Does multi-detector row CT pulmonary angiography reduce the incremental value of indirect CT venography compared with single-detector row CT pulmonary angiography?

PURPOSE: To compare retrospectively the incremental value of indirect computed tomographic (CT) venography performed after multi-detector row CT pulmonary angiography and single-detector row CT pulmonary angiography for the diagnosis of venous thromboembolism (VTE). MATERIALS AND METHODS: The institutional ethics committee approved this study; informed consent was not required. The authors retrospectively reviewed results of 1100 combined single-detector row CT pulmonary angiographic and indirect CT venographic examinations (542 men, 558 women; mean age, 61 years +/- 17 [standard deviation]) (group 1) and 308 combined multi-detector row CT pulmonary angiographic and indirect CT venographic examinations (150 men, 158 women; mean age, 62 years +/- 18) (group 2), performed in 1408 patients suspected of having pulmonary embolism (PE). Frequency of deep venous thrombosis (DVT), PE, and VTE, and the incremental value of indirect CT venography were recorded in both groups. Data were compared by means of the Student t test for continuous data and z statistics for independent proportions. RESULTS: VTE, PE, and DVT were found in 23.3% (n = 256), 19.9% (n = 219), and 18.3% (n = 201) of the 1100 patients in group 1, respectively, and in 23.7% (n = 73), 17.2% (n = 53), and 18.8% (n = 58) of the 308 patients in group 2, respectively (P values ranging from .273 to .876). The incremental value of indirect CT venography was 14.4% (37 of 256 patients) in group 1 and 27.4% (20 of 73 patients) in group 2. CONCLUSION: Despite potential improved accuracy of multi-detector row CT pulmonary angiography for the diagnosis of PE, the addition of indirect CT venography increased the diagnosis of VTE in 27.4% of patients.     

16层螺旋CT肺血管造影对亚段肺栓塞诊断的成像技术探讨

目的:研究16层螺旋CT肺血管造影在急性肺动脉栓塞(PE)诊断中的应用价值。着重探讨亚段水平周围型肺栓塞的适宜扫描参数及显示方法。方法:应用16层螺旋CT扫描机(GE ligtspeed 16)对临床拟诊肺栓塞的42例患者进行前瞻性研究。依据患者屏气时间长短,设定3组扫描参数。结果:CT诊断肺栓塞31例。中央型22例,周围型9例。3组扫描参数均可清晰显示亚段水平肺动脉栓子。高质量扫描模式肺动脉CTA成像质量最高,常规扫描模式次之,高速扫描模式再次之。结论:16层螺旋CT肺血管造影快速、无创、敏感性、特异性高。选择适宜扫描参数及显示方法,急性肺栓塞诊断可以达到亚段水平。2组常规扫描模式更为适宜PE患者。     

Pulmonary artery CTA

The latest with the introduction of multidetector row computed tomography (MDCT), CT has been firmly established as the modality of choice for imaging the pulmonary arteries, particularly as the de facto first line test for imaging patients with suspected acute pulmonary embolism (PE). Before the introduction of MDCT, remaining concerns regarding CTs accuracy for diagnosis of isolated peripheral emboli had prevented the unanimous acceptance of this test as the reference standard for imaging PE. After a decade of uncertainty, there is now conclusive evidence that CT, if positive, provides reliable confirmation of the presence of PE and, more importantly, if negative effectively rules out clinically significant PE. Current endeavors to streamline and facilitate workflow for CT diagnosis of PE will further improve the acceptance, utility, and importance of this test. Examples include improvements in workflow, CT derivation of right ventricular function parameters for triage and prognostication of patients with acute PE and the comprehensive assessment of patients with acute chest pain for PE, coronary disease, aortic disease, and pulmonary disease by means of a single, contrast enhanced, ECG-synchronized CT scan. Although the diagnosis or exclusion of acute PE is the most common and important application of CT pulmonary angiography, the ease of scan acquisition and the high spatial resolution of modern CT techniques make this test ideally suited for the greatest majority of congenital and acquired, acute and chronic disorders of the pulmonary arteries.     

