Catheter-Malposition-Induced Cardiac Tamponade via Contrast Media Leakage During Computed Tomography Study

We present a rare case of a central venous catheter-malposition-induced life-threatening cardiac tamponade as a result of computed tomography (CT) with contrast enhancement in an infant with a ventricular septal defect and pulmonary atresia after a modified Blalock–Taussig shunt. The diagnosis was confirmed by chest radiographs and CT study with catheter perforation through the right atrial wall and extravasation of the contrast medium into the pericardium, leading to cardiac tamponade and subsequent circulatory collapse. Two hours after successful cardiopulmonary resuscitation, the patient gradually resumed normal hemodynamic status.     

Radiation Dose from Diagnostic Computed Tomography in Saskatchewan

Objective

To calculate the effective dose from diagnostic computed tomography (CT) scans in Saskatchewan, Canada, and compare with other reported dose levels.

Methods

Data from CT scans were collected from 12 scanners in 7 cities across Saskatchewan. The patient age, scan type, and selected technique parameters including the dose length product and the volume computed tomography dose index were collected for a 2-week period. This information then was used to calculate effective doses patients are exposed to during CT examinations. Data from 2,061 clinically indicated CT examinations were collected, and of them 1,690 were eligible for analysis. Every examination during a 2-week period was recorded without selection.

Results

The average provincial estimated patient dose was as follows: head, 2.7 mSv (638 scans; standard deviation [SD], ±1.6); chest, 11.3 mSv (376 scans; SD, ±8.9); abdomen-pelvis, 15.5 mSv (578 scans; SD, ±10.0); abdomen, 11.7 mSv (80 scans; SD, ±11.48), and pelvis, 8.6 mSv (18 scans; SD, ±6.04). Significant variation in dose between the CT scanners was observed (P = .049 for head, P = .001 for chest, and P = .034 for abdomen-pelvis).

Conclusions

Overall, the estimated dose from diagnostic CT examinations was similar to other previously published Canadian data from British Columbia. This dose varied slightly from some other published standards, including being higher than those found in a review conducted in the United Kingdom in 2003.     

Contrast Media in Abdominal Computed Tomography: Optimization of Delivery Methods

Objective

To provide a systematic overview of the effects of various parameters on contrast enhancement within the same population, an animal experiment as well as a computer-aided simulation study was performed.

Materials and Methods

In an animal experiment, single-level dynamic CT through the liver was performed at 5-second intervals just after the injection of contrast medium for 3 minutes. Combinations of three different amounts (1, 2, 3 mL/kg), concentrations (150, 200, 300 mgI/mL), and injection rates (0.5, 1, 2 mL/sec) were used. The CT number of the aorta (A), portal vein (P) and liver (L) was measured in each image, and time-attenuation curves for A, P and L were thus obtained. The degree of maximum enhancement (Imax) and time to reach peak enhancement (Tmax) of A, P and L were determined, and times to equilibrium (Teq) were analyzed. In the computed-aided simulation model, a program based on the amount, flow, and diffusion coefficient of body fluid in various compartments of the human body was designed. The input variables were the concentrations, volumes and injection rates of the contrast media used. The program generated the time-attenuation curves of A, P and L, as well as liver-to-hepatocellular carcinoma (HCC) contrast curves. On each curve, we calculated and plotted the optimal temporal window (time period above the lower threshold, which in this experiment was 10 Hounsfield units), the total area under the curve above the lower threshold, and the area within the optimal range.

Results

A. Animal Experiment: At a given concentration and injection rate, an increased volume of contrast medium led to increases in Imax A, P and L. In addition, Tmax A, P, L and Teq were prolonged in parallel with increases in injection time The time-attenuation curve shifted upward and to the right. For a given volume and injection rate, an increased concentration of contrast medium increased the degree of aortic, portal and hepatic enhancement, though Tmax A, P and L remained the same. The time-attenuation curve shifted upward. For a given volume and concentration of contrast medium, changes in the injection rate had a prominent effect on aortic enhancement, and that of the portal vein and hepatic parenchyma also showed some increase, though the effect was less prominent. A increased in the rate of contrast injection led to shifting of the time enhancement curve to the left and upward. B. Computer Simulation: At a faster injection rate, there was minimal change in the degree of hepatic attenuation, though the duration of the optimal temporal window decreased. The area between 10 and 30 HU was greatest when contrast media was delivered at a rate of 2-3 mL/sec. Although the total area under the curve increased in proportion to the injection rate, most of this increase was above the upper threshould and thus the temporal window was narrow and the optimal area decreased.

