闭塞性细支气管炎伴机化性肺炎的高分辨CT表现

目的探讨闭塞性细支气管炎伴机化性肺炎的高分辨CT表现,并与慢性嗜酸性肺炎和寻常型间质性肺炎进行鉴别。方法结合相关文献回顾性分析12例闭塞性细支气管炎伴机化性肺炎高分辨CT表现。结果12例闭塞性细支气管炎伴机化性肺炎的高分辨CT表现如下:(1)肺内多发斑片状肺实变影和磨玻璃影(n=8),其中肺实变影中见支气管充气征(n=5)。(2)肺内多发小结节影和不规则线状影(n=7)。(3)肺内多发斑片状肺实变影和磨玻璃影伴小结节影和不规则线状影(n=3)。(4)细支气管扩张、壁增厚伴周围肺实变影(n=6)。(5)肺内肺实变影和磨玻璃影呈游走性(n=3)。结论高分辨CT可以更好地显示闭塞性细支气管炎伴机化性肺炎的病理改变,并使其能与慢性嗜酸性肺炎和寻常型间质性肺炎在影像上进行鉴别,也为纤维支气管镜下肺活检提供准确的定位。     

HRCT findings of chest complications in patients with leukemia

High-resolution CT (HRCT) findings of several chest complications occurring in leukemic patients were reviewed. Although most entities show non-specific HRCT findings including ground-glass opacity and air-space consolidation, characteristic findings are observed in several pulmonary complications including Pneumocystis carinii pneumonia, fungal infections, miliary tuberculosis, leukemic infiltration, pulmonary edema, bronchiolitis obliterans, and bronchiolitis obliterans organizing pneumonia. A combination of these characteristic HRCT findings and the information obtained from the clinical setting may help in achieving a correct diagnosis of chest complications occurring in leukemic patients.     

Lung diseases in patients with common variable immunodeficiency: chest radiographic, and computed tomographic findings

OBJECTIVE: To evaluate chest radiographic and computed tomographic (CT) findings of lung disease related to common variable immunodeficiency. METHODS: Thirty-five chest radiographs and 30 CT scans of 46 patients were assessed. Lung parenchymal abnormalities that were evaluated included airspace consolidation, ground-glass attenuation, nodules, bronchiectasis, and air trapping. RESULTS: On CT, ground-glass attenuation and nodules were the most frequent findings, observed in 60% (n = 18/30) and 83% (n = 25/30), respectively. Three major CT patterns were identified: airway disease (n = 13), nodules (n = 8), and parenchymal opacification (n = 6). All 13 patients with airway disease showed centrilobular opacities. One patient with peribronchial nodules showed lymphoid interstitial pneumonia, and 1 with randomly distributed nodules showed noncaseating granulomas. Patients with a CT pattern of parenchymal opacification showed lower lung predominance; surgical biopsies showed organizing pneumonia in 1 patient and lymphoid interstitial pneumonia with nonnecrotizing granulomas in another. CONCLUSIONS: Common variable immunodeficiency is associated with 3 major CT patterns: airway disease, nodules, and parenchymal opacification.     

Mycoplasma pneumoniae pneumonia: radiographic and high-resolution CT features in 28 patients

OBJECTIVE: The aim of the study was to compare the radiographic and the high-resolution CT findings of Mycoplasma pneumoniae pneumonia. MATERIALS AND METHODS: The chest radiographs and 1.5-mm collimation CT scans obtained in 28 patients with serologically proven M. pneumoniae pneumonia were retrospectively reviewed. The radiographs and CT scans were analyzed independently by two observers. RESULTS: The most common finding on radiography was the presence of air-space opacification (n = 24), which was patchy and segmental (n = 9) or nonsegmental (n = 15) in distribution. On high-resolution CT, areas of ground-glass attenuation were seen in 24 patients (86%) and air-space consolidation in 22 (79%). In 13 patients (59%), the areas of consolidation had a lobular distribution evident on CT. Nodules were seen more commonly on high-resolution CT (25 of 28 patients, 89%) than on radiography (14 patients, 50%) (p < 0.01, chi-square test). In 24 (86%) of the 28 patients, the nodules had a predominantly centrilobular distribution on CT. Thickening of the bronchovascular bundles was identified more commonly on CT (23 of 28 patients, 82%) than on radiography (five patients, 18%) (p < 0.01, chi-square test). CONCLUSION: The lobular distribution, centrilobular involvement, and interstitial abnormalities in M. pneumoniae pneumonia are often difficult to recognize on radiography but can usually be seen on high-resolution CT.     

