| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Thoracic Imaging |
1 From the Departments of Radiology (L.R.G., R.S.K., Y.L., D.J.O.) and Medicine, Division of Pulmonary Medicine and Critical Care Medicine (L.R.G., R.J.L.), and the Division of Biostatistics (T.L.M.), Medical College of Wisconsin, 9200 W Wisconsin Ave, Milwaukee, WI 53226-3596. Received July 23, 1999; revision requested September 29; revision received November 3; accepted November 15. Supported in part by a research grant from GE Medical Systems, Milwaukee. Address correspondence to L.R.G. (e-mail: lgoodman@mcw.edu).
 |
Abstract |
|---|
 TOP Abstract IntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
MATERIALS AND METHODS: Patients with negative helical CT scans were prospectively compared with patients with negative or low-probability scintigrams. In a 460-bed university hospital and clinic, 1,015 adult patients underwent either scintigraphy or helical CT for possible PE for 25 months. Five hundred forty-eight patients who had negative images and were not receiving anticoagulation therapy were prospectively followed up for 3 months for clinical, new imaging, death certificate, or autopsy evidence of subsequent PE. Ninety-seven patients were lost to follow-up.
RESULTS: Subsequent PE was found in two (1.0%) of 198 patients with negative CT scans, none of 188 patients with negative ventilation-perfusion (V-P) scans, and five (3.1%) of 162 patients with low-probability V-P scans (not statistically significant). Patients in the helical CT group were hospitalized more often, had more severe disease, had more substantial PE risk factors, and had a higher death rate. No deaths were attributed to PE in either group.
CONCLUSION: The frequency of clinical diagnoses of PE after a negative CT scan was low and similar to that after a negative or low-probability V-P scan. Helical CT is a reliable imaging tool for excluding clinically important PE.
Index terms: Computed tomography (CT), comparative studies, 60.12112, 60.12115, 60.12116, 944.12912, 944.12915, 944.12916 • Computed tomography (CT), helical, 60.12115, 944.12915 • Embolism, pulmonary, 60.7212, 60.723, 60.724, 944.751, 944.77 • Lung, perfusion, 60.12171 • Lung, ventilation, 60.12176 • Pulmonary arteries, CT, 944.12912, 944.12915, 944.12916
|
Introduction |
|---|
|
TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
Although most clinicians readily accept a helical CT–based diagnosis of PE, many are hesitant to accept a negative helical CT scan as a definitive indication to exclude PE. Especially troubling is the inability of helical CT to reliably depict emboli when they are small or limited to only the subsegmental vessels. Although recent advances in helical CT equipment, such as multisection detectors, enable better visualization of the subsegmental vessels, these small vessels remain difficult to evaluate. If emboli in these small vessels are frequent or harmful, helical CT has a limited role. Conversely, if these small emboli are infrequent or of limited clinical consequence, then helical CT has a major role. The results of large series in which patients suspected of having PE were studied have demonstrated that isolated subsegmental clots are relatively uncommon, occurring in 4%–6% of cases (6,7), whereas limited clinical series with selected patients have shown that subsegmental clots are more frequent (3,8,9). In the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study, 17% of patients with low-probability scintigrams had clots limited to the subsegmental vessels at angiography (5).
Furthermore, there is controversy regarding the importance of small, nontreated clots. Gurney (10) argued that small emboli are common and a healthy lung acts as a filter to protect the systemic circulation. In the PIOPED study, 20 patients who had small clots that were missed at the initial pulmonary angiogram reading and had not received anticoagulation therapy were retrospectively identified. Two (10%) patients had subsequent PEs, one of which led to death (11). Others fear that small emboli may be lethal in patients with limited cardiopulmonary reserve and that they may be the initial warning that larger thrombi lurk in the lower extremity veins (1,12,13).
Because of these concerns, many have expressed the need for clinical outcome studies to examine patients with negative helical CT scans to determine the rate of subsequently discovered PE (12–17). We prospectively followed up patients with negative helical CT scans for 3 months to determine the rate of occurrence of subsequent PE and the overall clinical outcome and compared the results with those in a group of control patients with negative or low-probability scintigrams. The negative predictive values were calculated.
|
MATERIALS AND METHODS |
|---|
|
TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
In the second approach, helical CT was substituted for scintigraphy. If the helical CT scan was negative, then Doppler US was suggested but not mandatory. In this clinical study, clinicians were free to order additional examinations—that is, pulmonary angiography and/or V-P scintigraphy—if they deemed it appropriate.
