Left atrial appendage occluder detachment treated with transthoracic ultrasound combined with digital subtraction angiography guided catcher:A case report

BACKGROUND There are very few cases of cardiac occluder detachment,and it is rare to completely remove the occluder using interventional methods without undergoing thoracotomy surgery after detachment.This case innovatively used ultrasound guidance combined with digital subtraction angiography(DSA)to completely remove the occluder,accumulating some experience.CASE SUMMARY The patient underwent left atrial appendage occlusion surgery in our hospital due to atrial fibrillation.After the surgery,the occluder fell off and became free in the left ventricle,which is very dangerous.We innovatively used ultrasound guidance,combined with DSA,and interventional surgery to successfully capture the free occluder using a catcher,completely remove it,and then re implant a new left atrial appendage occluder.After the surgery,the patient recovered very well.CONCLUSION The size selection of the occluder is slightly conservative,and the shape of the left atrial appendage opening is irregular.

Enhancing transjugular intrahepatic portosystemic shunt procedure efficiency with digital subtraction angiography image overlay technology in esophagogastric variceal bleeding

BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)is a pivotal intervention for managing esophagogastric variceal bleeding in patients with chronic hepatic schistosomiasis.AIM To evaluate the efficacy of digital subtraction angiography image overlay tech-nology(DIT)in guiding the TIPS procedure.METHODS We conducted a retrospective analysis of patients who underwent TIPS at our hospital,comparing outcomes between an ultrasound-guided group and a DIT-guided group.Our analysis focused on the duration of the portosystemic shunt puncture,the number of punctures needed,the total surgical time,and various clinical indicators related to the surgery.RESULTS The study included 52 patients with esophagogastric varices due to chronic hepatic schistosomiasis.Results demonstrated that the DIT-guided group expe-rienced significantly shorter puncture times(P<0.001)and surgical durations(P=0.022)compared to the ultrasound-guided group.Additionally,postoperative assessments showed significant reductions in aspartate aminotransferase,B-type natriuretic peptide,and portal vein pressure in both groups.Notably,the DIT-guided group also showed significant reductions in total bilirubin(P=0.001)and alanine aminotransferase(P=0.023).CONCLUSION The use of DIT for guiding TIPS procedures highlights its potential to enhance procedural efficiency and reduce surgical times in the treatment of esophagogastric variceal bleeding in patients with chronic hepatic schistoso-miasis.

Detection of hypervascular hepatocellular carcinoma: Comparison of multi-detector CT with digital subtraction angiography and Lipiodol CT

AIM: The purpose of this study was to compare the diagnostic accuracy of biphasic multi-detector row helical computed tomography (MDCT), digital subtraction angiography (DSA)and Lipiodol computed tomography (CT) in detection of hypervascular hepatocellular carcinoma (HCC).METHODS: Twenty-eight patients with nodular HCC underwent biphasic MDCT examination: hepatic arterial phase (HAP) 25 s and portal venous phase (PVP) 70 s after injection of the contrast medium (1.5 mL/kg). They also underwent hepatic angiography and intra-arterial infusion of iodized oil. Lipiodol CT was performed 3-4 wk after infusion. MDCT images were compared with DSA and Lipiodol CT images for detection of hepatic nodules.RESULTS: The three imaging techniques had the same sensitivity in detecting nodules ＞20 mm in diameter. There was no significant difference in the sensitivity among HAP-MDCT, Lipiodol CT and DSA for nodules of 10-20 mm in diameter. For the nodules ＜10 mm in diameter, HAP-MDCT identified 47, Lipiodol CT detected 27 (X2= 11.3, P= 0.005＜0.01, HAP-MDCT vs Lipiodol CT) and DSA detected 16(X2= 9.09, P= 0.005＜0.01 vs Lipiodol CT and X2= 29.03,P = 0.005＜0.01 vs HAP-MDCT). However, six nodules ＜10 mm in diameter were detected only by Lipiodol CT.CONCLUSION: MDCT and Lipiodol CT are two complementary modalities. At present, MDCT does not obviate the need for DSA and subsequent Lipiodol CT as a preoperative examination for HCC.

Digital subtraction angiography for the analysis of supraaortic vessels: What is its role nowadays?

