64层螺旋CT冠状动脉CTA对比剂浓度选择优化

目的 探讨不同浓度对比剂在64层螺旋CT冠状动脉CT血管造影(CTA)中的应用价值. 资料与方法 将51例行冠状动脉CTA筛查者随机分为3组,分别采用300 mgI/ml、370 mgI/ml、400 mgI/ml浓度的对比剂,以相同注射流率(5 ml/s)行增强扫描,对血管强化程度、重组血管清晰度进行评价. 结果 370 mgI/ml、400 mgI/ml组冠状动脉强化明显高于300 mgI/ml组(P＜0.05),370 mgI/ml组与400 mgI/ml组差异无统计学意义,重组血管的图像质量3组间无差异. 结论 64层螺旋CT冠状动脉CTA检查时,300 mgI/ml、370 mgI/ml、400 mgI/ml 3种浓度的对比剂在注射流率相同时均能满足诊断;在使用高浓度对比剂时,可适当降低注射流率.     

不同碘浓度对比剂在MSCT腹部血管成像的临床应用研究

目的探讨不同碘浓度对比剂对MSCT腹部血管成像质量的影响。方法 150例腹部CT血管成像受检者随机分成3组(每组50例),采用不同碘浓度的对比剂:300mgI/ml、320mgI/ml和370mgI/ml行MSCT扫描,根据原始图像和后处理重建图像,主要观察三组病例腹主动脉及其分支血管的显示程度,从而对图像质量进行评判。分别测量腹腔干水平、肾动脉水平、髂动脉分叉水平处腹主动脉CT值。结果 3组不同平面腹主动脉内对比剂浓度均维持在较高的水平,差异无统计学意义。3组不同碘浓度对比剂显示腹主动脉、腹腔干、肝总动脉、肾动脉及分支能力的差异无统计学意义(P>0.05)。结论在相同注射速率条件下多层螺旋CT腹部血管成像使用低浓度对比剂可以获得满意的CTA图像,同时减轻了对比剂不良反应。     

256层80kV多层螺旋CT及团注对比剂扫描3D减影血管成像评估颅内动脉瘤

正目的评估256层多层螺旋CT在80 kV并团注对比剂条件下行颅内动脉减影三维CT血管成像(CTA)的价值。方法 32例病人应用100 kV,对比剂剂量为370 mgI/kg,     

遗传性根髓动脉或胸腹主动脉动脉瘤的显示：64层CT血管成像中最佳对比剂的应用

本研究的目的是前瞻性地研究对比剂的浓度及注射速度．以获得使用64层螺旋CT显示根髓动脉的最佳影像。该实验将80例病人平均分为4组：A,100mL对比剂,浓度300mgI／mL,注射速度5．0mL／s;B,100mL对比剂,浓度350mgI／mL,注射速度5．0mL／s;C,100mL对比剂,浓度300mgI／mL,注射速度3．5mL／s;D,100mL对比剂,浓度350mgI／mL,注射速度3．5mL／s。测量胸5～腰3平面主动脉的CT值并计算其平均值,进行定量评价。     

四肢动脉损伤的双源CT血管成像临床应用

目的 探讨双源CT血管成像在四肢动脉损伤中的临床应用价值及技术优势.方法 对11例疑有四肢动脉损伤的患者行双源CT血管成像检查, 其中上肢动脉双源CT血管成像4例,下肢动脉双源CT血管成像7例,并对术后患者行双源CT血管成像复查.使用德国西门子Somatom Definition 双源CT扫描机,对比剂浓度350 mg I/ml或 370 mg I/ml,总量80~100 ml,注射速率为4.0 ml/s.对薄层横断面图像分别采用多平面重建(multiplanar reformation,MPR),容积重建( volume rendering,VR) , 最大密度显影(maximum intensity projection, MIP)等后处理技术进行血管重建.结果 11例血管成像均显示血管丰富、清晰, 血管边缘光滑自然,图像质量优良完全满足临床诊断要求,其中4例动脉血管显示正常,肱动脉断裂2例,腘动脉断裂3例,股动脉断裂2例.术前诊断与术后诊断的符合率达100%.结论 对于疑有动脉损伤的肢体外伤患者,双源CT血管成像可以作为一种首选的血管成像方法,通过多种重建技术进行三维血管重建,为临床诊断和治疗方案的制订提供了有力的证据.     

