Evaluation of the deep venous system in patients with suspected pulmonary embolism with multi-detector CT: a prospective study in comparison to Doppler sonography

OBJECTIVE: This prospective study was done to evaluate the ability of indirect multidetector row CT venography (CTV) in detecting deep venous thrombosis of the pelvis and the thighs in comparison with Doppler sonography in patients with suspected pulmonary embolism (PE). METHODS: Forty-one patients with suspected PE were included, and CTV (collimation 4 x 2.5 mm, table feed 12.5 mm, 120 kV, eff. mAs 165) from the iliac crest to the knees was done after CT angiography (CTA) of the pulmonary arteries. Doppler sonography was performed within 24 hours. Applied radiation doses were estimated using the PC program WinDose. RESULTS: PE was diagnosed in 20 patients with additional DVT in 11 patients. The CTV has a sensitivity of 100%, specificity of 96.6%, a positive and negative predictive value of 91.7% and 100%, respectively. The median cumulative effective dose for CTV was 8.26 mSv with a gonadal dose of 3.87 mSv. Changing the CTV protocol to a collimation of 4 x 5 mm with a 25 mm table feed could reduce the dose by approximately 11% (p < 0.05) to 7.25 mSv and 3.35 mSv, respectively. CONCLUSION: CTV is a safe and quick diagnostic tool for detecting DVT in patients with suspected PE. Due to the relevant increase in radiation dose, the indication has to be considered very carefully.     

Computed tomography pulmonary angiography with pelvic venography in the evaluation of thrombo-embolic disease

A prospective study was performed to evaluate the usefulness of CT pelvic venography (CTV) in the detection of pelvic vein thrombosis in patients referred for CT pulmonary angiography (CTPA) for suspected pulmonary embolism. Fifty consecutive patients referred for CTPA had CTV performed at the time of CTPA. All patients had duplex ultrasound (DUS) of the lower limb veins for evaluation of deep venous thrombosis (DVT) within 24 h of the CT study. Twelve (24%) of the 50 patients had pulmonary embolism diagnosed on CTPA. Associated DVT was detected in six of these patients; two cases were detected by CTV alone, while one case was detected by both CTV and DUS. The remaining three cases had DVT diagnosed by DUS alone. In the 38 patients with a negative CTPA, three patients had venous thrombus diagnosed by CTV. Of these three patients, two had a negative DUS study. CTV therefore led to a definitive imaging diagnosis of thrombo-embolic disease in two (4%) more patients. CTV adds little time and cost to the CTPA examination and leads to a moderate increase in definite imaging diagnosis of thrombo-embolic disease.     

Combined magnetic resonance imaging of deep venous thrombosis and pulmonary arteries after a single injection of a blood pool contrast agent

Objective

Agreement rate between magnetic resonance imaging (MRI) and Doppler ultrasound (DUS) for the detection of deep vein thrombosis (DVT) in the lower extremities was attempted by using the intravascular MRI contrast agent gadofosveset trisodium. The potential of this method to detect pulmonary embolism (PE) was also evaluated.

Material and Methods

Forty-three consecutive inpatients with ultrasound-confirmed DVT but no clinical signs of PE were prospectively enrolled in this feasibility study. MRI was performed after a single injection of gadofosveset trisodium. The pulmonary arteries were imaged using a 3D Fast Low Angle Shot (FLASH) gradient recalled echo sequence. Additionally, pulmonary arteries, abdominal veins, pelvic and leg veins were imaged using a fat-suppressed 3D gradient echo Volume Interpolated Breath-hold Examination (VIBE FS).

Results

Gadofosveset trisodium-enhanced MRI detected more thrombi in the pelvic region, upper leg and lower leg than the initial DUS. In addition, PE was detected in 16 of the 43 DVT patients (37%).

Conclusion

This study shows the feasibility of a combined protocol for the MRI diagnosis of DVT and PE using gadofosveset trisodium. This procedure is not only more sensitive in detecting DVT compared to standard DUS, but is also able to detect PE in asymptomatic patients.     

A retrospective study of the value of indirect CT venography: a British perspective

Objective

The aim of this study was to establish the value of indirect CT venography (CTV) in clinical practice within the UK.

