min in the TTUS probe. Qha was 0.17 ± 0.10 L/min in the PC-MRI, and 0.13 ± 0.06 L/min in the TTUS probe. The Bland-Altman method revealed that the estimated bias of Qca in the PC-MRI was 32%(95% CI:-49% to 15%); Qha 17%(95% CI:-15% to 51%); and Qpv 40%(95% CI:-62% to 18%). The TTUS probe had a higher weight in predicting adverse outcomes after 75% resection compared to the PC-MRI( β= 0.35 and 0.43 vs β = 0.22 and 0.07, for tissue changes and premature death, respectively). Conclusions: There is a tendency of the PC-MRI to underestimate the flow measured by the TTUS probes. The TTUS probe measures are more predictive of relevant post-hepatectomy outcomes.

Real Time Ultrasound Elastography for the Differentiation of Benign and Malignant Thyroid Nodules

The purpose of this study was to evaluate the predictive value of real-time ultrasound elastography (RUE) in differentiating benign from malignant thyroid nodules, with fine needle aspiration cytology analysis as the reference standard. A total of 78 consecutive patients with thyroid nodules who were selected for fine needle aspiration biopsies were examined in this prospective study. 78 nodules in these patients were examined by conventional ultrasound, and ultrasound elastography. The final diagnosis was obtained from cytological findings. Tissue stiffness on ultrasound elastography was scored from 1 (low stiffness over the entire nodule) to 5 (high stiffness over the entire nodule and surrounding tissue). On real-time ultrasound elastography, 47 of 62 benign nodules (76%) had a score of 1 or 2, whereas 15 of 16 malignant nodules had a score of 3 to 5, with sensitivity of 93.7%, specificity of 90%, a positive predictive value of 71%, and a negative predictive value of 98%. Real-time ultrasound elastography is a promising imaging technique that is useful in the differential diagnosis of thyroid cancer. Utilization of ultrasound elastography could reduce the rate of thyroid biopsies because of its high elasticity being highly associated with benign cytology.

Comparison of Dwell-Times of Two Commonly Placed Peripheral Intravenous Catheters: Traditional vs. Ultrasound-Guided

Introduction: Because establishing venous access in patients can be difficult and time consuming, the use of ultrasound to guide the insertion of peripheral intravenous catheters has become more common. Anecdotal evidence indicates ultrasound-guided catheter insertion may result in decreased catheter survival in the vein (dwell-time), but there is little evidence to support this observation. The purpose of this study was to compare dwell-times for peripheral intravenous catheters placed with ultrasound guidance with intravenous catheters placed by means of traditional anatomic insertion in patients in an acute care hospital. Methods: This secondary data analysis examined outcomes of 298 patients who received ultrasound-guided catheter insertion and 299 patients who received traditionally placed intravenous catheters. Multivariable linear regression was used to identify significant predictors of dwell-time for both the traditional and US-guided catheters. Results: The average dwell-times for ultrasound-guided and traditionally placed catheters were significantly different (p 2 = 0.22). Discussion: Dwell-times of catheters placed with ultrasound guidance are shorter than traditionally placed catheters. Ultrasound-guided catheters should be monitored closely for inadvertent removal or infiltration. A plan to place a more permanent type of intravenous access should be considered for patients admitted for patients longer than 24 hours.

超声VTI引导液体复苏治疗ARDS伴右心功能不全的效果研究

目的以常规中心静脉压(CVP)指导下复苏为对照,研究超声左心室流出道速度时间积分(VTI)引导液体复苏应用于急性呼吸窘迫综合征(ARDS)伴右心功能不全的价值。方法按照随机数字表法将2021年7月—2023年8月海南医学院第二附属医院收治的80例ARDS伴右心功能不全患者分为CVP组、VTI组,各40例。CVP组在常规CVP指导下进行液体复苏,VTI组在超声VTI引导下进行液体复苏。比较两组复苏前后急性生理学和慢性健康状况评分(APACHEⅡ)、序贯器官衰竭评分(SOFA)、中心静脉压(CVP)、心指数、每搏输出量指数(SVI)、脉搏血氧饱和度(SpO_(2))、氧合指数、动脉氧分压(PaO_(2))、血乳酸、pH值、机械通气时间、液体复苏量、ICU住院时间、去甲肾上腺素用量、血管外肺水指数(ELWI)、肺毛细血管通透性指数(PVPI)。结果VTI组复苏后APACHEⅡ、SOFA评分与CVP组比较,差异无统计学意义(P>0.05);VTI组复苏后CVP、心指数、SVI、SpO_(2)高于CVP组(t=2.137、2.540、2.134,P=0.036、0.013、0.036);VTI组复苏后氧合指数、PaO_(2)、血乳酸、pH值与CVP组比较,差异无统计学意义(P>0.05);VTI组24 h液体复苏量高于CVP组,24 h去甲肾上腺素用量低于CVP组(t=2.492、6.914,P=0.015、0.000);VTI组复苏后ELWI、PVPI与CVP组比较,差异无统计学意义(P>0.05);两组均无肺水肿等不良反应发生。结论与常规CVP相比,超声VTI引导液体复苏应用于ARDS伴右心功能不全,对复苏量把控更精准,能避免液体复苏不充分,有效改善血流动力学,减少血管活性药物的使用。

