[CT Scan in early detection of lung cancer in patients with chronic obstructive pulmonary disease : a retrospective monocentric study]

OBJECTIVE

To explore the possible benefit of detecting lung cancer in COPD patients and to assess the pulmonologist's compliance with the Fleischner Society guidelines for management of pulmonary nodules.

METHODS

This monocentric retrospective study was approved by the institutional ethical Committee. Patients with COPD undergoing a CT scan between January 2010 and March 2017 were included. Depending on CT indication (respectively screening or other indications), patients were divided into Group 1 and 2. Follow-up intervals were compared to those recommended in the Fleischner Society guidelines. Data were compared between groups using Chisquared test, Student test, or Wilcoxon test when appropriate.

RESULTS

254 patients were included (134 in Group 1 and 120 in Group 2). 235 opacities were found in 119 patients (47 %). 13 among 254 patients had a lung cancer; 9 in Group 1 (6.7 %) and 4 in Group 2 (3.3 %). The median follow-up by CT after nodule detection was six months regardless of their diameter or attenuation. No statistical significance was found between the observed follow-up and recommendations (P = 0.058).

CONCLUSION

COPD in patients with a history of smoking is associated with a higher CT detection rate of lung cancer. This finding may be useful when evaluating selection criteria in lung screening programs. In contrast with the recommendations, CT detected nodules are followed-up regardless of their diameter and attenuation.

Low Grade Coal Worker's Pneumoconiosis

We compared CT with chest radiography (CR) in the assessment of low grade coal worker's pneumoconiosis (CWP) in a population of 83 subjects. All subjects had a high-voltage p.a. CR, graded according to the ILO classification between 0/0 and 1/1, a conventional CT (CCT) using contiguous 1-cm-thick sections on the entire thorax and a set of 10 high-resolution CT (HRCT) images. CR and CT were separately read by consensus by 2 teams of 2 trained readers. CR were coded 0/0 in 9 subjects; 0/1 in 31; 1/0 in 28; 1/1 in 15. Among these groups of patients, micronodules were detected by CT in respectively 2 (22%), 14 (45%), 17 (61%) and 10 (67%) patients. In all groups, micronodules were more often detected by CT when the opacities detected on CR were scored as rounded (p, q) than irregular (s, t). Among the patients graded 0/0 or 0/1, CT showed micronodules in 40%. By contrast, among the patients graded 1/0 or 1/1, CT did not show micronodules in 37%, but revealed in numerous patients that opacities detected on CR were related to bronchiectasis and/or emphysema only. Comparative analysis of HRCT and CCT showed that both techniques are complementary and proved the usefulness of CCT in the detection or confirmation of low profusion of micronodules.

Conventional and High-Resolution CT in Asymptomatic Asbestos-Exposed Workers

To compare the value of conventional CT (CCT) and high-resolution CT (HRCT) to detect benign asbestos-related diseases, 159 exposed workers with a normal chest radiography were imaged by both techniques. Pleural plaques were detected in a total of 59 cases (37.1%). Ten cases (16.9%) were detected by CCT only and one case (1.7%) by HRCT only. Pulmonary lesions compatible with parenchymal asbestosis were detected by HRCT in 20 cases, whereas CCT showed abnormalities in 45% of these. Rounded atelectasis was equally recognized by both techniques. The results confirm that in a subject with a normal chest radiography, HRCT is a better diagnostic tool to demonstrate lesions of asbestosis. On the other hand, HRCT is insufficient to exclude the presence of pleural plaques. When HRCT does not reveal pleural abnormalities, CCT should be performed.

Value of the "spine sign" on lateral chest views

OBJECTIVE

To determine the performance of the spine sign in detecting lower chest abnormalities in the lateral view.

METHODS

This retrospective study included 200 patients who had undergone lateral view and CT scans of the chest within 1 week. Two radiologists independently read the lateral views, and a third radiologist, blinded to the aim of the study, read the scans. The spine sign was considered as positive if the progressive increase in lucency of the vertebral bodies was altered. Interreader agreement was calculated through k-statistics. Sensitivity, specificity, positive- and negative-predictive values, and accuracy were calculated compared with CT.

RESULTS

Agreements between readers ranged from 0.12 to 0.68. Positive spine sign could appear in two ways: absent or inversed progressive increase in lucency of the vertebral bodies. Sensitivity, specificity, positive- and negative-predictive values, and accuracy were, respectively, 60% and 70%; 64% and 84%; 91% and 97%; 19% and 29%; and 61% and 72% for each reader (p-value ranging from 0.026 to 0.196). Abnormalities most frequently associated with positive spine sign were plate-like atelectasis, ground-glass opacity, pleural effusion and consolidation.

CONCLUSION

The spine sign can present as an absent or inversed progressive increase in lucency of the vertebral bodies. It has a moderate sensitivity but a good positive-predictive value, so it can be useful especially when it appears as inversed progressive increase in lucency of the vertebral bodies to detect various abnormalities usually identifiable on chest radiographs.

ADVANCES IN KNOWLEDGE

On lateral chest radiographs, the spine sign is useful to detect lower chest abnormalities and is related to various underlying abnormalities and is, per se, non-specific.

Tuning of automatic exposure control strength in lumbar spine CT

OBJECTIVE

To investigate the impact of tuning the automatic exposure control (AEC) strength curve (specific to Care Dose 4D®; Siemens Healthcare, Forchheim, Germany) from "average" to "strong" on image quality, radiation dose and operator dependency during lumbar spine CT examinations.

METHODS

Two hospitals (H1, H2), both using the same scanners, were considered for two time periods (P1 and P2). During P1, the AEC curve was "average" and radiographers had to select one of two protocols according to the body mass index (BMI): "standard" if BMI <30.0 kg m(-2) (120 kV-330 mAs) or "large" if BMI >30.0 kg m(-2) (140 kV-280 mAs). During P2, the AEC curve was changed to "strong", and all acquisitions were obtained with one protocol (120 kV and 270 mAs). Image quality was scored and patients' diameters calculated for both periods.

