Interpretation of Update: Standardized CT/HRCT Classification of Occupational and Environmental Thoracic Diseases in Germany published in 2014 / 中国职业医学

@#Imaging diagnosis is one of the main bases for the diagnosis of occupational pneumoconiosis. At present the - diagnosis of occupational pneumoconiosis is mainly based on high kV X ray chest radiography or chest digital radiography. With （ ） ， （ ） the wide application of computed tomography CT in occupational lung diseases high resolution CT HRCT is increasingly Update： Standardized CT/HRCT Classification of Occupational valuable in the diagnosis of occupational pneumoconiosis. The and Environmental Thoracic Diseases in Germany， ， published in 2014 is the latest and highly reliable standard. The standard - - - recommends the use of low dose HRCT scanning regimens and whole lung thin layer volumetric scanning with a thickness of - ， ， 1.0 mm and high resolution reconstruction which classify CT image quality into four levels and describes methods for （ ， classification and quantitative recording of CT manifestations of lung lesions including round opacities irregular and/or linear ， ， ， ， ） opacities ground glass opacity honeycombing emphysema and large opacities and pleural lesions. It is beneficial for ， ， ， epidemiological research early screening diagnosis and differential diagnosis treatment and prognosis of occupational ， pneumoconiosis as well as the comparison of international data related to occupational pneumoconiosis.

Interpretation of Update: Standardized CT/HRCT Classification of Occupational and Environmental Thoracic Diseases in Germany published in 2014 / 中国职业医学

@#Imaging diagnosis is one of the main bases for the diagnosis of occupational pneumoconiosis. At present the - diagnosis of occupational pneumoconiosis is mainly based on high kV X ray chest radiography or chest digital radiography. With （ ） ， （ ） the wide application of computed tomography CT in occupational lung diseases high resolution CT HRCT is increasingly Update： Standardized CT/HRCT Classification of Occupational valuable in the diagnosis of occupational pneumoconiosis. The and Environmental Thoracic Diseases in Germany， ， published in 2014 is the latest and highly reliable standard. The standard - - - recommends the use of low dose HRCT scanning regimens and whole lung thin layer volumetric scanning with a thickness of - ， ， 1.0 mm and high resolution reconstruction which classify CT image quality into four levels and describes methods for （ ， classification and quantitative recording of CT manifestations of lung lesions including round opacities irregular and/or linear ， ， ， ， ） opacities ground glass opacity honeycombing emphysema and large opacities and pleural lesions. It is beneficial for ， ， ， epidemiological research early screening diagnosis and differential diagnosis treatment and prognosis of occupational ， pneumoconiosis as well as the comparison of international data related to occupational pneumoconiosis.

High-Resolution CT Findings of Re-Expansion Pulmonary Edema

OBJECTIVE: To describe the high-resolution CT (HRCT) findings of re-expansion pulmonary edema (REPE) following a thoracentesis for a spontaneous pneumothorax. MATERIALS AND METHODS: HRCT scans from 43 patients who developed REPE immediately after a thoracentesis for treatment of pneumothorax were retrospectively analyzed. The study group consisted of 41 men and two women with a mean age of 34 years. The average time interval between insertion of the drainage tube and HRCT was 8.5 hours (range, 1-24 hours). The patterns and distribution of the lung lesions were analyzed and were assigned one of the following classifications: consolidation, ground-glass opacity (GGO), intralobular interstitial thickening, interlobular septal thickening, thickening of bronchovascular bundles, and nodules. The presence of pleural effusion and contralateral lung involvement was also assessed. RESULTS: Patchy areas of GGO were observed in all 43 patients examined. Consolidation was noted in 22 patients (51%). The geographic distribution of GGO and consolidation was noted in 25 patients (58%). Interlobular septal thickening and intralobular interstitial thickening was noted in 28 patients (65%), respectively. Bronchovascular bundle thickening was seen in 13 patients (30%), whereas ill-defined centrilobular GGO nodules were observed in five patients (12%). The lesions were predominantly peripheral in 38 patients (88%). Of these lesions, gravity-dependent distribution was noted in 23 cases (53%). Bilateral lung involvement was noted in four patients (9%), and a small amount of pleural effusion was seen in seven patients (16%). CONCLUSION: The HRCT findings of REPE were peripheral patchy areas of GGO that were frequently combined with consolidation as well as interlobular septal and intralobular interstitial thickening.