Conclusion

Increases in volume, concentration and injection rate all resulted in improved arterial enhancement. If cost was disregarded, increasing the injection volume was the most reliable way of obtaining good quality enhancement. The optimal way of delivering a given amount of contrast medium can be calculated using a computer-based mathematical model.     

螺旋CT肝脏增强扫描造影剂注射量和注速的应用研究

目的：应用时间—密度曲线分析比较不同注射量和注速对肝增强峰值造成的影响，选择适合肝脏螺旋增强扫描的较佳注射方案。方法：４８例正常肝脏患者，随机分成四组，以不同注射量和注速，单时相注射离子型造影剂，于肝门区水平行单层动态扫描，分别求出肝实质、主动脉、脾脏增强峰值及其发生时间，并进行统计学处理。结果：１００ｍｌ注射量比８０ｍｌ注射量产生更高的肝增强峰值（Ｐ＜０．０５）；３ｍｌ／ｓ注速与２ｍｌ／ｓ注速产生相似的ＰＨＣＥ（Ｐ＞０．０５），但前者发生更大的造影剂毒副反应。结论：１００ｍｌ注射量、２ｍｌ／ｓ注速为最佳注射方案，适合肝脏螺旋增强扫描     

多层螺旋CT肺动脉成像中对比剂剂量使用固定值的可行性研究

目的 探讨肺动脉CT成像中对比剂用量使用固定值的可行性.方法 肺动脉成像患者分为两组,试验组(A组):对比剂用量使用固定值(370 mgI/ml,35 ml);对照组(B组):对比剂用量按照0.7 ml/kg体重(370 mgI/ml)计算.分别测量A组与B组的肺动脉主干、上腔静脉及左心房的平均CT值,分析两组数据差异有无统计学意义.结果 A、B两组肺动脉主干、左心房平均CT值差异无统计学意义,上腔静脉CT平均值有显著性差异,B组大于A组.结论 肺动脉CT成像中对比剂用量使用固定值是可行的.     

胰腺实性-假乳头状瘤的多层螺旋CT诊断

目的:探讨胰腺实性-假乳头状瘤(SPTP)在多层螺旋CT上的影像特点.方法:回顾性分析40例经手术切除和病理学证实的胰腺实性-假乳头状瘤的临床、多层螺旋CT影像学资料,结合CTA、多平面重建和二维曲面重建等影像技术观察其影像学表现,分析影像学表现与病理结果的相关性.结果:女性35例,男性5例.40例患者SPTP影像学表现中,22例位于胰头,5例位于胰颈体交界区,6例位于胰体,3例位于胰体尾部,3例位于胰尾部,1例胰头、胰体尾部均见;类圆形30例,圆形5例,分叶状4例,表现为胰头增大1例,边界清楚,包膜完整;肿块多数较大,最大横断面达15 cm×18 cm,最小1.0 cm×1.1 cm;肿块完全实性7例,囊实性成分33例,其中囊性为主8例,实性为主17例,囊实性相仿8例.实性部分CT平扫呈稍低或等密度,增强扫描动脉期实性部分可见中等强化,至门静脉期肿瘤实性部分渐进性强化略高于动脉期,但强化程度均略低于正常胰腺组织,囊性部分平扫及增强均呈低密度.CT表现1例患者见恶性倾向,9例推压、包绕肠系膜血管,8例脾血管受压,3例累及肝总动脉及分支,2例累及十二指肠,11例伴有胰管扩张,其中1例伴有明显胆总管及肝内胆管扩张,13例伴有钙化.病理示良性37例,潜在恶性或低度恶性3例.结论:胰腺实性-假乳头状瘤具有特征性的影像学表现,螺旋CT能协助诊断,运用CTA、多平面重建和二维曲面重建等影像技术有助于术前评估肿瘤的良恶性.     

