对比剂不同流率对门静脉CT血管成像质量的影响

目的 探讨对比剂不同注射流率对多层螺旋CT肝门静脉成像质量的影响.方法 30例患者随机分为3组,每组10例,年龄与体重无明显差异,行腹部CT增强扫描.按1.5 ml/kg剂量前臂静脉注射浓度为300 mg Ⅰ/ml的非离子型对比剂,注射流率分别为2.0 ml/s、3.0 ml/s和4.0 ml/s.腹主动脉兴趣区智能跟踪技术触发动脉期扫描,动脉期后延迟7 s与20 s行门静脉期扫描.在工作站测量3组CT源图像上门静脉(PV)与肝实质的CT值,并重组PV斜轴位与冠状位最大密度投影(MIP)图像,观察PV显示的分支级别.采用SPSS 11.5软件行统计学分析.结果 2.0 ml/s组、3.0 ml/s组、4.0 ml/s组门静脉CT值分别为(150.80±21.16)HU、(170.90±17.26)HU与(181.90±22.88)HU,2.0 ml/s组与4.0 ml/s组间有明显差别(P=0.017).2.0 ml/s组、3.0 ml/s组、4.0 ml/s组PV与肝实质CT值差别分别是(50.20±17.40)HU、(67.10±23.08)HU与(76.20±22.75)HU,2.0 ml/s组与4.0 ml/s组间有明显差别(P=0.039).2.0 ml/s组、3.0 ml/s组、4.0ml/s组对PV分支显示级别分别为4.20±1.14、4.90±0.99及5.50±0.53,2.0 ml/s组与4.0 ml/s组间有明显差别(P=0.013).结论 注射流率对PV CT血管成像的质量有影响,流率为4.0 ml/s时SCTP质量最佳.     

肝脏CT门静脉成像中对比剂剂量的估算方法

目的 比较不同体型指数对肝脏CT门(静)脉成像的影响,探讨对比剂剂量估算的优化方法.方法 回顾分析72例行上腹部CT检查患者的病例资料.所有患者均注射相同剂量的对比剂.采用线性回归分析门脉期图像的门脉-肝实质对比度和肝实质增强与体重、体表面积(BSA)和体重指数(BMI)的关系,并计算根据不同体型指数估算对比剂剂量时,增强每增加1 HU所需碘投放量(EU).结果 门脉-肝实质对比度与BSA、体重和BMI的相关性(r分别为-0.53、-0.50、-0.41,P＜0.001)依次递减.按体重和BSA估算对比剂剂量的平均碘投放量增强比EUBW和EUBSA分别为0.01005 gI/kg/HU和0.36299 gI/m2/HU.结论 为了提高患者间门脉增强的一致性,应根据BSA估算对比剂剂量.     

能谱单能量结合低剂量对比剂与常规CT增强扫描在门静脉成像中的对比研究

目的:探讨能谱单能量(60 keV)结合低剂量对比剂方案在门静脉成像中的应用价值.方法:将50例行腹部CT增强的患者随机分为A、B两组(每组各25例),均采用非离子型对比剂优维显370(370 mg I/mL).A组行宝石能谱成像(GSI)扫描(60 keV),对比剂用量为0.9 mL/kg;B组行常规CT增强扫描(120 kVp),对比剂用量1.3 mL/kg.采用独立样本t检验对A、B两组的门静脉CT值、噪声、肝内、外门静脉对比噪声比(CNR)、主观质量评分、容积CT剂量指数(CTDIvol)及有效辐射量(ED)进行统计学分析.结果:A组的门静脉主干、左支及右支的CT值均高于B组(P均＜0.05);A组的门静脉主干、左支及右支的噪声均低于B组(P均＜0.05);A组的肝内门静脉CNR高于B组(P＝0.03＜0.05);A、B组肝外门静脉CNR无统计学差异(P＝0.90＞0.05).A组的主观评分(4.49±0.64)稍高于B组(4.35±0.65),但两组间差异无统计学意义(P＝0.41).A、B组的CTDIvol及ED均无统计学差异(P＝0.12,P=0.58),A组的对比剂碘摄入量[(23.06±3.18)g]较B组[(30.49±4.99) g]约较少25％ (P＜0.001).结论:在辐射量相当的条件下,单能量GSI结合低剂量对比剂在门静脉成像中优于常规CT增强扫描,且对比剂碘摄入量减少约25％.     

