平衡法核素显像诊断下肢深静脉血栓

目的：建立诊断下肢深静脉血栓的平衡期核素检查方法。方法：上肢静脉给药，体内法９９ｍＴｃ标记ＲＢＣ，３０分钟后先做平衡期静脉显像，然后用放射性核素体积描记术（ＲＰＧ）做血流测量。获得双下肢深静脉影像、ＲＰＧ曲线、深静脉回流血量和回流速度。结果：３５０例病人接受检查，其中回流正常者７８例，单侧梗阻１３３例，双侧病变１０８例，深静脉功能不全３１例。５０例病人同时做核素深静脉显像（ＲＮＶ），１０例同时做Ｘ线静脉造影，结果与核素平衡法的符合率均为９０％。结论：核素平衡法可用于临床常规检查，并可取代ＲＮＶ。     

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.     

Subcutaneous whole-body radionuclide venography using Tc-99m in vivo tagged red blood cells

PURPOSE: The accurate diagnosis of deep vein thrombosis (DVT) is essential to prevent its complications and to initiate appropriate treatment. Doppler ultrasound (DUS), contrast venography, and intravenous radionuclide venography have been used for many years to detect DVT. However, obtaining venous access in the foot for injection of contrast agent can be difficult. METHODS: The authors introduce the technique of subcutaneous radionuclide venography using Tc-99m in vivo tagged red blood cells and compare it with DUS, a widely used method. Sixty patients (120 lower extremities) underwent subcutaneous radionuclide venography and DUS. RESULTS: The concordance rate was 94% in the femoral veins and 95% in the popliteal veins. Subcutaneous radionuclide venography revealed 10 iliac vein thromboses and 2 inferior vena cava thromboses that were not detected by DUS. CONCLUSIONS: Subcutaneous radionuclide venography is a useful alternative method for detecting DVT. It is particularly valuable for evaluating DVT in the iliac veins and in the inferior vena cava.     

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: diagnosis by using venous enhanced subtracted peak arterial MR venography versus conventional venography

PURPOSE: To assess diagnostic accuracy and interobserver variability at venous enhanced subtracted peak arterial (VESPA) magnetic resonance (MR) venography compared with those at conventional venography for the diagnosis of femoral and iliac deep venous thrombosis (DVT). MATERIALS AND METHODS: A single anteroposterior maximum intensity projection (MIP) venogram of the femoral and iliac veins was constructed by using VESPA MR venography in 55 symptomatic patients suspected of having lower limb DVT. All patients also underwent conventional venography, results of which were used as the standard of reference. VESPA MR venograms were interpreted by two independent reviewers (reviewers A and B) who were unaware of other results. Sensitivity and specificity of VESPA MR venography for the diagnosis of thrombus in the femoral and iliac veins were calculated. Interobserver variability was calculated for these observations by using weighted kappa with equally spaced weights for positive, nondiagnostic, and negative studies. Nondiagnostic studies were reinterpreted separately by reviewer A on the basis of source data. RESULTS: Sensitivity of VESPA MR venography for the femoral veins (20 of 20) and iliac veins (seven of seven) was 100% for both reviewers. Specificity was 100% (39 of 39 for reviewer A, 40 of 40 for reviewer B) for the iliac veins and 97% (31 of 32) for the femoral veins for both reviewers. Segments in which the VESPA MR venograms were nondiagnostic were excluded from this analysis. Interobserver variability as calculated by using weighted kappa for positive, negative, and nondiagnostic studies was 0.85 for femoral veins and 0.97 for iliac veins. Interpretation of the source data led to correct diagnosis in six of six cases in which the VESPA MR venograms were nondiagnostic. CONCLUSION: VESPA MR venography yielded MIP venograms that were highly accurate for the diagnosis of DVT in femoral and iliac veins. Interpretation of the studies was also highly reproducible.     