Feasibility of Automated Quantification of Regional Disease Patterns Depicted on High-Resolution Computed Tomography in Patients with Various Diffuse Lung Diseases

OBJECTIVE: This study was designed to develop an automated system for quantification of various regional disease patterns of diffuse lung diseases as depicted on high-resolution computed tomography (HRCT) and to compare the performance of the automated system with human readers. MATERIALS AND METHODS: A total of 600 circular regions-of-interest (ROIs), 10 pixels in diameter, were utilized. The 600 ROIs comprised 100 ROIs that represented six typical regional patterns (normal, ground-glass opacity, reticular opacity, honeycombing, emphysema, and consolidation). The ROIs were used to train the automated classification system based on the use of a Support Vector Machine classifier and 37 features of texture and shape. The performance of the classification system was tested with a 5-fold cross-validation method. An automated quantification system was developed with a moving ROI in the lung area, which helped classify each pixel into six categories. A total of 92 HRCT images obtained from patients with different diseases were used to validate the quantification system. Two radiologists independently classified lung areas of the same CT images into six patterns using the manual drawing function of dedicated software. Agreement between the automated system and the readers and between the two individual readers was assessed. RESULTS: The overall accuracy of the system to classify each disease pattern based on the typical ROIs was 89%. When the quantification results were examined, the average agreement between the system and each radiologist was 52% and 49%, respectively. The agreement between the two radiologists was 67%. CONCLUSION: An automated quantification system for various regional patterns of diffuse interstitial lung diseases can be used for objective and reproducible assessment of disease severity.

Radiological Findings of Extensively Drug-Resistant Pulmonary Tuberculosis in Non-AIDS Adults: Comparisons with Findings of Multidrug-Resistant and Drug-Sensitive Tuberculosis

OBJECTIVE: This study was designed to describe the radiological findings of extensively drug-resistant (XDR) pulmonary tuberculosis (TB) and to compare the observed findings with findings of drug-sensitive (DS) and non-XDR multidrug-resistant (MDR) TB in non-AIDS patients. MATERIALS AND METHODS: From September 1994 to December 2007, 53 MDR TB patients (M:F = 32:21; mean age, 38 years) and 15 XDR TB non-AIDS patients (M:F = 8:7; mean age, 36 years) were enrolled in the study. All of the MDR TB patients had received no treatment or less than one month of anti-TB treatment. In addition, all XDR TB patients received either no anti-TB treatment or only first-line anti-TB drugs. In addition, 141 consecutive DS TB patients (M:F = 79:62; mean age, 51 years) were also enrolled in the study for comparison. Chest radiograph, CT and demographic findings were reviewed and were compared among the three patient groups. RESULTS: For patients with XDR TB, the most frequent radiographic abnormalities were nodules (15 of 15 patients, 100%), reticulo-nodular densities (11 of 15, 73%), consolidation (9 of 15, 60%) and cavities (7 of 15, 47%) that were located mainly in the upper and middle lung zones. As seen on radiographs, significant differences were found for the frequency of nodules and ground-glass opacity lesions (all p < 0.001) (more frequent in DS TB patients than in MDR and XDR TB patients). For the use of CT, significant differences (more frequent in MDR and XDR TB patients) were found for the frequency of multiple cavities, nodules and bronchial dilatation (p = 0.001 or p < 0.001). Patients with MDR TB and XDR TB were younger as compared to patients with DS TB (p < 0.001). Imaging findings were not different between patients with MDR TB and XDR TB. CONCLUSION: By observation of multiple cavities, nodules and bronchial dilatation as depicted on CT in young patients with acid-fast bacilli (AFB) positive sputum, the presence of MDR TB or XDR TB rather than DS TB can be suggested. There is no significant difference in imaging findings between patients with XDR TB and MDR TB.