个体化对比剂注射方案在256层CT冠状动脉成像中的应用

目的探讨个体化对比剂注射方案在256层CT冠状动脉成像中的应用价值。方法 100例临床怀疑冠心病需接受冠状动脉CT(CTA)检查者,按照对比剂注射方案个体化原则,对比剂总量(ml)=患者体重(kg),对比剂流率ml/s=对比剂总量/(扫描时间+8)ml/s,同样流率追加30ml生理盐水}进行冠脉CTA检查,测量升主动脉根部左冠开口处CT值并对冠状动脉的显示进行评分,分析对比剂注射方案个体化的可行性。结果按照个体化对比剂注射方案行冠脉CTA检查后,100例检查者升主动脉根部左冠开口处平均强化程度为(420.19±56.59)HU,冠状动脉显示评分得3分比例为88.78%,得2分比例为11.22%,无得1分者。结论个体化对比剂注射方案在256层CT冠状动脉成像中具有良好的应用价值。     

64层螺旋CT心脏检查对比剂注射方案的优化

目的：探讨64层螺旋CT心脏检查中应用三时相一次扫描获得理想的冠状动脉图像、心脏形态和功能分析的对比剂优化注射方案。方法：将326例患者以不同注射方案随机分成5组：方案A,30例,单期注射,仅团注80～90ml对比剂。方案B30例,双期注射,团注60～80ml对比剂后于第二时相注射30ml生理盐水。方案C、D、E共266例,均行三期注射。其中,方案C 92例;方案D 83例;方案E91例。第一时相团注50～60ml对比剂,第二时相分别以不同比率（方案C 50％,方案D 40％,方案E 30％）注射30～40ml对比剂-生理盐水混合液,第三时相注射30ml生理盐水。分别测量升主动脉根部、同层面胸主动脉、主肺动脉、左心室及右心室的CT值,计算心室腔-心室壁的对比噪声比（CNR）。比较不同对比剂注射方案冠状动脉各级分支显示情况及右心室内对比剂均匀性。结果：CNR左心室各组间差异无统计学意义（P〉0．05）;CNR右心室各组间有显著性差异（P〈0．01）,C组CNR右心室明显高于其他各组（P〈0．01）。左心室、升主动脉根部和降主动脉的平均CT值差异无统计学意义（P〉0．05）;主肺动脉和右心室的平均CT值有显著性差异（P〈0．01）,其中,右心室CT值C组高于其他各组（P〈0．01）。各组在冠状动脉的显示方面无统计学意义（P〉0．05）。右心室的均匀性各组间存在显著性差异（P〈0．01）,C组优于A、B、D组（P〈0．05）,与E组间差别无明显统计学意义（P〉0．05）。结论：应用三时相注射方案,先团注50～60ml对比剂（第一时相）,再以50％的比率注射30～40ml对比剂-生理盐水混合液（第二时相）,随后注射30ml生理盐水（第三时相）,一次扫描不仅可以在清晰显示冠状动脉的同时行心脏形态和功能分析,而且减少了对比剂的用量,可以为临床冠心病的筛查提供相应的综合?     

个体化对比剂注射方案在冠状动脉CT成像中的应用

【摘要】冠状动脉CT血管成像已成为临床工作者筛查和诊断冠状动脉疾病的重要手段,而合适且均匀的血管强化程度是准确诊断的前提。当前,根据影响血管强化的相关因素制定的个体化对比剂注射方案受到研究者的广泛关注。本文旨在对近年来国内外关于个体化对比剂注射方案在临床中的应用及进展进行综述。     

64层螺旋CT冠状动脉成像中优化对比剂注射技术对图像质量的影响

目的：比较常规固定对比剂注射方案和依据患者体重选择对比剂用量和流率技术对64层螺旋CT冠状动脉成像质量的影响。方法：研究中分别采用两种不同的对比剂应用方案,方案1：固定对比剂用量（70ml Iopamidol 370）,方案2：依据患者的体重选择对比剂用量（0.8ml/kg）。100位行前瞻性心电门控冠状动脉检查的患者随机分为2组（50人/组）,分别采用上述不同的对比剂方案。对横断面图像、多平面重组图像的图像质量进行评价（5分优,1分差）,并选择冠状动脉不同节段处测量对比剂增强水平。统计分析两种方案下的图像质量、对比剂增强水平和对比剂用量。结果：方案1和方案2条件下的图像质量评分分别为4.17±0.23和4.24±0.18,无统计学差异（P〉0.05）。对比剂平均增强水平存在统计学差异,方案1增强水平为（446±75）HU,而方案2为（387±69）HU。对比剂用量同样存在统计学差异,分别为70ml和53.1ml。结论：与固定对比剂应用方案相比,在冠状动脉成像中依据患者体重选择对比剂用量技术可以获得令人满意的图像,能够显著降低对比剂的用量,同时有助于获得更佳并且更为一致性的对比剂增强水平。     

