Asbestos-related pleural disease and asbestosis: a comparison of CT and chest radiography

High-resolution CT (HRCT) has the ability to demonstrate both asbestos-related pleural disease and parenchymal abnormalities consistent with asbestosis. The role of CT in the diagnosis of asbestosis can be defined by comparing it with radiography. We evaluated 60 men who had a history of occupational exposure to asbestos and whose outside chest radiographs were considered abnormal. Chest radiographs (inside films) and HRCT were performed in all patients at our institution and were interpreted independently by experienced radiologists. Outside film results were compiled from the submitted reports. The final conclusion regarding the interpretation of the radiologic examinations was determined by consensus when disagreements existed. Positive predictive values (the likelihood that a positive report is correct) for pleural disease were: outside films 56%, inside films 79%, HRCT 100%. The positive predictive values for parenchymal disease were: outside films 51%, inside films 83%, HRCT 100%. The addition of HRCT to chest radiography is most useful in eliminating false-positive diagnoses of asbestos-related pleural disease caused by subpleural fat and false-positive diagnoses of parenchymal asbestosis in patients with extensive plaques or emphysema obscuring lung detail. The interpretation of chest radiographs in patients exposed to asbestos is often extremely difficult and subjective, and we recommend that positive findings (except calcified plaques) be confirmed with HRCT.     

High resolution CT in children with cystic fibrosis.

High resolution CT (HRCT) was performed in 24 children (median age 57.9 months) suffering from cystic fibrosis (CF). In 23 patients (one examination unacceptable because of motion artifacts) the most frequent finding was bronchial wall thickening, shown in 21 patients (91%), followed by bronchiectasis in 15 patients (65%). Less frequent findings were mucus plugging and patchy consolidations, which could be demonstrated in 11 patients each (48%). Findings were classified using a CT scoring system and including only irreversible pulmonary changes; a statistically significant correlation with lung function tests (FEV1/FVC; MEF50) could be established. HRCT to date seems to be the most valuable method to determine extent and severity of lung involvement in children with CF and should therefore be routinely used for the staging of this disease.     

Asbestos-related pleural thickening: effect of threshold criteria on interpretation

Radiographic evidence of pleural thickening was evaluated in 1,216 shipyard workers (high-risk group) and 214 executives (low-risk group) and classified according to two threshold levels: low (any detectable thickening) and high (thickening less than or equal to 2 mm excluded). Results were markedly different, affecting the low-risk group more than the high-risk group. Changing from the high to the low threshold markedly increased pleural findings and scores as well as inter-reader correlation while reducing both differences between risk groups and detection of additional findings on supplementary oblique views. When data on prevalence and extent of pleural thickening were combined, differences between risk groups were maximized; however, when only prevalence was considered, such differences were minimized, particularly with a low threshold. These findings indicate that different or ambiguous threshold criteria produce divergent results in screening surveys for asbestos-related disease. The authors recommend that explicit minimal pleural threshold criteria be adopted.     

Bolus contrast medium enhancement for distinguishing pleural from parenchymal lung disease: CT features

Various morphologic criteria have been proposed to distinguish pleural from pulmonary parenchymal processes using CT. Although these criteria are helpful in most instances, they are not infallible. In a retrospective review of chest CT over a 1 1/2 year period, previously described signs were not sufficient to distinguish pleural from parenchymal disease in five patients who underwent routine contrast-enhanced CT. This was true in cases of large, localized areas of air-space disease and in cases of combined pleural and parenchymal disease. In these patients bolus intravenous contrast medium administration at the plane of major abnormality proved extremely useful for diagnosis by directly demonstrating pulmonary blood vessels and/or contrast enhancement in parenchymal processes.     

An assessment of low-dose high resolution CT in the detection of benign asbestos-related pleural abnormalities

PURPOSE: To assess the reliability of low-dose high-resolution computed tomography (HRCT) in the detection of benign asbestos-related pleural abnormalities. METHODS: Fourty-one patients exposed to asbestos were imaged on two occasions; the first time with conventional HRCT parameters: 140kVp, 220mAs; the second time with low-dose HRCT parameters: 120kVp, 60mAs. RESULTS: The qualitative assessment dit not show any difference in the visibility of benign pleural abnormalities from one technique to the other in 98% cases. CONCLUSION: The detection of pleural plaques and thickening did not vary with the two scanning protocols and, when compared with conventional HRCT, low-dose HRCT allows reduced radiation exposure by at least 76.5%, with an absorbed dose close to that delivered when using conventional chest radiography. Nevertheless, low-dose HRCT is a complementary study to helical acquisitions.     