The first approach (ie, scintigraphy) was suggested for patients with normal or near-normal chest radiographs, and the second approach (ie, helical CT) was suggested for patients with abnormal chest radiographs because the likelihood of a definitive interpretation (ie, normal or high-probability scintigram) was low in such cases (18). Other than these broad policy suggestions, no attempt was made to influence the clinician's decision.
The study population consisted of patients without helical CT evidence of PE and patients with either a normal or a low-probability V-P scan. Patients were excluded if they had received anticoagulation therapy for any reason (eg, prior deep venous thrombosis, PE, or cardiac disease), had an inferior vena cava filter, or had had documented PE in the previous 3 months. If the patient had within 24 hours undergone other imaging (ie, US or angiography) that depicted PE, they were excluded because the diagnosis was part of their initial work-up.
Patients were followed up at 1 and 3 months by a team consisting of a pulmonologist (R.J.L.), research physician (Y.L.), and research coordinator (D.J.O.). Imaging was not systematically performed to evaluate for possible subsequent venous thromboembolism. All hospital, clinic, and emergency department charts were reviewed for signs and symptoms of subsequent PE or deep venous thrombosis, objective (ie, imaging- or autopsy-based) evidence of subsequent PE or deep venous thrombosis, or a clinical diagnosis of subsequent PE or deep venous thrombosis that resulted in treatment. In addition, for all study patients, either the patient, the patient's family, or the referring physician was interviewed by phone at 1 and 3 months. Our hospital's autopsy records and the death certificates from our two local counties also were examined. Patients lost to follow-up during the 3 months were dropped from the study. The charts and supporting data for every patient believed to have had a subsequent PE and for every patient who died were thoroughly reviewed by the pulmonologist. In addition to the usual demographic data, we recorded the patient's referral location—that is, emergency department, outpatient clinic, inpatient clinic, or intensive care unit—at the time of the index imaging study and the presence or absence of nine risk factors frequently associated with venous thromboembolism (Table 1) (19,20).
|
V-P Scintigraphy
Perfusion scanning.—The lung perfusion images were obtained in eight projections—that is, anterior and posterior, left anterior and posterior oblique, right anterior and posterior oblique, and both lateral views—after the intravenous injection of 3.0 mCi (111 GBq) of technetium 99m-macroaggregated albumin. A large field-of-view gamma camera (Starcam; GE Medical Systems) was used with a low-energy all-purpose collimator and 20% window setting at 140 keV. Each view was acquired for 500K by using a matrix of 256.
Aerosol study.—If perfusion abnormalities were seen, then an aerosol ventilation study was performed. Forty mCi (1,480 GBq) of 99mTc-pyrophosphate in a total volume of 4 mL was administered by means of inhalation with an aerosol delivery unit. The camera detector was positioned over the suspicious area seen on the perfusion image. After acquiring a 2-minute preaerosol static image and without moving the patient, the dynamic inhalation images were obtained with an oxygen flow setting of 10–13 L/h. The dynamic inhalation data were acquired for 30 seconds per image for 16 frames by using a 128 matrix, and then a 2-minute, static postaerosol image was obtained. Static pre- and postaerosol images were acquired by using a matrix of 256. An aerosol image was obtained after subtracting both images. The images were interpreted by one of three experienced nuclear medicine specialists by using modified PIOPED criteria (22).
Lower Extremity Venous US Technique
The lower extremity venous studies included venous compression US and color Doppler US, both with a 5- or 7-MHz transducer. The studies were performed from the common femoral vein to the popliteal vein. Deep venous thrombosis was diagnosed if the vascular lumen was not compressible, there was diminished venous flow, or there was absence of respiratory periodicity.
Pulmonary Angiographic Technique
Digital subtraction angiograms were obtained during injection of 40–50 mL of nonionic contrast material (iohexol; [Omnipaque 350]; Nycomed-Amersham) at 20–25 mL/sec through a 7-F, multi–side- hole catheter in the main pulmonary artery. Additional subselective studies were obtained in oblique projections when indicated. The images were obtained with an LCA unit (GE Medical Systems) by using a 1,024 x 1,024 matrix and a 16-cm field of view. Acute PE was diagnosed if a partially occluding intravascular filling defect was observed or a vessel ended abruptly in a meniscus.