64排螺旋CT冠状动脉成像时不同对比剂注射方案的特点

目的:探讨64排螺旋CT冠状动脉成像时不同对比剂注射方案的特点。方法:冠状动脉CT成像患者297例,随机分为3组。A组,双时相组,97例,第1时相注射对比剂60～70ml;第2时相注射生理盐水20ml。B组,3时相组,又分B1组及B2组。B1组101例,第1时相注射对比剂40～50ml;第2时相对比剂与生理盐水按6∶4比例混合注射20～30ml;第3时相注射生理盐水20ml。B2组99例,第1时相及第3时相注射方案同B1组,第2时相对比剂与生理盐水混合比例为7∶3,注射20～30ml。注射速率4.5～5.0ml/s。评价内容包括冠状动脉成像质量、上腔静脉及右心室伪影、右心室壁及肺动脉显示情况,所得结果进行统计学处理。结果:3组间,冠状动脉成像质量差异无统计学意义。上腔静脉及右心室伪影A组与B组间差异有统计学意义,A组伪影较明显。B1组与B2组间差异无统计学意义。右心室壁评价A组最佳,与B组间差异有统计学意义。B2组优于B1组,两者差异有统计学意义。肺动脉显示A组最佳,与B组间差异有统计学意义。B组中,B2组肺动脉显示率约63.64%,高于B1组。结论:3种注射方案均可提供良好的冠状动脉图像。双时相注射可较好显示右心室壁及肺动脉,但上腔静脉及右心室伪影较明显。6∶4比例的3时相注射上腔静脉及右心室伪影最小,但右心室壁显示较差,基本不能观察肺动脉。7∶3比例的3时相注射方案上腔静脉及右心室伪影小,可进行右心室评价,但肺动脉显影不可靠。可根据临床需求选择不同的注射方案。     

心脏CT检查时对比剂注射方案的优化

多层螺旋CT（MSCT）的间世拓展了CT在心脏检查中的应用范围,新一代MSCT尤其是64层以上的螺旋CT,因其良好的时间分辨力、空间分辨力及密度分辨力,得到了临床医生的广泛认可。冠状动脉CT血管成像（CCTA）对冠状动脉疾病的诊断,其阴性预测值可达到98％～99％,与传统冠状动脉造影相比,MSCT对冠心病的筛查、斑块及组成成分的观察、斑块危险度的预测、     

根据体重个体化对比剂注射方案在64层螺旋CT冠状动脉成像中的应用

目的：探讨根据体重个体化对比剂注射方案在64层螺旋CT冠状动脉血管成像检查中的应用价值。方法：90例患者随机分成3组,每组30例,均使用双期对比荆注射。A组采用对比剂总量(75 ml)注射法;B组根据体重13 s对比剂注射法;C组根据体重16 s对比剂注射法。分别比较各组冠脉分支显示情况和评分,测量升主动脉根部、左心室...     

不同浓度对比剂对脑血管3D-DSA成像效果的影响

目的 探讨不同浓度对比剂对脑血管3D-DSA成像效果的影响及应用价值.方法 前瞻性收集疑似颅内动脉瘤患者并依据对比剂应用浓度及注射速率随机分为5组:A组350 mg I/ml,3 ml/s;B组350 mg I/ml,4 ml/8;C组400 mg I/ml,3 m1/s;D组400 mg I/ml,4 m1/s;E组270 mg I/ml,4 ml/s.计算轴位图像上颈内动脉岩段(C2)、眼段(C6)、大脑中动脉水平段(M1)、大脑前动脉水平段(A1)信噪比(SNR)、对比噪声比(CNR),对容积再现(VR)及最大密度投影(MIP)重建图像进行评分,记录患者所用对比剂总量及术前、术后24h、术后48 h血清肌酐(SCr)值.结果 比较不同浓度相同注射速率对比剂应用结果,A、C两组间C2、C6、M1、A1段SNR、CNR值差异均有统计学意义(P＜0.05);B、D两组,B、E两组及D、E两组间C2段SNR、CNR值差异均有统计学意义(P＜0.05),C6、M1、A1段SNR、CNR值差异均无统计学意义(P＞0.05);A、B两组,C、D两组间C2、C6、M1、A1段SNR、CNR差异均无统计学意义(P＞0.05).5组间VR、MIP图像主观评分差异均无统计学意义(P＞0.05).采用3种不同浓度对比剂患者间对比剂注射总量及术前、术后24 h、48 h Scr升高值差异均无统计学意义(P＞0.05).结论 脑血管3D-DSA检查中,较高浓度对比剂可用于无肾功能异常患者,但肾功能异常患者应慎用.3种浓度对比剂对患者48 h内SCr值的影响无差异.     

