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.     

Deep venous thrombosis with suspected pulmonary embolism: detection with combined CT venography and pulmonary angiography

PURPOSE: To determine the frequency and location of deep venous thrombosis at computed tomographic (CT) venography after CT pulmonary angiography in a large series of patients clinically suspected of having pulmonary embolism and to compare the accuracy of CT venography with lower-extremity venous sonography. MATERIALS AND METHODS: Venous phase images were acquired from the diaphragm to the upper calves after completion of CT pulmonary angiography in 650 patients (373 women, 277 men; age range, 18-99 years; mean age, 63 years) to determine the presence and location of deep venous thrombosis. Results of CT venography were compared with those of bilateral lower-extremity venous sonography in 308 patients. RESULTS: A total of 116 patients had pulmonary embolism and/or deep venous thrombosis, including 27 patients with pulmonary embolism alone, 31 patients with deep venous thrombosis alone, and 58 patients with both. Among 89 patients with deep venous thrombosis, thrombosis was bilateral in 26, involved the abdominal or pelvic veins in 11, and was isolated to the abdominal or pelvic veins in four. In patients in whom sonographic correlation was available, CT venography had a sensitivity of 97% and a specificity of 100% for femoropopliteal deep venous thrombosis. CONCLUSION: Combined CT venography and pulmonary angiography can accurately depict the femoropopliteal deep veins, permitting concurrent testing for venous thrombosis and pulmonary embolism. CT venography also defines pelvic or abdominal thrombus, which was seen in 17% of patients with deep venous thrombosis.     

Combined CT venography and pulmonary angiography in suspected thromboembolic disease: diagnostic accuracy for deep venous evaluation

OBJECTIVE: Combined CT venography and pulmonary angiography is a new diagnostic test that evaluates both pulmonary embolism and deep venous thrombosis (DVT) in a single study. Our purpose was to compare the CT venous findings with lower extremity venous sonography. SUBJECTS AND METHODS: Seventy-one consecutive patients with suspected pulmonary embolism underwent helical CT pulmonary angiography during rapid i.v. infusion of contrast medium. Axial scans at 5-cm intervals from the patient's upper calves to the diaphragm were generated 3.5 min after the beginning of contrast medium injection. CT venous phase images were interpreted prospectively and compared with subsequent bilateral lower extremity venous sonography performed within 12 hr. RESULTS: DVT was revealed by CT venous phase images in 19 patients, 12 of whom also had pulmonary embolism. CT and sonographic findings correlated exactly in the femoropopliteal deep venous system, where most pulmonary emboli originate. CT venous phase images also revealed pelvic extension of DVT in six patients and isolated vena cava thrombus in one patient. CONCLUSION: CT venous phase imaging at the time of CT pulmonary angiography is comparable with venous sonography in the evaluation of femoropopliteal DVT. The iliac veins and vena cava, vessels poorly shown on sonography but sometimes the source of significant pulmonary emboli, are also depicted by CT venography.     

Using dual-detector helical CT angiography to detect deep venous thrombosis in patients with suspicion of pulmonary embolism: diagnostic value and additional findings

OBJECTIVE: The purpose of this study was to assess the value of dual-slice helical CT angiography in detecting deep venous thrombosis in patients in whom acute pulmonary embolism was suspected and to describe the additional extrathoracic findings. SUBJECTS AND METHODS: Sixty-five consecutive patients were examined for suspected pulmonary embolism using helical CT of the chest (2.7-mm collimation; table speed, 7.5 mm/sec; 100-140 mL of contrast medium injected at a rate of 3 mL/sec) followed by CT of the lower limbs (6.5-mm collimation; table speed, 10 mm/sec) without any additional contrast medium injection. Sequential scanning of the abdomen was performed using 10-mm collimation and an interval of 40 mm. Color Doppler sonography of the lower limbs was done within 24 hr of CT by two radiologists who were unaware of CT findings. Results of CT venography were compared with those of Doppler sonography and with phlebography or repeated focalized sonography in cases of discrepancy. RESULTS: Twenty-two patients had pulmonary embolism revealed on chest CT. Sixteen patients had a deep venous thrombosis. Thirteen patients with pulmonary embolism had a deep venous thrombosis. Three patients with deep venous thrombosis had no pulmonary embolism. Sensitivity and specificity for diagnosing deep venous thrombosis with CT was 93% and 97%, respectively (kappa = 0.88). Additional extrathoracic findings were observed in four patients. CONCLUSION: Combined CT venography with dual-slice scanning is an accurate method to diagnose deep venous thrombosis that may reveal additional imaging findings in some patients with possible pulmonary embolism.     

