CT和MR血管成像诊断急性肺栓塞的Meta分析

目的：应用 Meta 分析法,以 DSA 为金标准,探讨 CT 肺动脉成像（CTPA）和磁共振肺血管成像（MRPA）对肺动脉栓塞（PE）的诊断价值。方法：检索 Cochrane 图书馆、Medline 数据库、Springerlink 数据库及 Ovid 循证医学数据库中1994～2013年发表的英文文献以及知网数据库和万方医学数据库中1994～2013年发表的中文文献,按照 Cochrane 协作网推荐的诊断性实验的纳入标准,严格筛选与“CTPA 和／或 MRPA 诊断急性 PE”相关的文献。在符合条件的文献中提取诊断信息（包括真阳性值、假阳性值、真阴性值、假阴性值）和其它相关数据。采用 Stata 12软件和 Meta-disc 1．4软件对纳入文献行统计学处理,包括异质性检验,计算敏感度和特异度及其95％可信区间,选择相应的效应模型予以加权定量合并,绘制汇总的工作特征曲线（SROC）,最后进行敏感性分析。结果：按照纳入标准共获取有效文献17篇,其中与 CTPA相关的文献10篇,与 MRPA 相关的文献7篇。17篇文献均满足诊断性研究质量评价工具（QUADAS）中提出的14项标准中的10项以上。CTPA 及 MRPA 两组中的相关研究均有异质性,按照随机效应模型对纳入文献进行汇总分析。结果显示,CTPA 诊断肺栓塞的敏感度、特异度及各自的95％可信区间分别为0．78（0．74～0．82）和0．90（0．87～0．92）,MR-PA 为0．86（0．79～0．92）和0．97（0．94～0．99）,SROC 下面积分别为94％和98％。结论：CTPA 和 MRPA 对急性肺栓塞的诊断均具有很高的价值,两种方法的诊断特异度均很高,作为诊断肺栓塞的无创性检查方法可基本替代 DSA 检查。     

Comparison of doses for pulmonary embolism detection with helical CT and pulmonary angiography

The objective of this study was to compare the radiation exposure delivered by helical CT and pulmonary angiography (PA) for the detection of pulmonary embolism (PE), with an anthropomorphic phantom. A preliminary survey defined a representative standard procedure for helical CT and PA (n=148) by choosing the exposure settings most frequently used. Then, radiation doses were measured with thermoluminescent dosimeters TLD 100 (Lif) introduced into the depth of an anthropomorphic phantom. Average doses were approximately five times smaller with helical CT than with PA (6.4±1.5 and 28±7.6 mGy, respectively). The most important doses were abreast the pulmonary apex for CT, and abreast the pulmonary arteries for PA. Compared with PA, helical CT dose distribution was relatively uniform (10–13 mGy). Finally, concerning abdomen and pelvis, doses were more important for PA than for CT scan (0.06–2.86 and 0.2–11.5 mGy, respectively). For the diagnostics of PE, radiation exposure is five times smaller with helical CT than with pulmonary angiography.     

Prediction of short term outcome of pulmonary embolism: Parameters at 16 multi-detector CT pulmonary angiography

Purpose

To evaluate the accuracy of computed tomography pulmonary angiography (CTPA) parameters, for predicting short-term mortality in patients with acute pulmonary embolism (PE).

Materials and methods

Thirty-two patients with proven PE had CT pulmonary angiography were included in the study. The clot burden using the Qanadli score (QS), and the right ventricular dysfunction (RVD) parameters were assessed on CT by calculating right ventricular/left ventricular (RV/LV) diameter ratios, interventricular septum abnormality, inferior vena cava contrast reflux, azygous vein and superior vena cava measures. Contrast density in pulmonary artery and descending aorta was evaluated for all patients. Patients were followed up for 30 days and then classified as survivors or non survivors.