Thoracic manifestations of systemic autoimmune diseases: radiographic and high-resolution CT findings.

The systemic autoimmune diseases include collagen vascular diseases, the systemic vasculitides, Wegener granulomatosis, and Churg-Strauss syndrome. They can cause a variety of thoracic abnormalities that are influenced by the pathophysiologic characteristics of the underlying disease process. Although many of the abnormalities can be detected at chest radiography, high-resolution computed tomography (CT) has been shown to be superior in depicting parenchymal, airway, and pleural abnormalities. Thoracic manifestations of collagen vascular diseases include pleural disease, pulmonary fibrosis, diaphragm weakness, aspiration pneumonia, bronchiolitis obliterans organizing pneumonia, bronchiolitis obliterans, and bronchiectasis. Wegener granulomatosis may be associated with multiple nodules or masses with irregular margins that are frequently cavitated. Patients with Churg-Strauss syndrome often have consolidation or ground-glass attenuation at chest radiography and CT. Goodpasture syndrome is associated with extensive bilateral air-space consolidation.     

Pediatric diffuse lung disease: diagnosis and classification using high-resolution CT.

OBJECTIVE: Our purpose was to categorize high-resolution CT findings in children with diffuse lung disease and to evaluate the accuracy of diagnoses made using CT. MATERIALS AND METHODS: The chest radiographs and high-resolution CT scans of 20 children (1-16 years old; median, 9 years old) with biopsy-proven chronic diffuse lung diseases were reviewed separately by two independent chest radiologists. Thirteen types of diffuse lung disease were included in the study. Radiographic and CT features were noted, and three choices of diagnosis were recorded, with the confidence level. RESULTS: Diagnoses were made with a high degree of confidence (definite or probable) in 25 of 40 interpretations of CT scans, compared with only five of 40 interpretations of chest radiographs (p < .001). Fourteen (56%) of the 25 confident first-choice diagnoses on CT scans were correct, compared with two (40%) of the five interpretations on chest radiographs. Diseases were classified as belonging to one of five distinct groups on the basis of dominant CT features. Airway disease (n = 5) (bronchiolitis obliterans or bronchocentric granulomatosis) showed geographic hyperlucency on CT. Septal disease (n = 4) (lymphangiomatosis, hemangiomatosis, or microlithiasis) showed septal thickening. Infiltrative lung disease (n = 7) (desquamative interstitial pneumonitis, hypersensitivity pneumonitis, or lymphoid interstitial pneumonitis) showed ground-glass opacity. Air-space disease (n = 3) (aspiration, vasculitis, or bronchiolitis obliterans organizing pneumonia) showed lung consolidation. Langerhans' histiocytosis (n = 1) showed cysts and nodules. Surprisingly little overlap was seen among these groups. CONCLUSION: CT increases the level of diagnostic confidence for pediatric infiltrative lung disease, improves diagnostic accuracy, and provides a useful classification system.     

Chronic eosinophilic pneumonia: CT findings in six cases

We reviewed the chest radiographs and CT scans in six patients with proved chronic eosinophilic pneumonia. In all patients, the chest radiographs showed patchy air-space consolidation, and in five of six cases, the consolidation was most marked in the middle and upper lung zones. In only one patient was the classic pattern of air-space consolidation that is confined to the outer third of the lungs readily apparent. In three patients, the consolidation appeared to be diffuse, although a slight peripheral predominance was present. In two patients, a peripheral predominance was difficult to appreciate, even in retrospect. The CT scans in all cases showed peripheral air-space consolidation. In addition, mediastinal adenopathy was identified on CT scans in three cases. This has not been described before in association with chronic eosinophilic pneumonia. A follow-up CT scan in one patient showed resolution of the adenopathy and marked improvement in the peripheral air-space disease within 2 weeks. We conclude that patients with chronic eosinophilic pneumonia show predominantly peripheral air-space consolidation on CT scans, even when this distribution is not readily apparent on the radiograph. CT may be helpful in the diagnosis when the clinical findings are suggestive, but the radiographic pattern is nonspecific.     

Can acute interstitial pneumonia be differentiated from bronchiolitis obliterans organizing pneumonia by high-resolution CT?

