CT pulmonary angiography in the detection of pulmonary emboli: a meta-analysis of sensitivities and specificities

OBJECTIVE: To determine the overall sensitivity and specificity for CT pulmonary angiography (CTPA) in the diagnosis of pulmonary emboli (PE) using a meta-analysis of the published literature. MATERIALS AND METHODS: A Medline search was constructed to include all English language publications indexed in the Index Medicus from 1990 to 2000, which included the terms CT, PE and pulmonary angiography. Studies selected were designed principally to compare CTPA in the overall detection of PE as confirmed by an abnormal fluoroscopic pulmonary angiogram or a high probability V:Q scan. Results were corrected for the patient sample size in the respective studies prior to pooling the data. In the absence of an accepted technique for calculating a ROC curve in the meta-analysis of imaging studies, a previously untested theoretical technique was used to obtain a composite ROC curve. RESULTS: Twelve studies of CTPA comprising a total of 1250 patients were analyzed. The overall sensitivity and specificity for CTPA after correction for study size was 74.1% and 89.5% with a range of 57-100% and 68-100%, respectively, for the detection of PE. No trend was detected with respect to the year of publication or sample size. CONCLUSIONS: CTPA has acceptable sensitivity and specificity with a strong ROC curve making it a good first line investigation for PE.     

Ventilation-perfusion lung scintigraphy as a guide for pulmonary angiography in the localization of pulmonary emboli.

PURPOSE: To assess the appropriateness of ventilation-perfusion (V-P) scintigraphic abnormalities as a guide to pulmonary angiography for the diagnosis of pulmonary embolism (PE). MATERIALS AND METHODS: V-P scintigrams and pulmonary angiograms of 104 patients with angiographically proved PE were reviewed by two nuclear medicine physicians and two interventional radiologists. For V-P scintigrams, the lung with the larger amount of perfusion abnormality was determined followed by identification of specific lobes. Pulmonary angiograms were similarly evaluated for lateralization and lobar distribution of PE. Conclusions were initially reached independently and subsequently by consensus. RESULTS: Interobserver agreement for lateralization was 88% (kappa = 0.75) for V-P scintigraphy and 98% (kappa = 0.96) for pulmonary angiography. In 72 patients, V-P scintigrams predicted unilateral embolus; 64 patients underwent pulmonary angiography of the suspected side. Eight patients underwent contralateral angiography only. Of the 64 patients, 61 (95%) had PE on the predicted side at angiography. V-P scintigrams predicted lobar distribution in 55 patients. Of these, PE was found in the predicted lobe in 42 (76%). CONCLUSION: Localization of perfusion abnormalities at V-P scintigraphy provides useful information for the interventional radiologist and serves as an accurate guide for determining the initial approach for pulmonary angiography.     

Detection of pulmonary emboli in dogs using digital subtraction angiography

Digital subtraction angiography (DSA) was performed in six dogs to define the limits of detection of pulmonary emboli. Three angiograms were initially obtained in three normal control animals, two of which were subsequently embolized. A total of ten pulmonary angiograms were then obtained in five dogs that had experimentally produced emboli of Ivalon cubes (2, 3, and 10 mm). The intravenous angiograms were followed by selective arterial angiograms to confirm the presence and location of the emboli. The intravenous angiograms were independently reviewed by two radiologists. The criterion for detection was identification of a vessel cutoff. Perfusion defects were also seen. No intraluminal filling defects were seen. This study indicates that pulmonary emboli greater than 2 mm in diameter may be detected in dogs by DSA.     

Dual-energy CT pulmonary angiography in patients with suspected pulmonary embolism: value for the detection and quantification of pulmonary venous congestion

Objective:

To evaluate if vascular and pulmonary parenchymal enhancement values in dual-energy (DE) CT pulmonary angiography (CTPA) can suggest the diagnosis of pulmonary congestion.

Methods:

DE-CTPA images of 90 out of 1321 patients negative for pulmonary embolism showed signs of congestive heart failure. We measured DE-derived pulmonary parenchymal [perfused blood volume (PBV)], pulmonary artery (PA) and left atrium (LA) enhancement values in these patients and in 142 control patients. Enhancement values were compared between the populations and correlated with serum values of B-type natriuretic peptide (BNP) and proBNP, where available.

Results:

No significant difference of PBV but significant differences of mean PA and LA enhancement and individual enhancement differences (PA − LA) were found between the populations. PA − LA was higher in patients with elevated BNP and proBNP and was positively correlated with these values. Receiver operating characteristic analysis revealed a moderate discriminatory power of the PA − LA difference for the presence of cardiac biomarker elevations.

Conclusion:

PBV in DE-CTPA is not altered in patients with signs of congestive heart failure. However, differences in enhancement values in the pre- and post-pulmonary vessels were found in comparison with the control population.