Results

Thirty-two patients were included in the study, 23 (71.8%) of them were classified as survivors, and the other nine (28.1%) patients died within the first month (non survivors). There was a positive, but weak correlation between the Qanadli score and the short term mortality (P value = 0.05). There was a statistically significant relationship between the RV/LV ratio and PE-related mortality, with a P value < 0.001. Also, there was a good correlation between degree of IVC reflux and PE outcome (P < 0.001). The PA/AO diameter ratio, SVC diameter and azygous vein diameter showed no statistically significant difference between survivors and non survivors.

Conclusions

CTPA findings that may predict short term mortality are the high grades of inferior vena cava reflux, RV/LV diameter ratio more than 1.2, and clot burden >18 according to the Qanadli score and to a lesser degree the interventricular septum abnormality.     

CT angiography of pulmonary embolism in patients with underlying respiratory disease: impact of multislice CT on image quality and negative predictive value

Our objective was to evaluate the impact of multislice CT (MSCT) on image quality and diagnostic value of spiral CT angiograms. Over an 8-month period (January 2000 to August 2000), 134 consecutive patients, including 55 patients with underlying lung disease, underwent MSCT (group 1). Image quality and diagnostic results of CT angiograms were compared with those obtained in 125 consecutive patients, including 58 patients with underlying lung disease, evaluated with thin-collimation single slice CT (SSCT; group 2) over a similar period of time (January 1999 to August 1999). A 3-month clinical follow-up was systematically obtained in all patients who were not anticoagulated in the two groups. For a significantly longer mean z-axis coverage, the mean duration of data acquisition was significantly shorter with MSCT. The frequency of examinations devoid of motion artifacts was significantly higher in group 1 than in group 2. In the absence of significant difference in the quality of vascular enhancement, mainly coded as good or excellent, the proportion of examinations interpretable down to the subsegmental arteries was higher in group 1 (57.5%) than in group 2 (13%) ( p<0.0001). The benefits of MSCT were more marked for patients with underlying respiratory disease and did not lead to a higher detection rate of peripheral pulmonary embolism. The negative predictive values of single-slice and multislice CT were 100 and 99%, respectively. Improvement in image quality on MSCT scans accounts for the improved diagnostic accuracy of CT angiography, in particular for patients with impaired respiratory function.     

64层螺旋CT血管成像在肺动脉栓塞中的诊断价值

目的:探讨64层螺旋CT血管成像在诊断肺动脉栓塞中的价值。方法:回顾性分析19例临床确诊为肺动脉栓塞的64层螺旋CT肺动脉成像资料,并用最大密度投影(MIP)、多平面重组(MPR)、容积再现(VR)等方法显示肺动脉。结果:19例患者中,其中左右肺动脉栓塞有8支,叶肺动脉栓塞27支,段及亚段肺动脉栓塞56支。偏心型41支,闭塞型38支,中央型8支,附壁环形型4支。结论:64层螺旋CT肺动脉成像可作为肺动脉栓塞诊断的首选方法。     

CTPA对肺动脉栓塞的诊断及临床应用价值

目的:探讨多层螺旋CTPA及后处理技术对肺动脉栓塞的诊断及临床应用价值。方法:回顾性分析40例经多层螺旋CTPA确诊为肺动脉栓塞的影像资料,并应用MPR、MIP、VR等后处理方法不同角度显示肺动脉及其栓子情况,观察肺动脉栓塞的征象,10例经临床治疗后行CTPA复查并与临床结果对照指导治疗。结果:40例肺动脉栓塞(PE)病例中,中央型PE32例,周围型PE8例。肺动脉内栓子表现为中心型、偏心型及闭塞型的充盈缺损。经治疗复查CTPA显示栓子变小或消失。结论:MSCTPA已成为诊断肺动脉栓塞的可靠方法,并为肺动脉栓塞的治疗提供必要的指导。     

