Pulmonary involvement in mixed connective tissue disease: high-resolution CT findings in 41 patients

The objective of this study was to describe the pulmonary abnormalities on high-resolution computed tomography (CT) in patients with mixed connective tissue disease (MCTD). The study included 41 patients who met the diagnostic criteria for MCTD and showed abnormal findings on high-resolution CT. The presence, extent, and distribution of various high-resolution CT findings were evaluated. The predominant abnormalities included areas of ground-glass attenuation (n = 41), subpleural micronodules (n = 40), and nonseptal linear opacities (n = 32). Other common findings included peripheral predominance (n = 40), lower lobe predominance (n = 39), intralobular reticular opacities (n = 25), architectural distortion (n = 20), and traction bronchiectasis (n = 18). Less common findings included honeycombing, ill-defined centrilobular nodules, airspace consolidation, interlobular septal thickening, thickening of bronchovascular bundles, bronchial wall thickening, bronchiectasis, and emphysema. Pulmonary involvement of MCTD is characterized by the presence of ground-glass attenuation, nonseptal linear opacities, and peripheral and lower lobe predominance. Ill-defined centrilobular opacities were uncommonly seen.     

Lymphocytic interstitial pneumonia: follow-up CT findings in 14 patients

The aim of the present study was to assess the evolution of various computed tomographic (CT) findings of lymphocytic interstitial pneumonia (LIP) with determination of potentially reversible or irreversible features. The study included 14 patients with biopsy-proved LIP who had serial thin-section CT examination 4 to 82 months (median 13 months) apart. Initial and follow-up CT scans were evaluated independently and then directly compared with each other by two observers. The main parenchymal abnormalities on the initial CT scan consisted of ground-glass attenuation (n = 14), thickening of interlobular septa (n = 13), centrilobular nodules (n = 12), cystic airspaces (n = 10), and airspace consolidation (n = 4). On follow-up CT, nine patients improved, one showed no change, and four showed increased extent of disease. With the exception of cysts, the parenchymal opacities were reversible. On follow-up CT, new cysts were seen in three patients; these developed mainly in areas with centrilobular nodules on initial CT. Honeycombing was seen on follow-up CT in four patients; in three patients it developed in areas of airspace consolidation and in one patient it developed in an area with ground-glass attenuation on initial CT. The majority of patients with LIP improved on follow-up. However, airspace consolidation may progress to honeycombing and centrilobular nodules may precede cystic formation.     

Churg-Strauss syndrome: high resolution CT and pathologic findings

OBJECTIVES: The purpose of this study was to evaluate high-resolution CT findings in 7 patients with Churg-Strauss syndrome and to compare the CT with the histopathologic findings. MATERIALS AND METHODS: High-resolution CT scans of 7 asthmatic patients (4 women, 3 men, age range, 34-62 years, mean 49 years) with Churg-Strauss syndrome were reviewed by 2 observers. Histologic specimens of lung obtained at surgical (n = 3) or transbronchial (n = 3) biopsy or autopsy (n = 1) were reviewed by an expert lung pathologist. The diagnosis of Churg-Strauss was based on clinical, laboratory, and histologic findings. RESULTS: Parenchymal and airway abnormalities included ground-glass opacities (n = 5), areas of air-space consolidation (n = 4), centrilobular nodules (n = 5), nodules 1-3 cm in diameter (n = 3), interlobular septal thickening (n = 4), bronchial wall thickening (n = 4), and areas of atelectasis (n = 1). Surgical biopsy (n = 3) and autopsy (n = 1) specimens demonstrated airspace disease in 3 patients, interlobular septal thickening in 3 patients, and airway abnormalities in 2 patients. Histologically, the airspace disease included eosinophilic pneumonia (n = 2) and small foci of organizing pneumonia (n = 1). The septal thickening was due to edema combined with numerous (n = 2) or few (n = 1) eosinophils. The airway abnormalities (n = 2) included muscle hypertrophy and large airway wall necrosis (n = 1) and eosinophilic infiltration of the airway walls (n = 1). Transbronchial biopsy (n = 3) demonstrated increased eosinophils. CONCLUSION: The main high-resolution CT findings of Churg-Strauss syndrome consist of airspace consolidation or ground-glass opacities, septal lines, and bronchial wall thickening. These reflect the presence of eosinophilic infiltration of the airspaces, interstitium, and airways, and interstitial edema.     