The effect of contrast agents on renal function

Contrast agent nephropathy accounts for a substantial number of hospital acquired incidences of acute renal failure and the functional damage induced may sometimes be irreversible. The true incidence of the complication is still uncertain but seems to be low in patients with normal renal function. Among numerous risk factors proposed, pre-existing renal failure is the most important. Diabetes only seems to be a significant risk when there is pre-existing renal functional deficiency. Among four main theories for the mechanism of contrast agent nephropathy, interest is mainly focused on post contrast vasoconstriction and direct tubolotoxicity of the contrast agent. No dramatic decrease in the overall incidence of contrast agent nephropathy has been observed following the change from ionic to non-ionic agents. However, several recent clinical trials confirm that non-ionic contrast agents are less nephrotoxic than ionic agents in patients with pre-existing renal insufficiency.     

MR imaging of portal vein thrombosis

MR imaging is emerging as a potential means of detecting portal venous thrombosis (PVT). Therefore, we attempted to establish specific criteria with which to diagnose PVT on conventional spin-echo images. In a retrospective review of 342 consecutive abdominal MR scans performed with a 0.5-T magnet, we identified nine patients with persistent signal in the portal vein and used the findings in these patients to establish criteria with which to diagnose PVT. We subsequently applied these criteria to 109 additional consecutive abdominal MR scans performed with the same magnet. Fifteen cases were found in which all images showed either (1) signal involving the entire width of the portal vein lumen, which approximated (with T1 weighting) and exceeded (with T2 weighting) the intensity of the hepatic parenchyma in images in which the hepatic veins showed a complete flow void or (2) complete nonvisualization of the portal vein and its major branches in images that showed a flow void in portal venous collaterals and hepatic veins. All patients had unequivocal findings of PVT on at least one other imaging study (CT or sonography) or at surgery. Although the sensitivity of these signs could not be calculated, their specificity was 100%. We conclude that in the presence of these signs, the diagnosis of PVT can be made with confidence.     

Distinction of hepatic vein from portal vein by MR imaging

Fast magnetic resonance (MR) imaging techniques are assuming importance in imaging of the abdomen in part due to their ability to produce images during breath-holding, which ensures high spatial resolution and no respiratory motion artifacts. One problem with rapid scanning of the liver, shared with other MR techniques, is confusion between portal and hepatic veins due to similarity in signal intensity. The fast low angle shot (FLASH) technique (flip angle 40 degrees, repetition time 28 ms, and echo time 16 ms) produces high signal in both venous systems. To remedy the problem we incorporated presaturation pulses applied across the portal and mesenteric veins to the FLASH technique; this induced a decrease in signal in the portal venous system and facilitated their differentiation from hepatic veins. Moreover, in one patient an intraportal tumor thrombus not detected on the standard FLASH technique was rendered visible by presaturation. Although the presaturation pulses in the present series were confined to the sagittal plane, the technique should be applicable in any plane as dictated by the anatomy and direction of blood flow. We anticipate wide use of combined presaturation and rapid scanning techniques.     

Comparison of different contrast agents and doses for quantitative MR myocardial perfusion imaging

PURPOSE: To investigate three different contrast agents at different injection volumes for repetitive quantitative multislice myocardial perfusion imaging using the prebolus technique. MATERIALS AND METHODS: Two consecutive prebolus perfusion measurements were performed on a 1.5 T scanner using identical injection volumes for the first and second examination to test the reproducibility for possible rest and stress examination in normal volunteers. Either 1-8 mL, 1-12 mL Gd-DTPA, 1-4 mL, 1-6 mL, 1-9 mL Gd-BOPTA, or 1-4 mL, 1-6 mL gadobutrol were applied. RESULTS: In cases where injection volumes were sufficiently small, there was no indication of significant differences in quantitative perfusion values with respect to the different contrast agents. Increasing the bolus volume improved the contrast-to-noise ratio (CNR) but led to saturation effects and underestimation of the true perfusion. The highest CNR was measured for gadobutrol (6 mL, p < 0.0005 compared to 8 mL Gd-DTPA). The smallest difference of perfusion values between the first and the second prebolus examination was found for Gd-BOPTA (p < or = 0.006 compared Gd-DTPA). CONCLUSION: Prebolus examinations for quantitative myocardial perfusion imaging are possible with all three contrast agents for sufficient small injection volumes. Gd-BOPTA was found to be advantageous for a combined quantitative rest and stress examination.     