An Automated Classification System for the Differentiation of Obstructive Lung Diseases based on the Textural Analysis of HRCT images

PURPOSE: To develop an automated classification system for the differentiation of obstructive lung diseases based on the textural analysis of HRCT images, and to evaluate the accuracy and usefulness of the system. MATERIALS AND METHODS: For textural analysis, histogram features, gradient features, run length encoding, and a co-occurrence matrix were employed. A Bayesian classifier was used for automated classification. The images (image number n=256) were selected from the HRCT images obtained from 17 healthy subjects (n=67), 26 patients with bronchiolitis obliterans (n=70), 28 patients with mild centrilobular emphysema (n=65), and 21 patients with panlobular emphysema or severe centrilobular emphysema (n=63). An five-fold cross-validation method was used to assess the performance of the system. Class-specific sensitivities were analyzed and the overall accuracy of the system was assessed with kappa statistics. RESULTS: The sensitivity of the system for each class was as follows: normal lung 84.9%, bronchiolitis obliterans 83.8%, mild centrilobular emphysema 77.0%, and panlobular emphysema or severe centrilobular emphysema 95.8%. The overall performance for differentiating each disease and the normal lung was satisfactory with a kappa value of 0.779. CONCLUSION: An automated classification system for the differentiation between obstructive lung diseases based on the textural analysis of HRCT images was developed. The proposed system discriminates well between the various obstructive lung diseases and the normal lung.

Diffuse Micronodular Pattern of Bronchiolitis Obliterans Organizing Pneumonia: A Case Report

The typical radiographic findings of bronchiolitis obliterans organizing pneumonia (BOOP) are known to be patchy air-space consolidation that is often subpleural, and with or without ground-glass opacities. However, there are scant radiologic reports about the micronodular pattern of BOOP. We report here on a case of BOOP that manifested as diffusely scattered ill-defined centrilobular micronodules on HRCT.

Artificial Intelligence Aiding the Thin-section CT Diagnosis of Diffuse Pulmonary Diseases

PURPOSE: We wanted to develop and test an artificial intelligence (AI) to assist physicians in making the thin-section CT diagnosis of diffuse pulmonary diseases. MATERIALS AND METHODS: The AI was composed of knowledge bases (KB) of 12 diffuse pulmonary diseases and an inference engine (IE). The KB of a disease included both the inclusion criteria (IC) and the exclusion criteria (EC), which were the clinical or thin-section CT findings that were known to be present or absent in that particular disease, respectively. From imputing the clinical or thin-section CT findings by the operator who was reading the thin-section CT, AI instantly executed the following two steps. First, the IE eliminated all diseases from the list which the EC had for those particular findings. Next, from a list of remaining diseases, the AI selected those diseases having those findings in its IC to formulate the 1st-step differential diagnosis (DD1). For the differential diagnosis in the next step, the reader could choose one more clinical or thin-section CT finding from the new list: [(all the findings in the IC or EC of DD1) - (the findings in the IC common to all the DD1s)]. The reader could proceed even further if needed. The system was tested on 10 radiology residents who solved 24 problems (two problems for each of 12 diffuse pulmonary diseases) without and then with the aid of the AI. The scores were compared using the Wilcoxon signed rank test. RESULTS: An AI was made; it was composed of 280 rules (214 IC and 66 EC) and three interfaces (two for program management and another for problem solving). Contestants scored higher (p = 0.0078) using the AI (167 vs. 110 respectively), and they responded that they felt that the program was helpful in making decisions. CONCLUSION: AI appeared to be helpful in making thin-section CT diagnosis.

Radiologic Approach to Diffuse Infiltrative Lung Disease

The Radiology approach to diffuse infiltrative lung disease (DILD) is based on a chest radiography and CT. Chest radiography can categorize DILD into five main patterns of abnormality: linear, reticular, cystic, nodular, and ground-glass patterns. The CT patterns of DILD can be classified into six patterns including thickened interlobular septa, reticular, cystic, nodular, ground-glass, and consolidation patterns. The pertinent differential diagnosis of DILD is based on the pattern recognition approach of abnormalities, and a specific diagnosis can often be made using chest radiography and CT. This pictorial essay illustrates the radiology pattern recognition approach for DILD using chest radiography and CT.

Three-year Follow-up of Niemann-Pick Disease with Pulmonary Involvement: A Case Report

Niemann-Pick disease is a rare inherited metabolic storage disease that causes excessive intracellular storage of sphingomyelin in various organs. We present the pulmonary imaging findings with particular emphasis on the CT findings in a case of Niemann-Pick disease type B with pulmonary involvement. The chest radiograph showed fine reticulonodular opacities in both basal lung fields, and the high-resolution chest CT showed centrilobular nodular opacities and smooth thickening of the interlobar fissure and interlobular septum with a basal lung predominance. Coronal reformatted CT revealed a prominent interlobular septal thickening around the diaphragm. The follow-up high-resolution chest CT showed no significant interval changes over a 3-years period.