Methods

804 combined CT pulmonary angiogram and CTV studies were retrospectively reviewed. CTV was performed 180 s after the injection of contrast using an incremental technique with a 5-mm collimation and a 5-cm interspace between images extending from the iliac crests to the tibial plateaus.

Results

12.9% of studies had isolated pulmonary emboli (PE), 3.0% had both a PE and deep vein thrombosis (DVT) and 1.1% had an isolated DVT. The proportion of positive cases diagnosed by CTV alone was 6.6%.

Conclusion

In a UK-based practice, the incidence and the proportion of isolated DVT diagnosed by CTV are lower than expected from published data. An analysis of possible causes for this is made within the paper.More than 250 000 cases of pulmonary embolism were identified in the UK between 1996 and 2006, yet the accurate diagnosis of this condition remains problematic [1]. Autopsy studies indicate that 88% of pulmonary emboli (PE) are unsuspected clinically prior to death. Although the majority of these PE are an incidental complication of an underlying comorbid condition, less than half of cases of fatal PE are correctly diagnosed ante-mortem [2,3]. It is accepted that PE originate from distant sites of venous thrombosis and that both PE and deep vein thrombosis (DVT) are facets of the same disease process, with the majority of DVT arising within the lower limb veins. The evaluation of the presence of DVT is therefore considered part of the investigation of PE, and the presence of DVT in the absence of radiological evidence of PE can be accepted as surrogate evidence of venous thromboembolism (VTE). Lower limb indirect CT venography (CTV) may be added to CT pulmonary angiography (CTPA) to identify the presence of DVT, but this is at the expense of an increased examination time and an increased radiation dose, particularly to the reproductive organs. The prospective investigation of the PE diagnosis II study demonstrated the addition of CTV to CTPA increased the sensitivity for detection of PE from 83% to 90% [4]. Despite this, the routine addition of CTV to CTPA is not recognised in current British Thoracic Society guidelines, and it is not known how many centres in the UK have adopted this technique [5].The aim of this study is to establish the incremental value of CTV in clinical practice within a British institution and ascertain whether factors such as image quality significantly influence the value of the examination. To our knowledge this is the first large British study of the value of CTV in the investigation of PE.     

Correlation between the site of pulmonary embolism and the extent of deep vein thrombosis: evaluation by computed tomography pulmonary angiography and computed tomography venography

Purpose  

The aim of this study was to evaluate the relation between the sites of pulmonary embolism (PE) and deep vein thrombosis (DVT) by computed tomography pulmonary angiography (CTPA) and CT venography (CTV) of the pelvis and lower extremities.     

64层螺旋CT直接法静脉造影对下肢深静脉血栓的临床应用价值初步研究

目的 探讨64层螺旋CT直接法静脉造影在下肢深静脉血栓(DVT)中的诊断价值. 资料与方法 19例临床怀疑DVT患者行64层螺旋CT直接法下肢深静脉造影检查,着重分析DVT的CT征象,探讨影响其诊断准确性的因素.结果 64层螺旋CT直接法静脉造影对DVT显示较好,在15例患者中共发现DVT 25处,分别位于髂静脉(4)、股静脉(7)、胭静脉(9)和腓静脉(5).结论 64层螺旋CT直接法下肢深静脉造影结合多种后处理技术可以清楚显示DVT,具有较高的临床应用价值.     

Assessment of embolism risk in deep vein thrombosis in various locations using radionuclide phlebography and perfusion scintigraphy of the lungs

With the aim of the estimation of embolism at certain locations of deep vein thrombosis (DVT) 3 groups comprising 22 patients were investigated in whom isolated thrombosis in one of the deep veins segments: lower leg, upper leg, and pelvis was determined by radionuclide phlebography (RNF) and contrast phlebography. Afterwards, all necessary investigations relevant for pulmonary thromboembolism (PTE), including perfusion scintigraphy of the lungs (PSL) were performed. Out of all patients with DTV, 17% were with pulmonary changes confirming PTE. Out of patients with DVT, 59% were with the changes in the upper leg segment, and 66% of patients were with changes in pelvic segment, respectively.     