Statistical Analyses
The univariate association between imaging modality and 3-month subsequent diagnosis of PE and overall survival status was tested by using 
2 analysis. Additional analyses by each risk factor and patient location were performed. The Kruskal-Wallis test was used to examine the comparability of study groups with respect to age. Stepwise logistic regression analysis was used to allow multivariate adjustment for age, referral location, sex, and the nine risk factors in testing for differences in subsequent PE and 3-month survival between patients in the helical CT group and those in the V-P scintigraphy group. To avoid the potential effect of confounding data as a result of the different risk characteristic patterns of the imaging modality groups, multivariate logistic regression was used to test for an association between imaging modality and death or subsequent diagnosis of PE within 90 days. A stepwise logistic regression analysis approach was used to model the association between death or subsequent diagnosis of PE within 90 days and imaging modality while adjusting for age, sex, referral location, and the nine risk characteristics.
|
RESULTS |
|---|
|
TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
In the helical CT–negative group of 285 patients, 198 (69.5%) completed 3-month follow-up, whereas 24 (8.4%) were lost to follow-up and 63 (22.1%) received anticoagulation therapy (Table 2). In the V-P scintigraphy–negative group of 527 patients, 350 (66.4%) completed 3-month follow-up—188 patients had normal scans and 162 had low-probability scans—whereas 73 (13.8%) were lost to follow-up and 104 (19.7%) received anticoagulation therapy. Patients in the V-P group were lost to follow-up almost twice as often as patients in the helical CT group (13.8% vs 8.4%; P = .001).
|
|
|
Subsequent PE occurred in two (1.0%) of 198 patients who underwent helical CT and in five of 350 (1.4%) patients who underwent scintigraphy (not significant, Fisher exact test). None of the patients with a normal V-P scan had subsequent PE, and five (3.1%) of the 162 patients with a low-probability V-P scan had subsequent PE (not significant, Fisher exact test). The negative predictive values for helical CT, normal V-P scintigraphy, and low-probability V-P scintigraphy were 99%, 100%, and 97%, respectively. The mean time to diagnosis of subsequent PE was 21.1 days (range, 1.5–74.0 days). Five of the seven patients had had a negative lower extremity Doppler US scan within 48 hours after the initial lung imaging. The subsequent diagnosis of PE in the seven patients was made on the basis of a positive helical CT scan in four patients, a positive angiogram in one patient, a high-probability V-P scan in one patient, and an autopsy diagnosis of an organized clot in one patient (Table 5).
|
|
To adjust for differences in potential risk characteristics between imaging modality groups, multivariate logistic regression analysis was used to model the relationships between death within 90 days and imaging modality, age, sex, referral location, and the nine risk characteristics. The four referral locations, CT imaging type, male sex, and the nine risk characteristics were included as binary variables. Patient age was dichotomized into younger than 67 years and older than 67 years. Because of colinearity among the covariates, stepwise multivariate logistic regression analysis was used to develop a best-fitting model for the occurrence of death within 90 days. The best-fitting stepwise logistic regression model included intensive care unit referral location, age, CT imaging type, and the two risk factors of immobilization and malignancy (goodness-of-fit test, P = .87).
The logistic regression coefficient, significance, and odds ratio of each factor in the final model are listed in Table 7. Each variable in the model represents a significant independent risk for death within 90 days after adjusting for the remaining factors. The patients referred from the intensive care unit had almost six times the odds of dying within the first 90 days as the other patients (odds ratio, 5.93; P = .001). The patients in the CT imaging group had more than twice the odds of dying within 90 days as those in the V-P scintigraphy group (odds ratio, 2.54; P = .004). Patient age older than 67 years (odds ratio, 2.12; P = .024), immobilization for more than 7 days (odds ratio, 3.52; P = .002), and malignancy (odds ratio, 2.39; P = .012) were the remaining statistically significant independent risk factors for dying within 90 days. The other referral locations (inpatient and outpatient facilities and emergency department) and the remaining seven characteristics were not significant independent predictors after controlling for the variables in the final model. Subsequent PE was diagnosed in too few patients to allow meaningful multivariate analysis.
|
|
DISCUSSION |
|---|
|
TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
In our study, the 1.0% prevalence of subsequent PE after a negative helical CT scan was very similar to that in studies of subsequent thromboembolism after negative pulmonary angiographic, scintigraphic, helical CT, and lower extremity imaging results, and/or a combination of these. A review of five published series of negative pulmonary angiograms revealed subsequent PE in 25 of 1,095 (2.3%) patients during a 3–12 month follow-up period (5,23–26). The results of two studies (4,27) involving 159 patients with low-probability scintigrams who did not receive anticoagulation therapy showed no evidence of further emboli. Mayo et al (4) followed up 44 patients with negative helical CT scans for 3 months, and none of these patients had recurrence, whereas Ferretti et al (27) followed up 112 patients for 3 months and found three (2.7%) subsequent PEs and three (2.7%) subsequent deep venous thrombi. Hull et al (26) examined patients with non–high-probability V-P scans who underwent serial deep venous studies and reported a 2.7% (10 of 371) prevalence of subsequent venous thromboembolism. van Beek et al (28) followed up patients who had either negative scintigrams or negative angiograms for 6 months and observed thromboembolism in 12 (4.9%) of 243 patients.