Pulmonary involvement in sarcoidosis: CT findings at diagnosis and their changes at follow-up in cases without corticosteroid treatment]

To review the pulmonary CT findings in sarcoidosis at diagnosis, and to analyze the change in each finding at follow-up in cases without corticosteroid treatment. The study included 21 cases of pulmonary involvement of sarcoidosis. We analyzed the presence or absence and grade of each HRCT finding: bronchial wall thickening, enlargement of vascular shadows, pleural involvement, septal thickening, small nodules, ground-glass opacities, centrilobular opacities, consolidation, nodules, and volume loss. Afterwards, we compared the initial CT with the follow-up CT, and described the change of each finding as "improved" or "not improved". Furthermore, we decided if each case as a whole was improved or not after considering all of the pulmonary CT findings. Twelve of the 21 cases were improved. Small nodules, ground-glass opacities, centrilobular opacities, and nodules had improved in more than 50% of the cases since the initial CT. However, pleural involvement (10/11) and volume loss (6/9) were not improved. Pleural involvement and volume loss correlated the radiological irreversibility (p < 0.05). Of the several pulmonary CT findings in sarcoidosis, pleural involvement and volume loss show the highest rates of irreversible pulmonary changes.     

Clinical/pathologic correlations in 553 patients with primary centrilobular findings on high-resolution CT scan of the thorax

BACKGROUND: Clinical/pathologic correlations in patients with high-resolution CT (HRCT) scan findings presenting with two patterns of centrilobular opacity remain unclear. METHODS: Chest HRCT scans in 553 patients with predominant centrilobular opacities or preferential centrilobular disease were retrospectively evaluated. In 141 patients who underwent biopsy, CT scan images were compared with actual specimens. RESULTS: Centrilobular nodules with a tree-in-bud appearance and bronchial wall thickening were observed in most patients who were carriers of human T-lymphotropic virus type 1 (88 patients and 57 of 99 patients, respectively), Mycoplasma pneumoniae pneumonia (44 patients and 45 of 52 patients, respectively), Mycobacterium tuberculosis (38 patients and 37 of 52 patients, respectively), Mycobacterium avium-intracellulare complex (22 patients and 27 of 37 patients, respectively), Mycobacterium kansasii (27 patients and 19 of 33 patients, respectively), allergic bronchopulmonary aspergillosis (6 patients and 7 of 9 patients, respectively), diffuse panbronchiolitis (12 patients and 10 of 12 patients, respectively), and diffuse aspiration bronchiolitis (12 patients and 12 of 13 patients, respectively). On the other hand, ill-defined centrilobular nodules of ground-glass attenuation were frequently seen in patients with subacute hypersensitivity pneumonitis (all 15 patients), metastatic calcification (all 4 patients), Churg-Strauss syndrome (4 of 12 patients), microscopic polyangiitis (27 of 48 patients), systemic lupus erythematosus (7 of 8 patients), and respiratory bronchiolitis-associated interstitial lung disease (all 8 patients). Pathologically, the tree-in-bud appearance correlated well with the plugging of small airways with mucous, pus, or fluid; dilated bronchioles; and bronchiolar wall thickening. Ill-defined centrilobular nodules represented peribronchiolar inflammation or the deposition of hemorrhagic materials. CONCLUSIONS: Knowledge of the two centrilobular patterns is of proven worth for generating differential diagnoses and is of particular value in suggesting a likely infectious etiology in cases with tree-in-bud appearance.     

