Martine Remy-Jardin

Pulmonary Embolism in Patients with Unexplained Exacerbation of Chronic Obstructive Pulmonary Disease: Prevalence and Risk Factors

Context Pulmonary embolism (PE) is common in patients with chronic obstructive pulmonary disease (COPD) exacerbations, and the 2 conditions present similarly. Content For 45 months, every patient presenting with severe COPD exacerbation of unknown cause received an evaluation for PE that included a spiral computed tomography scan and color Doppler ultrasonography of the legs. Twenty-five percent of 197 patients had PE. Malignant disease, history of thromboembolism, and a decrease in Paco 2 level relative to baseline were the only factors associated with PE. Cautions This was a single-center study. Implications We need additional studies to confirm the high prevalence of PE in unexplained severe exacerbations of COPD and to study the value of routine testing for PE in patients with this clinical presentation. The Editors The management of patients with suspected acute pulmonary embolism (PE) has greatly improved in recent years because of clinical assessment of the probability of PE, pretest probability, ultrasonography, ventilationperfusion scanning, and spiral computed tomography angiography (CTA) (1, 2). However, clinical diagnosis of acute PE is difficult in patients with chronic obstructive pulmonary disease (COPD). Pulmonary embolism resembles COPD exacerbation so closely that these 2 entities are often impossible to distinguish clinically (3). The reported incidence of PE in studies done postmortem of patients with COPD ranges from 28% to 51% (4, 5). Pulmonary embolism is known to increase the rate of death from COPD at 1 year (6), but the clinical probability of PE and the value of noninvasive tests to rule out the diagnosis in patients with COPD have not yet been clearly assessed. To date, 2 studies have evaluated PE in patients with this disorder (3, 7). In the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study, Lesser and colleagues (3) examined the characteristics of 108 patients with COPD and suspected PE; 21 (19%) received diagnoses of PE by pulmonary angiography. In this population, risk factors, symptoms, and arterial blood gas values were similar in patients with and without PE. The second study (7) showed that the presence of COPD does not affect the diagnostic performance of d-dimer testing, CTA, or pulmonary angiography for PE (7). The true frequency of PE in patients with COPD in whom PE is clinically suspected ranges from 19% to 29% (3, 7-9). Thus, clinical detection of PE in these patients is particularly difficult. In this study, we prospectively evaluated PE in patients with COPD exacerbation of unknown origin and examined factors associated with the presence of PE, including the Geneva score (1). Methods Study Objectives The objectives of our study were to assess the presence of PE in patients with COPD exacerbation of unknown origin and to explore factors associated with the presence of PE, including the Geneva score. Study Group Between April 1999 and December 2002, all consecutive patients with COPD referred to the Lung Department at the 59-bed Lille University Hospital for severe exacerbation of unknown origin were assessed for PE. Chronic obstructive pulmonary disease was diagnosed and its severity was determined according to the criteria of the American Thoracic Society (10). All patients smoked or were former smokers. Patients with asthma were not included in the study. Severe exacerbation was defined as acute deterioration from a stable condition that required hospitalization. The absence of a lower respiratory tract infection (increased sputum volume and/or increased sputum purulence, fever, history of cold, and sore throat); absence of pneumothorax and iatrogenic intervention; presence of parenchymal condensation without fever and chills; or presence of a discrepancy between clinical and radiologic features and hypoxemia severity classified the exacerbation as of unknown origin. Physicians were required to discuss each case of COPD with 1 of the referring physicians. Patients requiring invasive mechanical ventilation were referred to the intensive care unit and were not included in the study. Intervention All patients were examined within 48 hours of admission to the hospital and had spiral CTA of pulmonary circulation and color Doppler and venous lower-limb ultrasonography. These are the first-line diagnostic tests for acute PE at our institution. The decision to perform additional examinations, including d-dimer determination and ventilationperfusion scanning, was left to the discretion of the attending physician. Our local ethics committee approved the study protocol, which did not require informed patient consent. Spiral CTA In 1999, spiral CTA of pulmonary circulation was performed with a Somatom Plus 4A (Siemens Medical Systems, Forchheim, Germany) using a collimation of 3 mm3 mm, a pitch of 2, and a scanning time of 0.75 second per revolution. The results were read during the