Deep vein thrombosis using noncontrast‐enhanced MR venography with electrocardiographically gated three‐dimensional half‐fourier FSE: Preliminary experience

Three noncontrast‐enhanced MR venography techniques are presented for assessing deep vein thrombosis (DVT) at 0.5T in patients with metallic implants. Two cardiac‐gated 3D half‐Fourier FSE fresh blood imaging sequences with flow‐refocusing pulses (FR‐FBI) in the read‐out (RO) direction and without FR pulses (non‐FR‐FBI) were developed for slower‐flowing blood. For faster flowing blood, a swap phase‐encode arterial double‐subtraction elimination (SPADE) technique was developed. The three techniques were assessed both quantitatively using signal‐to‐noise (SNR) and contrast‐noise‐ratio (CNR) measurements and qualitatively by subjective image analysis in 15 volunteers. SPADE was compared to FR‐FBI in the pelvic veins and FR‐FBI was compared to non‐FR‐FBI in the thigh and calf veins. Both SPADE and FR‐FBI techniques produced significantly higher SNRs, CNRs, and image quality in each comparative study (P < 0.001). Five patients with metallic implants and confirmed DVT underwent SPADE (pelvic veins) and FR‐FBI (thigh and calf veins) examinations and the results were compared to conventional venography. The SPADE and FR‐FBI images showed all DVTs from all five patients without interference from implant susceptibility artifacts. The excellent image quality produced by both SPADE and FR‐FBI throughout peripheral vasculature demonstrates their promise for detecting DVT in postsurgery patients. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Acute iliofemoral deep vein thrombosis: evaluation of underlying anatomic abnormalities by spiral CT venography

PURPOSE: To evaluate the spectrum of underlying anatomic abnormalities in iliofemoral deep vein thrombosis (DVT) by spiral computed tomographic (CT) venography. MATERIALS AND METHODS: During the past 4 years, 56 patients with acute iliofemoral DVT have been evaluated by CT venography at our institution. Forty-four patients had left-sided DVT, nine had right-sided DVT, and the remaining three had DVT in both extremities. CT venography was performed with use of 2.5-3.2-mm x-ray beam collimation and a 1.25-2.0-mm reconstruction interval. Spiral scans were initiated 5 minutes after intravenous contrast medium injection. The CT venograms were correlated with catheter venograms. In addition, with use of axial sections and their three-dimensional reconstructions, including multiplanar reformation and volume rendering, the presence or absence of central obstructing lesions and their causes were evaluated. RESULTS: Among 44 patients with left-sided DVT, 37 had significant anatomic abnormalities in their iliofemoral veins or inferior vena cava (IVC). The most common lesion was left common iliac vein compression by the right common iliac artery (n = 27; exaggerated by a bony spur in nine and associated with extrinsic compression by the left internal iliac artery in two). Of the nine patients with right-sided DVT, six had significant anatomic abnormalities including encasement or extrinsic compression of their iliac veins by various causes (n = 3) and venous stricture without extrinsic lesions (n = 3). Among three patients with DVT in both extremities, two had anatomic abnormalities in the IVC. Therefore, 45 of 56 patients had anatomic abnormalities central to the thrombosed deep veins. CONCLUSION: The majority of patients with acute iliofemoral DVT had underlying anatomic abnormalities. The presence of central stenosis or obstruction and their causes can be evaluated by spiral CT venography.     

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.     

机械性血栓清除术联合同期髂静脉支架植入治疗合并左髂静脉受压综合征的急性下肢深静脉血栓形成

目的：评价经皮机械性血栓清除术联合同期髂静脉支架植入治疗合并左髂静脉受压综合征的急性下肢深静脉血栓（DVT）形成的可行性、安全性及有效性。 方法：选取2015年4月-2017年6月收治左髂静脉受压综合征伴急性下肢DVT的患者33例,发病时间6 h-14 d,平均年龄（57.97±14.44）岁。所有患者均在滤器保护下进行治疗。AngioJet血栓清除术、球囊扩张和髂静脉支架植入均在同期完成,术后保留鞘管予以溶栓治疗,每天复查造影,若血栓完全溶解,取出下腔静脉滤器并结束溶栓。术后第1、3、6、12个月进行门诊随访,行彩色超声和（或）下肢静脉造影检查了解下肢深静脉及髂支架内血流通畅情况。 结果：33例患者均同期完成手术,技术成功率100%,AngioJet抽吸时间为（224.70±72.78）s,溶栓时间（34.00±15.37）h,尿激酶用量（112.58±49.92）万U。33例患者同期植入髂静脉支架33枚。血栓清除率Ⅲ级患者29例,血栓清除率Ⅱ级患者4例。无出血、症状性肺栓等严重并发症发生。术后随访1例患者术后两月血栓复发,32例患者术后随访超声和（或）下肢静脉造影检查提示下肢深静脉及髂静脉支架内血流通畅。 结论：机械性血栓清除术联合同期髂静脉支架植入治疗合并左髂静脉受压综合征的急性下肢深静脉血栓形成是一种安全有效的方法。     