Evaluation of the lower extremity veins in patients with suspected pulmonary embolism: a retrospective comparison of helical CT venography and sonography. 2000 ARRS Executive Council Award I. American Roentgen Ray Society

OBJECTIVE: In patients undergoing a combined CT angiographic and CT venographic protocol, the accuracy of helical CT venography for the detection of deep venous thrombosis was compared with that of lower extremity sonography. MATERIALS AND METHODS: Patients who had undergone a combined CT angiographic and CT venographic protocol and sonography of the lower extremities within 1 week were identified. The final reports were evaluated for the presence or absence of deep venous thrombosis. Statistical measures for the identification of deep venous thrombosis with helical CT venography were calculated. In each true-positive case, the location of the thrombus identified with both techniques was compared. All false-positive and false-negative cases were reviewed to identify the reasons for the discrepancies. RESULTS: Seventy-four patients were included. There were eight patients (11%) with true-positive findings, 61 patients (82%) with true-negative findings, four patients (5%) with false-positive findings, and one patient (1%) with a false-negative finding. When comparing helical CT venography with sonography for the detection of lower extremity deep venous thrombosis, the sensitivity measured 89%; specificity, 94%; positive predictive value, 67%; negative predictive value, 98%; and accuracy, 93%. Of the eight true-positive cases, five had sites of thrombus that were in agreement on both CT venography and sonography. Of the five discordant cases, four were false-positives and one was a false-negative. Possible explanations for all discrepancies were identified. CONCLUSION: Compared with sonography, CT venography had a 93% accuracy in identifying deep venous thrombosis. However, the positive predictive value of only 67% for CT venography suggests that sonography should be used to confirm the presence of isolated deep venous thrombosis before anticoagulation is initiated. In addition, interpretation of CT venography should be performed with knowledge of certain pitfalls.     

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。     

Assessment of deep venous thrombosis using routine pelvic CT.

OBJECTIVE: The purpose of this study was to assess routine pelvic CT both for accuracy in diagnosis of deep venous thrombosis and for frequency of detection of clinically unsuspected pelvic thrombi. MATERIALS AND METHODS: We reviewed the CT records of patients who had undergone pelvic CT during a 6-month period and cross-referenced these records to reports on lower extremity venous sonography to identify patients who had undergone this test within 1 week of pelvic CT. We compared the frequency and location of venous thrombosis revealed through these two tests. To identify unsuspected deep venous thrombosis detected on pelvic CT, we reviewed the charts of patients for whom a clot was reported to determine if it had been clinically suspected before CT. RESULTS: Among the 52 patients who underwent both CT and lower extremity venous sonography, the findings were in agreement for 49 (94%). The techniques disagreed for three patients; two patients had deep venous thrombosis detected on sonography but not on CT and the other had a clot detected on CT but not on sonography. The prevalence of unsuspected deep venous thrombosis detected by CT was 1.1%, and 73% of these patients underwent anticoagulation therapy without further confirmatory tests. CONCLUSION: Unsuspected deep venous thrombosis is commonly seen on routine pelvic CT and should be carefully sought during such examinations. CT appears to be relatively accurate in the detection of deep venous thrombosis. Thus, CT venography combined with pulmonary CT angiography may significantly increase the percentage of patients who are appropriately treated for thromboembolic disease because both deep venous thrombosis and pulmonary emboli can be identified by this combined test.     