RESULTS

497 examinations were analysed. There was no significant difference in mean diameters according to hospitals and periods (p > 0.801) and in quality scores between periods (p > 0.172). There was a significant difference between hospitals regarding how often the "large" protocol was assigned [13 (10%)/132 patients in H1 vs 37 (28%)/133 in H2] (p < 0.001). During P1, volume CT dose index (CTDIvol) was higher in H2 (+13%; p = 0.050). In both hospitals, CTDIvol was reduced between periods (-19.2% in H1 and -29.4% in H2; p < 0.001).

CONCLUSION

An operator dependency in protocol selection, unexplained by patient diameters or highlighted by image quality scores, has been observed. Tuning the AEC curve from average to strong enables suppression of the operator dependency in protocol selection and related dose increase, while preserving image quality.

ADVANCES IN KNOWLEDGE

CT acquisition protocols based on weight are responsible for biases in protocol selection. Using an appropriate AEC strength curve reduces the number of protocols to one. Operator dependency of protocol selection is thereby eliminated.

Reduced z-axis coverage in multidetector-row CT pulmonary angiography decreases radiation dose and diagnostic accuracy of alternative diseases

OBJECTIVE

To investigate the effect of a two-third reduction of the scanned length (i.e. 10 cm) on diagnosis of both pulmonary embolism (PE) and alternative diseases.

METHODS

247 consecutive patients suspected of acute PE had a CT pulmonary angiography (CTPA) of the thorax (standard length, L). Based on this acquisition, a second set of images was created to obtain a scan length of 10 cm caudally to the aortic arch (l). Images were anonymized, randomized and interpreted by two independent readers. The quality of enhancement, the presence of PE and the possible alternative and/or complementary diagnoses were recorded. A McNemar exact test investigated differences in discrepancies between readers and between scan lengths.

RESULTS

57 (23%) patients had an acute PE. Among l sets, PE was missed by both readers in one (1.8%) patient, because the unique clot was localized in a subsegmental artery out of the 10-cm range. There were discrepancies between L and l sets in 9 (3.6%) and 11 (4.5%) patients, by Readers 1 and 2 (p=0.820), respectively. Discrepancies between the readers of L sets and those between both sets were not different regardless of the reader (p>0.99). There were discrepancies between both sets for alternative and/or complementary diagnoses in 43 (17.2%) patients.

CONCLUSION

Although its performance in diagnosing PE is maintained, CTPA should not be restricted to a range of 10 cm centred over the pulmonary hilum, because alternative and/or complementary diagnoses could be missed.

ADVANCES IN KNOWLEDGE

(1) A 10-cm CTPA acquisition reduces the radiation dose by two-thirds as compared with a standard one, but does not impair the accuracy for the diagnosis of PE. (2) Significant alternative diagnoses are missed in 17.2% of patients when reducing the acquisition height to 10 cm.

Optimised z-axis coverage at multidetector-row CT in adults suspected of acute appendicitis

OBJECTIVE

To compare diagnostic performances of two reduced z-axis coverages to full coverage of the abdomen and pelvis for the diagnosis of acute appendicitis and alternative diseases at unenhanced CT.

METHODS

This study included 152 adults suspected of appendicitis who were enrolled in two ethical committee-approved previous prospective trials. Based on scans covering the entire abdomen and pelvis (set L), two additional sets of images were generated, each with reduced z-axis coverages: (1) from the top of the iliac crests to the pubis (set S) and (2) from the diaphragmatic crus to the pubis (set M). Two readers independently coded the visualisation of the appendix, measured its diameter and proposed a diagnosis (appendicitis or alternative). Final diagnosis was based on surgical findings or clinical follow-up. Fisher exact and McNemar tests and logistic regression were used.

RESULTS

46 patients had a definite diagnosis of appendicitis and 53 of alternative diseases. The frequency of appendix visualisation was lower for set S than set L for both readers (89% and 84% vs 95% and 91% by Readers A and B, respectively; p=0.021 and 0.022). The probability of giving a correct diagnosis was lower for set S (68%) than set L (78%; odds ratio, 0.611; p=0.008) for both readers, without significant difference between sets L and M (77%, p=0.771); z-axis coverage being reduced by 25% for set M.

CONCLUSION

Coverage from diaphragmatic crus to pubis, but not focused on pelvis only, can be recommended in adults suspected of appendicitis.

ADVANCES IN KNOWLEDGE

In suspected appendicitis, CT-coverage can be reduced from diaphragmatic crus to pubis.

Relationship between the extent of deep venous thrombosis and the extent of acute pulmonary embolism as assessed by CT angiography

The aim of our study is to investigate prospectively the quantitative relationship between deep venous thrombosis (DVT) and acute pulmonary embolism (PE). 110 patients clinically suspected of having venous thromboembolic disease underwent combined CT pulmonary angiography (CTPA) and venography of lower limb veins. 44 patients presented with clinical signs of DVT and positive ultrasonography or ascending venography, but no clinical sign of PE (Group 1). 66 patients presented with clinical signs of PE and positive CTPA (Group 2). Clot load in lower limb veins and pulmonary arteries were scored by two independent readers, each using two separate systems for DVT and two for PE. 27 (61%) patients in Group 1 also had PE, and 55 (83%) patients in Group 2 also had DVT. Correlations between PE and DVT scores were weak but statistically significant in Group 2 (r(s) ranging from 0.470-0.520; p< or =0.001), but only some were significant in Group 1 (r(s) ranging from 0.253-0.318; p-values ranging from 0.035-0.097). In conclusion, although PE occurs in a majority of patients with DVT, and vice versa, the amount/burden of clot load in one condition does not necessarily indicate - or indicates only weakly - the degree of burden in the other condition.

Radiation dose in computed tomography of the chest

Since the beginning of the eighties, computed tomography (CT) has been more and more widely used as this technique provides precise anatomical details on the lungs, the mediastinum, and the chest wall. However, CT requires the use of ionizing radiations. The collective radiation from CT is therefore in constant increase. As evaluated on atomic bomb survivors, ionizing radiations increase the mortality by cancer. The risk is proportional to the dose and the dose related to CT is much higher than that related to a chest radiograph, both being in the field "of low-level radiations" a range of radiation dose from which no increase in cancer mortality could be demonstrated. This article outlines the risk estimation in the field of low-level radiations, the various methods to measure and estimate the radiation dose, the CT parameters influencing the radiation dose, dose comparisons between CT and most other imaging techniques of the chest, the newly developed so called "Low-Dose" CT techniques and highlights some of the unresolved questions related to radiation dose in clinical CT practice.