Bronchiolitis Obliterans after Allogenic Bone Marrow Transplantation: HRCT Findings

OBJECTIVE: To evaluate the high resolution computed tomography (HRCT) findings of bronchiolitis obliterans (BO) after bone marrow transplantation (BMT). MATERIALS AND METHODS: During the past three years, 11 patients were diagnosed as having BO after BMT when they developed irreversible air flow obstruction, with an FEV1 value of less than 80% of the baseline value, without any clinical evidence of infection. All 11 patients underwent HRCT, of whom eight also underwent follow-up HRCT. The HRCT images were assessed retrospectively for the presence of decreased lung attenuation, segmental or subsegmental bronchial dilatation, diminution of peripheral vascularity, centrilobular nodules, and branching linear structure on the inspiratory images. The lobar distribution of the decreased lung attenuation and bronchial dilatation was also examined. The presence of air trapping was investigated on the expiratory images. The interval changes of the HRCT findings were evaluated in those patients who had follow-up images. RESULTS: Abnormal HRCT findings were present in all cases; the most common abnormalities were decreased lung attenuation (n=11), subsegmental bronchial dilatation (n=6), diminution of peripheral vascularity (n=6), centrilobular nodules or branching linear structure (n=3), and segmental bronchial dilatation (n=3). Expiratory air trapping was noted in all patients. The decreased lung attenuation and bronchial dilatations were more frequent or extensive in the lower lobes. Interval changes were found in all patients with follow-up HRCT: increased extent of decreased lung attenuation (n=7) ; newly developed or progressed bronchial dilatation (n=4) ; and increased lung volume (n=3). CONCLUSION: HRCT scans are abnormal in patients with BO, with the most commonly observed finding being areas of decreased lung attenuation. While the HRCT findings are not specific, it is believed that their common features can assist in the diagnosis of BO in BMT recipients.

Mediastinal and Extrapleural Fat Hypertrophy in Idiopathic Pulmonary Fibrosis on High-resolution CT: Comparison with Normal Individuals

PURPOSE: We wished to compare the amount of mediastinal and extrapleural fat on high resolution CT for patients with idiopathic pulmonary fibrosis (IPF) with that of normal individuals, and we wished to evaluate the correlation between the amount of fat and the degree of pulmonary fibrosis. MATERIALS AND METHODS: We selected a group of 25 patients with radiologically and clinically diagnosed IPF and we also selected another group of 25 age and gender-matched patients having no abnormalities on pulmonary function testing as well as HRCT as controls from our radiologic database search (mean age: 59 years, M:F=11:14). We measured the area of mediastinal and extrapleural fat at the levels of the aortic arch and at the origin of the right pulmonary artery and right inferior pulmonary vein on three sections of HRCT by using software (Rapidia; 3DMED, Seoul, Korea). The total amount of fat was calculated by summing up the areas of the mediastinal and extrapleural fat, which is corrected by the body mass index; we also evaluated statistical differences between the two groups. At same sections of CT, the ratio (%) of the honeycombing area to the total areas of the lung was calculated. We evaluated the relationship between the amount of extrapleural or mediastinal fat with the ratio (%) of the honeycombing area. RESULTS: The total amount of fat in patients with IPF and normal individuals were 67.24+/-19.03 cm2 and 32.55+/-11.91 cm2, respectively. The fat amount corrected by body mass index was 280.48+/-74.43 mm2/kg/m2 in the IPF patients and 137.06+/-41.76 mm2/kg/m2 in normal individuals. The differences between two groups for the total amount of fat and fat amount, as corrected for by the body mass index, were statistically significant (p<0.0001). The ratio (%) of the honeycombing area and the total amount of fat showed a moderate correlation (rho= 0.43, p= 0.032). CONCLUSION:Patients with IPF have a larger amount of mediastinal and extrapleural fat than normal individuals. The hypertrophy of mediastinal and extrapleural fat in IPF may be affected by the severity of the interstitial fibrosis of the lung.