Advances in knowledge:

Altered pulmonary vascular haemodynamics in pulmonary venous congestion are not reflected in dual-energy-derived PBV maps. In the diagnosis of left heart failure in patients with chest pain and dyspnoea, density measurements in the pulmonary artery and in the left atrium in CTPA images may be a helpful diagnostic tool.In the diagnostic algorithms for patients with acute dyspnoea, CT pulmonary angiography (CTPA) plays a major role, specifically in cases when pulmonary embolism (PE) is suspected. Whenever no PE can be detected, radiologists face the challenge to detect alternative pathological thoracic findings. An undiagnosed acute or chronic left heart failure with pulmonary congestion can be an alternative cause of acute dyspnoea. Although there are some direct and indirect CT criteria that suggest the diagnosis of congestive heart failure with pulmonary venous hypertension (e.g. dilated pulmonary veins with a blurry appearance of the vessel walls, thickening of the interlobular septal lines, ground-glass opacities/alveolar oedema, pleural effusions and an enlargement of the left atrium and/or ventricle), the diagnosis of left heart failure on the basis of CT findings is often equivocal and rather rater dependent. For suspected left heart failure, chest radiography represents the primary diagnostic tool rather than CT. Still, if CTPA is performed in chest pain workup, an improved, more objective diagnosis of congestive heart failure would be desirable.Dual-energy CTPA (DE-CTPA) can quantify the iodine-related pulmonary beam absorption and thus allow an automated, reader-independent, software-based quantification of the pulmonary content of iodinated contrast material [termed “perfused blood volume” (PBV)].¹ Based on the assumption that an impaired left heart function leads to variances in the pulmonary blood content and in the dynamics of the pulmonary passage of the contrast bolus, we tried to find out if measured absorption values in iodine-enhanced DE-CTPA, that is, DE-based pulmonary PBV values as well as density measurements in the pulmonary trunk and the left atrium, can be helpful in the diagnosis of pulmonary congestion.For this purpose, we retrospectively compared pulmonary parenchymal, pulmonary artery (PA) and left atrium (LA) enhancement values in patients with CT signs of pulmonary congestion with those from patients with no detectable cardiopulmonary pathologies in DE-CTPA and correlated those values with serum levels of established left heart insufficiency markers [cardiac peptides: B-type natriuretic peptide (BNP) and proBNP].     

Pulmonary angiography for pulmonary emboli: rational selection of oblique views.

In the performance of pulmonary arteriography, the anteroposterior projection may be insufficient for the diagnosis of pulmonary embolism, and additional views, usually oblique, are required. Of 57 positive pulmonary arteriograms which were reviewed, additional views were necessary in 26 cases. The efficacy of the additional views in each case was assessed with regard to the demonstration of the segmental arteries of the various lobes of the lung. Following an inconclusive anteroposterior injection, the best visualization of the arteries of the right lung can generally be obtained with an injection made in the right posterior oblique projection. Similarly, following an inconclusive anteroposterior injection, the left posterior oblique or lateral view is recommended for optimal visualization of the pulmonary vasculature of the left lung.     

The value of pulmonary angiography for the differential diagnosis of pulmonary embolism

The aim this study was to evaluate potential additional information of pulmonary angiography in patients with suspected pulmonary embolism and non-diagnostic lung scan findings. In a series of 150 patients who underwent pulmonary angiography for suspected venous thromboembolism, the images for potential alternative diagnoses other than pulmonary embolism were evaluated. All patients had non-diagnostic lung scan findings. Angiography was performed both by conventional and by digital subtraction angiography techniques. Images were evaluated by at least two experienced readers. Angiograms were scored for both presence or absence of pulmonary embolism, as well as other diagnoses. Pulmonary embolism was proven in 40 patients (27 %) and excluded in 105 patients (70 %), whereas non-interpretable images were obtained in 5 patients (3 %). A range of alternative diagnoses were detected by angiography: atelectasis (n = 24), pleural effusion (n = 15), pneumonia (n = 11), emphysematous bullae (n = 8), neoplasm (n = 3), atrial septum defect (n = 2), chronic thromboembolism (n = 1), and other diagnoses (n = 3). Overall, only 54 patients (36 %) had completely normal angiograms. Although pulmonary angiography remains the reference method for the diagnosis of pulmonary embolism, one has to be aware of other, often unexpected, but equally important findings which could influence the management of the patient. This aspect of pulmonary angiography has been insufficiently emphasized in the literature. Received: 2 April 1998; Revision received: 22 July 1998; Accepted: 4 November 1998     