Evaluation of deep vein thrombosis with multidetector row CT after orthopedic arthroplasty: a prospective study for comparison with Doppler sonography

OBJECTIVE: This prospective study evaluated the ability of indirect 16-row multidetector CT venography, in comparison with Doppler sonography, to detect deep vein thrombosis after total hip or knee replacement. MATERIALS AND METHODS: Sixty-two patients had undergone orthopedic replacement surgery on a total of 30 hip joints and 54 knee joints. The CT venography (scan delay time: 180 seconds; slice thickness/increment: 2/1.5 mm) and Doppler sonography were performed 8 to 40 days after surgery. We measured the z-axis length of the beam hardening artifact that degraded the image quality so that the presence of deep vein thrombosis couldn't be evaluated on the axial CT images. The incidence and location of deep vein thrombosis was analyzed. The diagnostic performance of the CT venograms was evaluated and compared with that of Doppler sonography as a standard of reference. RESULTS: The z-axis length (mean +/- standard deviation) of the beam hardening artifact was 4.5 +/- 0.8 cm in the arthroplastic knees and 3.9 +/- 2.9 cm in the arthroplastic hips. Deep vein thrombosis (DVT) was found in the popliteal or calf veins on Doppler sonography in 30 (48%) of the 62 patients. The CT venography has a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 90%, 97%, 96%, 91% and 94%, respectively. CONCLUSION: The ability of CT venography to detect DVT was comparable to that of Doppler sonography despite of beam hardening artifact. Therefore, CT venography is feasible to use as an alternative modality for evaluating post-arthroplasty patients.     

联合应用多层螺旋CT肺动脉造影和间接CT静脉造影诊断静脉血栓栓塞症

目的探讨联合应用多层螺旋CT肺动脉造影（MSCTPA）和间接CT静脉造影（CTV）诊断静脉血栓栓塞症（VTE）的价值。资料与方法对临床疑似VTE的87例患者,联合应用MSCTPA和间接CTV进行检查,在胭静脉至股总静脉水平,比较间接CTV与多普勒血管超声（DVUS）诊断深静脉血栓形成（DVT）的价值,计算间接CTV的敏感性、特异性、阴性预测值和阳性预测值。结果87例患者中,MSCTPA扫描肺血栓栓塞症（PTE）和DVT均显示32例,显示DVT未显示VIE8例,显示PTE未显示DVT22例。DVUS检查中,DVT42例。与DVUS相比,下肢间接CTV诊断DVT的敏感性95．5％、特异性99．2％、阳性预测值97．7％、阴性预测值98．5％。结论联合应用MSCTPA和间接CTV实现了一次检查同时诊断VIE和DVT,并能显示胸部和下肢的其他异常。     

Diagnosis of femoropopliteal venous thrombosis: comparison of duplex sonography and plethysmography

Duplex sonography and impedance plethysmography were correlated with contrast venography to compare the sensitivity, specificity, and accuracy of the two noninvasive techniques for the diagnosis of femoropopliteal venous thrombosis. Sensitivity, specificity, and accuracy of duplex sonography were 90%, 100%, and 97%, respectively, when compared with venography in 32 patients. Sensitivity, specificity, and accuracy of plethysmography were 100%, 63%, and 72%, respectively, when compared with venography in 25 patients. In 21 patients, plethysmography was either nondiagnostic or could not be done because of clinical difficulties. Eighteen of these patients had diagnostic duplex examinations. Duplex sonography exhibits similar sensitivity but higher specificity than plethysmography. Duplex sonography also permits diagnostic examinations in patients in whom diagnostic plethysmography cannot be performed.     

Can a state-of-the-art D-dimer test be used to determine the need for CT imaging in patients suspected of having pulmonary embolism?