PURPOSE: In the early stages, clinical and chest radiographic findings of acute interstitial pneumonia (AIP) are often similar to those of bronchiolitis obliterans organizing pneumonia (BOOP). However, patients with AIP have a poor prognosis, while those with BOOP can achieve a complete recovery after corticosteroid therapy. The objective of this study was to identify differences in high-resolution CT (HRCT) findings between the two diseases. METHODS: The study included 27 patients with AIP and 14 with BOOP who were histologically diagnosed [open-lung biopsy (n=7), autopsy (n=17), transbronchial lung biopsy (n=17)]. The frequency and distribution of various HRCT findings for each disease were retrospectively evaluated. RESULTS: Traction bronchiectasis, interlobular septal thickening, and intralobular reticular opacities were significantly more prevalent in AIP (92.6%, 85.2%, and 59.3%, respectively) than in BOOP (42.9%, 35.7%, and 14.3%, respectively) (p<0.01). Parenchymal nodules and peripheral distribution were more prevalent in BOOP (28.6% and 57.1%, respectively) than in AIP (7.4% and 14.8%, respectively) (p<0.01). Areas with ground-glass attenuation, air-space consolidation, and architectural distortion were common in both AIP and BOOP. CONCLUSION: For a differential diagnosis of AIP and BOOP, special attention should be given to the following HRCT findings: traction bronchiectasis, interlobular septal thickening, intralobular reticular opacities, parenchymal nodules, pleural effusion, and peripheral zone predominance.     

Hypersensitivity pneumonitis: evaluation with CT

Thirteen chest radiographs and computed tomographic (CT) scans obtained from 11 patients with hypersensitivity pneumonitis were reviewed. The CT findings were correlated with open lung biopsy findings in seven patients. The two patients with acute hypersensitivity pneumonitis showed air-space opacification on CT scans. An open lung biopsy, done in one of these patients, demonstrated noncaseating granulomas and filling of the air spaces with macrophages. The nine patients with subacute hypersensitivity pneumonitis showed small, rounded opacities and patchy air-space opacification on CT scans. These findings reflected the histologic findings, which consisted of interstitial pneumonitis, cellular bronchiolitis, and small, noncaseating granulomas. The six patients with symptoms for 12 months or longer also showed irregular linear opacities on CT scans, corresponding to areas of fibrosis. CT scans were superior to radiographs in helping to assess the type and extent of abnormalities, and high-resolution CT scans were superior to conventional CT scans.     

Pleuropulmonary paragonimiasis: radiologic findings in 71 patients.

Pleuropulmonary paragonimiasis is a disease caused by lung flukes characterized by migration of a juvenile worm in the early stage and by formation of cysts around the worm later on. The purpose of this study was to describe the radiologic manifestations of pleuropulmonary paragonimiasis, with special emphasis on the worm cyst and worm migration track. We retrospectively studied 71 patients who had evidence of pleuropulmonary paragonimiasis on chest radiographs (n = 71) and CT scans (n = 17). The diagnosis was based on the detection of eggs or on positive antibody tests. On chest radiographs, 59 patients (83%) had pulmonary lesions and 43 patients (61%) had pleural lesions. Pulmonary findings included patchy air-space consolidation (n = 37) with or without cystic changes; ring shadows (n = 16); and peripheral linear opacities (n = 29), which were more prominent in patients with pleural effusion. Twelve patients (17%) had bilateral pleural effusions or pneumothoraces. On CT scans, round low-attenuation cystic lesions (5-15 mm), filled either with fluid (n = 5) or gas (n = 5), were characteristically seen within the consolidation. Peripheral linear opacities seen on radiographs were suggestive of worm migration tracks on CT scans. CT may reveal an intracystic worm. Although the findings vary depending on the stage of the disease, findings on chest radiographs are usually typical of paragonimiasis. CT provides more specific information about the worm cyst and the worm migration track.     

Imaging of small airways disease.