clinical work-up as previously described (9, 11-13). Because the equipment at our institution was upgraded during this study, spiral CTA of pulmonary circulation between January 2000 and December 2002 was performed with a multislice spiral computed tomography (CT) scanner, using a collimation of 4 mm1 mm, a pitch of 2, and a rotation time of 0.5 second. All patients with negative results on spiral CTA had a 3-month follow-up visit after inclusion in the study to assess critical events that were potentially related to PE. A chest physician reported death, subsequent admission to the hospital, new symptoms, and use of anticoagulant medications. Ultrasonography Venous compression ultrasonography of both legs was done from the common femoral vein and including the calf vein. Lack of compressibility was considered to indicate deep venous thrombosis. Definition Patients were classified as PE positive (positive results on spiral CTA or negative results on spiral CTA and positive results on ultrasonography) or PE negative (negative results on spiral CTA and negative results on ultrasonography or negative results on spiral CTA and no recurrence of PE at follow-up 3 months later). Assessment of the Geneva Score Because the Geneva score (1) was published by the time our study ended in 2001, we evaluated this score a posteriori in our sample before reviewing the data on PE. The probability of PE was expressed as low (a score 4), intermediate (a score of 5 to 8), or high (a score 9) (Table 1) (1). Table 1. The Geneva Score and the Modified Geneva Score Statistical Analysis Statistical analysis was done by using Epi Info software, version 3.3.2 (Centers for Disease Control and Prevention, Atlanta, Georgia), and CIs were calculated with StatExact and Stata, version 7 (Stata Corp., College Station, Texas). We calculated risk ratios and exact CIs for the various risk factors and clinical symptoms and determined P values using the Fisher exact test. A P value less than 0.05 indicated statistical significance. Role of the Funding Source No funding was received for this study. Results Study Group A total of 211 consecutive patients with COPD were referred for severe exacerbation of unknown origin. Fourteen patients were not included in the study because the results of the spiral CTA and ultrasonography were inconclusive (8 patients) or because of iodine intolerance (6 patients). Thus, the study group included 197 patients with COPD and severe exacerbation of unknown origin. There were 165 men and 32 women, and their mean age was 60.5 years (SD, 12.1). A total of 136 patients (69%) were referred from the emergency department, and 61 (31%) were inpatients who developed severe exacerbation while hospitalized. Arterial blood gas values on room air were 61.9 mm Hg (SD, 10.9) for Pao 2 and 42 mm Hg (SD, 9) for Paco 2. The mean number of risk factors for PE per patient was 0.87 (SD, 0.7). In 160 of the 197 study patients, results of a pulmonary function test performed within 3 months of the severe exacerbation were available. The mean FEV1 was 1.56 L (SD, 0.6), 52% (SD, 19%) of the predicted value. The mean FEV1vital capacity ratio was 56.4% (SD, 14.8%). The severity of respiratory disease was assessed according to the criteria of the American Thoracic Society (10): grade I, FEV1 greater than 50% of the predicted value (66 patients [41%]); grade II, FEV1 between 35% and 50% of predicted (67 patients [42%]); and grade III, FEV1 less than 35% of predicted (27 patients [17%]). Forty-nine (25%) patients were receiving long-term oxygen therapy. Pulmonary Embolism All patients had spiral CTA (37 patients had a single-slice CT scan, and 160 had a multislice CT scan), and 180 had venous ultrasonography (Table 2). None of the 197 study patients were thought to have clinical recurrence of PE during the 3 months of follow-up. Forty-three patients had positive results on CT. Twenty-five patients had deep venous thrombosis on ultrasonography; of these patients, 6 had negative results on spiral CTA. Nineteen (44%) of the 43 patients with positive results on spiral CTA also had positive results on ultrasonography. One hundred forty-eight patients did not have PE, on the basis of negative results on CT and ultrasonography and negative findings at 3-month follow-up. Thus, the prevalence of PE in our study group was 49 of 197 patients (25% [95% CI, 19% to 32%]). Table 2. Results of Spiral Computed Tomography Angiography in Patients Initially Referred for Suspected Acute Pulmonary Embolism Clinical Characteristics according to the Presence or Absence of Pulmonary Embolism The 49 patients with COPD who had PE did not differ statistically significantly from the 148 patients with COPD who did not have PE in terms of referral location (data not shown). We performed a bivariate analysis of baseline characteristics (Table 3) and clinical characteristics at admission (Table 4) that were potentially associated with PE. Clinical symptoms, such as change in dyspnea, pleuritic pain, hemoptysis, tachycardia (pulse rate >100 beats/m