For about 50 years, angiography represented the only imaging method for studying carotid arteries in order to detect the presence of pathological stenosis due to atherosclerotic plaque. Recently, thanks to the use of non-invasive methods, physicians are able to study and quantify the presence of carotid atherosclerosis in vivo These procedures have enabled the introduction of new concepts: (1) the degree of carotid stenosis is approxi- mate to the volume and extension of carotid plaque; and (2) a set of parameters, easily identifiable by com- puted tomography angiography, magnetic resonance angiogram and ultra-sound echo-color Doppler, are closely linked to the development of ischemic symptoms and can significantly increase the risk of stroke regard- less of the degree of stenosis. In light of these findings vulnerable plaques should be identified early, and the role of Digital Subtraction Angiography which is a purely technical luminal technique should be determined.

Interventional digital subtraction angiography for small bowel gastrointestinal stromal tumors with bleeding

AIM: To retrospectively evaluate the diagnostic efficacy of interventional digital subtraction angiography (DSA) for bleeding small bowel gastrointestinal stromal tumors (GISTs).

Modified magnetic resonance angiography of the liver using sensitivity encoding in comparison with digital subtraction angiography and CT arterial portography

BACKGROUND: Over 355 patients have received ortho- topic liver transplantation ( OLT) at this hospital since 1993. Preoperative imaging studies of both hepatic vessels and parenchyma in these recipients bettered surgical plan- ning or even precluded the necessity of surgery. Here we report our preliminary results of modified magnetic reso- nance angiography ( MRA ) using sensitivity encoding ( SENSE) through comparative study with conventional digital subtraction angiography (DSA) and CT arterial por- tography (CTAP). METHODS: Sixteen patients with suspected liver diseases were included in the study. All of them received both dy- namic MRI of the liver using SENSE and digital DSA with CTAP within a two-week interval. The four-phase MRA was reconstructed from source images of the coronal dy- namic study. The arterial phase of the modified MRA was compared with DSA in the evaluation of hepatic arteries and the portal phase compared with CT portography recon- structed from source images of CTAP. In dynamic study of the liver, a fixed dose (20 ml) of contrast medium and scan timing were used. RESULTS: The main branches and variations of the hepatic arterial system were well shown on the modified MRA, al- though the marginal branches of hepatic arteries were of poor quality. The figures of portal veins on MRA were as clear as or superior to those of CTAP. In addition, the su- prarenal inferior vena cava (IVC) was well demonstrated on MRA and/or non contrast-enhanced coronal balanced fast-field echo (b-FFE) scan sequence in most cases. MRI detected most parenchymal lesions of the liver and hemo- dynamics of these lesions could be evaluated on source ima- ges of the modified MRA. MRI/MRA also serendipitously revealed several extrahepatic disease entities or variations that were not found on DSA/CTAP. CONCLUSIONS: The modified MRA using SENSE is a cost-effective modality of examination for the demonstra- tion of the whole hepatic vascular system. Combined with MRI, it has the potential as a one-stop imaging modality in the preoperative evaluation in fields such as OLT.

Carbon dioxide digital subtraction angiography manifestations of hepa-tocellular carcinoma

Objective: To investigate the imaging features and clinical significance of carbon dioxide digital subtraction angiography (CO2-DSA) in the diagnosis and treatment of hepatocellular carcinoma (HCC). Methods: Both CO2-DSA and conventional DSA were performed in all 47 patients with HCC, and the angio-graphic manifestations of CO2-DSA were compared with those of conventional DSA in the same patients. Results: Peripheral arterial and capillary imaging by CO2-DSA was inferior to that by conventional DSA, although blood pools were well visualized with CO2. Improved visualization of arterioportal shunting (APS) was obtained with CO2-DSA compared with that by conventional angiography. APS was observed in 33 cases by CO2-DSA and in 12 cases by conventional angiography (P<0. 001). Retrograde visualization of the portal vein (PV) trunk and its large branches was demonstrated in 16 cases by CO2-DSA and in 1 case by conventional DSA (P<0. 001). The manifestation of lipiodol retention in the tumors was consistent with CO2-DSA images after TAE in 38 cases, and with those of conventional DSA in 23 cases (P<0. 01). Conclusion: CO2-DSA was superior to conventional DSA in the detection of APS and retrograde visualization of PV system, and the former can provide usefulness information for the treatment planning (chemoembolization) and patient prognosis. Demonstration of APS by CO2-DSA may suggest the presence of intrahepatic metastases.