Diagnosis of acute pulmonary embolism in outpatients: comparison of thin-collimation multi-detector row spiral CT and planar ventilation-perfusion scintigraphy

PURPOSE: To compare multi-detector row computed tomography (CT) and ventilation-perfusion (V-P) scintigraphy in the diagnosis of acute pulmonary embolism (PE) in outpatients who were cared for in the emergency department. MATERIALS AND METHODS: Ninety-four nonconsecutive patients, in whom acute PE was suspected, underwent thin-collimation multi-detector row CT (collimation, 4 x 1 mm; pitch, 1.25; scanning time, 0.5 second) and V-P scintigraphy. Concordance between CT and scintigraphic images was used in the diagnosis of PE. Pulmonary angiography was performed within 24 hours if interpretations of V-P and spiral CT images were inconclusive or discordant. Sensitivity and specificity values were calculated for V-P scintigrams and CT scans of the lungs. The rates of conclusive results for scintigraphy and CT were compared. RESULTS: The sensitivity of thin-collimation multi-detector row CT and V-P scintigraphy for the detection of PE was 96% (27 of 28; CI: 82%, 99%) and 98% (65 of 66; CI: 92%, 99%), respectively. The specificity of CT and V-P scintigraphy was 86% (24 of 28; CI: 67%, 96%) and 88% (58 of 66; CI: 77%, 94%), respectively. Seven V-P scintigrams were of intermediate probability, and one spiral CT study was indeterminate. Examinations with spiral CT yielded conclusive results more often than examinations with planar V-P scintigraphy (P <.05). Five V-P scintigrams and spiral CT scans were discordant. Twelve pulmonary angiographic examinations were performed. Angiographic findings were concordant in 10 (91%) of 11 patients with conclusive CT scans in whom pulmonary angiography was attempted. CT was used to establish an alternative diagnosis in 19 (29%) of 66 patients in whom PE was excluded. CONCLUSION: Thin-collimation multi-detector row CT is more accurate than V-P scintigraphy in the diagnosis of acute PE in outpatients. Furthermore, CT provides alternative diagnoses for patients without PE on high-quality transverse or near-isotropic reformatted images.     

40层螺旋CT在肺动脉栓塞诊断中的应用价值

目的:探讨40层螺旋CT在肺动脉栓塞中的应用价值.方法:使用40层螺旋CT扫描机(Siemens Defination AS 40)对临床初步诊断肺动脉栓塞的38例患者进行研究.采用层厚5 mm行胸部增强扫描.利用3D后处理工作站进行重建为0.75 mm的轴面及多平面重建(MPR).比较层厚5 mm和1mm的轴面图像及MPR图像.结果:CT诊断肺动脉栓塞31例.病变共累计肺动脉260支.对于主肺动脉及肺叶动脉栓塞,3种图像检出结果一致.但对于肺段及亚段肺动脉栓塞的显示,层厚0.75 mm优于5 mm,差异有显著性意义(P<0.01),0.75 mm的MPR与轴面图像间差异无显著性意义(P＞0.05).结论:40层螺旋CT在肺动脉栓塞诊断中具有无创、快速、敏感性高的优点,应当作为肺动脉栓塞的首选检查方法.     

Use of intra-arterial multi-detector row CT angiography for the evaluation of an ischaemic limb in a patient with renal impairment

The vastly improved scanning speed and z-axis resolution afforded by multi-detector technology has allowed CT to refine its traditional roles and to explore many new applications in imaging. We present a case report of a patient with renal failure and an ischaemic leg, which illustrates a useful new CT vascular imaging application. By carrying out 16-channel multi-detector row CT angiography through a sheath introduced into the common femoral artery, we obtained a high-quality angiographic image of the affected leg, using only 30 mL of iodinated contrast material. The examination definitively showed the number, distribution and patency of the tibial run-off arteries, with significant influence on the patient's subsequent clinical management. This simple and relatively minimally invasive technique is useful in peripheral vascular imaging, when conventional CT angiography using a large volume of i.v. contrast and MR angiography are unsuitable or unavailable.     