Chest computed tomography using iterative reconstruction vs filtered back projection (Part 2): image quality of low-dose CT examinations in 80 patients

PurposeTo evaluate the image quality of an iterative reconstruction algorithm (IRIS) in low-dose chest CT in comparison with standard-dose filtered back projection (FBP) CT.Materials and methodsEighty consecutive patients referred for a follow-up chest CT examination of the chest, underwent a low-dose CT examination (Group 2) in similar technical conditions to those of the initial examination, (Group 1) except for the milliamperage selection and the replacement of regular FBP reconstruction by iterative reconstructions using three (Group 2a) and five iterations (Group 2b).ResultsDespite a mean decrease of 35.5% in the dose-length-product, there was no statistically significant difference between Group 2a and Group 1 in the objective noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and distribution of the overall image quality scores. Compared to Group 1, objective image noise in Group 2b was significantly reduced with increased SNR and CNR and a trend towards improved image quality.ConclusionIterative reconstructions using three iterations provide similar image quality compared with the conventionally used FBP reconstruction at 35% less dose, thus enabling dose reduction without loss of diagnostic information. According to our preliminary results, even higher dose reductions than 35% may be feasible by using more than three iterations.

Chest computed tomography using iterative reconstruction vs filtered back projection (Part 1): evaluation of image noise reduction in 32 patients

ObjectiveTo assess noise reduction achievable with an iterative reconstruction algorithm.Methods32 consecutive chest CT angiograms were reconstructed with regular filtered back projection (FBP) (Group 1) and an iterative reconstruction technique (IRIS) with 3 (Group 2a) and 5 (Group 2b) iterations.ResultsObjective image noise was significantly reduced in Group 2a and Group 2b compared with FBP (p < 0.0001). There was a significant reduction in the level of subjective image noise in Group 2a compared with Group 1 images (p < 0.003), further reinforced on Group 2b images (Group 2b vs Group 1; p < 0.0001) (Group 2b vs Group 2a; p = 0.0006). The overall image quality scores significantly improved on Group 2a images compared with Group 1 images (p = 0.0081) and on Group 2b images compared with Group 2a images (p < 0.0001). Comparative analysis of individual CT features of mild lung infiltration showed improved conspicuity of ground glass attenuation (p < 0.0001), ill-defined micronodules (p = 0.0351) and emphysematous lesions (p < 0.0001) on Group 2a images, further improved on Group 2b images for ground glass attenuation (p < 0.0001), and emphysematous lesions (p = 0.0087).ConclusionCompared with regular FBP, iterative reconstructions enable significant reduction of image noise without loss of diagnostic information, thus having the potential to decrease radiation dose during chest CT examinations.

CT angiography of pulmonary embolism in patients with underlying respiratory disease: impact of multislice CT on image quality and negative predictive value

Abstract. Our objective was to evaluate the impact of multislice CT (MSCT) on image quality and diagnostic value of spiral CT angiograms. Over an 8-month period (January 2000 to August 2000), 134 consecutive patients, including 55 patients with underlying lung disease, underwent MSCT (group 1). Image quality and diagnostic results of CT angiograms were compared with those obtained in 125 consecutive patients, including 58 patients with underlying lung disease, evaluated with thin-collimation single slice CT (SSCT; group 2) over a similar period of time (January 1999 to August 1999). A 3-month clinical follow-up was systematically obtained in all patients who were not anticoagulated in the two groups. For a significantly longer mean z-axis coverage, the mean duration of data acquisition was significantly shorter with MSCT. The frequency of examinations devoid of motion artifacts was significantly higher in group 1 than in group 2. In the absence of significant difference in the quality of vascular enhancement, mainly coded as good or excellent, the proportion of examinations interpretable down to the subsegmental arteries was higher in group 1 (57.5%) than in group 2 (13%) (p<0.0001). The benefits of MSCT were more marked for patients with underlying respiratory disease and did not lead to a higher detection rate of peripheral pulmonary embolism. The negative predictive values of single-slice and multislice CT were 100 and 99%, respectively. Improvement in image quality on MSCT scans accounts for the improved diagnostic accuracy of CT angiography, in particular for patients with impaired respiratory function.