Modified B-ultrasound method for measurement of antral section only to assess gastric function and guide enteral nutrition in critically ill patients

AIM To establish a modified B-ultrasound method of measuring the antral section only to assess gastric motility in healthy people,and evaluate its application in guiding enteral nutrition(EN) in critically ill patients. METHODS First,30 healthy volunteers were selected. The modified B-ultrasound method and the traditional B-ultrasound method were applied to assess gastric function. The correlation of indices of gastric function between the two groups was analyzed statistically. In addition,64 critically ill patients were selected,and the modified B-ultrasound method and the gastric juice withdrawal method were applied to guide the implementation of EN. Daily caloric value,the time required to achieve complete EN,ICU stay,hospitalization time,and serum prealbumin and albumin levels were recorded and compared between the two groups. Kaplan-Meier survival curve was used to compare the complications of EN between the two groups. RESULTS In healthy subjects,there was a good correlation among gastric emptying time,antral contraction frequency andantral motility index between the two groups(r = 0.57,0.61 and 0.54,respectively). The study on critically ill patients also revealed that a better effect of EN was achieved in the modified B-ultrasound method group,in which patients had shorter ICU stay and hospitalization time and higher levels of serum prealbumin and albumin. The Kaplan-Meier survival analysis revealed that the improved B-ultrasound method was associated with significantly fewer EN complications(P = 0.031).CONCLUSION The modified B-ultrasound method can provide a good real-time assessment of gastric function and has a better effect than the traditional method in guiding EN in critically ill patients.

医护一体化管理模式在超声造影检查中的应用研究

目的探讨医护一体化管理模式在经静脉注射六氟化硫微泡超声造影(CEUS)检查中的应用效果及意义。方法选取2019年1月至2023年12月于我院超声科接受CEUS检查的患者39616例,根据是否实施医护一体化管理模式将患者分为对照组(2019年1月至2020年12月采用常规管理模式,18942例)和研究组(2022年1月至2023年12月采用医护一体化管理模式,20674例)。比较两组CEUS检查时工作效率、患者候诊时间、不良反应发生率及患者满意度。结果在相同时间段及医护人员、诊室未增加情况下,研究组患者较对照组增加了9.1%。与对照组比较,研究组候诊时间明显缩短、满意度明显提高、不良反应发生率降低,差异均有统计学意义(均P<0.05)。所有发生不良反应的患者均经积极救治转危为安,痊愈出院。结论在CEUS检查中实施医护一体化管理模式,能有效提高工作效率、缩短患者候诊时间、降低不良反应发生率、提高患者满意度,有一定的临床意义。

Real-time virtual sonography visualization and its clinical application in biliopancreatic disease

AIM:To evaluate the usefulness of real-time virtual sonography(RVS)in biliary and pancreatic diseases.METHODS:This study included 15 patients with biliary and pancreatic diseases.RVS can be used to observe an ultrasound image in real time by merging the ultrasound image with a multiplanar reconstruction computed tomography(CT)image,using pre-scanned CT volume data.The ultrasound used was EUB-8500with a convex probe EUP-C514.The RVS images were evaluated based on 3 levels,namely,excellent,good and poor,by the displacement in position.RESULTS:By combining the objectivity of CT with free scanning using RVS,it was possible to easily interpret the relationship between lesions and the surrounding organs as well as the position of vascular structures.The resulting evaluation levels of the RVS images were12 excellent(pancreatic cancer,bile duct cancer,cholecystolithiasis and cholangiocellular carcinoma)and 3 good(pancreatic cancer and gallbladder cancer).Compared with conventional B-mode ultrasonography and CT,RVS images achieved a rate of 80%superior visualization and 20%better visualization.CONCLUSION:RVS has potential usefulness in objective visualization and diagnosis in the field of biliary and pancreatic diseases.