High-resolution computed tomography (HRCT) is the most useful modality for imaging of small airways disease. Direct signs of small airways disease that appear on HRCT scans are the result of changes in the airway wall or lumen. Abnormal small airways can be seen as tubular, nodular, or branching linear structures on HRCT scans. Indirect signs of small airways disease result from changes in the lung parenchyma distal to the diseased small airway and include air trapping, subsegmental atelectasis, centrilobular emphysema, and air-space nodules. Diverse inflammatory and infectious processes, such as bronchiolitis obliterans (BO), bronchiolitis obliterans with organizing pneumonia (BOOP), smoking-related diseases, and asthma affect the small airways of the lungs. HRCT findings of BO include air trapping and bronchiectasis. The predominant findings of BOOP are consolidation and ground-glass attenuation. HRCT can show abnormalities such as small nodules and areas of ground-glass attenuation even in asymptomatic smokers, but emphysema predominates in smokers with moderate or severe obstructive disease. Patients with asthma can have thickened airway walls, plugged large and small airways, subsegmental atelectasis, and air trapping, but emphysema is rarely seen even in severe asthma patients. HRCT scans can often accurately depict disease processes in the small airways and can occasionally lead to a specific diagnosis from among several clinically relevant possibilities.     

Interstitial lung disease in association with polymyositis-dermatomyositis: long-term follow-up CT evaluation in seven patients

PURPOSE: To determine the long-term follow-up computed tomographic (CT) findings of interstitial lung disease associated with polymyositis-dermatomyositis. MATERIALS AND METHODS: CT scans in seven patients with interstitial lung disease and associated polymyositis-dermatomyositis were evaluated retrospectively. Six patients underwent sequential CT (follow-up range, 2-8 years; mean, 4.3 years). Histologic confirmation of pulmonary involvement was available in five patients. RESULTS: The predominant finding on the initial CT scans in four patients was subpleural consolidation, which corresponded to bronchiolitis obliterans organizing pneumonia with or without coexistent chronic eosinophilic pneumonia. In most cases, consolidation improved with use of corticosteroid and/or immunosuppressive therapy; in two patients, however, consolidation evolved into honeycombing. In one patient, diffuse areas of ground-glass opacity and consolidation appeared rapidly during illness; this patient died of sudden, rapid deterioration. In one patient with subpleural linear opacities, parenchymal abnormalities slowly progressed, and linear opacities had evolved into honeycombing at 8-year follow-up. In one patient with histologically proved organizing diffuse alveolar damage, bilateral patchy areas of ground-glass opacity and consolidation were seen. In one patient, subpleural bands changed to subpleural lines on sequential CT scans. CONCLUSION: CT provides an excellent demonstration of the lung changes in patients with interstitial lung disease and associated polymyositis-dermatomyositis.     

Near drowning: thin-section CT findings in six patients

PURPOSE: The purpose of this study was to assess the thin-section CT findings of near drowning in six patients. METHOD: Thin-section (1 mm collimation) CT scans of six patients who experienced near drowning were retrospectively analyzed. The CT scans were performed 0-5 days (median 1 day) after near drowning. RESULTS: Thin-section CT findings included bilateral patchy or diffuse areas of ground-glass attenuation (n = 6) with geographic pattern (n = 3) and fine intralobular reticular opacities ("crazy-paving" appearance) (n = 3), ill-defined centrilobular nodules (n = 4), and air-space consolidation (n = 1). Distribution of ground-glass attenuation was predominantly central (n = 4) or diffuse (n = 2). Interstitial pulmonary emphysema and pneumomediastinum were present in two patients. CONCLUSION: The thin-section CT findings of near drowning consist of ground-glass opacities with or without associated reticular opacities and centrilobular nodules.     

Follicular bronchiolitis: thin-section CT and histologic findings.

PURPOSE: To evaluate the thin-section computed tomographic (CT) findings of follicular bronchiolitis and compare them with the histologic findings. MATERIALS AND METHODS: Thin-section CT scans obtained in 12 patients (age range, 24-77 years; mean age, 47 years) with follicular bronchiolitis proved at open lung biopsy were reviewed by two observers. Underlying conditions included rheumatoid arthritis (n = 8), mixed collagen vascular disorders (n = 2), autoimmune disorder (n = 1), and acquired immunodeficiency syndrome (n = 1). All patients had thin-section CT scans (1.0-1.5-mm collimation, 11 patients; 3.0-mm collimation, one patient; high-spatial-frequency reconstruction algorithm) obtained at 10-mm intervals through the chest. RESULTS: The main CT findings included bilateral centrilobular (n = 12) and peribronchial (n = 5) nodules. All 12 patients had nodules smaller than 3 mm in diameter; six patients also had nodules 3-12 mm in diameter. Areas of ground-glass opacity were present in nine (75%) patients. Histologically, all patients had lymphoid hyperplasia along the bronchioles; eight had peribronchiolar lymphocytic infiltration. CONCLUSION: The cardinal CT feature of follicular bronchiolitis consists of small centrilobular nodules variably associated with peribronchial nodules and areas of ground-glass opacity.     