前瞻性心电门控技术在CT肺动脉血管成像中的应用

目的：研究256层螺旋CT前瞻性心电门控技术在肺动脉血管成像（CTPA）中的应用价值。方法：连续选取本院使用Philips 256层螺旋CT行CTPA检查的患者资料90例,利用完全随机设计每组30例分为3组：①非心电门控螺旋扫描组（简称非门控组）;②前瞻性心电门控组（简称前瞻组）;③回顾性心电门控组（简称回顾组）。记录各组患者年龄、性别、心率、扫描时间、扫描范围、容积CT剂量指数（CTDIvol）、剂量长度乘积（DLP）,根据公式计算出有效放射剂量（ED）。由3位有经验的放射科医生以双盲法对肺动脉图像质量进行评分,并评价在扫描范围内的冠状动脉运动伪影。结果：三组95.6%（86/90）的病例评分≥3分。图像质量评分、冠状动脉运动伪影出现率、扫描时间、辐射剂量差异有显著性意义。图像评分：前瞻组明显优于非门控组,与回顾组相近;冠状动脉运动伪影出现率：三组分别为88.1%、21.5%和15.9%,前瞻组和回顾组明显低于非门控组;辐射剂量：前瞻组和非门控组的辐射剂量分别为（7.59±0.87）和（7.49±0.80）mSv,两者差异无显著性意义,明显低于回顾组辐射剂量[（18.96±1.60）mSv];扫描时间：前瞻组平均扫描时间为（8.66±0.86）s,比回顾组和非门控组分别增加1.0s和5.5s。不同心率患者前瞻性心电门控CTPA的图像质量评分差异无显著性意义。结论：应用256层螺旋CT前瞻性心电门控技术行CTPA检查是一种可行方法,在不增加患者辐射剂量的前提下,明显改善肺动脉图像质量。     

Value of pulmonary vein wedge angiography in visualization of obstructed ipsilateral pulmonary artery

Left ventricular cineangiogram in a 2-year-old child with a large ventricular septal defect, pulmonary atresia and a previous Waterston anastomosis opacified clearly the right pulmonary artery but the left pulmonary artery could not be visualized. The later was thought to be due to obstruction or kinking of the right pulmonary artery proximal to the Waterston anastomotic site. A left pulmonary vein wedge angiogram performed via a No. 5 end-hole catheter with 4.0 cc of meglumine diatrizoate (75% Hypaque) injected under pressure (less than 100 PSI) visualized the left pulmonary artery in a retrograde fashion. The size of the left pulmonary artery at this study was comparable to its size measured at the time of a subsequent left Blalock-Taussig anastomosis. Pulmonary vein wedge angiography with 0.3 cc/kg body weight of contrast material injected over a two second period (less than 100 PSI) appears to be a useful technique in demonstrating the pulmonary arteries when these cannot be visualized by conventional antegrade techniques.     

Radiolabeled fibronectin for the scintigraphic detection of pulmonary emboli in dogs

Plasma fibronectin, a glycoprotein that is a component of blood thrombi, was evaluated for the in vivo scintigraphic detection of pulmonary emboli in dogs. Fibronectin (canine or human) was labeled with either 131I or with 111In and diethylenetriaminepenta-acetic acid (DTPA) as the bifunctional chelating agent using a modification of the mixed anhydride method. The radiolabeled proteins were administered intravenously 20 to 30 minutes after the embolization of a 99mTc-labeled thrombus. The uptake of radioactivity by the embolus was monitored scintigraphically up to 24 hours. At the end of each experiment, the animal was killed and in vitro tissue counting of radioactivity was performed. Comparative study of the 131I- and 111In-labeled agent is presented with particular reference to their pharmacokinetics. The in vivo uptake of radioactivity by the emboli was limited, indicating that radiolabeled fibronectin is not a good scintigraphic agent for the detection of pulmonary emboli.     

The value of intraoperative angiography in surgery of intracranial aneurysms: a prospective study in 126 patients

The value of intraoperative digital subtraction angiography in surgery for intracranial aneurysms, the benefits and cost-effectiveness are a matter of discussion. We prospectively studied 126 patients with 144 aneurysms, most on the anterior intracranial circulation, who underwent clipping and intraoperative angiography. Follow-up was 28.4 ± 13.1 months. We tried to work out the indications for intraoperative angiography of the anterior circulation and its cost-effectiveness. In 10.3 % of patients (9 % per aneurysm) unexpected findings were shown by intraoperative angiography: inadequately clipped aneurysms in 10 (7.9 %), a completely unclipped aneurysm in one (0.8 %) and occluded major arteries in two (1.6 %). A broad neck was a variable of statistical significance for inadequate clipping or stenosis or occlusion of an adjacent vessel. There was a strong trend for aneurysms more than 15 mm in diameter to be “risky”. Their site was not a predictive factor. We believe that intraoperative angiography is indicated in surgery not only on large and giant aneurysms, but also broad-based aneurysms of the anterior cerebral circulation regardless of their size. It is cost-effective compared to postoperative angiography. The rate of stroke in our hands was 0.8 %. Received: 19 January 2000 Accepted: 3 November 2000     