Interobserver Variability in the CT Assessment of Honeycombing in the Lungs

PURPOSE To quantify observer agreement and analyze causes of disagreement in identifying honeycombing at chest computed tomography (CT). MATERIALS AND METHODS The institutional review board approved this multiinstitutional HIPAA-compliant retrospective study, and informed patient consent was not required. Five core study members scored 80 CT images with a five-point scale (5 = definitely yes to 1 = definitely no) to establish a reference standard for the identification of honeycombing. Forty-three observers from various subspecialties and geographic regions scored the CT images by using the same scoring system. Weighted κ values of honeycombing scores compared with the reference standard were analyzed to investigate intergroup differences. Images were divided into four groups to allow analysis of imaging features of cases in which there was disagreement: agreement on the presence of honeycombing, agreement on the absence of honeycombing, disagreement on the presence of honeycombing, and other (none of the preceding three groups applied). RESULTS Agreement of scores of honeycombing presence by 43 observers with the reference standard was moderate (Cohen weighted κ values: 0.40-0.58). There were no significant differences in κ values among groups defined by either subspecialty or geographic region (Tukey-Kramer test, P = .38 to >.99). In 29% of cases, there was disagreement on identification of honeycombing. These cases included honeycombing mixed with traction bronchiectasis, large cysts, and superimposed pulmonary emphysema. CONCLUSION Identification of honeycombing at CT is subjective, and disagreement is largely caused by conditions that mimic honeycombing.

Multiplanar and three-dimensional reconstruction techniques in CT: impact on chest diseases

Abstract. The purpose of this review is to capture the current state-of-the art of the technical aspects of multiplanar and three-dimensional (3D) images and their thoracic applications. Planimetric and volumetric analysis resulting from volumetric data acquisitions obviates the limitations of segmented transverse images. Among the 3D reconstruction techniques currently available, the most recently introduced technique, i. e., volume rendering, has to be evaluated in comparison with 3D shaded surface display and maximum or minimum intensity projection. Slabs are useful in detecting and localizing micronodular or microtubular patterns and in analyzing mild forms of uneven attenuation of the lungs. Three-dimensional angiography is helpful in the pretherapeutic evaluation and posttreatment follow-up of pulmonary arteriovenous malformations, in the comprehension of the postoperative reorientation of the pulmonary vessels, in the surgical planning of pulmonary tumors, and in the diagnosis of marginated thrombi. The systemic supply to the lung and superior vena cava syndromes are also relevant to these techniques. In acquired or congenital tracheobronchial diseases including stenosis, extraluminal air and complex airway anatomy, multiplanar and 3D reformations have a complementary role to both transaxial images and endoscopy. New developments are also expected in various topics such as 3D conformal radiation therapy, planning of intraluminal bronchoscopic therapy, virtual endoscopy, and functional imaging of the bronchial tree. Miscellaneous clinical applications are promising in the analysis of diaphragmatic morphology and pathophysiology, in the volumetric quantification of the lung parenchyma, and in the vascular components of the thoracic outlet syndromes.

Computed tomography assessment of ground-glass opacity: semiology and significance.

Among the computed tomography (CT) signs of parenchymal lung disease, the ground-glass pattern is the one most difficult to diagnose and most influenced by CT technique. Ground-glass opacity may result from changes in the airspaces or interstitial tissues in acute or chronic infiltrative lung disease. It may also be seen as a consequence of increased capillary blood volume in redistribution of blood flow due to airway disease, emphysema, or pulmonary thromboembolism. Definition of this sign on high-resolution CT (HRCT) images, its various HRCT patterns, and potential pitfalls in its recognition are described with special attention to optimal HRCT technique.

Pulmonary function tests and high resolution computed tomography of the lungs in patients with rheumatoid arthritis

OBJECTIVE To compare the results of pulmonary function tests (PFTs) and high resolution computed tomography (HRCT) of the lungs in rheumatoid arthritis (RA) patients. METHODS Sixty eight patients (54 women, 14 men) fulfilling the revised criteria for RA were consecutively included in a transversal prospective study. Their mean age was 58.8 years (range: 35–82) and the mean duration of the disease was 12 years (range: 5–16). Rheumatoid factor was positive in 52 patients (76.5%). Fifty two patients (76.5%) were lifelong non-smokers. Detailed medical and drug histories were obtained. PFTs comprised spirometry and gas transfer measurements. Results for PFTs were expressed as percentage of predicted values for each individual adjusted for age, sex, and height. HRCT was undertaken with a Siemens Somatom Plus. RESULTS A significant decrease of FEV1/FVC, FEF25%, FEF50%, FEF75%, FEF25–75%, and TLCO was observed (p<0.05) and 13.2% of the patients had a small airways involvement defined by a decrease of FEF25–75% below 1.64 SD. The most frequent HRCT findings were: bronchiectasis (30.5%), pulmonary nodules (28%), and air trapping (25%). The patients with small airways involvement had a high frequency of recurrent bronchitis (75% v 34%, p=0.05) and bronchiectasis (71% v 23%, p=0.019). The patients with bronchiectasis were characterised by low values of FEV1, FVC, FEF25–75%, and TLCO (p<0.01), a high prevalence of small airways involvement (29% v 5%, p=0.019), and a low prevalence of HLA DQA1 *0501 allele (14% v 33%, p<0.05). CONCLUSION This study suggests a significant association between small airways involvement on PFTs and bronchiectasis on HRCT in unselected RA patients.