Comparison of pulmonary abnormalities on high-resolution computed tomography in patients with early versus longstanding rheumatoid arthritis

OBJECTIVE: To identify the predominant radiological abnormalities in the lungs of patients with early rheumatoid arthritis (RA) and in those with longstanding RA. METHODS: We performed high-resolution computed tomography (HRCT) on a total of 126 patients with early RA (n = 65) and longstanding RA (n = 61). The most likely diagnosis for each case was made on the basis of the predominant HRCT findings and their extent in the lungs. Pulmonary function tests were done for RA patients with parenchymal abnormalities. RESULTS: The most frequent finding was bronchial dilatation (41.3%), followed by ground-glass attenuation (27.0%), parenchymal micronodules (15.1%), subpleural micronodules (15.1%), reticulation (11.9%), bronchial wall thickening (11.9%), nodules (10.3%), honeycombing (8.7%), and airspace consolidation (4%). Parenchymal micronodules and bronchial wall thickening, indicative of small airway diseases, were more prominent in the patients with longstanding RA. There were no significant differences in the frequency of interstitial abnormalities such as ground-glass attenuation, reticulation, honeycombing, or consolidation between the 2 groups. We identified 10 patients with bronchiolitis pattern, 11 with nonspecific interstitial pneumonia (NSIP) pattern, 2 with usual interstitial pneumonia (UIP) pattern, and 2 with organizing pneumonia (OP) pattern. Mean values of FEV1/FVC ratio and FEV25-75 were lower in the patients with the bronchiolitis pattern, and DLCO was decreased in the patients with the NSIP or UIP pattern. CONCLUSION: Interstitial abnormalities were frequently observed even in patients with early RA, although most of them had no respiratory symptoms. Bronchiolar abnormalities were associated with the duration of RA.     

新型冠状病毒肺炎130例CT分布特点及征象研究

目的探讨2019新型冠状病毒肺炎(COVID-19)影像学表现。方法根据纳入标准和排除标准收集2020年1月20日至2月5日来自全国多家医院确诊COVID-19病例130例,按分布特点进行分型,分析其影像学特征。结果(1)分布:单侧14例(10.7%),双侧116例(89.3%);胸膜下型(102例78.4%),小叶核心型99例(76.1%),弥漫型8例(6.1%);(2)数目:单发病灶9例(6.9%),多发病灶113例(86.9%),弥漫8例(6.1%);(3)密度:仅为磨玻璃影(GGO)70例(53.8%),GGO与实变影兼有60例(46.2%);(3)伴随征象:血管增粗100例(76.9%),胸膜平行征98例(75.3%),"细网格征"100例(76.9%),"晕征"13例(10%),"反晕征"6例(4.6%),3例胸腔积液(2.3%),2例肺气囊(1.5%)。未见空洞。35患者行CT复查,21例(60%)好转,14例(40%)加重。结论COVID-19影像学特点主要以胸膜下及小叶核心分布为主,两者均可融合成片,重症者发展为双肺弥漫;最有价值的特征是"胸膜平行征";恢复期表现为边缘收缩的实变影,支气管扩张,胸膜下线或纤维条索影。     

Methotrexate-induced pulmonary injury: serial CT findings

We describe serial computed tomographic (CT) findings of methotrexate (MTX)-induced pulmonary injury. MATERIALS AND METHODS: The cases of 8 patients (3 men and 5 women; mean age 58.6 years, range 16 to 75 years) of clinically diagnosed MTX-induced pulmonary injury were reviewed. Six patients had rheumatoid arthritis, 1 had lupus erythematosus profundus, and 1 had juvenile rheumatoid arthritis. CT findings on admission and at follow-up were evaluated. RESULTS: The most common CT features were diffuse and patchy bilateral ground-glass opacity with (n = 3) or without reticulation (n = 4) and consolidation (n = 1). These opacities showed no predilection for any particular lung zone in 6 patients but did show dependent predilection in 1 patient and upper lobe predilection in 1. Diffuse centrilobular ill-defined nodules were noted in 1 patient, which disappeared on follow-up. During the average post-treatment follow-up period of 31.0 days (range 3 to 76 days), the opacities quickly improved after treatment in 6 patients; however, in 2 patients with pre-existing interstitial pneumonitis the opacities were refractory. CONCLUSION: CT features of MTX-induced pulmonary injury were variable and included diffuse parenchymal opacification, reticular opacities, and centrilobular nodules. These opacities usually responded quickly to treatment; however, those patients with lung fibrosis at presentation may have worse prognosis.     