多层螺旋CT低剂量高浓度对比剂腹部血管成像应用研究

目的:探讨多层螺旋CT应用低剂量、高浓度对比剂腹部血管成像的可行性.方法:40例腹部CT血管成像(CTA)分为2组,A组:采用300 mg I/ml对比剂剂量为100 ml、生理盐水30 ml;B组:采用400 mg I/ml对比剂剂量为60 ml、生理盐水30 ml.注射流率均为4 ml/s.根据原始图像和最大强度投影(MIP)像,评价两组病例腹主动脉及其分支、肾动脉及其分支的显示程度;并测量动脉内对比剂的浓度.结果:两组病例均清晰显示腹主动脉、腹腔干、肝总动脉、脾动脉、肠系膜上动脉、肾动脉及其分支;两组动脉内的对比剂浓度虽然均维持在较高的水平,但B组明显高于A组,差异有显著性意义.肾动脉及其分支显示程度评分,B组明显优于A组,两组间存在显著性差异.结论:多层螺旋CT腹部血管成像使用低剂量、高浓度对比剂可以满足临床需要.     

Dual-Energy Computed Tomography Arthrography of the Shoulder Joint Using Virtual Monochromatic Spectral Imaging: Optimal Dose of Contrast Agent and Monochromatic Energy Level

Objective

To optimize the dose of contrast agent and the level of energy for dual-energy computed tomography (DECT) arthrography of the shoulder joint and to evaluate the benefits of the optimized imaging protocol.

Materials and Methods

Dual-energy scans with monochromatic spectral imaging mode and conventional single energy scans were performed on a shoulder phantom with 10 concentrations from 0 to 210 mg/mL of iodinated contrast medium at intervals of 15 or 30 mg/mL. Image noise, tissue contrast, and beam hardening artifacts were assessed to determine the optimum dose of contrast agent and the level of monochromatic energy for DECT shoulder arthrography in terms of the lowest image noise and the least beam hardening artifacts while good tissue contrast was maintained. Material decomposition (MD) imaging for bone-iodine differentiation was qualitatively assessed. The optimized protocol was applied and evaluated in 23 patients.

Results

The optimal contrast dose and energy level were determined by the phantom study at 60 mg/mL and 72 keV, respectively. This optimized protocol for human study reduced the image noise and the beam-hardening artifacts by 35.9% and 44.5%, respectively. Bone-iodine differentiation by MD imaging was not affected by the iodine concentration or level of energy.

Conclusion

Dual-energy scan with monochromatic spectral imaging mode results in reduced image noise and beam hardening artifacts.     

多层螺旋CT头颈部低剂量对比剂血管成像的可行性研究

目的 探讨16排多层螺旋CT低剂量对比剂头颈部血管成像的可行性。资料与方法 30例头颈部CT血管成像(CTA)分为3组．采用不同的对比剂量：100ml、80ml和60ml。根据原始图像和最大强度投影(MIP)重建像评价3组病例颈部动脉、颅内动脉的显示程度、静脉充盈程度以及伪影;并测量动脉内对比剂的浓度。结果 颈动脉、椎动脉及颅内动脉在3组病例中均清晰显示．显示程度评分上3组间无统计学差异。静脉充盈程度和伪影的主观评分亦无显著性差异。3组动脉内的对比剂浓度均维持在较高的水平,统计学无显著性差异。结论 16排多层螺旋CT头颈部血管成像使用低剂量对比剂可以满足临床需要。     