肺通气血流灌注显像、螺旋CT肺动脉造影及D-二聚体测定对诊断肺栓塞的临床价值

目的探讨放射性核素肺通气血流灌注比值(V/Q)显像和螺旋CT肺动脉造影(SCTPA)以及血浆D-二聚体(dimer)检测对肺栓塞(PE)诊断的临床价值。方法对我院2010年2月—2013年2月可疑肺栓塞的患者,行V/Q显像、SCTPA检查和血浆D-二聚体测定以及相关检查,以最终临床诊断为依据,分别评价V/Q显像、SCTPA和血浆D-二聚体测定对PE的诊断价值。结果 278例高度怀疑PE患者经上述检查确诊PE患者151例,V/Q显像、SCTPA检查和血浆D-二聚体测定诊断PE的灵敏度、特异性、阳性预测值、阴性预测值分别为93.6%(132/141)、96.0%(120/125)、96.4%(132/137)、93.0%(120/129);95.8%(137/143)、96.9%(124/128)、97.2%(137/141)、95.4%(124/130);99.3%(140/141)、43.1%(59/137)、64.2%(140/218)、98.3%(59/60)。结论血浆D-二聚体测定的价值主要用于排除PE。对PE患者的检查应力求全面,V/Q显像、SCTPA检查均有其优点和不足,只有全面掌握各项检查的特点,才能对该项检查对疾病的诊断价值做出正确评价,从而正确运用这一诊断方法更好地服务于临床。     

Multi-detector row CT angiography of pulmonary circulation with gadolinium-based contrast agents: prospective evaluation in 60 patients

PURPOSE: To prospectively evaluate gadolinium dose safety and effectiveness for 16-detector pulmonary computed tomographic (CT) angiography. MATERIALS AND METHODS: Ethics committee approval and informed consent were obtained. Sixty patients with contraindications to iodine underwent CT of the pulmonary circulation with 0.5 mmol/L gadolinium chelate given at either 0.3 (n = 29, group A) or 0.4 (n = 31, group B) mmol/kg; clinical and biologic tolerances were evaluated. Enhancement of central and segmental pulmonary arteries was measured (poor enhancement, <100 HU; good, 100-150 HU; excellent, >150 HU). Subsegmental artery enhancement was assessed as similar or inferior to that of segmental arteries. Confidence in analysis of the pulmonary arterial bed was graded according to arterial enhancement: Grades 1-3, diagnostic images; grade 4, nondiagnostic. The main effectiveness parameter for comparison between groups A and B was diagnostic value of CT angiograms. Nonparametric statistics were used to analyze results. RESULTS: The mean (+/- standard deviation) contrast material volume was 50.09 mL +/- 8.45 (all patients: range, 30-64 mL; group A: 46.54 mL +/- 8.59; group B: 53.42 mL +/- 6.92). Diagnostic images were obtained in 55 (92%) patients, and confident analysis of pulmonary arteries to the subsegmental level was achieved in 26 (grade 1, 44%) and to the segmental level, in 21 (grade 2, 35%). Mean attenuation was higher in group B than in group A in central (180.61 HU +/- 53.85 vs 148.14 HU +/- 52.61; P = .04) and segmental (201.59 HU +/- 54.70 vs 164.73 HU +/- 59.26; P = .03) arteries. Number of diagnostic CT angiograms was higher (P = .02) in group B (n = 31 [100%]) than in group A (n = 24 [83%]). In both groups, mean enhancement of pulmonary arteries was significantly higher at 80 or 100 kV than at 120 kV. Renal function was impaired in two group A patients. CONCLUSION: Gadolinium chelates may be used as an alternative CT contrast agent in patients who cannot receive iodine.     

16层螺旋CT血管造影在肺动脉栓塞诊断中的价值

肺动脉栓塞(pulmonary embolism,PE)是内源性或外源性栓子阻塞肺动脉及其分支引起的肺循环障碍的临床病理生理综合征,并发肺出血或坏死者称为肺梗死[1]。PE是一种常见的心血管疾病,它具有发病率高,临床表现缺乏特异性,易漏诊及误诊,未经治疗者死亡率高的特点,达20%~30%,及时诊断治疗者死亡率可降至2%~8%[2]。近年来,尤其是多层螺旋CT血管造影(MSCTA)等先进技术的应用使PE的及时诊断成为可能,本文报告23例PE的MSCTPA表现如下。1材料与方法1.1临床材料本组23例中,男14例,女9例,年龄14~82岁,平均61岁。其中10例有下肢深静脉血栓,4例有…