Computed tomography assessment of lung structure and function in pulmonary edema

By definition pulmonary edema is an abnormal accumulation of water in the lung. Consequently, the computed tomography (CT) appearance of pulmonary edema reflects the sequence of this accumulation. In early hydrostatic pulmonary edema, CT shows vascular engorgement and peribronchovascular cuffing that increases with the severity of edema and that is associate in late stage, with consolidations. In acute respiratory distress syndrome (ARDS), CT shows the proportion of injured parenchyma and depicts associated alterations as parenchymal infiltrate and consolidation, pleural effusion, pneumothorax. These merely morphological findings can be complemented with data from objective CT analysis of the lung parenchyma. Indeed CT can assess lung water noninvasively. Correlated with hydrodynamic parameter, these objective measurements show that the increase of lung density parallels parenchymal fluid overload. These data also show that the occurrence of ground glass opacities can precede the hemodynamic evidence of edema.

[The Erasme Foundation]

Created in 1982 to encourage the scientific research in the Erasme Hospital, the Erasme Foundation has founded 174 research grants, has financially supported the building of the Cellular and Molecular Therapy Unit, and has organized more than 60 lectures in various biomedical fields.

[The medical imaging and radiology department]

Technological developments arising from research have affected the whole wide spectrum of medical endeavor and have made a very significant impact on clinical practice and especially on imaging sciences. Ultrasonography brought spectacular advances, but CT and MRI became important landmark techniques. A further important development, which greatly increased the involvement of radiologists in direct patient management, was the growth of interventional and therapeutic techniques, called interventional radiology. Some statistics: approximately 155,000 patients per year including 19,000 CT Scans, 10,000 MRI exams, 21,000 ultrasound examinations and 1,000 therapeutic procedures. Some research activities: CT quantification of pulmonary emphysema, respiratory mechanics, MR and CT angiography, antenatal diagnosis of congenital and genetic diseases of the fetus, quantification of portal haemodynamics, MR imaging of bile and pancreatic ducts, morphologic and functional imaging of the brain, radiology of bone trauma, MR characterization in hepatic lesions.

[Bronchiolitis obliterans organizing pneumonia: eight cases and review of the literature]

Bronchiolitis obliterans and organizing pneumonia is characterized histologically by plugs of granulation tissue in terminal air spaces. Patients usually present with flu-like illness followed by cough, dyspnea and fever. The chest X-ray pattern is characterized by pneumonia like infiltrate which can migrate. Outcome is good with steroid treatment. The aim of this article is to define the clinical, biological, including bronchoalveolar lavage and radiological aspects of BOOP on the basis of 8 clinical cases. The pathophysiology, diagnosis methods and treatment of BOOP are also discussed.

Quantitative computed tomography assessment of lung structure and function in pulmonary emphysema

Accurate diagnosis and quantification of pulmonary emphysema during life is important to understand the natural history of the disease, to assess the extent of the disease, and to evaluate and follow-up therapeutic interventions. Since pulmonary emphysema is defined through pathological criteria, new methods of diagnosis and quantification should be validated by comparisons against histological references. Recent studies have addressed the capability of computed tomography (CT) to quantify pulmonary emphysema accurately. The studies reviewed in this article have been based on CT scans obtained after deep inspiration or expiration, on subjective visual grading and on objective measurements of attenuation values. Especially dedicated software was used for this purpose, which provided numerical data, on both two- and three-dimensional approaches, and compared CT data with pulmonary function tests. More recently, fractal and textural analyses were applied to computed tomography scans to assess the presence, the extent, and the types of emphysema. Quantitative computed tomography has already been used in patient selection for surgical treatment of pulmonary emphysema and in pharmacotherapeutical trials. However, despite numerous and extensive studies, this technique has not yet been standardized and important questions about how best to use computed tomography for the quantification of pulmonary emphysema are still unsolved.

Pulmonary lymphangiomyomatosis mimicking Langerhans cell histiocytosis

The authors describe a patient with histologically confirmed pulmonary lymphangiomyomatosis and thin-section computed tomography findings mimicking Langerhans cell histioctytosis. The description emphasizes the nonspecificity of the computed tomography findings in this patient. This report also suggests that the computed tomography diagnosis of lymphangioleiomyomatosis can be difficult at an early stage of the disease and should be complemented by biopsy verification.

Oleic Acid-induced Lung Injury: Thin-Section CT Evaluation in Dogs

PURPOSE

To validate lung attenuation measurements for quantifying extravascular lung water in oleic acid-induced pulmonary edema, compare subjective assessment with attenuation measurements, and compare this permeability-type pulmonary edema with hydrostatic-type pulmonary edema.

MATERIALS AND METHODS

Thin-section computed tomography (CT) and pulmonary hemodynamic examinations were performed sequentially in six dogs before and after intravenous administration of 0.08 mg of oleic acid per kilogram of body weight. Extravascular lung water and pulmonary capillary pressure were measured. Results were compared with those reported in a canine model of hydrostatic edema.

RESULTS

Oleic acid induced a progressive increase in extravascular lung water without a change in capillary pressure, which indicated pure permeability-type edema. Ground-glass opacification was detected as soon as extravascular lung water increased. Lung attenuation was highly correlated to extravascular lung water (r = 0.76, P<.001), as in hydrostatic edema, but was characterized by an almost absent gravitational gradient.

CONCLUSION

Thin-section CT is sensitive for early detection and quantification of oleic acid-induced pulmonary edema in a canine model. Different from early canine hydrostatic edema, which is characterized by a gravitational gradient, early oleic acid-induced pulmonary edema in a supine dog is characterized by nearly homogeneous distribution, except for ventral sparing.

The vacuum phenomenon: a CT sign of nonunited fracture

OBJECTIVE

The purpose of this study was to describe on CT scans the presence of a gas collection within a bone fracture reflecting the vacuum phenomenon as a sign of nonunited fracture.