RATIONALE AND OBJECTIVES: The purpose of this study was to determine whether a simple rapid blood test can obviate computed tomography (CT) in a sizable percentage of patients suspected of having pulmonary embolism, based on the hypothesis that negative D-dimer results could eliminate any further search for pulmonary embolism. MATERIALS AND METHODS: At the authors' institution, 2,121 sequential patients underwent a whole-blood antibody agglutination test for cross-linked fibrin degradation products (D-dimer). Of these patients, 844 had positive test results and were not further considered. A retrospective review included reports of all multisection combined CT venographic and pulmonary angiographic studies obtained within 48 hours of the D-dimer assay for the 1,277 patients with negative D-dimer results; 229 (18%) of these 1,277 patients underwent combined CT venography and pulmonary angiography, usually within 24 hours. RESULTS: Retrospective review of the imaging examinations that were discrepant with the D-dimer results revealed only three false-negative D-dimer results. Of the 229 patients in whom combined CT venography and pulmonary angiography was performed for suspected pulmonary embolism, 226 (98.7%) had no evidence of acute pulmonary embolism or deep venous thrombosis. The negative predictive value of a negative D-dimer result was therefore 98.7% (confidence interval, 96.2%-99.7%). CONCLUSION: The D-dimer assay is a simple rapid blood test that is sensitive to the presence of acute thrombosis. Very few patients with negative results have acute deep venous thrombosis or pulmonary embolism, with combined CT venography and pulmonary angiography used as the reference standard.     

双向多层螺旋CT下肢静脉造影法的研究和应用

目的探讨双向多层螺旋CT静脉造影(Bi-directionalMSCTV)对诊断下肢深静脉血栓(DVT)的临床应用价值。方法收集8人次超声难以显示的下肢肿胀病人行Bi-directiorralMSCTV检查,检查后经最大密度投影(MIP),表面遮盖法(SSD)及容积再现法(VR)重建。结果双向多层螺旋CT下肢静脉造影技术较常规静脉造影和常规单向CT静脉造影更清晰显示盆腔静脉血栓,尚能显示小腿等超声难以显示的血栓。结论双向多层螺旋CT下肢静脉造影法可作为诊断下肢静脉血栓性病变的最佳方法。     

Thromboembolic disease detection at indirect CT venography versus CT pulmonary angiography

PURPOSE: To assess the incremental increase in thromboembolic disease detection at indirect computed tomographic (CT) venography versus CT pulmonary angiography and to determine the importance of scan interval for indirect CT venography on the basis of thrombus length. MATERIALS AND METHODS: Institutional review board approval was obtained, and informed consent was not required. The study included 1590 consecutive patients undergoing CT pulmonary angiography for the suspicion of pulmonary embolism. Two minutes after completion of pulmonary angiography, a contiguous indirect CT venography was performed from the iliac crest to the popliteal fossa. The presence of pulmonary embolism or deep venous thrombosis (DVT) was recorded for all patients. The lengths of all deep venous thrombi found in the first 378 consecutive patients were recorded. RESULTS: Pulmonary embolism was detected in 243 (15%) of 1590 patients at CT pulmonary angiography, and DVT was detected in 148 (9%) patients at indirect CT venography. Among 148 patients with DVT, pulmonary embolism was detected in 100 patients at CT pulmonary angiography. Thus, the addition of indirect CT venography to CT pulmonary angiography resulted in a 20% incremental increase in thromboembolic disease detection compared with that at CT pulmonary angiography alone (99% confidence interval: 17%, 23%). Among the 378 patients, DVT was present in 33 patients at indirect CT venography. Two (6%) of 33 patients had clots measuring 2 cm or less, six (18%) had clots measuring 3-4 cm, and 25 (76%) had clots measuring more than 4 cm in length. CONCLUSION: The addition of indirect CT venography to CT pulmonary angiography incrementally increases the detection rate of thromboembolic disease by 20%. Performance of indirect CT venography by using contiguous section intervals, with a section width of 1 cm, is recommended to accurately detect DVT.     