The 0%–5% subsequent occurrence of venous thromboembolism in these studies must be compared with the mortality and morbidity associated with PE, the imaging complications, and the anticoagulation therapy risks. The risk of death from nontreated PE is probably in the 10%–30% range, although this is difficult to ascertain because many individuals with PE either are asymptomatic or do not receive a diagnosis (29,30). Autopsy results have shown that approximately 5% of patients die as a result of nondiagnosed PE and that PE contributes to death in another 10% of cases (30,31). Carson et al (29), in a study of 375 patients with PE who had received anticoagulation therapy, found that 33 (8.8%) of these patients had clinically apparent recurrent PE and 10 (2.7%) died as a result of subsequent PE within a year. The hospital mortality rate was 9.5%, and the death rate from all causes at 1 year was 24.0%. Hirsh (34) followed up 1,100 patients who had received anticoagulation therapy and found subsequent PE in 54 (4.9%), and 79 (7.2%) patients died from all causes.
Major complications of pulmonary angiography occur in approximately 1% of patients (32,33).
Anticoagulation is not without complications. Landefeld and Beyth (35) reviewed the complications following warfarin therapy in 937 patients. Four (0.4%) had fatal hemorrhage, and 60 (6.0%) had major nonfatal hemorrhage. They also examined 3,931 patients who received heparin therapy and found 37 (0.9%) deaths and 130 (3.0%) major bleeding complications.
Our decision to follow up patients for 3 months rather than a year was based on reports that the majority of subsequent thromboemboli occur within the first few weeks after a negative imaging study for PE or after treatment for PE. Carson et al (29) found that 98% of PE recurrences and 80% of PE-related deaths in treated patients occurred within a week. Hirsh (34) reported that 60% of PE recurrences in treated patients occurred within 2 weeks. Similar results have been reported after negative angiograms and negative helical CT scans (24,25,27). We found the mean time to subsequent PE to be approximately 21 days. If a patient develops signs of acute venous thromboembolism more than 3 months after a negative diagnostic examination, it is considerably more likely that this is a new occurrence in a patient who remained at high risk for venous thromboembolism rather than a venous thromboembolism that was missed at initial imaging.
The majority of follow-up studies in the literature have focused on clinical assessment rather than on routine repeated imaging. It is well recognized that the clinical diagnosis of thromboembolism, whether primary or recurrent, is extremely difficult, especially in hospitalized patients (30,31). Without a complete set of repeated images of the lungs and legs, one cannot be sure that PE or deep venous thrombosis did not occur, recur, or persist. With these limitations, one can only assess the clinical outcomes and the prognostic consequences of withholding treatment.
Diagnostic accuracy was not assessed in this study. It is possible, even probable, that some of our patients had or died as a result of unrecognized thromboembolism despite our thorough case review. The 17.2% death rate in the patients who had undergone helical CT was high, but it reflected a population of patients who had more severe disease, were older, and had a higher frequency of malignancy and/or immobility. The overall death rate, however, was similar to that after negative scintigraphic or pulmonary angiographic examinations in other published studies (23,25,36–38). The death rate in the helical CT group was almost identical to a crude 3-month death rate of 17.4% that was reported in 2,454 patients treated for PE (39).
Finally, 264 (32.5%) of the 812 patients with negative images were excluded because they received anticoagulation therapy (n = 167) or did not complete follow-up (n = 97). Most of the patients who received anticoagulation therapy were treated for other problems, such as ischemic or valvular heart disease, and had received anticoagulation therapy before the PE work-up. Undoubtedly, some patients received anticoagulation therapy because of a concern about thromboembolism, despite a negative imaging examination. However, the percentages of patients who received anticoagulation therapy in the V-P scintigraphy and helical CT groups were similar (19.7% vs 22.1%). There was no significant difference between the helical CT study group and the helical CT group lost to follow-up with respect to any of the 15 factors listed in Table 3. Among the patients who underwent V-P scintigraphy, the largest group lost to follow-up was that of patients referred from the emergency department. These patients were younger and had fewer risk factors; therefore, it is unlikely that many of these patients with negative images had missed PE or undiscovered subsequent emboli.