CT肺动脉成像结合D-二聚体对急诊肺栓塞病人的诊断价值

目的分析以胸痛为主要表现于急诊就诊的病人采用CT肺动脉成像(CTPA)结合D-二聚体检测肺栓塞的临床应用价值。方法回顾性分析自2015年1月1日—2017年6月30日于急诊以胸痛就诊并行CTPA检查的病人155例,其中男83例,女72例,年龄13~84岁,平均(55±16)岁。分析和记录肺栓塞的有无及其发生率,分析无肺栓塞病人伴发的有临床诊疗意义的病变。记录纳入病人的D-二聚体值。采用Fisher精确检验分析D-二聚体阳性组和阴性组CTPA上肺栓塞的检出率;采用独立样本t检验比较D-二聚体异常组CTPA上肺栓塞病人和非肺栓塞病人的D-二聚体值。以CTPA诊断为参考标准,评估D-二聚体在诊断肺栓塞中的价值。结果155例病人中,50例(32.3%)病人经CTPA诊断为肺栓塞,105例(67.7%)病人无肺栓塞。152例病人进行了D-二聚体测量。按照常规D-二聚体参考值0.5 mg/d L为阳性阈值,其中二聚体值阳性128例,阴性24例。24例D-二聚体值阴性者CTPA上均无肺栓塞(0/24),CTPA上有肺栓塞的50例病人(50/128,39.1%)的D-二聚体值为阳性,78例D-二聚体阳性者的CTPA上无肺栓塞,2组肺栓塞检出率的差异有统计学意义(Fisher精确检验,P<0.001)。D-二聚体值阳性组中,50例病人于CTPA上诊断为肺栓塞,78例CTPA上无肺栓塞,两者的平均D-二聚体值差异无统计学意义[分别为(6.11±5.59)mg/d L和(5.26±6.67)mg/d L,t=0.741,P=0.460]。以CTPA检测结果为参考,D-二聚体诊断肺栓塞的敏感度、特异度、阳性预测值、阴性预测值分别为100%、23.5%、39.1%、100%。结论本研究提示结合D-二聚体的测定推荐CTPA检查有助于进一步提高肺栓塞检测的阳性率。     

Dual-energy MDCT: Comparison of pulmonary artery enhancement on dedicated CT pulmonary angiography, routine and low contrast volume studies

Purpose

The aim of this study was (a) to compare arterial enhancement in simultaneously acquired high- and low-kilovoltage images; and (b) to determine whether low tube-voltage imaging would permit PE evaluation on routine chest CT studies or CTPA studies performed with a low volume of contrast media.

Materials and methods

We compared 20 CTPA studies (CTPA group), 20 routine thoracic CT studies (RT group) and 10 CTPA studies performed with reduced volume of contrast media (RC group). HU values were measured in all groups at 80 kVp and 140 kVp images in multiple pulmonary arterial segments bilaterally. The diagnostic quality of the central and peripheral vascular enhancement and the image noise were evaluated at both energies using a five-point scale.

Results

For all patients, the mean CT attenuation values were greater at 80 kVp than 140 kVp images (p < 0.001). At 80 kVp, CTPA group attenuation values were greater than RT group (p = 0.03) with a similar trend at 140 kVp (p = 0.08). At both 140 kVp and 80 kVp, CTPA group attenuation values were greater than RC group (p = 0.02 and p = 0.03, respectively). Qualitative analysis showed that at 140 kVp CTPA studies had better global image quality scores than RT (p = 0.003) and RC (p = 0.001) groups. However, at 80 kVp, there was no significant difference of global image quality between CTPA and the other groups (p = 0.4 and p = 0.5, respectively). Although measurable image noise was greater at 80 kVp than 140 kVp (p < 0.001), qualitative analysis revealed lower image noise at 80 kVp images.

Conclusion

DECT at 80 kVp increases arterial enhancement in both CTPA and routine studies. For routine studies this results in central and peripheral enhancement quality equivalent to that of CTPA studies. Low tube-voltage imaging allows marked contrast volume reduction for CTPA. In selected cases, satisfactory lower radiation dose CT might be achievable using lower kVp imaging alone.     