Intravascular hematocrit layering in equilibrium phase contrast-enhanced MR angiography of the peripheral vasculature

PURPOSE: To evaluate intravenous hematocrit (HCT) layering detected in patent calf veins that potentially simulate filling defects seen in deep venous thrombosis (DVT). MATERIALS AND METHODS: Flow characteristics, vessel size, and enhancement patterns of veins with HCT layering were examined and compared with those of normal veins in vivo. Ex vivo studies were conducted with conventional and blood pool contrast agents to study the effects of MRI parameters and intrinsic variables on detecting HCT layering. RESULTS: HCT layering was detected in high resolution equilibrium phase images in one of six healthy subjects, and five of five patients with peripheral vascular occlusive disease (PVOD). Layering occurred only in deep veins that had significantly slower flow and larger diameter (P < 0.001) compared to normal veins. Enhancement patterns observed in vivo were similar to those found in the ex vivo study. CONCLUSION: The HCT layering effect in MR venography has not been previously reported, likely because delayed equilibrium phase venous imaging is not frequently performed. The use of blood pool contrast agents and high resolution equilibrium phase imaging allows intravascular HCT layering to be observed within a 30-60-minute time frame. Several imaging characteristics that distinguish HCT layering from DVT are discussed.     

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.     

Chronic-stage deep vein thrombosis of the lower extremities: indirect CT venographic findings

OBJECTIVE: To describe the computed tomographic (CT) findings of chronic deep vein thrombosis (DVT) and its evolution from acute DVT. METHODS: Fifty-one consecutive patients with 52 legs confirmed as acute DVT by CT venography underwent follow-up computed tomography more than 2 months later. Follow-up CT findings were assessed retrospectively by consensus between 2 radiologists. The frequencies of CT findings were analyzed for affected venous segments: common iliac, external iliac, femoral, popliteal, and calf veins. RESULTS: Twelve legs (23%) were completely normalized on follow-up computed tomography, but 40 legs (77%) showed abnormal findings as follows: luminal obliteration (n = 16), decreased caliber (n = 30), residual thrombi (n = 3), fibrotic bands (n = 28), ipsilateral muscle enlargement (n = 28), ipsilateral subcutaneous edema (n = 11), and superficial collateral vein development (n = 23). The external iliac vein (26/40, 65%) was the most commonly affected site followed in decreasing order by femoral (29/50, 58%), common iliac (9/18, 50%), popliteal (22/47, 47%), and calf veins (9/43, 21%). Trends were observed whereby luminal obliteration affected iliac veins and fibrotic bands affected femoropopliteal veins. CONCLUSIONS: Luminal obliteration, decreased caliber, fibrotic bands, ipsilateral muscle enlargement, and superficial collateral vein development are common CT findings in chronic DVT of the lower extremity.     