We continue to believe that in patients with multiple risk factors or in those with limited cardiopulmonary reserve, a small embolus may be a harbinger of larger emboli to come or physiologically important (1); further imaging may be warranted. Lower extremity Doppler US provides assurance that no substantial clots reside in the femoropopliteal system. Pulmonary angiography is used to reexamine the pulmonary arteries and perhaps detect small overlooked PE.
Three recent advances should improve the results of helical CT in the assessment of thromboembolic disease:
1. Technical improvements. The current generation of helical CT scanners now provides thinner (2–3-mm) sections, shorter scanning times (0.75–8.00 seconds), and higher pitch (1.7/1.0). Multisection detectors provide even thinner (1.25-mm) sections while maintaining or decreasing the scanning time. Remy-Jardin et al (40) have emphasized that reducing the helical CT section thickness and increasing the scanning speed markedly improve the visibility of the smaller arteries.
2. Workstation viewing. Reading images on a workstation provides cine viewing of the pulmonary arteries; this enhances PE detection and reader certainty.
3. CT venography. Transverse CT scanning of the pelvic and leg veins after helical CT of the chest can demonstrate deep venous thrombosis without the need for additional intravenous contrast material. Loud et al (41) found that in 71 patients, 19 of whom had deep venous thrombosis, both the sensitivity and specificity were 100% compared with those at US. Shah et al (42) recently observed 94% (49 of 52) agreement between CT venography and venous US. If these results are validated, the pulmonary arteries, inferior vena cava, and iliac, femoral, and popliteal veins can be assessed in a single session in the helical CT suite.
In conclusion, in our study, helical CT had a negative clinical predictive value of 0.99, similar to the clinical predictive value of a negative scintigram (1.0) and a low-probability scintigram (0.97). Garg et al (43) recently reported similar negative predictive values in patients with negative helical CT scans. In the 70%–75% of patients suspected of having PE who do not have thromboembolic disease, helical CT frequently provides an alternative explanation for their cardiopulmonary symptoms (4,42,43). It can also help to diagnose or exclude PE in the presence of other lung diseases, such as pneumonia or atelectasis.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
Abbreviations: PE = pulmonary embolism PIOPED = Prospective Investigation of Pulmonary Embolism Diagnosis V-P = ventilation-perfusion
Author contributions: Guarantors of integrity of entire study, L.R.G., R.J.L.; study concepts, L.R.G., R.J.L., R.S.K.; study design, L.R.G., R.J.L., R.S.K., T.L.M.; definition of intellectual content, L.R.G., R.J.L., R.S.K.; literature research, L.R.G.; clinical studies, L.R.G., R.J.L., Y.L., D.J.O.; data acquisition, R.J.L., R.S.K., Y.L., D.J.O.; data analysis, L.R.G., R.S.K., T.L.M.; statistical analysis, T.L.M.; manuscript preparation, L.R.G., R.J.L.; manuscript editing, L.R.G., R.J.L., R.S.K.; manuscript review, all authors.