16层螺旋CT肺动脉造影图像质量的影响因素研究

目的:探讨16层螺旋CT肺动脉造影(CTPA)成像质量的影响因素,为进一步提高肺动脉栓塞(PE)诊断质量提供帮助。方法:对临床拟诊肺栓塞病例46例行CTPA。扫描准直为0.75mm×16,图像后处理包括5mm、0.75mm横断面图像,不同厚度MIP、MPR,不同窗位及颜色的VR。观察内容包括肺动脉、血栓及肺动脉伪影。结果:CTPA诊断PE病人37例均为双肺多发肺动脉栓子,累及动脉189支。2mm MIP、MPR清晰显示亚段及其1~2级分支动脉,并显示肺动脉内栓子的部位及形态;5mm MIP、20mm MIP对亚段及分支动脉的显示不如2mm MIP(P<0.05)。VR立体感强,调节窗位及颜色可观察肺动脉及血栓表现。16例(34.7%)出现肺动脉搏动伪影,心胸比例增大,则伪影加重。结论:CTPA的成像质量主要受扫描技术及图像后处理技术的影响,合理应用成像技术可进一步提高PE诊断准确率。     

Severity of acute pulmonary embolism: evaluation of a new spiral CT angiographic score in correlation with echocardiographic data

The purpose of this study was to investigate whether the severity of acute pulmonary embolism (PE) could be quantitatively assessed with spiral CT angiography (SCTA). Thirty-six consecutive patients without underlying cardiopulmonary disease and high clinical suspicion of PE underwent prospectively thin-collimation SCTA and echocardiography at the time of the initial diagnosis (T0) and after initial therapy (T1; mean interval of time T1–T2: 32 days). The CT severity score was based on the percentage of obstructed surface of each central and peripheral pulmonary arterial section using a 5-point scale (1: <25%; 2: 25–49%; 3: 50–74%; 4: 75–99%; 5: 100%). The sum of the detailed scores attributed to 5 mediastinal, 6 lobar and 20 segmental arteries per patient led to the determination of central, peripheral and global CT severity scores and subsequent determination of percentages of obstruction of the pulmonary circulation. Echocardiographic severity criteria included the presence of signs of acute cor pulmonale and/or systolic pulmonary hypertension (>40 mm Hg). The SCTA depicted acute PE in all patients at T0 with complete resolution of endovascular clots in 10 patients at T1. At T0, the mean percentage of obstruction of the pulmonary arterial bed was significantly higher in the 22 patients with echocardiographic signs of severity (56±13 vs 28±32%; p<0.001). A significant reduction in the mean percentage of pulmonary artery obstruction was observed in the 19 patients with resolution of echocardiographic criteria of severity between T0 and T1 T0: 57±14%; T1: 7±11%; p<0.001).The threshold value for severe PE on CT angiograms was 49% (sensitivity: 0.773; specificity: 0.214). The mean (±SD) pulmonary artery pressure was significantly higher in the 26 patients with more than 50% obstruction of the pulmonary artery bed (45±15 mm Hg) than in the 10 patients with less than 50% obstruction of pulmonary artery bed at T0 (31±11 mm Hg; p<0.01). The CT severity score evaluated in the present study enables quantitative assessment of acute PE severity on spiral CT angiograms, readily applicable in routine clinical practice. Electronic Publication     

64层螺旋CT肺血管造影在肺栓塞诊疗中的应用价值

目的 探讨64层螺旋CT在肺栓塞诊断及治疗中的指导作用。方法 63例患者均行64层螺旋CT肺血管造影(CTPA),并进行多种形式的图像重建结合轴位图像分析。结果 64层螺旋CTPA对63例患者肺动脉各级管腔内的栓子均明确显示,共累及肺动脉303支;图像分析结果伞部显示肺栓塞的直接征象为:主肺动脉和(或)左右肺叶、段、亚段血管腔内充盈缺损和血管阻塞;部分显示肺栓塞的间接征象为:马赛克征、右心房及右心室肥厚及扩张、肺动脉扩张、胸腔积液、肺不张及实变(肺梗死)等。62例患者经溶栓治疗后复查CTPA,其中,栓子完全消失者47例,栓子明显缩小者11例,溶栓治疗效果差者3例,考虑为慢性肺栓塞。结论 64层螺旋CTPA是临床最有效的诊断肺栓塞及溶栓后疗效评价的无创性方法之一。     