CONCLUSION

A gas collection between fractured bone fragments suggests a nonunited fracture.

Observer variation in computed tomography of pleural lesions in subjects exposed to indoor asbestos

To assess the reliability of computed tomography (CT) in detecting discrete pleural lesions, the interobserver and intra-observer variability in reading the conventional and high-resolution CT (HRCT) scans of 100 volunteers, who had worked for > or = 10 yrs in a building with known asbestos contamination, was evaluated. In the first session, pleural abnormalities were detected by a single radiologist (A1) in 13 subjects. In the second session, the scans were read again independently by the same radiologist (A2) and two other experienced radiologists (B, C). The final decision for the presence of pleural lesions was made in a final consensus reading. This gave a diagnosis of pleural abnormalities in 18 subjects, of whom eight (44%) had been detected by all three readers, five (28%) by two readers and four (22%) by only one reader; one scan, rated normal by all readers during the second session, was reconsidered because pleural abnormalities had been noted at the first reading (A1). The intra-observer agreement for reader A was good (kappa (kappa) 0.68) but the interobserver agreement between the readers was only fair to moderate (weighted kappa: A2-B=0.43, A2-C = 0.45, B-C = 0.26) in the second reading session. In conclusion, when looking for the prevalence of pleural lesions in indoor asbestos exposed subjects, the potential lack of consistency in reporting the presence of small pleural abnormalities must be borne in mind and strict precautions must be taken.

Bronchiolitis obliterans syndrome in heart-lung transplant recipients: diagnosis with expiratory CT

PURPOSE

To determine the test performance and longitudinal evolution of air trapping for diagnosing bronchiolitis obliterans syndrome (BOS).

MATERIALS AND METHODS

Over 7 years, 111 combined inspiratory and expiratory computed tomographic examinations were performed in eight healthy control subjects and 38 heart-lung transplant recipients. Functional impairment was assessed with the BOS classification. Receiver operating characteristic (ROC) analysis was performed to determine the optimal threshold of air trapping to distinguish between patients with and those without BOS and to compute sensitivity and specificity for diagnosing BOS.

RESULTS

The extent of air trapping increased with BOS severity (P =.001). A threshold of 32% of air trapping is optimal for distinguishing between patients with and those without BOS and provides a sensitivity of 83%, a specificity of 89%, and an accuracy of 88%. The prevalence of BOS and positive predictive value of air trapping increased with postoperative time, but the negative predictive value of air trapping remained high throughout the study. Patients without BOS who had air trapping exceeding 32% of the parenchyma were at significantly increased risk of developing BOS (P =.004).

CONCLUSION

At the threshold of 32%, air trapping is sensitive, specific, and accurate for diagnosing BOS. Patients with air trapping below 32% are unlikely to have BOS. Air trapping exceeding 32% may be an early indicator of future BOS.

Respiratory effects of the external and internal intercostal muscles in humans

The current conventional view of intercostal muscle actions is based on the theory of Hamberger (1749) and maintains that as a result of the orientation of the muscle fibres, the external intercostals have an inspiratory action on the lung and the internal interosseous intercostals have an expiratory action. Recent studies in dogs, however, have shown that this notion is only approximate. In the present studies, the respiratory actions of the human external and internal intercostal muscles were evaluated by applying the Maxwell reciprocity theorem. Thus the orientation of the muscle fibres relative to the ribs and the masses of the muscles were first assessed in cadavers. Five healthy individuals were then placed in a computed tomographic scanner to determine the geometry of the ribs and their precise transformation during passive inflation to total lung capacity. The fractional changes in length of lines with the orientation of the muscle fibres were then computed to obtain the mechanical advantages of the muscles. These values were finally multiplied by muscle mass and maximum active stress (3.0 kg cm-2) to evaluate the potential effects of the muscles on the lung. The external intercostal in the dorsal half of the second interspace was found to have a large inspiratory effect. However, this effect decreases rapidly in the caudal direction, in particular in the ventral portion of the ribcage. As a result, it is reversed into an expiratory effect in the ventral half of the sixth and eighth interspaces. The internal intercostals in the ventral half of the sixth and eighth interspaces have a large expiratory effect, but this effect decreases dorsally and cranially. The total pressure generated by all the external intercostals during a maximum contraction would be -15 cmH2O, and that generated by all the internal interosseous intercostals would be +40 cmH2O. These pressure changes are substantially greater than those induced by the parasternal intercostal and triangularis sterni muscles, respectively.

The CT fallen-lung sign

On chest radiograph, the diagnosis of tracheobronchial tear is usually suspected because of the persistence of a pneumothorax after chest tube insertion. Since this radiographic pattern is nonspecific, the diagnosis is usually made by bronchoscopy and delayed. The fallen-lung sign consists in the fall of the collapsed lung away from the mediastinum occurring when the normal central bronchial anchoring attachment of the lung is disrupted. In contrast to the persistent pneumothorax, this sign is specific but rarely observed. Our purpose is to present the corresponding CT patterns observed in two cases of right stem bronchus tear, consisting in a caudal-dependent displacement of the right upper lobe bronchus which becomes obliquely oriented.

Diagnosis of saphenous coronary graft aneurysm by spiral computed tomography

We report two cases of coronary saphenous vein graft aneurysms diagnosed by spiral computed tomography.

[Quantitative computed tomography of pulmonary emphysema]

Computed tomography, and particularly high-resolution computed tomography, allows a detailed exploration of the pulmonary parenchyma. We discuss here work on the use of this technique in the diagnosis and quantification of pulmonary emphysema. We stress first the subjective quantification then the objective approach based on specific software. We summarize our work which has demonstrated. 1) that the relative surface with density below -950 Hounsfield units and measured on millimetric tomographic slices obtained at the end of maximal inspiration is a valuable measurement of the extent of the macroscopic emphysema and reflects the microscopic emphysema; 2) that subjective quantification overestimates minimally extensive emphysema and shows important intra- and inter-operator variability; 3) that indexes derived from computed tomographic images acquired at the end of expiration reflect more the obstructive syndrome than emphysematous destruction; 4) that age and the size of the lungs influence computed tomographic measurements while hyperinflation appears to have no effect. Finally, we present an example of recent work applying the computed tomographic technique.