Asbestos-related pleuropulmonary diseases: evaluation with low-dose four-detector row spiral CT

PURPOSE: To evaluate the depiction of lung and pleural asbestos-related lesions with low-dose four-detector row spiral computed tomography (CT). MATERIALS AND METHODS: Eighty-three male workers with a mean duration of occupational exposure to asbestos of 18 years underwent CT as part of a medicolegal investigation. CT examination included low-dose multi-detector row spiral CT of the entire thorax, with reconstruction of contiguous 5-mm-thick images, and thin-section CT, which served as the reference standard for the detection of pleural and parenchymal asbestos-related abnormalities. Two main groups of abnormalities were identified: (a) pleural plaques and diffuse pleural thickening and (b) thickened interstitial short lines, curvilinear subpleural lines, ground-glass opacity with or without bronchiectasis, and honeycombing. The frequencies of the depiction of these abnormalities on the low-dose multi-detector row images and the thin-section images were compared by using the McNemar test. RESULTS: No significant differences were observed between the low-dose and thin-section CT images in the depiction of either (a) parietal pleural fibrosis consisting of pleural plaques (identified in 67 [81%] vs 65 [78%] workers, P =.157), which appeared mainly as thick, calcified pleural linear structures; or (b) features of parenchymal fibrosis, which consisted of various combinations of intralobular and septal lines (identified in 12 [14%] vs 13 [16%] workers, P =.564), subpleural curvilinear lines (identified in 10 [12%] vs eight [10%] workers, P =.157), and ground-glass opacity with (identified in six [7%] vs six [7%] workers) or without (identified in five [6%] vs three [4%] workers, P =.317) traction bronchiectasis. A honeycombing pattern was depicted on only the thin-section CT images (P <.001). Emphysema (identified in 26 [31%] vs 14 [17%] workers at low-dose and thin-section CT, respectively; P <.001) and noncalcified nodules (identified in 18 [22%] workers vs one [1%] worker, P <.001) were depicted significantly more frequently on the low-dose images than on the thin-section images. CONCLUSION: Low-dose multi-detector row spiral CT accurately depicts asbestos-related disease.     

Asbestos-related pleural disease: value of dedicated magnetic resonance imaging techniques

OBJECTIVES: We sought to compare respiratory-gated high-spatial resolution magnetic resonance imaging (MRI) and radial MRI with ultra-short echo times with computed tomography (CT) in the diagnosis of asbestos-related pleural disease. METHODS: Twenty-one patients with confirmed long-term asbestos exposure were examined with a CT and a 1.5-T MR unit. High-resolution respiratory-gated T2w turbo-spin-echo (TSE), breath-hold T1w TSE, and contrast-enhanced fat-suppressed breath-hold T1w TSE images with an inplane resolution of less than 1 mm were acquired. To visualize pleural plaques with a short T2* time, a pulse sequence with radial k-space-sampling was used (TE = 0.5 milliseconds) before and after administration of Gd-DTPA. CT and MR images were assessed by 4 readers for the number and calcification of plaques, extension of pleural fibrosis, extrapleural fat, detection of mesothelioma and its infiltration into adjacent tissues, and detection of pleural effusion. Observer agreement was studied with the use of kappa statistics. RESULTS: The MRI protocol allowed for differentiation between normal pleura and pleura with plaques. Interobserver agreement was comparable for MRI and CT in detecting pleural plaques (median kappa = 0.72 for MRI and 0.73 for CT) and significantly higher with CT than with MRI for detection of plaque calcification (median kappa 0.86 for CT and 0.72 for MRI; P = 0.03). Median sensitivity of MRI was 88% for detection of plaque calcification compared with CT. For assessment of pleural thickening, pleural effusion, and extrapleural fat, interobserver agreement with MRI was significantly higher than with CT (median kappa 0.71 and 0.23 for pleural thickening, 0.87 and 0.62 for pleural effusion, and 0.7 and 0.56 for extrapleural fat, respectively; P < 0.05). For detection of mesothelioma, median kappa was 0.63 for MRI and 0.58 for CT. CONCLUSION: High-resolution MR sequences and radial MRI achieve a comparable interobserver agreement in detecting pleural plaques and even a higher interobserver agreement in assessing pleural thickening, pleural effusion, and extrapleural fat when compared with CT.     

HRCT在检出恶性胸腔积液中胸膜病变的价值

目的 探讨HRCT检出恶性胸腔积液中胸膜病变的价值.方法 回顾分析恶性胸腔积液合并胸膜病变患者40例,复习恶性胸腔积液中胸膜病变的HRCT影像学表现.结果 本组40例患者CT平扫显示胸腔大量积液者12例,中等量或少量积液者28例.CT增强扫描,胸膜病变明显强化,主要表现为结节状强化.结论 HRCT主要用于肺部弥漫性病变的检出,通过本组病例发现HRCT对于检出恶性胸腔积液中的胸膜病变亦有较高价值.     

Asbestos-related focal lung masses: manifestations on conventional and high-resolution CT scans

In 260 asbestos-exposed individuals evaluated by means of computed tomography (CT), 43 unsuspected pulmonary masses were found in 27 individuals. The masses included fissural pleural plaques (n = 10), dense fibrotic bands (n = 3), round atelectasis (n = 11), carcinomas (n = 3), and other presumed benign masses (n = 16). The most helpful features in the diagnosis of rounded atelectasis with CT were (a) contiguity to areas of diffuse pleural thickening, (b) a lentiform or wedge-shaped outline, (c) evidence of volume loss in the adjacent lung, and (d) a characteristic "comet tail" of vessels and bronchi sweeping into the margins of the mass. Less advanced areas of focal atelectasis had fewer classic features. Intrafissural pleural plaques were readily identified with high-resolution CT. In asbestos-related masses, the demonstration of stability over time is necessary. Careful interpretation of CT and high-resolution CT features and close surveillance can obviate the need for biopsy in the majority of instances.     