|
References |
|---|
|
TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
Related Article
This article has been cited by other articles:
|
|
 |
|
  A.R. Akram, G.W. Cowell, L.J.A. Logan, M. Macdougall, J.H. Reid, J.T. Murchison, and A.J. Simpson Clinically suspected acute pulmonary embolism: a comparison of presentation, radiological features and outcome in patients with and without PE QJM, June 1, 2009; 102(6): 407 - 414. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. J. Kim, J. W. Lee, K. W. Park, J.-S. Yeom, H. S. Jeong, J. M. Park, and H. S. Kang Pulmonary Cement Embolism after Percutaneous Vertebroplasty in Osteoporotic Vertebral Compression Fractures: Incidence, Characteristics, and Risk Factors Radiology, April 1, 2009; 251(1): 250 - 259. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Burrill, Z. Dabbagh, F. Gollub, and M. Hamady Multidetector computed tomographic angiography of the cardiovascular system Postgrad. Med. J., November 1, 2007; 83(985): 698 - 704. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Rogers, J. A. Rebuck, and R. F. Sing Venous Thromboembolism in Trauma: An Update for the Intensive Care Unit Practitioner J Intensive Care Med, January 1, 2007; 22(1): 26 - 37. [Abstract] [PDF]
|
|
|
|
 |
|
 R. Coulden State-of-the-Art Imaging Techniques in Chronic Thromboembolic Pulmonary Hypertension Proceedings of the ATS, September 1, 2006; 3(7): 577 - 583. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M R Jones and J H Reid Emergency chest radiology: thoracic aortic disease and pulmonary embolism Imaging, September 1, 2006; 18(3): 122 - 138. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. K. Yousefzadeh, M. B. Ward, and C. Reft Internal Barium Shielding to Minimize Fetal Irradiation in Spiral Chest CT: A Phantom Simulation Experiment. Radiology, June 1, 2006; 239(3): 751 - 758. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Engelke, E. J. Rummeny, and K. Marten Pulmonary Embolism at Multi-Detector Row CT of Chest: One-year Survival of Treated and Untreated Patients Radiology, May 1, 2006; 239(2): 563 - 575. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Patel and E. A. Kazerooni Helical CT for the Evaluation of Acute Pulmonary Embolism Am. J. Roentgenol., July 1, 2005; 185(1): 135 - 149. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. J. Golding Multi-slice computed tomography (MSCT): the dose challenge of the new revolution Radiat Prot Dosimetry, May 17, 2005; 114(1-3): 303 - 307. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Quiroz, N. Kucher, K. H. Zou, F. Kipfmueller, P. Costello, S. Z. Goldhaber, and U. J. Schoepf Clinical Validity of a Negative Computed Tomography Scan in Patients With Suspected Pulmonary Embolism: A Systematic Review JAMA, April 27, 2005; 293(16): 2012 - 2017. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. R. Goodman Small Pulmonary Emboli: What Do We Know? Radiology, March 1, 2005; 234(3): 654 - 658. [Full Text] [PDF]
|
|
|
|
 |
|
 C. J Hammond and T. B Hassan Screening for pulmonary embolism with a D-dimer assay: do we still need to assess clinical probability as well? J R Soc Med, February 1, 2005; 98(2): 54 - 58. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. K. Moores, W. L. Jackson Jr., A. F. Shorr, and J. L. Jackson Meta-Analysis: Outcomes in Patients with Suspected Pulmonary Embolism Managed with Computed Tomographic Pulmonary Angiography Ann Intern Med, December 7, 2004; 141(11): 866 - 874. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M Riedel Diagnosing pulmonary embolism Postgrad. Med. J., June 1, 2004; 80(944): 309 - 319. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 U. J. Schoepf, S. Z. Goldhaber, and P. Costello Spiral Computed Tomography for Acute Pulmonary Embolism Circulation, May 11, 2004; 109(18): 2160 - 2167. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. P. Kanne and T. A. Lalani Role of Computed Tomography and Magnetic Resonance Imaging for Deep Venous Thrombosis and Pulmonary Embolism Circulation, March 30, 2004; 109(12_suppl_1): I-15 - I-21. [Abstract] [Full Text]
|
|
|
|
|
|
E. C. Kavanagh, A. O'Hare, G. Hargaden, and J. G. Murray Risk of Pulmonary Embolism After Negative MDCT Pulmonary Angiography Findings Am. J. Roentgenol., February 1, 2004; 182(2): 499 - 504. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