64层螺旋CT血管造影诊断糖尿病下肢动脉疾病的临床价值

目的:探讨64层螺旋CT血管造影(CTA)诊断下肢动脉疾病的临床价值.材料和方法:对125例临床疑有下肢动脉疾病的患者行CTA检查.扫描范围1000-1500 mm,层厚1.25 mm,螺距0.984.造影剂剂用量90-100 ml,注射速度3 ml/s,高压注射器自动触发扫描,扫描时间20-30 s,对全部图像进行MIP、VRT、MPR重建使下肢血管清晰显示,每例患者血管分段为10段,并对图像进行评价.其中有20例患者1周内行血管造影检查,并进行相同血管节段对照研究.结果:CTA结果与DSA结果有较好的一致性,阳性预测率92.5%,阴性预测率98.6%.结论:64层CTA能清晰地显示下肢动脉及其病变,可以成为糖尿病下肢动脉疾病术前评价和筛选的主要方法.     

16层螺旋CT血管造影诊断肺动脉栓塞并下肢深静脉血栓

目的 探讨下肢深静脉血栓和肺栓塞的多层CT联合成像的诊断价值。方法 31例患者行CT肺动脉血管造影,其中15例同时行下肢深静脉联合成像,采用16层螺旋CT,1.25mm×16模式采集,注射对比剂120～150ml,注射流率3.5～4.0ml/s,肺动脉延迟20～25s扫描,下肢静脉延迟150～180s扫描。并结合容积重建（VR）、最大密度投影（MIP）、多平面重建（MPR）、曲面重建（CPR）等重建技术进行图像分析。结果 共发现下肢深静脉血栓15例16侧,肺栓塞31例51处,其中肺栓塞和下肢深静脉血栓同时存在15例。结论 多层螺旋CT肺动脉和下肢静脉联合成像可一次性评价肺动脉和下肢静脉,是肺栓塞首选的影像检查方法。     

Smart Prep技术在肾动脉CTA中的临床应用

目的:探讨Smart Prep技术在肾动脉多层螺旋CT血管造影中的应用。方法:20例行同层动态增强扫描,通过时间-密度曲线获得肾动脉的有效浓度阈值。65例行肾动脉CTA造影,经肘静脉团注370mgI/ml优维显1.5ml/kg后,应用Smart Prep软件实时监控靶血管浓度,当感兴趣区对比剂浓度达有效浓度阈值时触发增强扫描完成数据采集,重组和重建图像显示肾动脉。结果:65例肾动脉CTA造影均获成功,58例(89.2%)增强时相处于最佳扫描时期。增强扫描的延迟时间15~38s不等,个体差异明显,而肾动脉CT值持续位于有效浓度阈值(100HU)以上。结论:Smart Prep技术实时监控肾动脉对比剂浓度变化并及时触发增强扫描,它不受个体差异影响即可确保增强扫描的实施,优于小剂量试验。     

MSCT肝脏增强扫描中的碘对比剂应用研究

目的:探讨MSCT肝脏增强扫描中碘对比剂浓度及注射速率对肝脏强化效果的影响。方法:90例受检者按对比剂碘浓度300mg/ml、350mg/ml、370mg/ml及注射速度3.0ml/s、4.0ml/s、5.0ml/s分成9组,各10例,保持每位检查者碘总量一致,即390mgI/kg体重。90例受检者均使用Siemens Somatom definition螺旋CT和Medrad Stellant双筒高压注射器行肝脏动态增强扫描。双盲式观察、分析肝脏峰值时间(Time to Peak)及强化峰值(Peak Contrast Enhance-ment)。结果:随着对比剂注射速度的增加肝脏各期峰值时间提前、强化峰值增高;对比剂碘浓度的增加肝脏强化各期峰值时间亦提前,但峰值变化不大,高浓度对比剂较低浓度肝脏强化峰值相近。结论:不同碘对比剂的浓度、注射速度对肝脏强化程度存在影响,低浓度对比剂、高速率注射、个性化给药可以得到满意的强化效果。     

多层螺旋CT髂静脉成像临床应用价值

目的探讨髂静脉多层螺旋CT成像的临床应用价值。方法50例患者行髂静脉多层螺旋CT血管造影,对比剂注射方案为经患侧足背浅静脉以2.5～3.0ml/s注射浓度为150mgI/ml的非离子型对比剂,延迟16～22s后开始扫描。利用多种重建方法进行重建。分析髂静脉的成像质量以及髂静脉疾病的影像特点。结果50例患者均成功完成CT血管造影。其中31例完全阻塞,9例管腔狭窄或见局部充盈缺损,10例完全通畅。图像质量优良率:优24%(12/50),良60%(30/50),差16%(8/50),总体优良率84%(42/50)。结论多层螺旋CT髂静脉成像对诊断静脉疾病有一定的临床价值。     

Principles of CT: multislice CT

This article describes the principles and evolution of multislice CT (MSCT), including conceptual differences associated with slice definition, cone beam effects, helical pitch, and helical scan technique. MSCT radiation dosimetry is described, and dose issues associated with MSCT-and with CT in general-as well as techniques for reducing patient radiation dose are discussed. Factors associated with the large volume of data associated with MSCT examinations are presented.     