特发性肺间质纤维化高分辨率CT表现

目的 研究特发性肺间质纤维化高分辨率CT表现.方法 收集98例经临床确诊的特发性肺间质纤维化高分辨率CT资料,其中男55例,女43例,年龄33~87岁,平均67.04岁.全部病例使用东芝公司或飞利浦公司的螺旋CT机,在工作站做1~2 mm层厚的高分辨率重建.结果 98例发现不同程度的肺间质纤维化损害.按照肺损害特点,可将其分为轻度损害28例,中度20例,重度50例.按照病变HRCT特征可分为渗出活动型70例(71.4%),静止稳定型28例(28.6%).24例做治疗前后HRCT比较,发现治疗后好转11例(45.8%),未见变化5例(20.8%),病变进展型8例(33.3%).结论 HRCT对特发性肺间质纤维化的分度、分期及治疗后随诊观察有重要的指导意义.     

Fluid within preexisting pulmonary air-spaces: a potential pitfall in the CT differentiation of pleural from parenchymal disease

There have been many reports of the ability of CT to distinguish between parenchymal and pleural disease. The purpose of this report is to describe the appearance of seven cases of intraparenchymal fluid-filled air-spaces (bullae or lung cysts) in which the CT findings may resemble those of pleural disease and, thus, cast doubt on the specificity of the established criteria.     

Acute coronary syndrome: evaluation of detection capability using non-electrocardiogram-gated parenchymal phase CT imaging

Purpose

To evaluate the capability to detect acute coronary syndrome (ACS) by using non-electrocardiogram-gated parenchymal phase CT imaging.

Materials and methods

Of 962 consecutive patients who underwent emergent coronary angiography for suspected ACS, 32 with ACS who underwent CT ≤24 h before angiography and 15 without ACS who underwent CT ≤24 h before or after angiography were included. Parenchymal phase was acquired at 100-s scan delay. The presence of a myocardial perfusion defect (MPD) on the left ventricle (a decrease of >20 HU) and its capability to detect ACS were evaluated. Results were compared with laboratory findings.

Results

MPD was detected in 29 of 32 ACSs. The sensitivity, specificity, and positive and negative predictive values were 91 % (29/32), 93 % (14/15), 97 % (29/30), and 82 % (14/17), respectively. The sensitivities of ST- and non-ST-elevation ACSs were 89 % (16/18) and 93 % (13/14), respectively, without significant difference (P > 0.99). Of the CT-detectable ACS, non-ST-elevation on the electrocardiogram and a normal creatine kinase-myocardial band were observed in 41 % (12/29) and 24 % (7/29), respectively.

Conclusion

ACS is highly detectable even using conventional parenchymal phase CT imaging. Therefore, even when CT is non-gating, radiologists should carefully evaluate the heart to avoid overlooking ACS.

     

CT of parenchymal and bronchial tuberculosis

Tuberculosis (TB) remains a common disease in the World. Its incidence has risen steadily since 1985, despite a preexisting continuous decreasing of its frequency due to an effective chemotherapy. Nonwhite people, socioeconomically disadvantaged, chronically debilitated groups and AIDS patients are the most concerned. Chest radiography remains the first imaging modality to evaluate TB. Widely radiographic appearances can be encountered, including normal chest X-ray. CT can be useful in all stages of the disease, particularly when clinical and radiological findings are in disagreement and/or when imaging findings are equivocal. CT should be proposed at the end of an effective antituberculous treatment to better subsequently detect fine lesions suggestive of reactivation TB.     

Serial high resolution CT findings in nonspecific interstitial pneumonia/fibrosis

PURPOSE: The purpose of this work was to evaluate the radiographic and serial high resolution CT (HRCT) findings in patients with nonspecific interstitial pneumonia/ fibrosis (NSIP). METHOD: We identified 15 patients with biopsy-proven NSIP. Radiography and initial and follow-up CT findings were reviewed. RESULTS: Predominant radiographic findings were bilateral infiltrates distributing in the middle and lower lung zones and decreased lung volumes. At initial CT, predominant patterns were peribronchovascular interstitial thickening (n = 6), parenchymal bands (n = 8), intralobular interstitial thickening (n = 12), and traction bronchiectasis (n = 14). Mixed pattern of ground-glass opacity and consolidation (n = 11) were predominant findings of increased lung opacity. At follow-up CT in 14 cases, the abnormalities had disappeared completely in 3, improved in 9, persisted in 1, and worsened in 1. CONCLUSION: The pulmonary abnormalities observed in NSIP on HRCT can disappear or be diminished in most cases after corticosteroid therapy. Intralobular interstitial thickening and traction bronchiectasis, which have been considered to be indicators of irreversible fibrosis, also show favorable responses.