MSCTPA对肺栓塞患者右心功能的诊断价值

目的以超声心动图作为诊断右心功能的标准,探讨64层CT肺血管造影(CTPA)对肺栓塞患者右心功能的诊断价值。方法前瞻性收集了临床疑诊肺栓塞的41例行CTPA检查的患者,阳性组根据右心功能、肺动脉栓塞部位及肺动脉压力指数分组,薄层数据进行最大密度投影(MIP)、多平面重建(MPR)和容积再现(VRT),分析各组数据中右心功能参数的差异。结果 41例患者中肺栓塞阳性24例,阴性17例,CTPA诊断右心功能不全13例,超声心动图诊断右心功能不全11例。以超声心动图为标准,64层CTPA诊断右心功能不全的灵敏度为76.9%,特异度为90.9%,阳性预测值90.9%,阴性预测值76.9%,Kappa值为0.669,诊断具有中度一致性。对于主肺动脉干(PA)、升主动脉(Aorta)、上腔静脉(SVC)、奇静脉(AV)、冠状静脉窦(CS)、PA/Aorta比、LVd、RVd及RVd/LVd比之间比较,第一组中差异有统计学意义的指标有PA、PA/Aorta比,LVd、RVd及RVd/LVd,CS;第二组中差异均无统计学意义;第三组中,差异有统计学意义的指标有PA/Aorta比。结论 MSCTPA及其后处理重建技术可以在诊断肺栓塞的同时对心功能作出评价。     

Features of cardiac disease demonstrated on CT pulmonary angiography

The heart and mediastinal structures can be overlooked at CT pulmonary angiogram (CTPA). This pictorial review will demonstrate the features of cardiac disease that may be evident on a CTPA. CTPA allows assessment of not only the pulmonary arteries for embolism, but also of the bronchi, lung parenchyma, mediastinum and heart. Co-existent underlying or incidental cardiac disease is often present. Potentially life-threatening alternative diagnoses in a patient with chest symptoms can be reliably identified. Pathologies of the myocardium including hypertrophic cardio myopathy, pericardial disease, valvular disease, coronary artery disease, and intracardiac abnormalities are demonstrated pictorially. CTPA is increasingly used for the detection of pulmonary embolism. Most patients investigated have pathology other than PE as a cause of their symptoms. Frequently information about the heart is produced that provides important clues to determine the cause for the presenting symptoms and signs or reveals co-existing pathology. It is important to have a clear understanding of the features of cardiac disease which may be seen on a CTPA.     

Thoracic helical CT: influence of subsecond scan time and thin collimation on evaluation of peripheral pulmonary arteries

The objective of this study was to analyze the influence of collimation on the identification of peripheral pulmonary arteries on helical CT scans. Three hundred sixty of 370 consecutive helical CT angiograms of the pulmonary circulation obtained during an 18-month investigation period were considered as technically acceptable for the detection of acute pulmonary embolism and were retrospectively analyzed. Patients in group A (n = 274) underwent CT with 2-mm collimation and pitch of 2; those in group B (n = 86) underwent CT with 3-mm collimation and pitch 1.7; a 0.75-s rotation time was systematically used. A total of 2160 segmental (six arterial zones per patient) and 2160 subsegmental (six arterial zones per patient) arterial zones were assessed. Whereas the percentage of segmental arteries was not significantly different between group A (86 %) and group B (89 %), the percentage of analyzable subsegmental arteries was greater in group A (65 %) than in group B (43 %) (P < 0.001). The causes of inadequately depicted subsegmental arterial zones were partial-volume effects (group A, n = 302; 52 %; group B, n = 197; 67 %; P < 0.001), suboptimal enhancement (group A, n = 145; 25 %; group B, n = 43; 15 %; P < 0.05), motion artifacts (group A, n = 113; 20 %; group B, n = 30; 10 %), and unincluded arteries (group A, n = 20; 3 %; group B, n = 25; 8 %). Helical CT with 2-mm collimation at 0.75 s per revolution enables marked improvement in the analysis of subsegmental arteries in routine clinical practice. Received: 25 January 2000; Revised: 28 March 2000; Accepted: 30 March 2000     