Prospective comparison of indirect CT venography versus venous sonography in ICU patients

OBJECTIVE: The purpose of our study was to prospectively compare indirect CT venography (CTV) and duplex venous sonography in the evaluation of acute deep venous thrombosis (DVT) in ICU patients with suspected pulmonary embolism. SUBJECTS AND METHODS: All ICU patients undergoing CT pulmonary angiography in the evaluation of acute pulmonary embolism during a 10-month period were included in the study group. Indirect CTV was performed 3 min after initiation of the contrast bolus and was compared with duplex venous sonography of the lower extremities. Both techniques were compared with a clinical standard when DVT was considered present if a positive result was obtained on sonography or on CTV in the setting of pulmonary embolism. RESULTS: The study group comprised 61 ICU patients. Using the clinical standard, DVT was detected in 10 of 61 patients. The sensitivity and specificity for CTV were 70% and 96%, respectively, and for sonography were 70% and 100%. CONCLUSION: The performance characteristics of CTV and deep venous sonography were similar when compared with a clinical standard. The results support the use of indirect CTV after CT pulmonary angiography as an alternative to sonography in the ICU population.     

Deep venous thrombosis: detection by using indirect CT venography. The Pulmonary Angiography-Indirect CT Venography Cooperative Group

PURPOSE: To assess the clinical benefits of performing indirect computed tomographic (CT) venography after pulmonary CT angiography to detect deep venous thrombosis (DVT) in patients suspected of having a pulmonary embolism. MATERIALS AND METHODS: The authors prospectively enrolled 541 consecutive patients who underwent pulmonary CT angiography for suspected pulmonary embolism at seven institutions. Using a protocol that optimizes venous enhancement without additional contrast material injection, the authors obtained contiguous images from the pelvis to the popliteal fossa. Ultrasonography (US) also was performed in 116 patients. RESULTS: DVT was found at indirect CT venography in 45 (8%), and pulmonary embolism was found at pulmonary CT angiography in 91 (17%) of 541 patients. Among the 45 patients with DVT, DVT occurred in 16 patients who had no pulmonary embolism at pulmonary CT angiography, which increased the diagnosis of thromboembolic disease by 18%. Among 116 patients who underwent US and indirect CT venography, 15 had DVT at US, and in all 15, DVT also was seen at indirect CT venography. In four additional cases, DVT was seen at only indirect CT venography. CONCLUSION: Among patients suspected to have pulmonary embolism, a substantial number had DVT in the absence of pulmonary embolism. Combined pulmonary CT angiography-indirect CT venography can depict these cases with accuracy comparable to that of US and thus could have a significant effect on patient care.     

Can multislice CT alone rule out reliably pulmonary embolism? A prospective study

PURPOSE: To evaluate the safety of withholding anticoagulation in patients with suspected acute pulmonary embolism after negative multislice computed tomography (MSCT) pulmonary angiography and lower-limb venography. MATERIALS AND METHODS: A total of 383 consecutive patients with suspected acute pulmonary embolism were prospectively studied. Patients underwent MSCT pulmonary angiography and lower-limb venography, as well as pulmonary scintigraphy and lower-limb ultrasound examination. Patients with negative MSCT results for both pulmonary embolism and venous thrombosis were not administered anticoagulants and were followed up for 6 months to rule out thromboembolism. RESULTS: At MSCT, 156 patients were positive for pulmonary embolism, venous thrombosis, or both; 224 were negative; and findings were inconclusive in three. False-negatives were five patients with high probability scintigram and two with venous thrombosis detected at US. A total of 184 patients with negative MSCT and without anticoagulation were followed up for 6 months. During this period of time just one recurrence of pulmonary embolism was detected. The negative predictive value of MSCT pulmonary angiography plus lower-limb venography was 95.8% (183/191). CONCLUSION: MSCT is efficacious in diagnosing pulmonary embolism, with negative predictive values reported in the literature ranging from 94% to 100%. This enables omission of anticoagulation in patients with suspected pulmonary embolism after negative MSCT findings without the need for other diagnostic tests.     

Efficacy of multi-slice helical CT venography for the diagnosis of deep venous thrombosis: comparison with venous sonography

OBJECTIVE: The purpose of this study was to assess the efficacy of contrast enhanced multi-slice helical CT (MSCT) venography for the diagnosis of deep venous thrombosis (DVT) in comparison with venous sonography. MATERIALS AND METHODS: MSCT was used to obtain contiguous, 5-mm thick axial CT images from the diaphragm to the ankles of 27 patients after intravenous injection of contrast material. These patients were clinically suspected of having DVT. The same patients underwent venous sonography before CT examination. The detectability of DVT with MSCT venography was compared with that with venous sonography. RESULTS: MSCT venography detected DVT in 21 patients, but venous sonography did so in only 17. MSCT venography detected DVT missed by venous sonography in five patients, while venous sonography detected DVT missed by MSCT venography in one patient. CONCLUSION: MSCT venography can be expected to make a valuable contribution to the diagnosis of DVT and to the prophylaxis of pulmonary embolism.     