Pulmonary emphysema: subjective visual grading versus objective quantification with macroscopic morphometry and thin-section CT densitometry

PURPOSE

To compare subjective visual grading of pulmonary emphysema with macroscopic morphometry and computed tomographic (CT) densitometry.

MATERIALS AND METHODS

In 62 consecutive patients who underwent thinsection CT before surgical lung resection, emphysema was objectively quantified with computer-assisted macroscopic morphometry and CT densitometry. The percentage of lung macroscopically occupied by emphysema was compared with the percentage occupied on CT scans by pixels with attenuation values lower than a predefined threshold (CT densitometry). Three readers with varying degrees of expertise subjectively graded emphysema with visual assessment at two reading sessions. Data from objective quantification and subjective grading were analyzed with correlation coefficients, and interobserver and intraobserver agreement were calculated.

RESULTS

Subjective grading of emphysema showed less agreement with the macroscopic reference standard results (r = 0.439-0.505; P < .05) than with objective CT densitometric results (r = 0.555-0.623; P < .001). The 95% CIs for the intercepts of the linear regression lines were suggestive of systematic subjective overestimation of emphysema by all three readers. Interobserver agreement was moderate (kappa = 0.431-0.589). Intraobserver agreement was good to excellent (kappa = 0.738-0.936). The expertise of individual readers did not substantially influence results.

CONCLUSION

Systematic overestimation and moderate interobserver agreement may compromise subjective visual grading of emphysema, which suggests that subjective visual grading should be supplemented with objective methods to achieve precise, reader-independent quantification of emphysema.

Diaphragm dimensions after single-lung transplantation for emphysema

We used three-dimensional reconstructions obtained with spiral computed tomography to measure total diaphragm surface area (Adi), and the surface area of the dome (Ado) and of the zone of apposition (Aap) of the diaphragm in nine patients with single-lung transplantation (SLT) for emphysema and nine normal subjects matched for age, sex, height, and weight. Measurements were obtained at supine FRC, midinspiratory capacity, and TLC. In the normal subjects, Ado and Adi were greater on the right than on the left side, and the right dome was positioned more cranially than the left one, presumably because of the presence of the liver. Compared with either the ipsilateral side in the controls or the native side in the patients, Ado was smaller on the transplanted side because the mediastinum was shifted toward the graft. Adi showed a similar trend. On the other hand, the radius of curvature of the dome in the coronal and sagittal planes was similar on the side of the graft and on the ipsilateral side in the controls. In conclusion, we found that after SLT for emphysema, diaphragm configuration comes back to normal but Ado, and with it Adi, remain smaller than in normal subjects because the mediastinum is displaced toward the graft.

Hydrostatic pulmonary edema: evaluation with thin-section CT in dogs

PURPOSE

To identify the hemodynamic determinants of ground-glass opacification on thin-section computed tomographic (CT) scans of hydrostatic pulmonary edema and to compare attenuation and subjective assessments of ground-glass opacification with extravascular lung water.

MATERIALS AND METHODS

Left atrial pressure, pulmonary arterial pressure, effective pulmonary capillary pressure, and extravascular lung water were measured in six dogs before and during progressive increase of effective pulmonary capillary pressure. A thin-section CT scan was obtained at each step. Lung attenuation and subjective assessments of ground-glass opacification were compared with hemodynamic variables and extravascular lung water.

RESULTS

Ground-glass opacification was identified when effective pulmonary capillary pressure equaled critical pulmonary capillary pressure. Extravascular lung water increased, and the distribution curve of lung attenuation coefficients shifted to higher attenuation from the second measurement at an effective pulmonary capillary pressure greater than the critical pulmonary capillary pressure. Attenuation was highly correlated (r = 0.98, P < .001) with extravascular lung water; ground-glass opacification was detected before a significant (P = .615, analysis of variance) increase in extravascular lung water.

CONCLUSION

Thin-section CT depicts ground-glass opacification when effective pulmonary capillary pressure equals critical pulmonary capillary pressure and before a detectable increase in extravascular lung water. Attenuation reflects extravascular lung water.

Volume of graft and native lung after single-lung transplantation for emphysema

To assess how the presence of the hyperinflated native lung influences the volume of the graft after single-lung transplantation (SLT) for emphysema, we used chest computed tomography to measure the TLC of each lung at a mean of 326 d before and 239, 588, and 932 d after SLT in nine patients. In addition, we obtained measurements of TLC and FRC in these nine patients plus one additional recipient at 697 d after surgery, and in 10 nonsmoking normal subjects matched for age, sex, height, and weight. On the nontransplanted side, TLC averaged 3.57 L before and 3.73 L, 3.70 L, and 3.73 L after SLT (NS). Corresponding values on the transplanted side were 3.42 L before and 2.06 L, 1.96 L, and 1.90 L after surgery, respectively (p < 0. 0002). Compared with the values obtained on the ipsilateral side in the control subjects, the FRC of the graft amounted to 100%, but its TLC was decreased to 79% (p < 0.005). We conclude that (1) the TLC of the graft and of the native lung do not change over time after SLT for emphysema, and (2) compared with the ipsilateral lung in normal control subjects, the TLC of the graft is substantially reduced, but its FRC is within normal limits.