Value of monoenergetic low-kV dual energy CT datasets for improved image quality of CT pulmonary angiography

Purpose

High vessel attenuation and high contrast-to-noise ratio (CNR) are prerequisites for high diagnostic confidence in CT pulmonary angiography (CTPA). This study evaluated the impact of calculated monoenergetic dual-energy (DE) CTPA datasets on vessel attenuation and CNR.

Materials and methods

50 Patients (24 men, mean age 68 ± 14 years) who underwent DE-CTPA were retrospectively included in this study. The 80 and 140-kV DE polyenergetic image data were used to calculate virtual monoenergetic image datasets in 10 kiloelectron volt (keV) increments from 40 to 120 keV. Vessel and soft tissue attenuation and image noise were measured in various regions of interest and the CNR was subsequently calculated. Differences in vessel attenuation and CNR were compared between the different monoenergetic datasets. The best monoenergetic dataset was then compared to the standard 120-kV polyenergetic dataset.

Results

Vessel attenuation and CNR of 70-keV CTPA datasets were superior to all other monoenergetic image datasets (all p < 0.05). 70-keV monoenergetic datasets provided a statistically significant 12% increase in mean vessel attenuation compared to standard 120-kV polyenergetic datasets (384 ± 117 HU vs. 342 ± 106 HU, respectively; p < 0.0001) and a statistically significant 18% increase in mean CNR (29 ± 13 vs. 24± 11 respectively; p < 0.0001).

Conclusion

Virtual 70-keV monoenergetic CTPA image datasets significantly increase vessel attenuation and CNR of DE-CTPA studies, suggesting that clinical application of low-keV monoenergetic reconstructions may allow a decrease in the amount of iodinated contrast required for adequate image quality in DE-CTPA examinations.     

Value of contrast-enhanced MR angiography and helical CT angiography in chronic thromboembolic pulmonary hypertension

The aim of this study was to evaluate the diagnostic value of contrast-enhanced MR angiography (ce MRA) and helical CT angiography (CTA) of the pulmonary arteries in the preoperative workup of patients with chronic thromboembolic pulmonary hypertension (CTEPH). The ce MRA and CTA studies of 32 patients were included in this retrospective evaluation. Image quality was scored by two independent blinded observers. Data sets were assessed for number of patent segmental, subsegmental arteries, and number of vascular segments with thrombotic wall thickening, intraluminal webs, and abnormal proximal to distal tapering. Image quality for MRA/CTA was scored excellent in 16 of 16, good in 11 of 14, moderate in 2 of 5, and poor in no examinations. The MRA/CTA showed 357 of 366 patent segmental and 627 of 834 patent subsegmental arteries. CTA was superior to MRA in visualization of thrombotic wall thickening (339 vs 164) and of intraluminal webs (257 vs 162). Abnormal proximal to distal tapering was better assessed by MRA than CTA (189 vs 16). In joint assessment of direct and indirect signs, MRA and CTA were equally effective (353 vs 355). MRA and CTA are equally effective in the detection of segmental occlusions of the pulmonary arteries in CTEPH. CTA is superior for the depiction of patent subsegmental arteries, of intraluminal webs, and for the direct demonstration of thrombotic wall thickening.     

Prospectively ECG gated CT pulmonary angiography versus helical ungated CT pulmonary angiography: impact on cardiac related motion artifacts and patient radiation dose

Objective

To compare prospectively ECG gated CT pulmonary angiography (CTPA) with routine helical ungated CTPA for cardiac related motion artifacts and patient radiation dose.