Small Airway Disease after Mycoplasma Pneumonia in Children: HRCT Findings and Correlation with Radiographic Findings

PURPOSE: To assess the high-resolution CT (HRCT) findings of small airway abnormalities after mycoplasma pneumonia and correlate them with the findings of chest radiography performed during the acute and follow-up phases of the condition. MATERIALS AND METHODS: We retrospectively evaluated HRCT and chest radiographic findings of 18 patients with clinical diagnosis of small airway disease after mycoplasma pneumonia (M:F=8:10, mean age: 8.3 years, mean time interval after the initial infection; 26 months). We evaluated the lung parenchymal and bronchial abnormalities on HRCT (n=18). In addition, presence of air-trapping was assessed on expiratory scans (n=13). The findings of HRCT were correlated with those of chest radiography performed during the acute phase of initial infection (n=15) and at the time of CT examination (n=18), respectively. RESULTS: HRCT revealed lung parenchymal abnormalities in 13 patients (72%). A mosaic pattern of lung attenuation was noted in ten patients (10/18, 56%), and air-trapping on expiratory scans was observed in nine (9/13, 69%). In nine of 14 (64%) with negative findings at follow-up chest radiography, one or both of the above parenchymal abnormalities was observed at HRCT. In four patients (27%), parenchymal abnormalities were seen at HRCT in areas considered normal at acute-phase chest radiography. Bronchiectasis or ateclectasis was observed in eight (44%) and four (22%) patients, respectively, at HRCT. The CT features of Swyer-James syndrome such as a unilateral hyperlucent lung with reduced lung volume and attenuated vessels were noted in two patients (11%). CONCLUSION: HRCT can clearly demonstrate lung parenchymal and bronchial abnormalities of small airway disease after mycoplasma pneumonia in children.

Positional Shifting of HRCT Findings in Patients with Pulmonary Edema

PURPOSE: To assess the value of positional shifting to a gravity-dependent area, as revealed by HRCT, in differ-entiating pulmonary edema (PE) from other conditions. MATERIALS AND METHODS: Sixteen consecutive patients in whom plain radiographs suggested the presence of pulmonary edema but the clinical findings were indefinite underwent HRCT of the lung. For initial scanning they were in the supine position, and then in the prone position. Findings of ground-glass opacity, interlobular septal thickening and peribronchovascular interstitial thickening were analyzed in terms of the presence and degree of shifting to a gravity-dependent area, a grade of high, intermediate or low being assigned. RESULTS: PE was diagnosed in 8 of 16 cases, the remainder being designated as non-pulmonary edema (NPE). Ground-glass opacity was observed in all 16, while the degree of positional shifting was found to be high in ten (PE:NPE=6:4), intermediate in four (PE:NPE=2:2), and low in two (PE:NPE=0:2). There was no significant difference between the two groups (p > 0.05). Interlobular septal thickening was observed in all but two NPE cases; the degree of shifting was high in six (PE:NPE=6:0), intermediate in one (PE), and low in seven (PE:NPE=1:6). Shifting was significantly more prominent in PE than in NPE cases (p<0.05). Peribronchovas-cular interstitial thickening was positive in all PE cases and one NPE case, with no positional shifting. CONCLUSION: Positional shifting of interlobular septal thickening to a gravity-dependent area, as demonstrated by HRCT, is the most specific indicator of pulmonary edema.

Ground-Glass Opacity in Lung Metastasis from Adenocarcinoma of the Stomach: A Case Report

Ground-glass opacity is a frequent but nonspecific finding seen on high-resolution CT scans of lung parenchyma. Histologically, this appearance is observed when thickening of the alveolar wall and septal interstitium is minimal or the alveolar lumen is partially filled with fluid, macrophage, neutrophils, or amorphous material. It has been shown that ground-glass opacity may be caused not only by an active inflammatory process but also by fibrotic processes. When a focal area of ground-glass opacity persists or increases in size, the possibility of neoplasm-bronchioloalveolar carcinoma or adenoma, or lymphoma, for example- should be considered. Diffuse nonsegmental ground-glass opacity in both lung fields was incidentally found on follow up abdominal CT in a stomach cancer patient and signet-ring cell-type metastatic lung cancer was confirmed by transbronchial lung biopsy. We report a case of diffuse ground-glass opacity seen in metastatic lung cancer from adenocarcinoma of the stomach.