16层螺旋CT对肺动脉栓塞及下肢静脉血栓行联合成像的技术优势

目的探讨16层螺旋CT同时扫描肺动脉和下肢静脉的联合成像技术。方法40例疑为肺动脉栓塞(简称肺栓塞)的病人于16层螺旋CT上行肺动脉和下肢静脉联合成像。CT后处理包括最大密度投影(MIP)、多平面重建(MPR)及容积再现(VR)。采用t检验进行统计学分析。结果肺栓塞、下肢静脉血栓同时存在者25例，单纯下肢静脉血栓者8例，单纯肺栓塞者2例，二者均正常者5例。不同重建层厚均可清晰显示肺动脉栓子。肺动脉、下肢静脉增强后的CT值显著高于栓子的CT值。MPR、MIP、VR三者对肺栓塞的显示率分别为100％、100％、65％，下肢静脉血栓的显示率分别为100％、60％、50％。结论16层螺旋CT联合肺动脉、下肢静脉成像将为肺栓塞的诊断提供新的方法。     

Deep venous thrombosis: comparison of indirect multidetector CT venography and sonography of lower extremities in 26 patients

OBJECTIVE: To compare the accuracy of indirect mutidetector row computed tomographic (MDCT) venography with lower extremity venous sonography for the diagnosis of femoropopliteal deep venous thrombosis (DVT), and to determine the frequency and location of DVT at MDCT venography. MATERIALS AND METHODS: Twenty-six consecutive patients suspected of having pulmonary embolism (PE) underwent both combined MDCT venography and MDCT pulmonary angiography and lower extremity venous sonography. Indirect MDCT venography was acquired from the upper calves to the mid-abdomen following MDCT pulmonary angiography. The CT venographic findings were compared with those of sonography for the diagnosis of femoropopliteal DVT. All CT scans were also reviewed for the frequency and location of DVT. RESULTS: Indirect MDCT venography disclosed DVT in 19 patients, and 12 of whom also had PE. Seventeen patients with thrombosis in the femoropopliteal veins were identified in both indirect MDCT venography and sonography. The sensitivity and specificity of indirect MDCT venography for femoropopliteal DVT, as compared with sonography, were both 100%. In one patient DVT in the superficial femoral vein was detected using only indirect MDCT venography. MDCT venography also showed superior extension of femoropopliteal DVT to the inferior vena cava and iliac veins in four patients and thrombosis isolated to the inferior vena cava and common iliac vein thrombosis in one patient. CONCLUSIONS: Indirect MDCT venography is as accurate as sonography in the diagnosis of femoropopliteal DVT. MDCT venography can further reveal thrombus in large pelvis veins and the inferior vena cava, an important advantage over sonographic screening for DVT.     

CT venography vs ultrasound in the diagnosis of thromboembolic disease in patients with clinical suspicion of pulmonary embolism

To assess the reliability of indirect computed tomography venography (CTV) in the detection of deep venous thrombosis (DVT) in patients with clinical suspicion of pulmonary embolism (PE). 235 consecutive patients with suspicion of PE underwent an imaging protocol composed of a CT pulmonary angiography (CTPA), a CTV and an ultrasound study of the deep venous system, which was considered the “gold standard.” Sensitivity, specificity, and predictive values were calculated for CTV. ith CTV, 30 (12.8%) cases of DVT were detected, 9 (3.8%) of them without pulmonary embolism in CTPA, increasing the diagnosis of thromboembolic disease in 3.8%. However, six of these nine diagnoses were false positives, and CTV missed six cases of DVT. CTV rendered a sensitivity of 58.8%, specificity of 95.0%, a positive predictive value of 66.7%, and a negative predictive value of 93.2%. In patients with clinical suspicion of pulmonary embolism, ultrasound is preferred to CTV for the detection of DVT.     