Subjects and methods

Twenty patients with signs and symptoms suspicious for pulmonary embolism and who had a heart rate below 85 were scanned with prospectively ECG gated CTPA. These gated exams were matched for several clinical parameters to exams from twenty similar clinical patients scanned with routine ungated helical CTPA. Three blinded independent reviewers subjectively evaluated all exams for overall pulmonary artery enhancement and for several cardiac motion related artifacts, including vessel blurring, intravascular shading, and double line. Reviewers also measured pulmonary artery intravascular density and image noise. Patient radiation dose for each technique was compared. Fourteen clinical prospectively ECG gated CTPA exams from a second institution were evaluated for the same parameters.

Results

Prospectively ECG gated CTPA resulted in significantly decreased motion-related image artifact scores in lung segments adjacent to the heart compared to ungated CTPA. Measured image noise was not significantly different between the two types of CTPA exams. Effective dose was 28% less for prospectively ECG gated CTPA (4.9 mSv versus 6.8 mSv, p = 0.02). Similar results were found in the prospectively ECG gated exams from the second institution.

Conclusion

Compared to routine helical ungated CTPA, prospectively ECG gated CTPA may result in less cardiac related motion artifact in lung segments adjacent to the heart and significantly less patient radiation dose.     

Imaging of acute pulmonary embolism using multi-detector CT angiography: An update on imaging technique and interpretation

Computed tomography angiography (CTA) of the pulmonary arteries has become the main diagnostic test for the evaluation of pulmonary embolism (PE). Not only due to the good availability, low cost and minimal invasiveness of this technique, but mainly because of the introduction of multi-detector CT techniques resulting in significant improvement in resolution, speed and image quality. This continuous gain in image acquisition speed went along with the introduction of new techniques of image acquisition, such as the dual-source CT scanning and novel concepts of image interpretation beyond morphological findings including the definition of the resulting perfusion defects and assessment of the cardiopulmonary circulation as a functional unit.This article will focus on technical and practical aspects to optimize CTPA examinations with modern multi-detector CT scanners, discusses aspects to be considered in specific patient groups (e.g., during pregnancy, young patients) and outlines new advents such as dual-source lung perfusion and automatic detection of pulmonary emboli.     

Multislice CT angiography

The introduction of multislice CT into clinical radiology constitutes a quantum leap that significantly widens the scope of vascular CT imaging. The advances over conventional spiral CT have been quantitative, mainly in terms of increased image acquisition speed which provides unprecedented volume coverage and spatial resolution. Moreover, significant technical innovations, such as cardiac scanning capabilities, have brought about a qualitative shift towards applications that were thought to be beyond the scope of CT imaging. This way multislice CT offers a wealth of new opportunities for quickly and accurately diagnosing suspected vascular disease in all organ systems; however, as we move towards faster and faster image acquisition techniques, we are also facing new challenges that require development of novel strategies in order to take full advantage of the increased capabilities of multislice CT in its current form and future generations of CT scanners.     

Quality of CT pulmonary angiography for suspected pulmonary embolus in pregnancy

The main objective of this study was to assess the quality of CT pulmonary angiography (CTPA) for suspected pulmonary embolus (PE) in the pregnant population. We retrospectively identified 40 consecutive pregnant patients who underwent CTPA from January 2005 to December 2006. Forty consecutive age-matched non-pregnant women were used as a control group. Studies were subjectively graded according to overall image quality by two readers in consensus, in randomised and blinded manner. Moreover, contrast enhancement of pulmonary arteries was subjectively and objectively evaluated. The proportion of sub-optimal studies was more than three times higher in the pregnant group (27.5%, n = 11) compared with the non-pregnant group (7.5%, n = 3; p = 0.015). Mean contrast enhancement was consistently higher in the non-pregnant group compared with pregnant group, both subjectively and objectively. The percentage of inadequately opacified vascular segments was more than two times higher in the pregnant group (28.7%, n = 264) than in the non-pregnant group (13.3%, n = 122; p = 0.0001). The incidence of sub-optimal CTPA studies is higher in pregnancy when compared with an age-matched non-pregnant control group. In addition to radiation issues, this should also be considered when implementing diagnostic strategies for suspected PE in pregnancy.