Head dual energy-computed tomography angiography versus neuro-digital subtraction angiography

Dual-energy X-ray absorptiometry provides two modes of head computed tomography （CT） angiography scanning： neuro-digital subtraction angiography and dual-energy CT angiography （DE-CTA）. Previous studies have compared image quality, radiation exposure, and bone removal between neuro-digital subtraction angiography and DE-CTA. However, the number of cases was relatively small. The present study examined 300 suspected cases of cerebrovascular disease and observed the methods and duration of post-processing, examination time, and data volume. Results demonstrated similar image quality between the two methods, but lower radiation doses and shorter examination time in DE-CTA. DE-CTA allowed for faster and more stable scanning performance and post-processing methods, facilitating accurate and direct diagnosis of cerebrovascular disease.

Value of digital subtraction angiography in endovascular graft exclusion for abdominal aortic aneurysms

Objective: To evaluate the value of digital subtraction angiography (DSA) in management of endovascular graft exclusion (EVGE) for abdominal aortic aneurysms. Methods: Monitored by DSA and fluoroscopy, stent-graft complex were introduced into the aneurysm sac via femoral arteries and were deployed at the proximal and distal necks to exclude the sac from circulation. Results: The success rate of deployment was 94. 74% (36/38). Endoleaks occurred in 4 cases. One converted to open surgery because of sac rupture 4 days after deployment. Thrombosis and stenosis occurred in 2 cases. Three patients died shortly after the operation (< 3 months). Conclusion: DSA can monitor EVCE on real-time throughout the whole procedure. It can meet the needs of measurement, location, evaluating, detecting, and also can be much helpful in correcting complications. Moreover, it provides large visual field and operating space, and is a very important monitoring method for EVGE.

Duodenal ulcer caused by coil wiggle after digital subtraction angiography-guided embolization: A case report

BACKGROUND Acute gastrointestinal bleeding(GIB)is a life-threatening medical emergency with high morbidity and mortality.Transcatheter embolization with endovascular coils under digital subtraction angiography guidance is a common and effective method for the treatment of GIB with high technical success rates.Duodenal ulcers caused by coils wiggled from the branch of the gastroduodenal artery,which is a rare complication,have not previously been reported in a patient with right intrathoracic stomach.CASE SUMMARY A 62-year-old man had undergone thoracoscopy-assisted radical resection of esophageal cancer and gastroesophageal anastomosis 3 years ago,resulting in right intrathoracic stomach.He was admitted to the hospital 15 mo ago for dizziness and suffered acute GIB during his stay.Interventional surgery was urgently performed to embolize the branch of the gastroduodenal artery with endovascular coils.After 15 mo,the patient was re-admitted with a chief complaint of melena for 2 d,esophagogastroduodenoscopy and abdominal computed tomography revealed that some endovascular coils had migrated into the duodenal bulb,leading to a deep ulcer.Bleeding was controlled after conservative treatment.Seven months later,duodenal balloon dilatation was performed to relieve the stenosis after the removal of a few coils,and the patient was safely discharged with only one coil retained in the duodenum due to difficulties in complete removal and risk of bleeding.Mild melena recurred once during the long-term follow-up.CONCLUSION Although rare,coil wiggle after interventional therapy requires careful attention,effective precautionary measures,and more secure alternative treatment methods.

Observation on 108 Normal Ophthalmic Arteries in 80 Patients by Digital Subtraction Angiography

By digital subtraction angiography(DSA), the authors made observations on 108 normal ophthalmic arteries in 80 patients with regard to the origins, courses, branching, morphology and anastomoses of the vessels. The merits and demerits of DSA in observing the ophthalmic artery were discussed. Eye Science 1994; 10: 157- 162.