Diagnosis of thrombosis of the deep veins of the lower extremities and pelvis and pulmonary thromboembolism using 99Tcm human serum albumin macroaggregates

Radionuclide phlebography of the lower extremities, pelvis and pulmonary scintigraphy was performed using 99Tcm human serum albumin macroaggregates (MAA) in 90 patients aged 20 to 80 years, 13 (14%) in post-operative period and 77 (85%) with suspected deep venous thrombosis or pulmonary thromboembolism. The aim of the study was to evaluate the diagnosis of thrombosis of the deep veins of the lower extremities and pelvis and pulmonary thromboembolism using a refined technique. Deep venous thrombosis (DVT) was detected in all surgical patients and in 59 patients with systemic diseases. Perfusion scintigraphic defects characteristic of pulmonary thromboembolism (PE) were discovered in 12 of the surgical patients and in 38 of the medical patients. The results of the examinations have again shown that patients after surgery are exposed to high risks of DVT and pulmonary thromboembolism, while a relatively high percentage of normal findings in patients with suspected DVT have indicated unreliability of clinical symptoms and signs in diagnosing this disease.     

Where is the most common site of DVT? Evaluation by CT venography

Purpose

Our aim was to clarify the common site of deep venous thrombosis (DVT) in patients suspected of having pulmonary embolism using computed tomography pulmonary angiography with computed tomography venography (CTV).

Materials and methods

We evaluated 215 patients. For all studies, 100?ml of 370?mg?I/ml nonionic contrast material was administered. CTV were scanned with helical acquisition starting at 3?min in four-slice multidetector-row computed tomography (MDCT) or 5?min in 64-MDCT after the start of contrast material injection. The site of DVT was divided into iliac vein, femoral vein, popliteal vein, or calf vein. Calf vein was divided into muscular (soleal and gastrocnemius) and nonmuscular (anterior/posterior tibial and peroneal) veins. The 2?×?2 chi-square test was used.

Results

One hundred and thirty-seven patients showed DVT; the muscular calf vein was more prevalent than other veins (P?Conclusions Our study showed that the most common site of DVT was the muscular calf vein.     

Benefit of CT venography for the diagnosis of thromboembolic disease

OBJECTIVE: The aim of this study was to determine the benefit of lower extremity CT venography (CTV) with pulmonary CT angiography (CTA) for diagnosing thromboembolic (TE) disease. SUBJECTS AND METHODS: Reports of all CTAs and CTVs over a 3-year interval (Group I) and CTAs, CTVs, and lower extremity Doppler ultrasounds (US) over a 1 1/2-year subset (Group II) were reviewed. Patient population was inpatients and emergency department patients who were assessed for pulmonary embolism (PE) and deep venous thrombosis (DVT) at a tertiary care hospital. Reported results for CTA or CTV were categorized as positive (CTA(P), CTV(P)), negative (CTA(N), CTV(N)), or indeterminate for PE or DVT. When CTV and US results were discrepant, medical records were reviewed for clinical management. Additional benefit of CTV was assessed by chi-square analysis. RESULTS: In Group I, 737 (81.1%) of 909 CTAs from combined CTA/CTV studies were negative. The diagnosis rate of TE disease increased from 13.0% to 17.3% with the addition of CTV(P)s (P=.01). Of the 119 cases in Group II undergoing combined CTA, CTV, and US, CTV and US were both positive in eight and both negative in 88. Of the seven discordant CTVs and USs with clinical follow-up, five CTVs were positive while USs were negative, three of which were treated clinically for TE disease, while two were considered falsely positive. As CTA also proved positive in one of the three, CTV therefore affected management in two of these five cases and increased the rate of thromboembolism diagnosis from 21.0% to 22.6%; however, this was not significant (P>.05). Two CTV(N)s were managed as false negatives. CONCLUSIONS: The combined use of CTA and CTV significantly increases the rate of TE disease over CTA alone. In cases in which ultrasound is performed, however, there is no significant advantage to performing combined CTA/CTV studies.     

Does addition of CT pelvic venography to CT pulmonary angiography protocols contribute to the diagnosis of thromboembolic disease?