16层螺旋CT肺血管造影在肺动脉栓塞诊断中的应用

目的　研究 16层螺旋CT肺血管造影在肺动脉栓塞诊断中的应用价值。方法　使用 16层螺旋CT扫描机 (SiemensSensation 16 )对临床拟诊肺栓塞的 4 9例患者进行前瞻性研究。采用层厚 3mm行胸部增强扫描。利用原始数据行层厚 1mm的轴面及多平面重建 (MPR)。比较层厚 3mm、1mm的轴面图像及MPR图像。结果　CT诊断肺栓塞 4 2例。病变共累及肺动脉 35 2支。对于主肺动脉及肺叶动脉栓塞 ,三种图像检出结果一致。但对于肺段及亚段动脉栓塞 ,层厚 1mm较 3mm显示率高 ,差异有显著意义 (P <0 0 1) ,1mm的MPR较轴面图像显示率高 ,但差异无显著性意义 (P >0 0 5 )。结论　 16层螺旋CT肺血管造影无创、快速、敏感性高 ,应当作为肺栓塞的首选检查方法。     

Right ventricular function in patients with acute pulmonary embolism: analysis with electrocardiography-synchronized multi-detector row CT

PURPOSE: To prospectively assess electrocardiography (ECG)-synchronized multi-detector row computed tomography (CT) for the evaluation of right ventricular (RV) function in patients suspected of having pulmonary embolism (PE). MATERIALS AND METHODS: All patients gave informed consent after the study details, including radiation exposure, were explained; institutional ethical committee approval was obtained. Nonsynchronized multi-detector row CT of the chest was performed in 66 consecutive patients (29 men, 37 women; mean age, 58 years+/-15 [standard deviation]) who were suspected of having PE. ECG-synchronized cardiac multi-detector row CT was performed to assess cardiac function. Dimension ratios for the RV and left ventricle (LV) were measured on nonsynchronized transverse and angulated four-chamber views. Furthermore, the RV end-diastolic and end-systolic volumes were measured on ECG-synchronized multi-detector row CT scans. An independent samples t test was performed to compare the mean value of different groups. An analysis of variance post hoc test was performed to investigate whether the values of the variables varied between groups. RESULTS: PE was detected in 29 of 66 patients. The location of PE was categorized as central (n=17) or peripheral (n=12). The RV/LV dimension ratio was larger on the four-chamber view (P=.002), and RV end-systolic volume was larger (P=.01) and ejection fraction was lower (P=.01) in patients with PE. The RV end-systolic volumes and RV/LV volume ratios, as assessed by using ECG-synchronized multi-detector row CT, showed significant differences (P<.005) between patients with central PE and those with peripheral PE. However, the RV/LV dimensions on nonsynchronized images revealed no significant differences. CONCLUSION: Retrospective ECG-synchronized multi-detector row CT facilitates detection of RV dysfunction, depending on pulmonary embolus location.     

Multi-detector row CT of mesenteric ischemia: can it be done?

Mesenteric ischemia is a complicated disorder whose prevalence in the United States is increasing as the population ages. It is often difficult to diagnose, both clinically and radiologically. In the past, computed tomography (CT) has allowed only limited success in the early detection of ischemia. However, with the introduction of multi-detector row CT and three-dimensional (3D) imaging, it is now possible to perform a detailed CT examination of the small bowel and mesenteric vessels. Multi-detector row CT allows routine studies to be performed much faster than with single-detector CT scanners and makes available new applications, especially in the field of CT angiography. Its increased speed and narrower collimation, coupled with the use of water as an oral contrast agent, improve visualization of the bowel wall and mesenteric vasculature. Multi-detector row CT with 3D reformatting may improve the ability to make an early diagnosis and identify the cause of disease in patients with suspected acute or chronic mesenteric ischemia. In many cases, this examination has eliminated the need for additional imaging studies such as Doppler ultrasonography or angiography. Further investigation will be needed to determine the scope of the utility of multi-detector row CT in this clinical setting.     