Manifestations of hepatic cavernous hemangioma in carbon dioxidedigi-tal subtraction angiography

Objective: To describe the characteristic appearance of cavernous hemangioma of the liver (CHL) presented in carbon dioxide digital subtraction angiography (CO2-DSA) and to evaluate the significance of CO2-DSA in the diagnosis of CHL. Methods: Both CO2-DSA and iodinated contrast DSA (IC-DSA) were performed in all 16 patients with CHL, and the angiographic manifestations in the same patients were compared. The image quality was rated by three experienced angiographers, and the complications were also assessed. Results: There was good correlation between angiographers on image quality (R = 0. 73). Diagnostic images were obtained with both CO2-DSA and IC-DSA in all CHL patients. No difference was noted between IC-DSA and CO2-DSA in visualizing the proper hepatic arteries and its branches (P>0. 05). CO2-DSA produced better images that clearly described the tumor size, shape and margination than those by IC-DSA (P< 0. 05), but both demonstrated characteristic appearances of early opacification and persistent contrast enhancement of the tumors. The portal vein branches near the tumors were constantly demonstrated by CO2-DSA in 15 cases (15/16) but only in 2 cases (2/16) by IC-DSA. Conclusion: CO2-DSA is sensitive in CHL diagnosis, and in patients with contraindications to IC or with unsatisfactory imaging results by IC-DSA, CO2-DSA is a good alternative. As show in most cases by CO2-DSA, the portal veins might act as the main drainage vein of CHLs.

基于深度学习的图像重建算法在下肢动脉病变CTA诊断中的研究

目的 探讨基于深度学习的图像重建算法对下肢动脉病变CT血管成像(Computed Tomography Angiography,CTA)的诊断价值。方法 回顾性收集2021年6月至2022年2月于我院就诊的51例下肢动脉狭窄或闭塞患者的CTA检查资料(65条下肢动脉)。分别基于深度学习的图像重建(Deep Learning Image Reconstruction,DLIR)算法和混合迭代重建(Hybrid Iterative Reconstruction,HIR)算法对CTA图像进行重建,以HIR法为参照进行质量评估;两位医师在不同重建算法下对血管狭窄的部位和程度进行评估,并采用Kappa检验观察者间一致性;以数字减影血管造影作为“金标准”比较HIR法和DLIR法诊断下肢动脉中度和重度狭窄的效能。结果与HIR法相比,DLIR法图像质量的噪声显著降低(Z膝上动脉=8.36,Z膝下动脉=9.46,Z足背动脉=7.19,均P<0.001),信噪比(Z膝上动脉=-7.32,Z膝下动脉=-7.91,Z足背动脉=-8.45,P<0.001)及对比噪声比(Z膝上动脉=-8.66,Z膝下动脉=-9.21,Z足背动脉=-8.52,均P<0.001)显著提高。DLIR法对动脉狭窄或闭塞程度的识别和评估均显示出更高的观察者间一致性(Kappa=0.86)。与HIR法相比,DLIR法的图像对膝下动脉重度狭窄的敏感度(72.2%vs.94.4%)、特异性(78.7%vs.95.7%),足背动脉中度狭窄的特异性(86.0%vs.97.7%)及重度狭窄的敏感度(50.0%vs.87.5%)均显著提高(P<0.05)。结论 DLIR算法可有效改善下肢动脉的CTA图像质量,并获得更优的诊断效能。

脑血管数字减影血管造影高分辨率分割网络设计

针对现存卷积神经网络对脑血管数字减影血管造影分割精度不高的问题,本文提出了一种基于U-Net的改进网络(IC-Net)。通过融合使用Inception和CAM通道注意力模块,以多种感受域提取更丰富的血管特征信息,并对特征信息进行筛选。增加7×7卷积层,通过压缩特征层分辨率的方式减少训练过程中产生的数据量。本文所提模型与U-Net、R2U-Net、Attention U-Net相比,IOU、Accuracy、F1-Score和ROC曲线下面积4项指标平均提升了1.82%、0.014%、1.19%和0.73%。结果验证了IC-Net模型明显提升了脑血管数字减影血管造影虚弱血管和血管末端的检测能力,提升了分辨伪影噪声的能力,为医生识别脑血管中产生的病变提供有力参考。