U. J. Schoepf and P. Costello CT Angiography for Diagnosis of Pulmonary Embolism: State of the Art Radiology, February 1, 2004; 230(2): 329 - 337. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. A. Froehling, P. L. Elkin, S. J. Swensen, J. A. Heit, V. S. Pankratz, and J. H. Ryu Sensitivity and Specificity of the Semiquantitative Latex Agglutination D-Dimer Assay for the Diagnosis of Acute Pulmonary Embolism as Defined by Computed Tomographic Angiography Mayo Clin. Proc., February 1, 2004; 79(2): 164 - 168. [Abstract] [PDF]
|
|
|
|
|
|
M. S. Ginsberg, V. King, and D. M. Panicek Comparison of Interpretations of CT Angiograms in the Evaluation of Suspected Pulmonary Embolism by On-Call Radiology Fellows and Subsequently by Radiology Faculty Am. J. Roentgenol., January 1, 2004; 182(1): 61 - 66. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. F. Gareen and C. Gatsonis Primer on Multiple Regression Models for Diagnostic Imaging Research Radiology, November 1, 2003; 229(2): 305 - 310. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Han, K. S. Lee, T. Franquet, N. L. Muller, T. S. Kim, H. Kim, O J. Kwon, and H. S. Byun Thrombotic and Nonthrombotic Pulmonary Arterial Embolism: Spectrum of Imaging Findings RadioGraphics, November 1, 2003; 23(6): 1521 - 1539. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. F. Fedullo and V. F. Tapson The Evaluation of Suspected Pulmonary Embolism N. Engl. J. Med., September 25, 2003; 349(13): 1247 - 1256. [Full Text] [PDF]
|
|
|
|
 |
|
 A. A. Donato, J. J. Scheirer, M. S. Atwell, J. Gramp, and R. Duszak Jr Clinical Outcomes in Patients With Suspected Acute Pulmonary Embolism and Negative Helical Computed Tomographic Results in Whom Anticoagulation Was Withheld Arch Intern Med, September 22, 2003; 163(17): 2033 - 2038. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Trotman-Dickenson Radiology in the Intensive Care Unit (Part 2) J Intensive Care Med, September 1, 2003; 18(5): 239 - 252. [Abstract] [PDF]
|
|
|
|
|
|
E. E. Chiang, P. M. Boiselle, V. Raptopoulos, K. F. Reynolds, M. P. Rosen, and M. Simon Detection of Pulmonary Embolism: Comparison of Paddlewheel and Coronal CT Reformations--Initial Experience Radiology, August 1, 2003; 228(2): 577 - 582. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. H. Mills, J. M. Wild, B. Eberle, and E. J. R. Van Beek Functional magnetic resonance imaging of the lung Br. J. Anaesth., July 1, 2003; 91(1): 16 - 30. [Full Text] [PDF]
|
|
|
|
|
|
M. J.H.A. Kruip, M. G.L. Leclercq, C. v. d. Heul, M. H. Prins, and H. R. Buller Diagnostic Strategies for Excluding Pulmonary Embolism in Clinical Outcome Studies: A Systematic Review Ann Intern Med, June 17, 2003; 138(12): 941 - 951. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 British Thoracic Society guidelines for the management of suspected acute pulmonary embolism Thorax, June 1, 2003; 58(6): 470 - 483. [Full Text] [PDF]
|
|
|
|
|
|
M. J.L. van Strijen, W. de Monye, J. Schiereck, G. J. Kieft, M. H. Prins, M. V. Huisman, P. M.T. Pattynama, and for the Advances in New Technologies Evaluating th Single-Detector Helical Computed Tomography as the Primary Diagnostic Test in Suspected Pulmonary Embolism: A Multicenter Clinical Management Study of 510 Patients Ann Intern Med, February 18, 2003; 138(4): 307 - 314. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Kucher, C.M. Luder, T. Dornhofer, S. Windecker, B. Meier, and O.M. Hess Novel management strategy for patients with suspected pulmonary embolism Eur. Heart J., February 2, 2003; 24(4): 366 - 376. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Bourriot, T. Couffinhal, V. Bernard, M. Montaudon, J. Bonnet, and F. Laurent Clinical Outcome After a Negative Spiral CT Pulmonary Angiographic Finding in an Inpatient Population From Cardiology and Pneumology Wards Chest, February 1, 2003; 123(2): 359 - 365. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. S. Ginsberg, J. Oh, A. Welber, and D. M. Panicek Clinical Usefulness of Imaging Performed After CT Angiography That Was Negative for Pulmonary Embolus in a High-Risk Oncologic Population Am. J. Roentgenol., November 1, 2002; 179(5): 1205 - 1208. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. S. Katz, P. A. Loud, D. Bruce, A. M. Gittleman, R. Mueller, D. L. Klippenstein, and Z. D. Grossman Combined CT Venography and Pulmonary Angiography: A Comprehensive Review RadioGraphics, October 1, 2002; 22(90001): S3 - 19. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. Tillie-Leblond, I. Mastora, F. Radenne, S. Paillard, A.-B. Tonnel, J. Remy, and M. Remy-Jardin Risk of Pulmonary Embolism after a Negative Spiral CT Angiogram in Patients with Pulmonary Disease: 1-year Clinical Follow-up Study Radiology, May 1, 2002; 223(2): 461 - 467. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Kelly, A. Rudd, R. R. Lewis, and B. J. Hunt Plasma D-Dimers in the Diagnosis of Venous Thromboembolism Arch Intern Med, April 8, 2002; 162(7): 747 - 756. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N.L. Muller Computed tomography and magnetic resonance imaging: past, present and future Eur. Respir. J., February 1, 2002; 19(35_suppl): 3S - 12s. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C.J. Herold Spiral computed tomography of pulmonary embolism Eur. Respir. J., February 1, 2002; 19(35_suppl): 13S - 21s. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Pistolesi and M. Miniati Imaging techniques in treatment algorithms of pulmonary embolism Eur. Respir. J., February 1, 2002; 19(35_suppl): 28S - 39s. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. J. Swensen, P. F. Sheedy II, J. H. Ryu, D. D. Pickett, C. D. Schleck, D. M. Ilstrup, and J. A. Heit Outcomes After Withholding Anticoagulation From Patients With Suspected Acute Pulmonary Embolism and Negative Computed Tomographic Findings: A Cohort Study Mayo Clin. Proc., February 1, 2002; 77(2): 130 - 138. [Abstract] [PDF]
|
|
|
|
 |
|
 S J Golding and P C Shrimpton Radiation dose in CT: are we meeting the challenge? Br. J. Radiol., January 1, 2002; 75(889): 1 - 4. [Full Text] [PDF]
|
|
|
|
|
|
S P G Padley Lung scintigraphy vs spiral CT in the assessment of pulmonary emboli Br. J. Radiol., January 1, 2002; 75(889): 5 - 8. [Full Text] [PDF]
|
|
|
|
|
|
E. A. Kazerooni Population and Sample Am. J. Roentgenol., November 1, 2001; 177(5): 993 - 999. [Full Text] [PDF]
|
|
|
|
 |
|
 A. K Dixon, R. A. Coulden, and A M. Peters The non-invasive diagnosis of pulmonary embolus BMJ, August 25, 2001; 323(7310): 412 - 413. [Full Text] [PDF]
|
|
|
|
|
|
D. I. Paterson and K. Schwartzman Strategies Incorporating Spiral CT for the Diagnosis of Acute Pulmonary Embolism : A Cost-effectiveness Analysis Chest, June 1, 2001; 119(6): 1791 - 1800. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Rubboli and D.E. Euler Letter to the Editor: Guidelines on the diagnosis of acute pulmonary embolism and their applicability in clinical practice Eur. Heart J., May 1, 2001; 22(9): 798 - 799. [PDF]
|
|
|
|
|
|
H. D. Royal, B. A. Siegel, and P. K. Woodard Use of Imaging for the Diagnosis of Pulmonary Embolism Dr Woodard responds: Radiology, March 1, 2001; 218(3): 912 - 913. [Full Text]
|
|
|
|
|
|
P. M. T. Pattynama, L. R Goodman, R. J. Lipchik, and P. K. Woodard Meaning of a Helical CT Angiogram Negative for Pulmonary Embolism Drs Goodman and Lipchik respond: Dr Woodard responds: Radiology, March 1, 2001; 218(3): 913 - 916. [Full Text]
|
|
|
|
 |
|
 M. Riedel VENOUS THROMBOEMBOLIC DISEASE: Acute pulmonary embolism 1: pathophysiology, clinical presentation, and diagnosis Heart, February 1, 2001; 85(2): 229 - 240. [Full Text]
|
|
|
|
|
|
L. R. Goodman 1999 Plenary Session: Friday Imaging Symposium : CT Diagnosis of Pulmonary Embolism and Deep Venous Thrombosis RadioGraphics, July 1, 2000; 20(4): 1201 - 1205. [Full Text] [PDF]
|
|
|
|
 |
|
 Risk for Pulmonary Embolism After Negative Helical CT Journal Watch (General), June 2, 2000; 2000(602): 4 - 4. [Full Text]
|
|
|
|
|
|
P. K. Woodard CT Scan Negative for Pulmonary Embolism: Where Do We Go from Here? Radiology, May 1, 2000; 215(2): 325 - 326. [Full Text]
|
|
|
|
|
|
V. Raptopoulos and P. M. Boiselle Multi-Detector Row Spiral CT Pulmonary Angiography: Comparison with Single-Detector Row Spiral CT Radiology, December 1, 2001; 221(3): 606 - 613. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
U. J. Schoepf, N. Holzknecht, T. K. Helmberger, A. Crispin, C. Hong, C. R. Becker, and M. F. Reiser Subsegmental Pulmonary Emboli: Improved Detection with Thin-Collimation Multi-Detector Row Spiral CT Radiology, February 1, 2002; 222(2): 483 - 490. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| RADIOLOGY | RADIOGRAPHICS | RSNA JOURNALS ONLINE |