Use of high resolution computed tomography of the lungs in patients with rheumatoid arthritis.

OBJECTIVE--To assess the usefulness of high resolution computed tomography (HRCT) of the lungs in patients with rheumatoid arthritis (RA) with and without respiratory symptoms. PATIENTS AND METHODS--Eighty eight RA patients with a mean duration of disease 12 (SD 8) years were evaluated. Eleven patients were excluded because of previous exposure to silica. The 77 remaining patients formed two groups according to the absence (group I, n = 38) or the presence (group II, n = 39) of chronic respiratory symptoms. A control group consisted of 51 non-smoking, healthy patients. RESULTS--The most frequent abnormalities observed in the 77 RA patients were bronchiectasis or bronchiolectasis (n = 23, 30%), pulmonary nodules (n = 17, 22%), subpleural micronodules or pseudoplaques (n = 13, 17%), ground glass opacities (n = 11, 14%), and honeycombing (n = 8, 10%). Bronchiectasis or bronchiolectasis (p = 0.012), rounded opacities (p = 0.016), ground glass attenuation (p = 0.004), and honeycombing (p = 0.002) were found more often in RA group II (with respiratory symptoms) than in group I (no respiratory symptoms). Non-linear septal opacities were more frequent in group I than in the control group, but other HRCT findings did not differ statistically significantly between group I and the control group. CONCLUSION--Bronchiectasis may be a characteristic lung change in RA patients. Abnormalities on HRCT are less frequently observed in the absence of respiratory symptoms than in the presence of such symptoms (29% versus 69%).

Spectral Optimization of Chest CT Angiography with Reduced Iodine Load: Experience in 80 Patients Evaluated with Dual-Source, Dual-Energy CT

PURPOSE To determine the energy levels that provide optimal imaging of thoracic circulation at dual-energy computed tomographic (CT) angiography with reduced iodine load in comparison with a standard technique. MATERIALS AND METHODS The institutional review board approved the study with waiver of patient consent. Eighty patients underwent a dual-source, dual-energy CT examination after administration of low-concentration contrast material (170 mg of iodine per milliliter), and eight series of images were reconstructed, including the original polychromatic images at 80 and 140 kV and six series of virtual monochromatic spectral images at 50, 60, 70, 80, 90, and 100 keV. For each vascular compartment, the energy level that provided optimal evaluation on virtual monochromatic spectral images was determined, and these series were compared with the polychromatic dual-energy images and with standard chest CT images that were used as controls. Comparisons between groups were performed by using the paired Student t test for continuous variables and the McNemar test for categorical variables. Comparisons between dual-energy and standard CT images were performed by using the unpaired Student t test for continuous variables and the χ(2) test for categorical variables. RESULTS For the aorta, pulmonary arteries, and veins, the reconstruction at 60 keV provided adequate attenuation without marked beam-hardening artifacts in 90% of patients, with the highest contrast-to-noise and signal-to-noise ratios, the lowest level of subjective noise, and no significant differences with images at 80 kV (mean energy, 54 keV). For the superior vena cava and brachiocephalic veins, the reconstructions at 100 keV enabled artifact-free analysis of the perivascular anatomic zone without a significant difference with images at 140 kV (mean energy, 92 keV). Compared with standard CT images acquired after administration of a 35% iodinated contrast agent, there was a statistically significant reduction in the frequency of artifacts around systemic veins at 100 keV (P < .001) and similar overall image quality for central vessels at 60 keV (P > .05). CONCLUSION An optimal analysis of thoracic circulation can be achieved on virtual monochromatic spectral images at 60 keV and 100 keV and on the original polychromatic images at 80 kV and 140 kV. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120195/-/DC1.