Principles of CT and CT technology

This article provides a review of the basic principles of CT within the context of the evolution of CT. Modern CT technology can be understood as a natural progression of improvements and innovations in response to both engineering problems and clinical requirements. Detailed discussions of multislice CT, CT image quality evaluation, and radiation doses in CT will be presented in upcoming articles in this series.     

PET/CT in malignant melanoma: contrast-enhanced CT versus plain low-dose CT

Purpose  

The aim of this study was to evaluate the diagnostic value of contrast-enhanced CT (CECT) versus non-enhanced low-dose CT (NECT) in the staging of advanced malignant melanoma with ¹⁸F-fluordeoxyglucose (FDG) positron emission tomography (PET)/CT.     

Multidetector CT and CT angiography in mesenteric ischemia

Purpose

To evaluate the role of 64-multidetector CT in assessment of mesenteric vascular ischemia in clinically suspected patients.

Patients and methods

This study included 38 patients during period from October 2009 to October 2011. The patients age ranged from 38 to 72 year old (mean age was 57 ± 11.2 years). All cases met the criteria of acute non traumatic (28 patients) or chronic abdominal pain (10 patients) and suspected mesenteric vascular ischemia. All 38 cases were evaluated in surgery department, then underwent CT of the abdomen and pelvis & CTA by using 64 multislice GE light speed VCT. MDCT& CT angiographic findings were correlated with surgical findings in acute mesenteric ischemia (AMI) cases & conventional angiography in chronic mesenteric ischemia (CMI) cases.

Results

MDCT findings alone were nonspecific for detection of MI. The sensitivity, specificity& accuracy of CTA in diagnosis of AMI after surgical confirmation were 96%, 66.6% & 92.8% respectively, while in CMI the sensitivity, specificity & accuracy were 88.8%, 100%, 90% respectively, after confirmation by conventional angiography.

Conclusion

CTA scan appears to be an excellent tool to find out and localize cases of AMI rather than in CMI cases.     

CT扫描参数对人体组织CT值影响的研究

目的 探索不同CT扫描参数对人体同一种组织CT值的影响。方法 通过在同一台CT机上,分别改变其中1个扫描参数,如X线管电压、毫安秒和重建函数等,而保持其他扫描参数不变,多次扫描标准体模,测量和分析体模中不同物质的CT值。结果 X线管电压的改变对物质的CT值影响具有显著意义。聚乙烯、聚碳酸酯、有机玻璃的CT值与管电压成正相关;聚四氟乙烯的CT值与管电压成负相关。毫安秒和重建函数对CT值的影响差异无统计学意义。结论 同一个人体组织在不同的X线管电压条件下CT值是变化的。因此,在临床影像诊断和放疗中应该考虑图像扫描参数的设置对诊断和治疗结果的影响。     

CT angiography

The advent of spiral (helical, volume ) CT has revolutionised the performance of body CT and allowed the development of CT angiography (CTA). CT angiography is a non-invasive method of visualising the vascular system and in some instances can replace conventional angiography. In spiral CT a volume of data is obtained rapidly with no respiratory misregistration at peak vascular opacification following the peripheral injection of contrast. Appropriate timing will ensure that either the venous or arterial tree is visualised and from the volume of data multiple overlapping slices can be obtained to generate 2D and 3D images with no increase in radiation to the patient. CT angiography may be performed as a dedicated study or be undertaken retrospectively using post-processing of data from a conventional diagnostic spiral scan to provide additional information about the vascular tree. When undertaken as a dedicated study CTA is quicker, less invasive and less costly than a conventional angiogram with a decrease in the radiation dose to the patient; however, the spatial resolution is limited with vessels less than 2 mm not visualised and there is no contrast saving. Received: 25 March 1998; Revision received: 16 July 1998; Accepted: 22 July 1998     

CT Enteroclysis

Computed tomographic (CT) enteroclysis is a hybrid technique that combines the methods of fluoroscopic intubation-infusion small-bowel examinations with that of abdominal CT. The use of multidetector CT technology has made this a versatile examination that has evolved into two distinct technical modifications. CT enteroclysis can be performed by using positive enteral contrast material without intravenous contrast material and neutral enteral contrast material with intravenous contrast material. CT enteroclysis has been shown to be superior to other imaging tests such as peroral small-bowel examinations, conventional CT, and barium enteroclysis, except in the demonstration of early apthous ulcers of Crohn disease. CT enteroclysis is complementary to capsule endoscopy in the elective investigation of small-bowel disease, with a specific role in the investigation of Crohn disease, small-bowel obstruction, and unexplained gastrointestinal bleeding.