Combined CT venography and pulmonary angiography: how much venous enhancement is routinely obtained?

OBJECTIVE: Combined CT venography and helical pulmonary angiography is a new diagnostic test that permits radiologists to check both the pulmonary arteries for embolism and the deep veins of the abdomen, pelvis, and legs for thrombosis in a single examination. The purpose of this study was to determine the degree of venous enhancement routinely obtained using this combined CT examination. MATERIALS AND METHODS: We identified all patients at a single institution who, during a 29-month period, had symptoms suggestive of pulmonary embolism and who underwent CT venography and helical pulmonary angiography. The examinations were performed after the patients received a rapid (3--5 mL/sec) IV injection of 150 mL of nonionic contrast medium (240 mg I/mL). CT venography of the abdomen, pelvis, and lower extremities was performed as follows: Beginning 3 min after the start of contrast medium infusion for helical CT pulmonary angiography, 1-cm axial images obtained at 5-cm intervals were acquired from an area ranging from the diaphragm to the calves. Patients who had evidence of deep venous thrombosis on CT scans were excluded from further analysis. The venous portions of the remaining 429 examinations were retrospectively reviewed at a CT console or workstation by one of two radiologists, and Hounsfield unit measurements were recorded from the inferior vena cava as well as from the right and left external or internal iliac, common femoral, superficial femoral, and popliteal veins. A single Hounsfield unit measurement was obtained from the center of each vessel using a region of interest that was approximately half the diameter of the vessel. Mean Hounsfield unit measurements were then calculated for these venous stations. RESULTS: Mean Hounsfield unit measurements at the inferior vena cava and at the right and left external or internal iliac veins were 97, 95, and 95 H, respectively. Mean measurements at the common femoral veins were 95 H for both the right and left; the mean measurements at the superficial femoral veins were 91 H for both the right and left, and those at the popliteal veins were 97 H for the right and 94 H for the left. CONCLUSION: CT venography of the abdomen, pelvis, and lower extremities begun 3 min after the start of contrast medium infusion for helical CT pulmonary angiography routinely produced high mean levels of venous enhancement.     

Diagnosis of portal vein thrombosis: value of color Doppler imaging.

This study was undertaken to determine the accuracy of color Doppler imaging in the diagnosis of portal vein thrombosis. Two hundred fifteen patients were studied with color Doppler imaging to determine patency of the main portal vein. Sonographic findings were confirmed in 75 patients, aged 19 to 66 years. Correlation with angiography was obtained in 13 patients, and surgical correlation was obtained in the remaining 62. Nine patients had portal vein thrombosis on the basis of these gold standards. Sonograms were classified as showing either patency or thrombosis, depending on the ability to show color flow within the main portal vein. Agreement between sonography and angiography or surgery was found in 69 patients (61 patent, eight thrombosed). One patient with a patent portal vein at sonography was found to have a thrombosed vessel at surgery, whereas five patients without portal venous flow at sonography had patent vessels at angiography (one patient) or surgery (four patients). Overall sensitivity and specificity for detection of portal vein thrombosis were 89% and 92%, with an accuracy of 92%, a false-negative rate of 0.11, a negative predictive value of 0.98, and a positive predictive value of 0.62. We postulate that the majority of errors in our study occurred in vessels that, although patent, had only sluggish flow, which could not be resolved because of technical limitations. We conclude that color Doppler imaging is a valuable screening procedure for the assessment of portal vein patency. If the sonogram shows a patent portal vein, no further studies are required. However, a lack of demonstrable flow does not always indicate thrombosis, and other imaging studies should be performed for confirmation.     

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.