多层螺旋CT肺血管造影对肺栓塞解剖分布及形态的评价

目的 评价肺栓塞（PE）在多层螺旋CT肺血管造影（CTPA）上的解剖位置分布及形态特点. 资料与方法 75例PE患者作CTPA,由两名有经验的放射科医师阅片,根据血栓在最大肺血管分支内的位置分为5型：肺动脉干型、左或右肺动脉型、肺叶动脉型、肺段动脉型和肺亚段动脉型;同时观察血栓在血管内的形态. 结果 75例PE中,肺动脉干型6例（8%）,左或右肺动脉型12例（16%）,肺叶动脉型28例（37.3%）,肺段动脉型19例（25.3%）和肺亚段动脉型10例（13.3%）.PE形态为：中央型51例（68%）,附壁型7例（9.3%）,闭塞型17例（22.7%）. 结论 CTPA可准确、清晰地显示PE的解剖位置分布及形态,能提高小PE的检出率,为临床治疗方案的选择提供依据.     

Multiplanar and three-dimensional multi-detector row CT of thoracic vessels and airways in the pediatric population

Multi-detector row computed tomography (CT) has changed the approach to imaging of thoracic anatomy and disease in the pediatric population. At the author's institution, multi-detector row CT with multiplanar and three-dimensional reconstruction has become an important examination in the evaluation of systemic and pulmonary vasculature and the tracheobronchial tree. In some clinical situations, multi-detector row CT with reformatted images is obviating conventional angiography, which is associated with higher radiation doses and longer sedation times. Although multi-detector row CT with multiplanar and three-dimensional reconstruction is expanding the applications of CT of the thorax, its role as a diagnostic tool still needs to be better defined. The purposes of this article are to describe how to perform multi-detector row CT with multiplanar and three-dimensional reconstruction in young patients, to discuss various reconstruction techniques available, and to discuss applications in the evaluation of vascular and airways diseases.     

Multi-detector row spiral CT pulmonary angiography: comparison with single-detector row spiral CT.

PURPOSE: To compare vascular conspicuity and ability to connect pulmonary arterial branches on pulmonary angiograms obtained with helical multi-detector row computed tomography (CT) with those on pulmonary angiograms obtained with helical single-detector row CT. MATERIALS AND METHODS: Of 93 consecutive patients suspected of having pulmonary embolism, 48 underwent scanning with multi-detector row CT and 45 with single-detector row CT; scans were obtained in 9 seconds and 28 seconds with 2.5-mm and 3.0-mm collimation, respectively. The lungs were divided into three zones: central, middle, and peripheral. Two independent observers used five-point grading scales. RESULTS: Conspicuity of pulmonary arteries in the central zone was ranked equal (median of 5), but in the middle and peripheral zones it was significantly higher at multi-detector row CT than at single-detector row CT (median 5 vs 4 and 4 vs 3, P < .001, respectively). In addition, multi-detector row CT improved the ability to connect peripheral arteries with their more centrally located pulmonary artery of origin in the peripheral but not the middle zone on transverse images and in both zones on multiplanar images. Viewing with a modified window setting (width, 1,000 HU; level, -100 HU) significantly increased pulmonary arterial conspicuity. Contrast material column in the pulmonary arteries was significantly more homogeneous at multi-detector row CT. CONCLUSION: Use of multi-detector row CT significantly improves pulmonary arterial visualization in the middle and peripheral lung zones.     

Multislice CT imaging of pulmonary embolism

In recent years CT has been established as the method of choice for the diagnosis of central pulmonary embolism (PE) to the level of the segmental arteries. The key advantage of CT over competing modalities is the reliable detection of relevant alternative or additional disease causing the patient's symptoms. Although the clinical relevance of isolated peripheral emboli remains unclear, the alleged poor sensitivity of CT for the detection of such small clots has to date prevented the acceptance of CT as the gold standard for diagnosing PE. With the advent of multislice CT we can now cover the entire chest of a patient with 1-mm slices within one breath-hold. In comparison with thicker sections, the detection rate of subsegmental emboli can be significantly increased with 1-mm slices. In addition, the interobserver correlation which can be achieved with 1-mm sections by far exceeds the reproducibility of competing modalities. Meanwhile use of multislice CT for a combined diagnosis of PE and deep venous thrombosis with the same modality appears to be clinically accepted. In the vast majority of patients who receive a combined thoracic and venous multislice CT examination the scan either confirms the suspected diagnosis or reveals relevant alternative or additional disease. The therapeutic regimen is usually chosen based on the functional effect of embolic vascular occlusion. With the advent of fast CT scanning techniques, also functional parameters of lung perfusion can be non-invasively assessed by CT imaging. These advantages let multislice CT appear as an attractive modality for a non-invasive, fast, accurate, and comprehensive diagnosis of PE, its causes, effects, and differential diagnoses.     