HRCT Findings of Hypersensitivity Pneumonitis: Correlation with Pulmonary Function Test

PURPOSE: To evaluate the HRCT findings of hypersensitive pneumonitis and to correlate the findings with the results of the pulmonary function test (PFT). MATERIALS AND METHODS: Seven patients in whom hypersensitive pneumonitis was histologically confirmed (by transbronchial lung biopsy in two, thoracoscopic lung biopsy in one, open lung biopsy in two, and typical clinical and laboratory findings in two) were involved in this study. Their radiological patterns were assessed by HRCT and the extent of each finding was evaluated semi-quantitatively and correlated with the results of the pulmonary function test. RESULTS: The HRCT findings were as follows: lobular overinflation (n = 7), ground glass attenuation (n = 7), centrilobular nodule (n = 6), reticular opacity (n = 5), interlobular septal thickening (n = 3), consolidation (n = 2), and irregular subpleural line (n = 1). Five patients showed lower lung predominance and two, middle lung predominance. In all, a restrictive pattern and diminished diffusion capacity was noted. The grade score of reticular opacity showed significant correlation with forced vital capacity and forced expiratory volume. There was, however, no significant correlation between other HRCT findings and PFT results. Two patientsin whom lobular overinflation associated with parenchymal fibrosis was noted showed a decreased maximal midexpiratory flow rate of 25 -75. CONCLUSION: Lobular overinflation, ground-glass attenuation and centrilobular nodules are commonly observed in hypersensitive pneumonitis. The only significant correlation between each HRCT finding and the pulmonary function test was that between reticular opacity and both forced expiratory volume and forced vital capacity. In cases of chronic hypersensitive pneumonitis presenting as pulmonary fibrosis, associated lobular overinflation could be helpful for differential diagnosis.

HRCT Findings of Asthmatic Children under Maintenance Therapy

PURPOSE: The purpose of this study was to evaluate the HRCT findings of bronchial asthma during maintenance bronchodilator therapy and to determine whether there were irreversible bronchial changes occurred in pediatric patients with this condition. MATERIALS AND METHODS: HRCT findings of the lung in 21 asthmatic children [14 boys and 7 girls aged between 3.5 and 13.8 (mean : 7.7) years] who were receiving maintenance bronchodilator therapy were retrospectively studied. At the time of CT examination, 16 were receiving nonsteroid bronchodilator therapy only, and five were receiving both bronchodilator and steroid therapy. Thirteen patients were defined as allergic and eight were nonallergic. The clinical severity of chronic asthma was graded as severe in seven cases, and moderate in 14. The duration of the disease ranged from 4 months to 6 years (mean 3.2 years). HRCT was performed in 19 cases for evalvation of the atelectasis, hyperinflation, and prominent bronchovascular bundles seen on plain radiographs, and in two cases for evaluation following acute exacerbation. A CT W-2000 scanner (Hitachi Medical Co. Tokyo, Japan) was used during the end inspiratory phase, and in addition, ten patients were scanned during the expiratory phase. Scans were reviewed for evidence of bronchial thickening, bronchiectasis, emphysema, abnormal density, mucus plugs, and other morphological abnormalities. The presence of bronchial wall thickening or air trapping was evaluated according to the duration, severity and type of asthma. RESULTS: Among the 21 patients, 7(33.3%) had normal HRCT findings, while in 14 (66.7%), bronchial wall thickening was demonstrated. Eleven of the 14 patients with bronchial wall thickening (78.6%) also had air trapping. No patient was suffering from bronchiectasis or emphysema. There were no statistically significant correlations between the presence of bronchial wall thickening or air trapping and the duration of the disease, its severity, or type of asthma. There was, however, a statistically significant correlation between bronchial wall thickening and air trapping (p < . 0 5 ). CONCLUSION: In asthmatic children who were under maintenance therapy, the most frequent HRCT findings were bronchial wall thickening and air trapping, with significant correlation between the presence of these two phenomena. No destructive lesion such as bronchiectasis or emphysema was found in these asthmatic children, however, and this is probably due to the short duration of the disease, and different disease processes.