Effect of 20 kHz ultrasound on alumina hydrate precipitation from seeded sodium aluminate solution

The effect of 20 kHz ultrasound on alumina hydrate precipitation from seeded sodium aluminate solution was studied. Compared with alumina hydrate precipitation without treatment of ultrasound, the precipitation time is reduced from 30 h to 15 h when the precipitation ratio is 45% under 20 kHz ultrasound. Furthermore, agglomeration is increased and the growth rate of alumina hydrate is increased under 20 kHz ultrasound by comparing the crystal size distribution and the SEM photographs. As a result, the average size of alumina hydrate is increased by 3.7 μm. The structure of product is not changed according to the results of X ray powder deflection.

Development of a High-frequency Ultrasound System for High-speed Image Scanning

High-frequency image technique has been widely applied in medical diagnosis recently. For high voltage protection, high speed stage and trigger control circuitry are difficult to implement a high-frequency ultrasound imaging system. In this study, we utilized a linear servo with high noise tolerance and a novel multi-depth expression method to overcome those issues in developed high-speed image system. B-mode image of the chicken phantom by 25 MHz transducer shows the resolution of lateral and axial resolutions are up to 123 μm and 59 μm respectively. In addition, the experiment demonstrates that the axial resolution and depth of field (DOF) can be improved by time gain compensation(TGC) and multi-depth method. The results indicate that the proposed system could achieve over 24 fps for 1 mm scan distance and 100 lines per frame. In the future, the developed system is potential for other clinical applications such as ophthalmology and dermatology.

Quantitative Assessment of Coronary Flow Reserve by the Variables of Time-Intensity Curve with Myocardial Contrast Echocardiography

The reliability and reliable indexes of q ua ntitative assessment of coronary flow reserve (CFR) by using time intensity cur ve (TIC) via myocardial contrast echocardiography were investigated. The TIC var iables were obtained by employing acoustic densitometry (AD) technique before an d after acetylcholine (Ach) injection in 12 dogs. Meanwhile, the correlation be tween these variables and CFR was analyzed. Among the variables derived from TIC , peak intensity (PI), area under the curve (AUC) and descending slope (DS) were increased significantly ( P <0.05) with the increase of coronary blood flow a fter Ach injection. Conversely, time to peak (TP), half time of descent (HT) , and mean transit time (MTT) were decreased remarkably ( P <0.0001). Th e P I and AUC ratios from post to pre Ach injection were strongly associated with CFR with the correlation coefficient (r) being 0.8366 and 0.8824, respectively. It is reliable by using the variables derived from TIC with myocardial contrast echocardiography to quantitatively evaluate regional myocardial CFR. The PI an d AUC ratios from post to pre Ach injection are the reliable indexes for quan titative assessment of CFR.

Effect of ultrasound exposure on sonicated microbubbles stability

Objectives and Methods: Both the concentration and the size of contrast microbubbles are the important factors that affect the quality of intravenous myocardial contrast echocardiography (IVMCE) image, but the interactions between microbubbles and ultrasound are poorly understood. In order to select optimal ultrasound exposure condition for IVMCE, the influences of ultrasound power, frequency and exposure time on sonicated microbubbles stability were evaluated by a 2 x 2 x 4 factorial analysis in the study. Results: It was found that the concentration of microbubbles was decreased when the ultrasound power increased or the exposure time of ultrasound prolonged (P < 0. 001). The frequency of ultrasound did not influence the concentration of the bubbles (P = 0. 061 ). The higher the power or the frequency and the longer the exposuretime, the smaller the mean size of the contrast bubbles (power, P = 0.004; frequency, P < 0.001); exposure time, P < 0. 00l ). The controlling factors of the condition did not interactively affect the concentration or the mean size of contrast mi- crobubbles. Conclusion: These findings could allow us to select ultrasound at lower frequency, lower ultrasound power and to reduce the exposure time bine of microbubbles to ultrasound for the improvement in the contrast effect in IVMCE.

Usefulness of contrast enhanced ultrasound in monitoring therapeutic response after hepatocellular carcinoma treatment

In the last years, the development in the oncology field has been huge and rapid. In particular, the evaluation of response to anti-tumour treatments has been being object of intense research, producing significant changes. Response assessment after therapy in solid neoplasias has always used radiological imaging techniques, with tumour size reduction representing a presumed therapeutic efficacy. However, with the introduction of anti-angiogenetic drugs the evaluation of tumour size has become unsuitable because some tumours, under treatment, show only tumour perfusion changes rather than lesion shrinkage. Between different imaging techniques with contrast-enhancement, contrastenhanced ultrasound(CEUS) and, in particular, dynamic CEUS have arisen as a promising and non-invasive device for monitoring cancer treatments. Moreover, the introduction of perfusion software has even more refined the technique since it is able to provide quantitative parameters related to blood flow and blood volume that can be associated with tumour response and clinical outcome such as the progression free survival and the overall survival. Here, we give an overview of the current status of CEUS in monitoring hepatocellular carcinoma response to different kind of treatments.