Computed tomography halo sign in pulmonary nodules: frequency and diagnostic value

On computed tomography (CT) scanning, a ground-glass opacity zone surrounding a pulmonary nodule has been named the computed tomography (CT) halo sign. To investigate the frequency and diagnostic value of the CT halo sign, the authors reviewed the CT examinations of 305 patients with proven diseases producing solitary or multiple nodules. The CT halo sign was seen in 22 patients (7%). Eleven patients had a solitary nodule; five patients had multiple nodules; and six patients had nodules associated with areas of pulmonary consolidation, or ground-glass opacity, or both. Solitary nodules were the result of bronchioloalveolar carcinoma (n = 5), tuberculoma (n = 2), squamous cell carcinoma, non-Hodgkin lymphoma, myxovirus infection, and metastasis (n = 1 each). Multiple nodules were the result of metastasis (n = 2), Kaposi sarcoma (n = 2), and Wegener granulomatosis (n = 1). Nodules associated with areas of consolidation or ground-glass opacity were the result of metastasis (n = 2), bronchioloalveolar carcinoma, bronchiolitis obliterans organizing pneumonia, eosinophilic pneumonia, and invasive pulmonary aspergillosis (n = 1 each). The data showed that the CT halo sign is a nonspecific finding. It is known that in immunocompromised patients the CT halo sign should suggest invasive pulmonary aspergillosis, Kaposi sarcoma, and lymphoproliferative pulmonary disorders. However, in immunocompetent patients, the authors found that a solitary nodule with the CT halo sign and pseudocavitations has a high likelihood of being a bronchioloalveolar carcinoma.     

HRCT findings for four cases of measles pneumonia]

Although, in Western countries, adult-onset pneumonia that is associated with measles is not rare, reports of its incidence in Japan have been sparse. Among eight adolescent and adult (16-34-year-old) measles patients hospitalized in National Sanatorium Tsuruga Hospital, we found four in whom chest radiography and CT revealed pneumonia. The high-resolution lung CTs of these patients revealed features differing from those characteristic of bacterial pneumonia: bronchial wall thickness, centrilobular nodules in ground glass opacity, interstitial lesions (interlobular septal thickening, fissure thickening, pleural effusion) and lymphadenopathy. Of these findings, the centrilobular nodules in ground glass opacity were marked in these cases, and so this may be the most prominent finding in measles pneumonia; and furthermore, since interlobular septal thickening has not been reported in mycoplasma pneumonia or other atypical pneumonias, it may indicate a measles-specific, virus-induced pneumonia.     

HRCT findings of proximal interruption of the right pulmonary artery

The purpose of this study is to present the characteristic HRCT findings of the lung parenchyma in patients with proximal interruption of the right main pulmonary artery. HRCT findings of proximal interruption of the right pulmonary artery demonstrated reticular opacities, septal thickening, subpleural consolidation, cystic lung changes, and pleural thickening in all 5 patients; bronchial dilation and bronchial wall thickening in 4 patients; and subpleural ground glass opacity (GGO) in 3 patients. The changes may be caused by absent pulmonary artery perfusion and development of systemic vessel collateralization.     

31例活动性肺结核治疗前及治愈后的CT征象分析

目的探讨抗结核疗前及治愈后活动性肺结核CT征象的变化特点。方法选取临床治愈的活动性肺结核31例,对比观察活动性肺结核的CT征象转归表现。结果肺结核活动性CT征象治愈前检出率为100.0%,治疗后检出率为35.5%。活动性CT征象中毛玻璃阴影、节段分布小叶中心结节影、小叶样实变影、树芽征、支气管壁增厚、厚壁空洞和肺实变治疗前检出率分别为87.1%、80.6%、80.1%、61.3%、58.1%、48.4%和32.3%、,治愈后检出率分别为0、19.4%、0、0、12.9%、0和3.2%。治疗前活动性肺结核CT检查可检出多种活动性影像,而疗程结束后上述征象减少并多以单发为主,两者有显著差异(P<0.01)。结论CT检查有助于活动性肺结核治疗疗效的判定,并具有较高的敏感度,但特异度较低。     

Viral pneumonia after hematopoietic stem cell transplantation: high-resolution CT findings