CT pulmonary angiography and suspected acute pulmonary embolism

PURPOSE: To evaluate the use and quality of CT pulmonary angiography in our department, and to relate the findings to clinical parameters and diagnoses. MATERIAL AND METHODS: A retrospective study of 324 consecutive patients referred to CT pulmonary angiography with clinically suspected pulmonary embolism (PE). From the medical records we registered clinical parameters, blood gases, D-dimer, risk factors and the results of other relevant imaging studies. RESULTS: 55 patients (17%) had PE detected on CT. 39 had bilateral PE, and 8 patients had isolated peripheral PE. 87% of the examinations showing PE had satisfactory filling of contrast material including the segmental pulmonary arteries, and 60% of the subsegmental arteries. D-dimer test was performed in 209 patients, 85% were positive. A negative D-dimer ruled out PE detected at CT. Dyspnea and concurrent symptoms or detection of deep vein thrombosis (DVT), contraceptive pills and former venous thromboembolism (VTE) were associated with PE. The presence of only one clinical parameter indicated a negative PE diagnosis (p < 0.017), whereas two or more suggested a positive PE diagnosis (p < 0.002). CT also detected various ancillary findings such as consolidation, pleural effusion, nodule or tumor in nearly half of the patients; however, there was no association with the PE diagnosis. CONCLUSION: The quality of CT pulmonary angiography was satisfactory as a first-line imaging of PE. CT also showed additional pathology of importance in the chest. Our study confirmed that a negative D-dimer ruled out clinically suspected VTE.     

肺动脉栓塞的螺旋CT血管造影的诊断研究(附七例报告)

目的评价螺旋ＣＴ血管造影（ＳＣＴＡ）诊断肺动脉栓塞（ＰＥ）的可信性。方法对７例临床怀疑ＰＥ的患者行螺旋ＣＴ血管造影,其中６例在溶栓治疗２０天后进行了复查。结果７例患者累及２０处肺动脉及其分支。栓子表现为肺动脉腔内柱状、丘状及不规则形充盈缺损。７例均有肺动脉高压,其中６例中心肺动脉扩张呈“残根征”改变。６例经溶栓治疗后,４例栓子完全消失,１例明显缩小,１例略有缩小。结论螺旋ＣＴ血管造影是诊断中心性肺动脉栓塞可靠而直观的检查方法,并可较准确地判断溶栓疗效。     

Multi-detector row computed tomography angiography of peripheral arterial disease

With the introduction of multi-detector row computed tomography (MDCT), scan speed and image quality has improved considerably. Since the longitudinal coverage is no longer a limitation, multi-detector row computed tomography angiography (MDCTA) is increasingly used to depict the peripheral arterial runoff. Hence, it is important to know the advantages and limitations of this new non-invasive alternative for the reference test, digital subtraction angiography. Optimization of the acquisition parameters and the contrast delivery is important to achieve a reliable enhancement of the entire arterial runoff in patients with peripheral arterial disease (PAD) using fast CT scanners. The purpose of this review is to discuss the different scanning and injection protocols using 4-, 16-, and 64-detector row CT scanners, to propose effective methods to evaluate and to present large data sets, to discuss its clinical value and major limitations, and to review the literature on the validity, reliability, and cost-effectiveness of multi-detector row CT in the evaluation of PAD. From the Program for the Assessment of Radiological Technology (ART Program).     

Multi-detector row CT of thoracic disease with emphasis on 3D volume rendering and CT angiography.