经直肠超声造影评估前列腺癌新辅助内分泌治疗反应的价值

目的:探讨经直肠超声造影(contrast-enhanced transrectal ultrasound)时间-强度曲线(time-intensity curve,TIC)参数评估前列腺癌(prostate cancer,PCa)患者对新辅助内分泌治疗(neoadjuvant hormonal therapy,NHT)的反应程度。方法:纳入27例接受NHT的PCa患者的临床资料,根据术后病理学检查结果分为有效组(n=16)和无效组(n=11)。对比两组患者临床病理学特征、治疗前后血清前列腺特异性抗原(prostate-specific antigen,PSA)和CETRUS检查指标及其变化率,以筛选与NHT反应性有关的潜在指标。进一步采用相关性分析评价其在评估患者对NHT反应方面的价值。结果:有效组和无效组在临床病理学特征、治疗前的血清PSA和C E T R U S检查指标方面的差异无统计学意义(均P>0.05)。治疗后,仅有效组的TIC曲线下面积(area under curve,AUC)低于无效组(560 dB·s vs 710 dB·s),其变化率大于无效组(-27.1%vs-5.3%)(均P<0.05)。相关性分析显示AUC变化率与组织学反应评分之间的相关性略高于治疗后AUC(r为-0.690 vs-0.630)。结论:CETRUS TIC参数中,NHT后的AUC及其变化率在评估PCa患者对NHT反应方面具有较好的价值。其中,AUC变化率可能与治疗反应程度更相关。

不同消毒剂对超声引导颈内静脉穿刺和敷贴粘合的影响

目的 明确不同消毒剂对超声引导颈内静脉穿刺情况和敷贴粘合的影响。方法 选择行超声引导颈内静脉穿刺置管的急诊外伤失血患者102例为研究对象,随机分为碘伏组(51例)和氯己定醇组(51例),分别于穿刺前使用0.5%有效碘的碘伏和2.0%葡萄糖酸氯己定+70.0%乙醇消毒。比较2组患者穿刺部位消毒效果、穿刺情况、超声成像情况和敷贴粘合力。结果 2组患者穿刺部位消毒前菌群计数、消毒后菌群计数及消毒合格率比较,差异均无统计学意义(P>0.05)。2组一次穿刺成功率、穿刺次数和穿刺置管时间比较,差异均有统计学意义(P<0.05)。2组超声成像清楚率、敷贴粘合力和穿刺后24 h敷贴起翘或脱落率比较,差异均有统计学意义(P<0.05)。结论 对于急诊外伤失血患者,在超声引导颈内静脉穿刺前使用0.5%有效碘的碘伏和2.0%葡萄糖酸氯己定+70.0%乙醇消毒,均可获得较好的消毒效果,其中碘伏消毒能获得更清楚的超声成像,且一次穿刺成功率更高,但敷贴粘合力较差,容易发生起翘或脱落。

多参数超声对PF患者针刺疗法治疗前后的分析

目的探讨常规超声成像与实时超声弹性成像(RTE)对慢性足底筋膜炎(PF)患者针刺疗法治疗前后超声参数变化,评估针刺疗法对慢性PF临床疗效与作用。方法选取慢性PF患者78例(95只足),分为针刺组(26例,33只足)、安慰针组(26例,32只足)及等待治疗组(26例,30只足)。针刺组使用针灸针治疗;安慰针组采用平头针治疗;等待治疗组不予特殊治疗。分别记录三组的人口学特征、临床特征及灰阶超声(厚度、回声、是否有钙化、筋膜内ROI中最高频率亮度水平和平均亮度水平)及彩色超声特征(筋膜血流)和超声实时组织弹性成像特征(计算观测部位与周围软组织的弹性应变比),评估灰阶成像与实时超声弹性成像对慢性PF治疗前后的疗效评估及诊断价值。结果针刺组治疗前后在筋膜厚度、弹性应变比、筋膜内ROI中灰阶最高频率亮度水平和平均亮度水平均差异有统计学意义(P<0.05),安慰针组治疗前后仅在筋膜厚度、弹性应变比差异有统计学意义(P<0.05),而等待治疗组各参数在治疗前后差异均无统计学意义(P>0.05)。结论常规超声成像及实时超声弹性成像能够清晰、量化显示慢性PF患者治疗前后各参数变化,对临床评估慢性PF治疗后效果提供依据。