Pulmonary alveolar proteinosis: CT findings

In pulmonary alveolar proteinosis (PAP), a proteinaceous material accumulates in the alveolar air spaces, causing hypoxemia, restrictive lung disease, and dramatic abnormalities on chest radiographs. Complications are unusual, but of the ones that do occur, infection, particularly with Nocardia asteroides, and fibrosis are the most common. Few computed tomographic (CT) studies of this condition have been reported. The CT scans of nine patients with PAP were reviewed. Varying combinations of air-space and interstitial patterns were seen. The CT appearance of air-space disease ranged from ill-defined nodules to patchy consolidation to large regions of confluence. Air-space consolidation was sometimes sharply demarcated from surrounding normal lung tissue, which created a geographic pattern. Despite the predominance of air-space patterns, air bronchograms were not a prominent feature. CT showed the interstitial component of disease and the extent of disease more clearly than did plain radiography. In two cases, CT demonstrated focal pneumonia that was not visible on the radiographs.     

Summer-type hypersensitivity pneumonitis: comparison of high-resolution CT and plain radiographic findings.

Summer-type hypersensitivity pneumonitis is an immunologic disease that occurs only in Japan. It is a form of hypersensitivity pneumonitis in which the clinical symptoms appear in the summer and subside spontaneously in mid autumn. The purpose of our study was to determine the CT findings in this condition, to compare the CT findings with those on chest radiographs, and to assess the variations in the CT findings over time. Accordingly, high-resolution CT scans and chest radiographs of 15 patients with summer-type hypersensitivity pneumonitis were retrospectively studied. Seven patients had sequential CT examinations 18-37 days apart. The CT scans and chest radiographs were reviewed by two observers independently. CT findings included diffuse micronodules (n = 15), slightly elevated lung density (n = 13), and patchy air-space consolidation (n = 13). In one patient, the findings on a chest radiograph were normal, while CT showed parenchymal abnormalities. In two cases, follow-up CT showed micronodular abnormalities after findings on the chest radiograph had returned to normal. Our results show that high-resolution CT findings of summer-type hypersensitivity pneumonitis include pulmonary micronodules, increased lung density, and air-space consolidation. High-resolution CT appears to be more useful than plain chest radiographs in the evaluation of pulmonary parenchymal abnormalities in this condition.     

Intrathoracic complications following allogeneic bone marrow transplantation: CT findings

The authors retrospectively reviewed computed tomographic (CT) scans of 18 patients who developed 21 episodes of intrathoracic complications after allogeneic bone marrow transplantation (BMT). Pathologic and/or microbiologic diagnoses were available for all patients. All patients were immunocompromised due to either graft-versus-host disease (GVHD), neutropenia, or recurrent malignancy after BMT. CT demonstrated diagnostically relevant findings that were not apparent at radiography in 12 of the 21 cases (57%). These included a ground-glass pattern in early pneumonia (n = 5); a peripheral distribution in GVHD, bronchiolitis obliterans organizing pneumonia, and eosinophilic drug reaction (n = 4); cavitating lesions in Pneumocystis carinii pneumonia (n = 1); hemorrhagic infarcts in aspergillosis (n = 1); and mediastinal adenopathy in recurrent Hodgkin disease (n = 1). The authors conclude that chest CT is superior to radiography in demonstrating the presence, distribution, and extent of intrathoracic complications developing in patients after allogeneic BMT. CT is useful in guiding procedures for tissue diagnosis.     