Areas of Decreased Parenchymal Attenuation Associated with Bronchiectasis: Correlation between Severity and Extent of Bronchiectasis on HRCT with Pulmonary Function Test

PURPOSE: To determine the correlation between areas of decreased parenchymal attenuation seen in cases of bronchiectasis, and the severity and extent of the condition, as revealed by HRCT and the plmonary function test (PFT). MATERIALS AND METHODS: The findings of forty-five patients with bronchiectasis who had undergone PFT and HRCT were retrospectively analysed. CT scores were calculated according to the severity and extent of the condition, and areas of low attenuation, and the correlation coefficients between these were determined. Bronchiectasis was classified as either cylindrical or cystic, and using Student's t test, the statistical significance of the results of the PFT were determined. RESULT: The severity and extent of bronchiectasis correlated with the extent of areas of low attenuation (r > .45, p .44, p < .01). The functional parameters of the PFT which help differentiate between cylindrical and cystic bronchiectasis are FEV1, FVC, MMEF, DLCO (p < .01), RV, and TLC (p < .05). CONCLUSION: In patients with bronchiectasis, the extent of the condition correlated closely with the extent of low attenuation, and the latter, especially in cases of cylindrical bronchiectasis, showed significant correlation with the extent of abnormalities revealed by the pulmonary function test.

Low Attenuation on High Resolution Computed Tomography in Pulmonary Embolism: An Experimental Study in Pigs

PURPOSE: To evaluate the incidence and type of low attenuation seen on high resolution computed tomography (HRCT) performed after artificially induced pulmonary embolism. MATERIALS AND METHODS: Using permanent embolic materials, pulmonary embolism was induced in ten Yorkshire pigs. Pre- and postembolic pulmonary angiography was performed, and HRCT was performed immediately and 1, 3, and 6 weeks after embolization. The incidence and type of low attenuation of all segments, as seen on HRCT, was evaluated. Low attenuation was classified as mottled, lobular, segmental, or peripheral. The pigs were sacrified after 6 weeks and contact radiographs were obtained. RESULTS: Low attenuation developed in eight of ten pigs. Pulmonary angiography revealed arterial occlusion in 15 large and 19 small segmental arteries (34 of 45 segments). In the remaining 11 segments, follow-up HRCT demonstrated areas of low attenuation. This was present in 25 of 35 segments (71%) as seen on HRCT images obtained immediately; in 16 of 41 segments (39 %) on images obtained 1 week after embolization; in 17 of 41 segments (41 %) on those acquired at 3 weeks; and in 25 of 45 segments (56 %) on those acquired at 6 weeks. The overall incidence of low attenuation was 83/166 (50 %). The types of low attenuation were mottled in 32/83 cases, lobular in 13/83, segmental in 13/83, and peripheral in 25/83. In large segmental arterial occlusion, the incidence of low attenuation on HRCT was 100% immediately, 57% at 1 week, 60% at 3 weeks, and 80 % at 6 weeks. In small segmental arterial occlusion, the incidence was 47%, 25 %, 11 %, and 21 % respectively. The overall incidence of low attenuation was 40/55 (73 %) in large segmental arterial occlusion and 18/71 ( 25%) in small segmental arterial occlusion. CONCLUSION: Low attenuation on HRCT is a finding of pulmonary embolism and is more common on HRCT performed immediately after embolization (71%) and in large segmental arterial occlusion (73%). Low attenuation on HRCT is an ancillary finding and may be useful in the diagnosis of pulmonary embolism.

Acute Respiratory Distress Sy n d rome (ARDS): HRCT Findings in Survivors

The purpose of this report is to describe the high-resolution computed tomography (H RCT) findings of the lung in survivors of acute respiratory distress syndrome (ARDS). Among eleven patients who survived ARDS for one ye a r, chest radiography and HRCT revealed pulmonary fibrosis in four. Causes of ARDS included pneumonia during pregnancy, near drowning, pneumonia during liver cirrhosis, and postoperative sepsis. Thoracoscopic biopsy and histopathologic correlation were available in one patient. HRCT showed diffuse interlobular septal thickening, ground glass opacity, parenchymal distortion, and traction bronchiectasis. Fuzzy centrilobular nodules were seen in two patients and one patient had multiple, large bullae in the left hemithorax. In all patients, lesions affected the upper and anterior zones of the lung more prominently. The distribution of pulmonary fibrosis was characteristic and reflected the pathogenesis of lung injury; fibrosis was largely due to hy p e r oxia caused by ventilator care. In one patient, histopathologic correlation showed that imaging findings were accounted for by thickening of the alveolar septum along with infiltration of chronic inflammatory cells and fibrosis. Fuzzy centrilobular nodules corresponded with bronchiolitis.