320排CT冠状动脉减影对冠脉钙化斑块狭窄程度诊断价值及图像质量影响因素分析

目的:探讨320排CT冠状动脉减影对冠脉钙化斑块狭窄程度诊断价值及图像质量影响因素。方法:选择我院2021年9月至2023年11月期间进行320排CT冠状动脉减影(Sub-CCTA)的193例患者作为研究对象,在这些患者中共检出狭窄的钙化斑块节段236个。以数字减影血管造影(DSA)检查结果作为金标准,对比Sub-CCTA与DSA对冠脉狭窄程度、狭窄率的诊断结果,并分析Sub-CCTA对冠脉不同狭窄程度诊断效能。利用Logistic回归分析Sub-CCTA图像质量的影响因素,采用限制性立方样条模型分析各影响因素与图像质量的关联强度。结果:Sub-CCTA与DSA在冠脉狭窄程度和狭窄率的诊断上表现出高度一致性(Kappa值为0.912,组内相关系数分别为0.983和0.972)。Sub-CCTA在不同狭窄程度冠脉的诊断中准确性高,尤其在对Ⅳ级狭窄的灵敏度和对Ⅱ级狭窄的特异度上。多因素Logistic回归分析显示BMI为影响Sub-CCTA图像质量的独立保护因素,心率为影响其图像质量的独立危险因素(P<0.05);BMI、心率与图像质量的关联强度呈非线性关系(非线性检测,P<0.001)。结论:Sub-CCTA对不同狭窄程度的冠脉具有较高的诊断准确性,并与DSA诊断结果高度一致。BMI是影响Sub-CCTA图像质量的独立保护因素,而心率是独立危险因素,二者与图像质量呈现非线性关系。

Fastunnel导管在颅内动脉狭窄介入治疗中的价值

目的探讨新型输送型球囊扩张导管(Fastunnel导管)在颅内动脉粥样硬化性狭窄介入治疗中的临床应用价值。方法回顾性分析2022-06—2024-02郑州大学第一附属医院采用Fastunnel导管治疗的18例颅内动脉粥样硬化性狭窄患者的临床资料,所有患者均接受球囊扩张联合支架成形术,分析患者的临床资料、治疗情况、手术成功率及术后并发症发生情况。结果18例患者均成功接受介入手术治疗,手术成功率100%。术前血管狭窄率(78.94±5.3)%,病变血管长度(7.14±2.14)mm。手术时长21~58(43.56±9.05)min,治疗期间射线暴露时间10~28(21.3±3.56)min,辐射剂量1526~5281(3436.50±626.39)mGy。术后血管狭窄率(13.50±4.94)%。所有患者围手术期及术后均未出现并发症。结论Fastunnel导管治疗颅内动脉粥样硬化性狭窄具有较好的疗效和安全性,可简化手术步骤,提高手术效率,具有良好的临床应用价值。

DSA联合3D ASL对优势侧椎动脉狭窄支架置入前后小脑半球血流动力学改变的评估

目的:探讨DSA联合3D动脉自旋标记技术(ASL)在椎动脉狭窄支架置入前后小脑半球血流动力学评估中的应用价值。方法:回顾性分析21例因优势侧椎动脉颅外段管腔狭窄行支架置入术患者的临床、DSA及ASL资料,评估不同标记后延迟时间(PLD)、椎动脉优势侧与非优势侧、支架置入术前后小脑半球不同供血区脑灌注的变化。结果:21例术前DSA显示优势侧椎动脉重度狭窄,支架置入部位均为优势侧椎动脉颅外段,术后狭窄均解除。PLD为2.5 s时,术前、术后,优势侧及非优势侧,小脑各供血区脑血流量(CBF)值均较PLD为1.5 s时高,差异均有统计学意义(均P<0.05)。术后在椎动脉优势侧,小脑上动脉供血区、小脑前下动脉供血区、小脑后下动脉供血区的CBF值均高于术前(包括PLD=1.5、2.5 s);椎动脉非优势侧,小脑上动脉供血区的CBF值高于术前(包括PLD=1.5、2.5 s)。结论:DSA联合ASL能定量评估小脑半球的血流动力学改变,优势侧椎动脉狭窄支架置入术能提高椎动脉优势侧小脑半球各区的脑血流灌注水平及椎动脉非优势侧的小脑半球小脑上动脉供血区的脑血流灌注水平。