Multi-detector row computed tomography (CT) with three-dimensional (3D) volume rendering provides a unique perspective on thoracic anatomy and disease. Multi-detector row CT allows shorter acquisition times, greater coverage, and superior image resolution. Three-dimensional volume rendering now permits real-time, interactive modification of relative pixel attenuation in an infinite number of planes and projections. In vascular imaging, this technique provides image quality that equals or surpasses that of conventional angiography. Its use has expanded to aid in diagnosis and surgical planning, often obviating conventional or digital angiography and reducing costs. It is reliable in depicting clot and the pulmonary vasculature and may also be used to evaluate thoracic venous anomalies (eg, pulmonary arteriovenous malformations) and to plan therapy. Airway imaging with multi-detector row CT with 3D volume rendering is particularly useful in the planning and follow-up of stent placement. In diffuse lung disease, this technique can increase nodule detection and help differentiate between small nodules and vessels. It is also helpful in imaging the musculoskeletal system and the thoracic cage. Multi-detector row CT with 3D volume rendering has enhanced the conventional roles of thoracic CT and challenged the supremacy of other imaging modalities. It will likely play a leading role in future radiologic research and practice.     

Suspected pulmonary embolism and deep venous thrombosis: A comprehensive MDCT diagnosis in the acute clinical setting

Both pulmonary arterial and peripheral venous sides of venous thromboembolism (VTE) can now be efficiently and safely investigated by multi-detector CT (MDCT) at the same time by a combined CT angiography/CT venography protocol. In the emergency setting, the use of such a single test for patients suspected of suffering from VTE on a clinical grounds may considerably shorten and simplify diagnostic algorithms. The selection of patients to be submitted to MDCT must follow well-established clinical prediction rules in order to avoid generalized referral to CT on a generic clinical suspicion basis and excessive population exposure to increased ionizing radiation dose, especially in young patients. Clinical and anatomical wide-panoramic capabilities of MDCT allow identification of underlying disease that may explain patients' symptoms in a large number of cases in which VTE is not manifest. The analysis of MDCT additional findings on cardiopulmonary status and total thrombus burden can lead to better prognostic stratification of patients and influence therapeutic options. Some controversial points such as optimal examination parameters, clinical significance of subsegmentary emboli, CT pitfalls and/or possible falsely positive diagnoses, and outcome of untreated patients in which VTE has been excluded by MDCT without additional testing, must of course be taken into careful consideration before the definite role of comprehensive MDCT VTE "one-stop-shop" diagnosis in everyday clinical practice can be ascertained.     

CT imaging of acute pulmonary embolism

CT pulmonary angiography (CTPA) has become the de facto clinical "gold standard" for the diagnosis of acute pulmonary embolism (PE) and has replaced catheter pulmonary angiography and ventilation-perfusion scintigraphy as the first-line imaging method. The factors underlying this algorithmic change are rooted in the high-sensitivity and specificity, cost-effectiveness, and 24-hour availability of CTPA. In addition, CTPA is superior to other imaging methods in its ability to diagnose and exclude, in a single examination, a variety of diseases that mimic the symptoms of PE. This article reviews the current role of CTPA in the diagnosis of acute PE as well as more recent developments, such as the use of CT parameters of right ventricular dysfunction for patient prognostication and the assessment of lung perfusion with CT.     

Computed tomography pulmonary angiogram diagnosis of pulmonary embolism

Over the last decade, contrast-enhanced spiral CT has been established as a non-invasive alternative to catheter angiography and is now regarded as the first-line imaging investigation for the diagnosis of pulmonary embolism (PE). The reported sensitivities for the diagnosis of PE of spiral CT vary from 45 to 100% and the specificities vary from 78 to 100%. Prospective outcome studies have shown a high negative predictive value for a single-detector spiral CT for PE. Patients' outcomes were not adversely affected in these studies when anticoagulation was withheld after a negative CT pulmonary angiogram. The main limitation of single-detector spiral CT has been its limited ability to detect isolated subsegmental PE. However, multidetector spiral CT allows evaluation of pulmonary vessels down to sixth-order branches and significantly increases the rate of detection of PE in segmental and subsegmental levels. The interobserver correlations for diagnosis of subsegmental PE with multidetector spiral CT exceed the reproducibility of selective pulmonary angiography. If appropriate equipment is available (multidetector CT), then CT pulmonary angiogram is safe to be used as the first-line imaging investigation for the diagnosis of PE.