面向多院区一体化超声实时会诊管理平台的应用探索

目的:针对多院区一体化管理的医院,做到跨院区超声实时会诊、超声检查信息共享。方法:基于多院区的超声需求,引入一体化超声实时会诊管理平台,通过远程超声实时会诊实现多院区超声一体化管理。结果:从漳州市医院多院区的实际超声需求出发,应用跨院区超声实时会诊管理平台,协助完成会诊47例,有5位会诊医生做到了跨院区超声实时会诊及超声检查信息的院区共享。结论:基于多院区一体化超声实时会诊管理平台的使用减少了患者的等待时间,提高了患者就诊效率,提升了患者的就医体验和医疗质量。

甲状腺癌患者超声造影参数与淋巴结转移的关系探讨

目的:分析甲状腺癌(TC)患者超声造影(CEUS)参数与淋巴结转移的关系。方法:选取2021年1月—2024年5月沛县人民医院收治的135例TC患者为研究对象,以病理诊断结果提示是否发生淋巴结转移,将患者分为转移组71例与无转移组64例。均行CEUS检查,对比两组超声造影特征及定量参数,并分析CEUS参数与甲状腺癌淋巴结转移的关系。结果:两组CEUS灌注特征比较差异无统计学意义(P>0.05);转移组肿瘤直径大于无转移组,差异有统计学意义(P<0.05);两组上升时间(RT)、上升斜率(WIS)、峰值降半时间(TPH)及达峰时间(TTP)水平比较,差异无统计学意义(P>0.05);转移组平均渡越时间(MTT)低于无转移组,峰值强度(PI)高于无转移组,差异有统计学意义(P<0.05);Pearson相关性分析显示,MTT与甲状腺癌患者淋巴结转移呈负相关,PI与甲状腺癌患者淋巴结转移呈正相关(P<0.05)。结论:TC患者淋巴结转移与癌结节大小、CEUS参数MTT及PI有关,通过测定CEUS参数可准确评估淋巴结转移情况,以指导临床治疗。

基于实时目标检测网络的胎儿颜面部超声切面识别及应用

目的:探讨基于实时目标检测网络的人工智能(AI)模型在胎儿颜面部超声检查中的应用价值。方法:以妊娠20~24周正常胎儿颜面部超声标准切面(FFUSP)图像为研究对象,构建基于实时目标检测网络的FFUSP识别模型,观察其对FFUSP及其解剖结构的识别精度;通过临床验证分析其对119例胎儿超声图像中FFUSP识别效能以评价其临床应用价值。结果:AI模型对胎儿颜面部结构识别的整体查准率为97.8%、查全率为98.5%、mAP@.5为98.1%、mAP@.5:.95为61.0%。在临床验证中,AI模型对颜面部解剖结构识别的敏感度、特异度、阳性预测值、阴性预测值及准确率分别为100.0%、98.5%、87.4%、100.0%、98.7%,与胎儿超声专家分类一致性强(k=0.925,P<0.001);对3类标准切面图像的识别准确率为100%;动态视频检测平均速度为33.93帧/s。结论:基于实时目标检测网络的FFUSP识别模型性能优越,可应用于实时超声检查辅助诊断、教学及智能化质量评价。

经阴道彩色多普勒超声在子宫内膜病变患者中的应用价值

目的分析经阴道彩色多普勒超声在子宫内膜病变患者中的应用价值。方法选取2021年2月至2022年4月南昌大学第四附属医院收治的88例子宫内膜病变患者作为研究对象,所有患者均接受经阴道彩色多普勒超声及病理学检查,按照病理学检查结果将患者分为息肉组与癌变组,每组44例。比较两组二维超声子宫内膜情况、病灶血流动力学情况、经阴道彩色多普勒超声血流相关参数;以病理学检查结果为金标准,分析经阴道彩色多普勒超声对子宫内膜癌变的诊断效能。结果癌变组子宫内膜厚度厚于息肉组,内膜-肌层分界清晰、病灶回声均匀占比均低于息肉组,差异有统计学意义(P<0.05);癌变组血流丰富占比高于息肉组,差异有统计学意义(P<0.05);癌变组血流阻力指数(RI)、搏动指数(PI)均低于息肉组,时间平均峰值流速(TAP)慢于息肉组,差异有统计学意义(P<0.05);经阴道彩色多普勒超声对子宫内膜癌变的诊断灵敏度为86.36%,特异度为84.09%,准确度为85.23%;诊断息肉的灵敏度为84.09%,特异度为86.36%,准确度为85.23%。结论经阴道彩色多普勒超声对子宫内膜病变的诊断准确率较高,能通过血流动力学、RI、PI、TAP及影像学表现鉴别息肉或癌变。