多层螺旋CT肠道造影在活动期溃疡性结肠炎评估中的应用

目的：总结活动期溃疡性结肠炎（UC）的多层螺旋CT肠道造影（CTE）特点,探讨多层螺旋CTE在全面评估UC中的价值。资料与方法35例经临床、肠镜及病理证实的活动期UC患者,均行多层螺旋CTE检查,根据改良Mayo评分系统将疾病分为轻度、中度、重度,比较不同组的CTE表现。结果35例UC患者中,轻度组6例,中度组13例,重度组16例,轻度组与中度组肠黏膜下气泡差异有统计学意义（P<0.05）,中度组与重度组肠壁分层、结肠袋消失及淋巴结肿大差异有统计学意义（P<0.05）,肠系膜血管增多在3组间差异均有统计学意义（P<0.05）,肠壁增厚、黏膜强化程度增加、肠腔狭窄及直肠周围脂肪沉积在各组间差异无统计学意义（P>0.05）。结论多层螺旋CTE可以全面评估UC的肠壁、肠管及肠外情况,对活动期UC的诊断及临床分度判断均有较高的价值。     

双能CT区分两种造影剂的研究

目的：探讨双能CT扫描区分铋造影剂和钆造影剂的可行性。资料与方法将两组不同比例的铋造影剂和钆造影剂混合物置于试管内,第一组为碘海醇注射液和钆特酸葡胺注射液,体积比分别为0∶1、1∶6、1∶1、6∶1、1∶0;第二组为碘海醇注射液和果胶胶体铋溶液,质量浓度分别为0∶1、1∶6、1∶1、6∶1、1∶0。使用双能CT扫描后,以80 keV进行单能量图像重建,应用Liver VNC软件将双能数据进行虚拟平扫及碘含量分析。结果在80 keV虚拟单能量成像的条件下,第一组混合液的CT值为379~383 HU,第二组混合液的CT值为170~173 HU,且两组实际碘浓度与测量碘浓度之间差异均无统计学意义（P>0.05）。物质分离图像中,碘造影剂和钆造影剂区分不明显,碘和铋造影剂区分明显。结论双能CT可以区分铋和钆这两种衰减率不同的造影剂,原子序数相差越大,区分效果越明显。     

多层螺旋CT三期扫描对正常胰腺和胰周血管增强特性的研究

目的　探讨多层螺旋CT多期增强扫描胰腺实质和胰周血管的强化特点。方法　对 60例正常人群行螺旋CT三期扫描 ,即动脉期 (2 0s)、胰腺期 (3 5～ 42s)、肝脏期 (75～ 80s) ,分别测量各期胰腺及胰周血管的CT值 ,并行统计学分析。结果　胰腺在胰腺期增强峰值高于其它两期 (Ρ <0 .0 1) ,对胰周动脉的增强值胰腺期与动脉期无明显差异 (Ρ >0 .0 5 ) ,但明显高于肝脏期 (Ρ <0 .0 1) ,对胰周静脉的增强值胰腺期与肝脏期无明显差异 (Ρ >0 .0 5 ) ,却明显高于动脉期 (Ρ <0 .0 1)。结论　多层螺旋CT三期扫描尤其胰腺期明显增强胰腺和胰周血管 ,对胰腺疾病的诊断和分期有重要价值。     

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.     

正常胸腺的CT表现

将１０３例经临床证实的正常胸腺胸部ＣＴ表现分为５个年龄组，详细描述了胸腺位置，各年龄组胸腺形态及密度变化。测量了各年龄组胸腺左右叶宽度、厚度平均值。结果显示，胸腺位于前上纵隔，ＣＴ扫描可清楚显示胸腺。随着年龄增大，胸腺实质的大小逐渐减小，密度减低。各年龄组胸腺厚度的平均值加上１．５个标准差可做为正常胸腺实质大小的上限来判断胸腺实质增大的情况。残留的胸腺实质呈线状及小结节状，小结节直径小于７ｍｍ。     

First European Seminar: Contrast Media in Radiology

Summary The First European Seminar on Contrast Media in Radiology, organized by Prof. M. Amiel in Lyon in 1981, included the majority of the groups working in this field in Europe, as well as several specialists from other regions (United States, Japan, Australia). The results of this meeting are an updating of the image creating drugs. The dominant themes were toxicity problems and development adapted to progress in radiology.Organized by Prof. M. Amiel, Lyon, 17–19 September 1981