AIM: To evaluate the contribution which addition of pelvic computed tomography venography (CTV) to a standard CT pulmonary angiography (CTPA) imaging protocol makes to a definitive diagnosis of thromboembolic disease. MATERIALS AND METHODS: One hundred and six consecutive patients over the age of 55 years referred for (CTPA) for suspected pulmonary embolism between June and November 1999 had pelvic CTV performed at the time of the CTPA study. RESULTS: Ninety-six of 106 CTPA studies were technically adequate. In total, 29/96 (29.6%) CTPA studies were positive for pulmonary embolism, 10/96 (10.4%) CTV studies were positive and five of these 10 examinations showed venous thrombus when the CTPA study was negative (n = 4) or equivocal (n = 1). CONCLUSION: Addition of CTV shows residual thrombus in the pelvis in a proportion of patients with positive CTPA studies and demonstrates venous thrombus in a small number of patients with no CT evidence of pulmonary embolism.     

Incidence and clinical feature of pulmonary embolism in patients with deep vein thrombosis: A prospective study

In 169 patients with suspected deep vein thrombosis (DVT), the incidence and clinical feature of pulmonary embolism (PE) was prospectively studied by means of noninvasive thrombosis tests (uptake tests, radionuclide venography) and combined ventilation (¹³³Xe, ^81mKr) and perfusion (^99mTc microspheres) lung scanning. DVT was detected in 62% of patients (105/169). The incidence of PE in patients with confirmed DVT was 57% (60/105), a figure which is in excellent agreement with data from autopsy studies. Concerning the thrombotic source of emboli, the incidence of PE was 46% in patients with DVT confined to the calf but increased to 67% if the thigh, and to 77% if the pelvic veins were involved as well. Fifty-nine percent of PE were clinically silent, 19% had “minor signs”, and 22% “major signs”. The size of the perfusion defects correlated significantly with clinical symptoms. Only 23% of clinically sumptomatic patients had a pathological chest X-ray. Incidence of both DVT and PE increased with advancing age, but in old patients the incidence of PE rose disproportionately.

     

肺栓塞和下肢深静脉血栓的多层CT联合成像

目的：探讨下肢深静脉血栓和肺栓塞的多层CT联合成像的诊断价值,并分析下肢深静脉血栓与肺栓塞的相关性。方法：对临床疑诊肺栓塞和/或下肢深静脉血栓的连续80例患者行CT肺动脉和下肢深静脉联合成像,采用16层CT,1.25mm×16模式采集,注射对比剂120ml,注射流率3～4ml/s,肺动脉延迟20～25s扫描,下肢静脉延迟150～180s扫描。结果：共发现下肢深静脉血栓52例55侧,肺栓塞21例37侧,其中肺栓塞和下肢深静脉血栓同时存在18例。结论：肺栓塞与下肢深静脉血栓关系密切,多层螺旋CT肺动脉和下肢静脉联合成像可一次性评价肺动脉和下肢静脉,是肺栓塞适宜的检查方法。     

320排CT血管造影和超声诊断下肢深静脉血栓价值比较

目的：探讨320排容积 CT 静脉造影(CTV)和超声(US)对下肢深静脉血栓(DVT)的诊断价值。方法回顾性分析经DSA 证实为下肢 DVT 的患者51例,对比直接法 CTV 及 US 对下肢不同部位栓子的检出率。结果51例患者中,CTV 共诊断DVT 48例,发现栓子124处,US 诊断静脉血栓46例,发现栓子86处。其中盆腔 DVT CTV 检出34处,US 检出10处,胫腓静脉血栓 CTV 检出25处,US 检出5处,CTV 检出股深静脉血栓2处,US 检出11处。结论直接法 CTV 及 US 对下肢 DVT 的诊断均具有较高的临床应用价值,而前者对盆腔 DVT 及胫腓静脉血栓的检出率更高,而对股深静脉血栓的显示不及后者。     