门静脉内径值与CT门静脉成像密度达峰值及达峰时间的相关性研究

目的:通过测量不同门静脉内径值的CT门静脉成像密度达峰值和达峰时间,探讨门静脉内径值与门静脉成像密度达峰值及达峰时间的相关性。方法:将60例门静脉内径值介于12.0~22.0 mm的患者分为3组,每组均采取特定区域多时间点扫描。对扫描结果进行统计分析,绘制TDC。对每例门静脉扫描密度达峰值与门静脉内径值行线性相关性分析。结果:门静脉内径值12.0~15.0 mm组达峰时间为60 s,15.1~19.0 mm组为70 s,19.1~22.0 mm组为75 s。达峰时间随门静脉内径值增加而延迟。密度达峰值也随门静脉内径值的增大而降低(r~2=0.652,P0.001),门静脉内径值与达峰值回归方程:y=173.599-2.276x。结论:门静脉内径值与门静脉成像密度达峰时间呈正相关、与密度达峰值呈反向线性变化趋势。为获得最佳门静脉成像质量,应根据不同门静脉内径值选择最佳的扫描时间。     

Left portal vein pseudothrombus: A pitfall on contrast medium-enhanced computed tomography

Portal vein (PV) thrombosis may be detected on contrast medium-enhanced computed tomographic (CECT) scans of patients with acute abdominal pathology. We describe a pitfall of dynamic CECT related to the normal arched configuration of the left PV umbilical segment. On axial images, just caudal to the left PV arch, there is an apparent discontinuity in the left PV lumen filled with low-attenuation fat in the intersegmental fisure. If opacified hepatic artery branches traverse the fissure at this level, an appearance mimicking segmental PV thrombosis with mural enhancement can result. A retrospective review of 180 CECT scans in patients without PV thrombosis revealed this phenomenon in seven cases (4%). Awareness of this pitfall obviates the need for superfluous investigations that might otherwise be necessary to confirm PV patency.     

Wedged hepatic venography for targeting the portal vein during TIPS: comparison of carbon dioxide and iodinated contrast agents

Purpose: Carbon dioxide (CO2) can traverse the hepatic sinusoids better than iodinated contrast medium and has been used by many interventionalists for wedged hepatic venography during transjugular intrahepatic portosystemic shunt (TIPS) procedures. Our study was designed to compare the extent of the portal vein opacification using either CO2 or iodinated contrast medium. Methods: Wedged hepatic venography for portal vein opacification during TIPS was performed using hand injection through a 6.5 Fr diagnostic catheter. Portograms of 36 patients performed with 10 ml of iodinated contrast medium were retrospectively compared with portograms of 45 patients performed with 30-40 ml of CO2. Opacification of the right portal vein branch including the portal vein bifurcation was defined as a successful study. Results: Using CO2 the right portal vein branch and the portal vein bifurcation were opacified in 87% of patients (39 of 45); only a part of the right portal vein branch was opacified in 6% of patients and no opacification of any portal vein branch was seen in 7% of patients. Using iodinated contrast medium, there was opacification of the portal vein bifurcation in 25% of patients (9 of 36), of a part of the portal vein branch in 36% and no opacification of any branch in 39%. There was one case of hepatic laceration from CO2 wedged venography which was treated with microcoil embolization. Conclusions: Using CO2 as a contrast medium, opacification of the portal vein bifurcation by wedged hepatic venography was seen in 87% of patients, in comparison with only 25% when iodinated contrast medium was used (p < 0.001). CO2 is superior to iodinated contrast medium for wedged hepatic venography during TIPS.     

Safety of magnetic resonance imaging contrast agents.

Many of the MR examinations performed in the world each year are accompanied by administration of one of these frequently used intravenous contrast agents: Magnevist, Omniscan, and ProHance. Accordingly, MR practitioners must understand the basic pharmacokinetics, side effects, and the potential for adverse events for these contrast agents. Additionally, MR practitioners must know how to manage side effects and adverse events that may occur in association with the administration of contrast agents. Notably, the use of MR imaging contrast agents in special patient populations must be understood. This article discusses each of these important issues.