Mechanical advantage of the human parasternal intercostal and triangularis sterni muscles

1. Previous studies in dogs have demonstrated that the maximum change in airway pressure (DeltaPao) produced by a particular respiratory muscle is the product of three factors, namely the mass of the muscle, the maximal active muscle tension per unit cross-sectional area ( approximately 3.0 kg cm-2), and the fractional change in muscle length per unit volume increase of the relaxed chest wall (i.e. the muscle's mechanical advantage). In the present studies, we have used this principle to infer the DeltaPao values generated by the parasternal intercostal and triangularis sterni muscles in man. 2. The mass of the muscles and the direction of the muscle fibres relative to the sternum were first assessed in six cadavers. Seven healthy individuals were then placed in a computed tomographic scanner to determine the orientation of the costal cartilages relative to the sternum and their rotation during passive inflation to total lung capacity. The fractional changes in length of the muscles during inflation, their mechanical advantages, and their DeltaPao values were then calculated. 3. Passive inflation induced shortening of the parasternal intercostals in all interspaces and lengthening of the triangularis sterni. The fractional shortening of the parasternal intercostals decreased gradually from 7.7 % in the second interspace to 2.0 % in the fifth, whereas the fractional lengthening of the triangularis sterni increased progressively from 5.9 to 13.8 %. These rostrocaudal gradients were well accounted for by the more caudal orientation of the cartilages of the lower ribs. 4. Since these fractional changes in length corresponded to a maximal inflation, the inspiratory mechanical advantage of the parasternal intercostals was only 2.2-0. 6 % l-1, and the expiratory mechanical advantage of the triangularis sterni was only 1.6-3.8 % l-1. In addition, whatever the interspace, parasternal and triangularis muscle mass was 3-5 and 1-3 g, respectively. As a result, the magnitude of the DeltaPao values generated by a maximal contraction of the parasternal intercostals or triangularis sterni in all interspaces would be only 1-3 cmH2O. 5. These studies therefore confirm that the parasternal intercostals in man have an inspiratory action on the lung whereas the triangularis sterni has an expiratory action. However, these studies also establish the important fact that the pressure-generating ability of both muscles is substantially smaller than in the dog.

Micronodules and emphysema in coal mine dust or silica exposure: relation with lung function

The aim of this study was to investigate the respective effects of micronodules and pulmonary emphysema, detected by computed tomography (CT), on lung function in workers exposed to silica and coal mine dust. Eighty-three subjects exposed to silica (n=35) or to coal mine dust (n=48), without progressive massive fibrosis, were investigated by high-resolution and conventional CT scans to detect micronodules and to quantify pulmonary emphysema by measuring the relative area of the lung with attenuation values lower than -950 Hounsfield units. Sixty-six (54.5%) subjects had evidence of micronodules on CT scans. Smokers had micronodules more rarely than nonsmokers. Significant correlations were found between the forced expiratory volume in one second (FEV(1); % predicted) (r=-0.41, p<0.001), FEV1/vital capacity (VC) (r=-0.61, p<0.001), diffusing capacity of the lung for carbon monoxide (DL,CO) (r=-0.36, p<0.001) and the extent of emphysema. No difference was demonstrated in the linear relationships between the extent of emphysema and the pulmonary function according to the type of exposure or the presence of micronodules on CT scans. This study suggests that micronodules detected by computed tomography have no influence, by themselves, on pulmonary function and that they should only be considered as a marker of exposure.

Role of the double-contrast barium enema in rectal stenosis due to suppositories containing paracetamol and acetylsalicylic acid

Self-treatment of chronic headache with suppositories containing paracetamol and acetylsalicylic acid may lead to serious complications. We report the radiological features of five cases of rectal stenosis following the use of such suppositories. The role of the double-contrast barium enema in suggesting the diagnosis of this complication of a chronic and often unrecognized self-treatment is emphasized.

Helical CT of aorta after endoluminal stent-graft therapy: value of biphasic acquisition

OBJECTIVE

We report our prospective study evaluating biphasic helical CT of the aorta after endoluminal stent-graft placement.

SUBJECTS AND METHODS

Biphasic helical CT scans in 95 patients with abdominal and thoracic aortic aneurysms who had undergone endoluminal stent-graft placement were reviewed. After a test bolus injection of 15 ml of contrast media at a rate of 3.5 ml/sec for the measurement of the optimal start delay, the aorta was scanned using the following parameters: collimation of 5 mm, table speed of 7 mm per rotation, tube rotation time of 0.75 sec, 120 kV, and 295 mA. A delayed helical CT scan was obtained 15 sec after the initial acquisition using the same parameters.

RESULTS

Biphasic helical CT scans showed perigraft leakage in 45 (47%) of 95 patients. Leakage was shown only on arterial phase CT in eight patients and only on the delayed scans in three patients. In two patients, leakage shown on the delayed acquisition was retrospectively seen on the first scan. Leakage and outflow vessels were most visible on the arterial phase acquisition in 17 patients and on the second acquisition in six patients. Overall, biphasic acquisition was superior to arterial phase acquisition alone in 15 (16%) of 95 patients.

CONCLUSION

The diagnostic value of biphasic helical CT is superior to arterial phase acquisition alone for the evaluation of the aorta after endoluminal stent-graft therapy.

Asbestosis, pleural plaques and diffuse pleural thickening: three distinct benign responses to asbestos exposure

The aim of this study was to investigate by computed tomography (CT) whether asbestosis, diffuse pleural thickening and/or pleural plaques are statistically associated. We also tried to find criteria to differentiate between diffuse and circumscribed pleural thickening. From 231 exposed workers, only those subjects whose radiograph showed neither bilateral calcified pleural plaques nor small pulmonary opacities higher than 1/1 grade according to the 1980 International Labour Office (ILO) Classification were considered. Scans were assessed for the presence of subpleural curvilinear lines, septal and intralobular lines, parenchymal bands, honeycombing, rounded atelectasis, pleural plaques and diffuse pleural thickening. CT scans revealed pleural and/or lung abnormalities in 99 workers. Pleural plaques were unilateral in one-third of cases with plaques. Diffuse pleural thickening, parenchymal bands and rounded atelectasis were unilateral in, respectively, 62 and 69 and 75% of cases with the abnormality. Septal and intralobular lines, and honeycombing were always bilateral. CT signs could be grouped into three patterns: 1) septal and intralobular lines, and honeycombing corresponding to pulmonary fibrosis; 2) pleural plaques corresponding to parietal pleural fibrosis; and 3) diffuse pleural thickening, rounded atelectasis and parenchymal bands corresponding to visceral pleural fibrosis. In these workers with a normal or near-normal radiograph, three groups of subjects with different responses were distinguished. Crow's feet and rounded atelectasis help to differentiate plaques from diffuse thickening.