64排螺旋CT静脉造影诊断下肢静脉血栓性病变

目的:探讨64排螺旋CT静脉造影(CTV)诊断下肢静脉血栓性病变的临床价值。材料和方法:下肢多层螺旋CT静脉造影(MSCTV)检查12例,同期均做下肢静脉Dopp ler超声(US)检查;其中1例同时进行了肺动脉CT血管造影,并于延迟2m in时行间接法下肢静脉造影检查。病例均采用5mm层厚和层间距行踝关节至髂骨上缘水平的增强CT扫描,并获得原始图像,图像经1.25mm层厚和50%的重叠处理后传送至工作站进行图像后处理。结果:64排螺旋CTV诊断下肢深静脉血栓(DVT)11例,诊断下肢慢性静脉功能不全1例,同时合并肺栓塞1例。以US作对照,64排螺旋CTV显示股静脉和腘静脉血栓的敏感性为100%,特异性98.6%。MSCTV上DVT表现为静脉腔内不规则低密度充盈缺损,慢性静脉功能不全表现为深静脉边缘不规则且于延迟2m in扫描见其远端引流静脉区造影剂点状残留。结论:64排螺旋CTV在显示股腘静脉血栓与US具有同等价值,MSCTV可作为下肢静脉血栓性病变诊断的常规检查方法。     

Indirect computed tomography venography: a report of vascular opacification

The clinical utility of indirect computed tomography venography (CTV) of the legs, performed after computed tomography pulmonary angiography (CTPA), to evaluate for deep venous thrombosis (DVT) remains a subject of ongoing debate. Visualization of DVT on CTV requires adequate opacification of venous blood. The objective of this study is to measure the Hounsfield unit (HU) clot-to-blood gradient on CTV and CTPA. Secondary analysis of computed tomography images from a prospective clinical trial was performed. All images were interpreted independently by a radiologist. Using the “region of interest” tool feature of the picture archiving and communication system, observers measured the HU of blood and thrombus on CTPA and CTV, using a structured anatomic approach. Interobserver coefficient of variability (CV%) was examined in all disease-positive cases and in a random sample of 25 disease-negative cases. One hundred seventy-nine patients were enrolled; and 23 had pulmonary embolus (PE) without DVT (13%), one had DVT without PE (0.6%), and 18 had both (10%), leaving 137 (77%) who had no venous thromboembolism (VTE). For the 137 patients with no VTE, the mean (±standard deviation) HU values measured for contrast-containing blood with no thrombus were as follows: left and right main pulmonary arteries (MPA), 291 ± 73 and 291 ± 76; left and right common femoral vein (CFV), 92 ± 17 and 88 ± 19; and left and right popliteal vein (PV), 87 ± 20 and 84 ± 20. On CTPA, the HU measured from the filling defects interpreted as acute PE was 51 ± 20, suggesting a between-group HU gradient of 250 or 471% for MPA (PE-to-blood). On CTV, the HU for DVT was 63, suggesting a gradient of 27 HU or 43% for CFV (DVT-to-blood) and 23 HU or 37% for PV (DVT-to-blood). Interobserver CV% were: left and right MPA, 5 ± 4.0% and 7 ± 5.4%; left and right CFV, 7 ± 6.8% and 7 ± 7.3%; left and right PV, 7 ± 8.4%, 6 ± 8.2%, and 32 ± 27.1% for PE thrombus, and 20 ± 30.5% for DVT thrombus. CTV imaging produces a very small HU gradient between clot and blood in leg veins. These findings highlight the importance of ancillary radiological findings in assessing presence of DVT on CTV.     

Isolated pelvic deep venous thrombosis: relative frequency as detected with MR imaging

PURPOSE: To determine the relative frequency of deep venous thrombosis (DVT) isolated to the pelvic veins, as demonstrated with magnetic resonance (MR) imaging. MATERIALS AND METHODS: The reports of 769 MR examinations performed from June 1993 through December 1999 in patients with suspected DVT were reviewed retrospectively. MR venography was performed by using a two-dimensional gradient-recalled-echo sequence (typically repetition time, 34 msec; echo time, 13 msec; flip angle, 60 degrees ). The presence of DVT was categorized by location in the pelvis, thigh, or calf. RESULTS: DVT was identified in 167 (21.7%) of the 769 MR examinations. Thirty-four (20.4%) of the 167 studies demonstrated DVT isolated to the pelvic veins. CONCLUSION: The relative frequency of isolated pelvic DVT detected with MR venography was higher than that reported in prior studies with ultrasonography (US) or ascending venography. MR venography should be performed in patients with suspected pelvic DVT or when clinical suspicion persists despite a negative US study.