Thin-section CT findings in rheumatoid arthritis-associated lung disease: CT patterns and their courses

PURPOSE: The purpose of this study was to describe the long-term follow-up CT evaluation in rheumatoid arthritis (RA)-associated lung disease. METHOD: Thin-section CT scans from 29 patients with RA and suspected associated lung disease were reviewed. Twenty-two patients underwent sequential CT evaluation during 3 to 108 months of follow-up (mean 28 months). Histologic comfirmation of pulmonary involvement was available in 19 patients. RESULTS: Three major patterns were identified: reticulation with or without honey-combing (n = 19), centrilobular branching lines with or without bronchial dilatation (n = 5), and consolidation (n = 5). Reticulation and centrilobular branching lines corresponded to usual interstitial pneumonia (n = 14) and bronchiolitis obliterans (n = 1), respectively. Consolidation corresponded to bronchiolitis obliterans organizing pneumonia (BOOP; n = 3) and coexistent chronic eosinophilic pneumonia (CEP) and BOOP (n = 1). Patients with reticulation had rapid deterioration when there was new appearance of multifocal areas of ground-glass attenuation. Centrilobular branching lines progressed to bronchiectasis in one case. There was mild progression of existing bronchiectasis associated with centrilobular branching lines in one case. Area of consolidation in two patients with BOOP and one with coexistent CEP and BOOP evolved into honeycombing at serial CT. CONCLUSION: Thin-section CT is a noninvasive technique for monitoring disease morphology in RA-associated lung disease. Initial CT findings and their evolution on sequential examinations may be useful in evaluating prognosis.     

High-resolution CT findings of respiratory syncytial virus pneumonia after bone marrow transplantation

OBJECTIVE: The aim of this study was to describe the high-resolution CT findings of respiratory syncytial virus pneumonia in 20 patients who had undergone allogeneic bone marrow transplantation. MATERIALS AND METHODS: The study included 20 consecutive patients who developed respiratory syncytial virus pneumonia after bone marrow transplantation and who had high-resolution CT of the chest performed within 24 hr after the onset of symptoms. The CT scans were reviewed by two chest radiologists who assessed the pattern and distribution of findings. RESULTS: Bone marrow transplantation was performed on 12 male and eight female patients ranging from 3 to 48 years old (mean age, 25 years) for treatment of various forms of leukemia (n = 12), severe aplastic anemia (n = 6), Fanconi's syndrome (n = 1), and paroxysmal nocturnal hemoglobinuria (n = 1). Sixteen patients (80%) had abnormal CT findings. The predominant patterns of abnormality on high-resolution CT scans were small centrilobular nodules (10/20, 50%), air-space consolidation (7/20, 35%), ground-glass opacities (6/20, 30%), and bronchial wall thickening (6/20, 30%). The abnormalities were distributed in the central and peripheral areas of the lungs in nine cases, only in the periphery in five cases, and only in the central regions in two cases. The abnormalities were bilateral and asymmetric in distribution in 13 patients, bilateral and symmetric in two patients, and unilateral in one patient. CONCLUSION: The most common high-resolution CT findings in patients with respiratory syncytial virus pneumonia after bone marrow transplantation consist of small centrilobular nodules and multifocal areas of consolidation and ground-glass opacities in a bilateral asymmetric distribution.     

High-resolution CT findings of severe acute respiratory syndrome at presentation and after admission

OBJECTIVE: The aim of this study was to assess the high-resolution CT (HRCT) findings at presentation and after hospital admission in patients with severe acute respiratory syndrome (SARS). MATERIALS AND METHODS: We reviewed the HRCT findings at presentation (n = 12) and after hospital admission (n = 25) of 29 patients with SARS and compared the HRCT findings with the radiographic findings. HRCT scans were obtained using 1-mm (n = 28) or 2-mm (n = 1) collimation. The radiographs and HRCT scans were reviewed independently by two observers who reached a decision by consensus. RESULTS: All patients had abnormal findings on HRCT at presentation. Eight of these 12 patients had normal findings on radiographs. The predominant HRCT findings at presentation consisted of unilateral (n = 6) or bilateral (n = 2) ground-glass opacities or focal unilateral (n = 2) or bilateral (n = 2) areas of consolidation. All patients showed progression of disease on follow-up. The predominant HRCT findings on follow-up CT scans consisted of unilateral (n = 2) or bilateral ground-glass opacities (n = 13), unilateral (n = 2) or bilateral consolidation (n = 5), or a mixed bilateral pattern of ground-glass attenuation, consolidation, and reticulation (n = 3). Reticulation with associated architectural distortion and mild traction bronchiectasis was present in eight patients. CONCLUSION: HRCT can show parenchymal abnormalities in patients with SARS who have normal findings on radiographs at presentation. Follow-up CT scans obtained in hospitalized patients show findings consistent with fibrosis in a small percentage of patients.