Pericardial effusion associated with asbestos exposure

The case history is presented of a 60 year old man who developed a pericardial effusion. Chest radiography showed pleural thickening and calcification. Pericardiotomy was performed and revealed nonspecific inflammatory lesions. Occupational exposure to asbestos and exclusion of other causes led to the diagnosis of benign asbestos pericardial effusion.

Pleural effusion during bromocriptine exposure in two patients with pre-existing asbestos pleural plaques: a relationship?

Two patients with pleural plaques developed pleural effusion and subsequent diffuse pleural fibrosis 50 and 39 yrs after their first exposure to asbestos. The diagnosis of benign asbestos pleural effusion was suggested, but the work-up finally suggested bromocriptine-induced pleural disease in both patients. These two cases illustrate that drug-induced pleural effusion is an important differential diagnosis of benign asbestos pleural effusion. It is, moreover, possible that pre-existing asbestos pleural lesions, or even asbestos exposure, increases the risk of developing bromocriptine-induced pleural disease.

Effect of chronic hyperinflation on diaphragm length and surface area

We have used three-dimensional reconstructions obtained with spiral computed tomography to measure total diaphragm length (Ldl) and surface area (Adl), the length (Ldo) and surface area (Ado) of the dome, and the length (Lap) and surface area (Aap) of the zone of apposition in 10 hyperinflated patients with severe chronic obstructive pulmonary disease, or COPD (FEV1 = 27% predicted: FRC = 225% predicted) and 10 normal subjects matched for age, sex, and height. Measures of Ldl, Adl, Lap, and Aap decreased linearly between FRC and TLC in the two groups, but Ldo and Ado did not change. On average, patients' Adl and Aap at FRC were reduced to 73% and 54% of normal values, whereas Ado was unaffected. When compared at similar absolute lung volumes, mean diaphragm dimensions were similar in patients with COPD and normal subjects, but individual values were very variable in both groups. This variability was partly accounted for by differences in body weight: i.e., the greater the weight, the longer the diaphragm. We conclude that (1) patients with COPD have marked reductions in Adl and Aap at FRC but have diaphragm dimensions similar to those of normal subjects when compared at similar absolute lung volumes, and (2) normal subjects and patients with COPD show substantial intersubject variability in diaphragm dimensions that is partly explained by differences in body weight.

[Imaging of the pleura]

We review the respective informations yielded to the physician bu the different techniques of medical imaging (conventional radiography, ultrasounds, and computed tomography) according to the presentation of pleural diseases. Conventional radiography is always useful for diagnosis. Ultrasound is useful to confirm and localize pleural effusion. Computed tomography contributes to precise the location of pneumothorax and pleural effusion, and the possible underlying pulmonary disorders. Computed tomography also allows to precisely characterize the different types of pleural thickening, including malignant mesothelioma.

Analysis of asbestos bodies in BAL from subjects with particular exposures

Four patients with asbestos-related diseases and with unusual exposures underwent bronchoalveolar lavage (BAL) for mineralogical analysis. Asbestos bodies (AB) were counted by light microscopy and analyzed by transmission electron microscopy and X-ray energy spectrometry. AB's were found in all cases, after a mean delay from the end of exposure of 27.7 years. Analysis of the core fibers indicated the type of alveolar asbestos burden and was compared with the previous exposures: Pleural plaques due to household exposure to amosite and crocidolite. Pleural plaques due to occult occupational exposure to crocidolite in a coal miner. Asbestosis due to environmental exposure to tremolite in Turkey. Asbestosis, pleural plaques, and peritoneal mesothelioma due to a short, intense exposure to crocidolite. AB counting in BAL and identification of the central fibers by analytical electron microscopy is a useful, non-invasive and reliable method to evaluate the alveolar retention of bio-persistent fibers and to relate them to specific exposures.

Radiological findings in nine AIDS patients with Rhodococcus equi pneumonia

Rhodococcus equi (R. equi) infections have been incidentally reported as a cause of pulmonary infection in severely immunocompromised hosts, including AIDS patients. Our purpose is to describe the radiological findings in nine AIDS patients with R. equi pneumonia assessed by bronchoalveolar lavage (BAL), biopsies, cultures of sputum, and hemocultures. All patients were examined by chest radiographs and contrast-medium-enhanced chest CT. Dense pulmonary consolidations with or without cavitations accounted for the most striking radiological patterns. Chest CT also revealed six mediastinal involvements, strongly mimicking a lymphoma. Two of them had multiple bilateral pulmonary nodular opacities. Pleural effusion was not identified. Although intensive therapies were administered, seven among nine patients died within few months. In an AIDS patient living in a rural area or exposed to horses and presenting these radiological patterns, the possibility of R. equi pneumonia should be considered in the differential diagnosis along with other infectious diseases or lymphomas.

The effects of age, sex, lung size, and hyperinflation on CT lung densitometry

OBJECTIVE

To test our proposal that, on high-resolution CT scans, the relative area of the lung with attenuation values lower than -950 H (RA950) can be a measurement of pulmonary emphysema, we examine the possible influences of sex, age, lung size, and hyperinflation on CT lung densitometry.

SUBJECTS AND METHODS

The RA950 and the mean lung density (MLD) were measured in 42 healthy subjects (21 men, 21 women) from 23 to 71 years old, in 10 patients with asthma before and after a bronchial challenge test, and in seven patients with asthma who have irreversible hyperinflation (defined as an increased total lung capacity).

RESULTS

In the healthy subjects, we found no significant difference between sexes and no significant correlation between age and the MLD, but we found a significant correlation between age and the RA950. In addition, we found a significant correlation between the total lung capacity expressed as absolute values and both the RA950 and the MLD. We did not observe any effect of acute airflow limitation either on the MLD or on the RA950 in the asthmatic subjects after the bronchial challenge test. Likewise, we observed no change in either the MLD or the RA950 in the asthmatic subjects with chronic hyperinflation.

CONCLUSION

This study shows that CT lung densitometry is influenced by total lung capacity and, to a lesser degree, by age. Thus, this study suggests that normal CT attenuation values for the lung should be established.