CT及磁共振血管成像诊断颅内动脉瘤的价值

目的分析CT血管成像(computed tomography angiography,CTA)、磁共振血管成像(magnetic resonance angiography,MRA)诊断颅内动脉瘤的价值。方法选取2020年6月-2023年1月广西贵港市人民医院90例疑似颅内动脉瘤患者,均接受CAT及MRA检查,将数字减影血管成像(digital subtraction angiography,DSA)或手术病理学检查结果作为金标准,比较两种方法检出情况、测量颅内动脉瘤瘤体直径与瘤颈宽度、对比不同大小的颅内动脉瘤检出情况,分析两种方法单独及联合诊断颅内动脉瘤的价值。结果90例疑似颅内动脉瘤患者经CTA检查后诊出64例单发颅内动脉瘤,经MRA检查后诊出61例单发颅内动脉瘤,两种方法检出情况比较无明显差异(P>0.05);当瘤体<3 mm时CTA检出率93.33%高于MRA 60.00%(P<0.05);CTA诊断颅内动脉瘤的准确率83.33%、敏感度83.56%、特异度82.35%、Kappa值=0.548;MRA诊断颅内动脉瘤的准确率82.22%、敏感度80.82%、特异度88.24%、Kappa值=0.543;CTA联合MRA诊断颅内动脉瘤的准确率95.56%、敏感度95.89%、特异度94.12%、Kappa值=0.861。结论CTA与MRA均可用于诊断颅内动脉瘤,其中CTA可明显提高<3 mm的微小颅内动脉瘤诊出率,但联合应用时的敏感度更高。

DSA引导下经皮入路应用无水乙醇联合聚桂醇治疗头颈部高回流型静脉畸形的安全性和有效性

目的探讨数字减影血管造影(DSA)引导下经皮入路应用无水乙醇联合聚桂醇治疗在头颈部高回流型静脉畸形中的应用效果。方法选取2020年2月至2023年6月在河南大学第一附属医院就诊的68例头颈部高回流型静脉畸形患者,根据治疗方法进行分组,即经DSA引导下经皮入路应用聚桂醇治疗的患者纳入对照组,经DSA引导下经皮入路应用无水乙醇联合聚桂醇治疗的患者纳入研究组。统计两组临床疗效、不良反应及并发症发生情况。结果两组一般资料比较,差异无统计学意义(P>0.05)。与对照组83.33%的临床有效率相比,研究组(97.37%)较高,差异有统计学意义(χ^(2)=4.105,P=0.043)。与对照组43.33%的不良反应及并发症总发生率相比,研究组(10.53%)较低,差异有统计学意义(χ^(2)=9.623,P=0.002)。结论DSA引导下经皮入路应用无水乙醇联合聚桂醇治疗头颈部高回流型静脉畸形安全有效,具有广泛的临床应用前景。

超声引导外周置入中心静脉导管失败的5年回顾性研究

目的探讨超声引导外周置入中心静脉导管(PICC)失败的原因及对策,提高PICC置管成功率。方法法选择2015年1月至2019年12月在青岛市市立医院接受超声引导PICC中置管失败患者32例,其中男性16例,女性16例;年龄43~85岁,平均年龄60.12岁;身体质量指数(BMI)16.55~31.26 kg/m^(2),平均BMI 22.56 kg/m^(2);恶性肿瘤32例,消化系统疾病12例,血管疾病8例,高血压5例,心脏病4例,糖尿病2例;置管原因,化学治疗19例(59.4%),静脉营养15例(46.9%);病变位置,颈胸部18例(56.3%),其他部位14例(43.7%);既往相关治疗,肿瘤切除21例(65.6%),放化疗19例(59.4%)。置管失败后移至介入手术室接受数字减影血管造影(DSA)辅助PICC复位/重置者。统计PICC相关指标。评估超声引导PICC失败原因,并分析失败原因与其他指标[年龄、性别、身体质量指数、血管病史、病变位置(颈胸部)、既往相关治疗、侧别和穿刺靶静脉]的相关性。结果左臂置入失败占56.3%(18/32)。穿刺贵要静脉者占65.6%(21/32),多于头静脉和肱静脉(P<0.001)。并发损伤仅为轻度痉挛或少量血栓占12.5%(4/32)。导管异位是置管失败主要原因占84.4%(27/32)。腋静脉最易发生异位(46.9%),贵要静脉(12.5%)、颈内静脉(9.38%)亦较常见。在DSA辅助下全部病例均复位/重置成功。导管异位与年龄、性别、BMI、血管病史、病变位置(颈胸部)、既往相关治疗、侧别和穿刺靶静脉指标均无显著相关性(P>0.05)。结论导管异位是超声引导PICC失败的首要原因,主要为血管变异所致。DSA辅助复位技术是解决超声引导PICC失败的有效方法,可显著提高置管成功率。