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Combined Spiral CT Pulmonary Angiography And Venography: The Utility In The Diagnosis Of Pulmonary Embolism And Deep Venous Thrombosis

Posted on:2006-10-31Degree:DoctorType:Dissertation
Country:ChinaCandidate:Q WangFull Text:PDF
GTID:1104360155466226Subject:Medical imaging and nuclear medicine
Abstract/Summary:PDF Full Text Request
PURPOSE: To assess the value of combined spiral CT pulmonary angiography(SCTPA) and venography(CTV) in the diagnosis of pulmonary embolism(PE) and deep venous thrombosis(DVT).MATERIALS AND METHODS:From December 2002 to February 2005, 94 patients suspected of PE underwent combined SCTPA and CTV by using 16-slice spiral CT scanner (Sensation 16, Siemens) prospectively. Sonography was performed in 26 of 72 cases with PE within 48 h after CT examination. Of 72 patients(aged 19-75 years, mean age 49.8 years) with PE diagnosed by SCTPA, 42 were men and 30 were women.CT Imaging The scanning protocol for the chest, abdomen, pelvis and lower extremities were from the lung apex to the dome of diaphragm, from the dome of diaphragm to the iliac crest, and from the iliac crest to the level of the lower calves respectively. SCTPA was performed with a section width of 3 mm. Scanning of abdomen started 55 seconds after the completion of SCTPA with a section width of 5 mm. Scanning of pelvis and lower extremities began 125 seconds after completion of scanning the abdomen with the same parameters for the abdomen.Automatic bolus trackng was performed for SCTPA. A circular region ofinterest (ROI) was placed in the right pulmonary artery. The enhancement threshold for initiation of the diagnostic scanning was set at the level of 200 HU. 140 mL of iodinated contrast media (Omnipaque, 300 mg I/mL) was injected in the anticubital vein with a power injector at a flow rate of 3.5 mL/sec. The monitoring scans were started with a delay of 12 seconds after the beginning of the injection at the same single slice, and the scans were repeated every 1 second. The diagnostic scan was triggered 5 s after passing of the threshold level.1-mm section thickness and MPR images were reformed by using the raw data for the pulmonary angiographic portion. CTV was obtained by using standard 5-mm section thicknesskmage Interpretation The chest images were reviewed with three different window setting: lung window, mediastinum window and vessel window. The axial images of 3-mm, 1-mm slice thickness and MPR were analyzed respectively. The images of abdomen, pelvis and lower extremities were viewed with the window setting of width 350 and center 50.The diagnostic criteria for PE was partial or complete intraluminal filling defect of the pulmonary artery. According to the location and morphology of the emboli, PE was classified into four types: centric, eccentric, marginal and occlusive. The associated findings with PE were pulmonary artery dilation, pulmonary infarction, pleural effusion, hypertrophy of right ventricle, bronchial artery dilation, pericardial effusion and embolus calcium. CT features of DVT was intraluminal filling defect of vein with various degree.Sonography 26 cases with PE underwent bilateral lower extremity venous sonography using standard compression and Doppler techniques within 48 h after CT examination. Results of CTV were compared with venous sonography.Statistical Analysis x2 test was used to assess the axial images of 3-mm, 1-mm section thickness and MPR, mediastinum window with vessel window for displaying emboli. The paired / test was performed to compare the results of CTV and sonography. All calculation were performed by using SPSS 11.0 software. Ap value of less than 0.05 was considered to indicate a significant differencestatistically.RESULTS: Of 94 patients suspected of PE, PE was detected in 72 cases (76.6%) and DVT detected in 48 cases(51.1%). SCTPA was positive in 72 cases, negative in 18 and undetermined in 4. CTV was positive in 48 cases, negative in 41 and undetermined in 5. 28 had PE in the absence of DVT, 44 had both PE and DVT, 4 had DVT in the absence of PE.In 72 patients with PE, 23 cases with emboli located in the right pulmonary artery, 12 cases in the left pulmonary artery, 37 cases in both right and left side. PE was detected in 518 pulmonary artery branches, including main pulmonary arteries(22), lobar arteries(148), segmental vessels(220) and subsegmental arteries(128). Of the 518 pulmonary artery branches with PE, centric filling defect was in 183 branches (35.3%^ eccentric in 156(30.1%). marginal in 44(8.5%), occlusivein 135(26.1%).The associated features with PE included the pulmonary artery dilation(175 branches), pulmonary infarction(16), pleural effusion(15), pericardial effusion(14), main pulmonary artery dilation(12), hypertrophy of right ventricle(6), bronchial artery dilation(3) and embolus calcium(2).Emboli in main and lobar pulmonary arteries were detected equally on both vessel window and mediastinum window(170 branches). But for segmental and subsegmental pulmonary arteries, vessel window setting demonstrated emboli in 348 branches, whereas mediastinum window demonstrated emboli in 293 branches.There was significant difference statistically between the two window settings^2 =4.058, P=0.Q44).PE was demonstrated in 450, 499, 518 branches for 3-mm, 1-mra axial images and MPR images. Emboli in main pulmonary arteries and lobar arteries were detected equally by using 3-mm, 1-mm axial images and MPR images, whereas emboli detection rate in the segmental and subsegmental pulmonary arteries was different for the three different imaging. Both 1 -mm-thick section axial images and MPR images were more sensitive for detecting emboli in segmental and subsegmental pulmonary arteries than 3-mm axial images (x2 =3.943, P=0.Q47-,x2 =5.443, P=0.020) .Although 1-mm-thick section MPR images achieved a good result to reveal the abnormalities in comparison with the axial images, but it had no significant differenc statistically (x 2= 0.121, P =0.727 ) .Of 48 patients with DVT, CTV studies demonstrated lower-limb DVT in 36 cases, inferior vena cava and left renal vein and pelvis DVT in 10, from calf to inferior vena cava in 2.Among 26 patients examined by sonography, sonography disclosed DVT in 20 patients and venous valves malfunction in 2 and no DVT in 4 patients. The results of CTV were identical to sonography in 19 patients with DVT and 4 patients without DVT. One patient with DVT was found by sonography but undetermined at CTV. Of two patients with valves malfunction disclosed by sonography, one was positive and another was negative at CTV. The rate of detecting lower extremity DVT was equivalent for CTV and sonography (t=-1.570, P =0.129) .CONCLUSIONS: SCTPA is safe, fast, noninvasive and sensitive technique, not only accurately for defining emboli both in the pulmonary arteries, but also for other nonembolic disease in thorax. 16-slice spiral CT scanner can further improve the detecting of PE by thinner sections and faster speed. CTV is as accurate as sonography in the diagnosis of lower extremities DVT. It can further reveal thrombus in pelvis veins and the inferior vena cava, an important advantage over sonographic screening for DVT. Combined SCTPA and CTV could provide "one-stop shopping" examination for the suspected patient with PE. It is recommended that combined SCTPA and CTV be the initial modality of choice for the diagnosis of PE and DVT.
Keywords/Search Tags:Pulmonary embolism, Tomography, X-ray computed, Deep venous thrombosis
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