Rib cage dimensions in hyperinflated patients with severe chronic obstructive pulmonary disease

Using computed tomography we assessed rib cage dimensions at the levels of Th4, Th6, Th8, and Th10 in seven supine patients with COPD who were severely obstructed (FEV1, 25 +/- 7% of predicted) and hyperinflated (FRC, 234 +/- 34% of predicted) and seven matched normal control subjects. The midsagittal anteroposterior (AP) diameter, the maximal AP diameter of the right and left hemithorax, and the maximal transverse (T) diameter were measured on scans obtained at relaxed TLC, FRC, and RV. At each volume, AP diameters were invariably 2 to 3 cm greater in patients with COPD than in normal subjects, but no significant differences in T diameters were found. When compared at a given absolute lung volume, T diameters at all thoracic levels and AP diameters at Th4-6 were smaller in patients with COPD than in normal subjects; in contrast, at Th8-10, AP diameters were similar in the two groups. We conclude that the marked hyperinflation of patients with severe COPD produces complex changes in rib cage dimensions: (1) there is an increase in AP but not in T diameters such that the rib cage adopts a more circular shape; (2) at a given absolute lung volume, AP diameters are smaller in patients with COPD than in normal subjects in the upper but not in the lower portion of the rib cage. These differences in rib cage dimensions may have implications regarding respiratory muscle length and function in patients with COPD.

Sonographic prediction of chronic lung disease in the premature undergoing mechanical ventilation

The aims of the study are to investigate the possible role of ultrasound (US) of the chest in predicting the development of chronic lung disease (CLD) in patients with hyaline membrane disease (HMD) and to determine the optimal age for the sonographic examination. One hundred and five consecutive prematures undergoing mechanical ventilation were prospectively studied by US of the chest. The US examinations were performed at birth and at least once a week until discharge from the neonatal unit. The sonographic patterns observed behind the diaphragm and their evolutions were recorded and correlated with the clinical and radiological data at day 28, which corresponds to the currently accepted limit for determining the presence of CLD. CLD is currently defined as oxygen dependency on day 28 with radiographic abnormalities. A diffuse retrodiaphragmatic hyperechogenicity was observed in all the patients with HMD. The hyperechogenicity resolved completely in patients with an uncomplicated clinical evolution. In contrast, in patients with CLD the hyperechogenicity resolved only partially, resulting in less diffuse and less extensive hyperechogenicity. Day 18 was the earliest day where the persistence of the abnormal retrodiaphragmatic hyperechogenicity was observed in 100% of the patients presenting CLD at day 28. At that time, 95.2% of the patients without abnormal hyperechogenicity showed uncomplicated evolution and no CLD. US can be a useful diagnostic tool to determine the occurrence of CLD and to predict as early as day 18 the prematures at risk for the disease.

Comparison of computed density and microscopic morphometry in pulmonary emphysema

The purpose of this prospective study was to verify whether the percentage area of lung occupied by lowest attenuation values on high-resolution computed tomography (HRCT) scans reflects microscopic emphysema and to compare this quantification with the information yielded by the most widely used pulmonary function tests (PFT). Preoperative HRCT scans were obtained with 1-cm intervals in 38 subjects. With a semiautomatic evaluation procedure, the percentage areas occupied by attenuation values inferior to thresholds ranging from -900 Hounsfield units (HU) to -970 HU were calculated for the lobe or lung to be resected. Emphysema was microscopically quantified by using a computer-based method, measuring the perimeters and interwall distances of alveoli and alveolar ducts. The strongest correlation was found for -950 HU. As a second step, we evaluated possible correlations between PFT and microscopic measurements. Finally, considering the microscopic measurements as a standard, we tried to investigate their relationships with each of the PFT and with the relative area occupied by attenuation values lower than -950 HU for both lungs. This revealed that the diffusing capacity for carbon monoxide associated with HRCT quantification is sufficient to predict microscopic measurements. We concluded that the percentage area of lung occupied by attenuation values lower than -950 HU is a valid index of pulmonary emphysema.

Pulmonary emphysema: quantitative CT during expiration

PURPOSE

To determine whether measurement of the relative area of lung with attenuation coefficients lower than a certain threshold on thin-section computed tomographic (CT) scans obtained during expiration is a valuable method of quantifying the extent of pulmonary emphysema.

MATERIALS AND METHODS

Eighty-nine patients underwent CT (with 1-mm collimation) preoperatively during inspiration and expiration. Relative areas of lung with attenuation coefficients lower than various thresholds were calculated. These relative areas were compared with areas found macroscopically to have emphysema (59 patients [51 men, eight women; aged 40-77 years]) and with two microscopic indices (35 patients [29 men, six women; aged 42-77 years]) assessed on the resected specimens.

RESULTS

The valid expiratory CT thresholds were found to be -820 and 910 HU for microscopic and macroscopic emphysema, respectively. However, results of stepwise multiple regression analyses showed that the inspiratory threshold of -950 HU was superior for both macroscopically and microscopically quantified emphysema. The correlation coefficients in expiratory CT were higher for the pulmonary volumes but similar for the diffusing capacity.

CONCLUSION

Expiratory quantitative CT is not as accurate as inspiratory CT for quantifying pulmonary emphysema and probably reflects air trapping more than reduction in the alveolar wall surface.

Sternomastoid muscle size and strength in patients with severe chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) imposes a major strain on the respiratory muscle pump, and it is conventionally thought that the inspiratory muscles of the neck adapt to this chronic overload by developing hypertrophy. Yet previous anthropometric studies have shown atrophy of the sternomastoid muscles. To solve this discrepancy, we have measured the cross-sectional area of these muscles by computed tomography. Ten stable patients with severe airflow obstruction (FEV1 = 0.76 +/- 0.12 L) and hyperinflation (FRC = 210 +/- 29% of predicted) and 10 control subjects matched for age, sex, and height were studied. The sternomastoid cross-sectional area in the patients averaged (mean +/- SD) 4.29 +/- 1.48 cm2, and that in the control subjects was 3.96 +/- 0.82 cm2. This small difference could be entirely accounted for by hyperinflation, and it was not statistically significant. Sternomastoid muscle torque in patients was also similar to that in the control subjects. In patients with severe COPD, therefore, the sternomastoid muscles are essentially normal. As a corollary, their frequent prominence on clinical examination is only apparent.