直接法多层螺旋CT静脉造影诊断下肢深静脉血栓简

目的：探讨直接法多层螺旋CT静脉造影（MSCTV）诊断下肢深静脉血栓的临床应用价值。方法直接法多层螺旋CT（MSCT）下肢静脉造影17例,同期均行彩色多普勒超声血流显像（CDFI）检查。直接法MSCTV检查后,所得图像经处理后传送至工作站进行多平面重建（MPR）、最大密度投影（MIP）、表面遮盖（SSD）及容积再现（VR）重建。结果直接法MSCTV检查显示13例存在下肢深静脉血栓（DVT）,彩色多普勒超声检查显示10例,2例髂静脉及1例胫腓静脉血栓彩色多普勒超声未能检出。直接法MSCTV上DVT主要表现为静脉腔内造影剂充盈缺损、静脉节段性不显影、栓塞静脉远端扩张及其周围侧支循环静脉迂曲扩张、周围软组织肿胀、皮肤增厚。结论直接法MSCT能清晰显示DVT形成的部位、范围、侧支静脉情况及病变血管周围的解剖结构,对彩色多普勒超声不易检出的盆腔及小腿深静脉栓塞也能清晰显示,可以作为下肢深静脉血栓检查的常规方法。     

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.     

MSCT静脉成像和超声诊断下肢静脉血栓的对比研究

目的:探讨多层螺旋CT静脉成像(MSCTV)和超声(US)对下肢静脉血栓形成的诊断价值。方法:将42例可疑下肢静脉血栓形成患者分别进行MSCT下肢静脉成像和US检查,并把检查结果进行对比分析。结果:42例患者中,MSCTV共发现栓子93处,US发现88处。下肢MSCTV和US对下肢静脉血栓的诊断结果无明显统计学差异(P>0.05),但本组中2例髂静脉、1例下腔静脉内栓子US均漏诊。结论:MSCTV和US对下肢静脉血栓形成均具有重要诊断价值,MSCTV对髂静脉、盆腔内深静脉血栓形成的诊断价值更大。     

Diagnosis of deep vein thrombosis using multi-detector helical CT

PURPOSE: To evaluate the usefulness of multi-detector helical CT (MDHCT) with contrast medium in the diagnosis of deep vein thrombosis (DVT). Materials and Methods: The bilateral veins of the dorsal pedis in 45 patients (12 men, 33 women; average age, 64 years) under clinical suspicion of DVT were first punctured using 22-G needles. Then CT scanning from the level of the foot to the inferior vena cava was started 20 sec after the initial injection of 200 mL of dilute contrast medium (50 mL nonionic iodinated contrast medium of 300 mgI/mL and 150 mL saline) at a rate of 5 mL/sec. RESULTS: Two patients were excluded because of unsuccessful venous puncture. The average scanning time in 43 patients was 38.5 +/- 7.9 seconds. Images of veins from the foot to the inferior vena cava were clearly demonstrated in each case. MDHCT showed DVT in 32 cases and patent deep vein in 11 cases. Simultaneous venography of the lower extremity in 18 patients clearly visualized DVT at the same level detected by contrast MDHCT. CONCLUSION: MDHCT for the diangosis of DVT has the advantages of wider scanning range, shorter scanning time, and finer Z-axis resolution than the other diagnostic modalities.     

64层螺旋CT静脉成像及曲面重建对下肢深静脉血栓的评价及意义

目的 探讨64层螺旋CT静脉成像(MSCTV)及曲面重建(CPR)对下肢深静脉血栓(DTV)的诊断价值. 方法对19例临床诊断下肢DVT的患者行骨盆入口至踝关节全程MSCIN扫描.经肘正中静脉团注对比剂,应用对比剂智能跟踪技术,当下腔静脉阈值达100 Hu时触发扫描.以髂总静脉、髂外静脉、股静脉、腘静脉及胫后静脉作为靶血管进行CPR成像,结合容积重建(VR)、多平面重建(MPR)及原始断面图像作出诊断,其中9例患者下肢静脉MSCTV与彩色多普勒超声(CDFI)结果进行比较. 结果 19例患者共显示下肢深静脉259段,其中血栓73段.CPR图像上,除胫后静脉显示欠佳外,其余各段靶血管均能得到全程清晰显示.静脉血栓在CPR上表现为"双轨征"或管腔节段性不规则狭窄或中断,统计学分析显示患侧下肢静脉管腔横径较正常侧明显增粗(P<0.05). 结论 MSCT及CPR对下肢DVT的诊断具有明显优势.     

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.     

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.     

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.