Hematopoietic stem cell transplantation (HSCT) is the treatment of choice for many hematologic malignancies and nonmalignant disorders of bone marrow function. Pulmonary infections from bacterial, fungal, and viral organisms are a major cause of morbidity and mortality in patients after HSCT. The radiographic and high-resolution computed tomography (HRCT) findings of the different lower respiratory tract viral infections are quite similar. Findings of viral pneumonia on HRCT include small poorly defined centrilobular nodules and patchy, often bilateral, areas of peribronchial ground-glass opacity and consolidation. Air trapping may be present because of associated bronchiolitis. Interlobular septal thickening, bronchial wall thickening, and tree-in-bud opacities may also be present. Advanced viral pneumonia with diffuse alveolar damage is characterized by patchy or confluent consolidation and ground-glass opacities. Although nonspecific, in the correct clinical setting, these HRCT findings can help suggest the diagnosis of viral pneumonia in recipients of HSCT.     

Pulmonary findings in Churg–Strauss syndrome in chest X-rays and high resolution computed tomography at the time of initial diagnosis

Churg–Strauss syndrome (CSS) is a rare, systemic, necrotizing, small- and middle-sized vessel vasculitis which is accompanied by blood eosinophilia, eosinophil infiltration of various tissues, and bronchial asthma. The lungs are the organs most often involved in CSS. The aim of this study was a retrospective evaluation of the pulmonary findings in chest X-rays and high resolution computed tomography (HRCT) in CSS patients at the time of initial diagnosis and to determine their frequency, character, and location. Seventeen CSS patients were studied (12 women; 5 men; aged 29–56 years). In all patients at the time of initial diagnosis, chest X-rays were performed, and in 15 patients, HRCT was performed additionally. The radiological images were evaluated independently by two radiologists who reached a decision by consensus. Out of 17 patients studied, chest X-rays revealed parenchymal abnormalities in 11, pleural effusion in three, and bronchial wall thickening in one. In five patients, no abnormalities in chest X-rays were found. In HRCT, abnormalities were found in all patients (15 patients, 100%). Predominant HRCT findings consisted of: ground-glass opacities and consolidations found in 13 patients (86.7%). Additionally, in four patients, pulmonary micronodules were described; in ten, interlobular septal thickening; in three, linear opacities; in ten, bronchial wall thickening and/or bronchial dilatation; and in three, pleural effusions. Ground-glass opacities and consolidation abnormalities distribution pattern were peripheral in seven and random in six patients. In patients with CSS, the most common pulmonary radiological findings are parenchymal opacities, which may be peripheral or random in distribution. Pathologic changes were found in 70.6% of patient in chest X-rays, and in 100%, when HRCT was performed. These changes are nonspecific; however, they should be not overlooked, as they may help in establishing the diagnosis and suggest the prognosis.     

High-resolution computed tomography patterns of organizing pneumonia

Organizing pneumonia is an uncommon lung disease with a wide variety of radiologic findings, few of which have been discussed in the literature. We performed high resolution computed tomography on 34 patients with a histological diagnosis of organizing pneumonia and studied the images they presented. Twenty-five of the cases were idiopathic and 9 secondary. The findings observed were parenchymal consolidation (76%), ground glass opacity (59%), bronchial dilatation (53%), centrilobular nodules (35%), septal thickening (23%), halo sign (15%), and reversed halo sign (12%). Secondary cases presented more findings of septal thickening and fewer complete remissions.     

Pulmonary vasculitis: CT features

The pulmonary vasculitides are a heterogeneous group of inflammatory disorders that may be primarily localized to the pulmonary vasculature or be systemic in nature. The primary pulmonary vasculitides usually affect small vessels, whereas the systemic vasculitides can involve any size pulmonary vessels. For all types of vasculitis, there is a high degree of overlap within groups in regard to their appearance at computed tomography (CT). The most common CT findings are the result of either diffuse or focal pulmonary hemorrhage, are nonspecific, and include ground-glass opacity, consolidation, and small centrilobular nodules. Therefore, the CT findings must be considered in concert with the history, physical examination, and laboratory examination when a specific diagnosis is sought. This review will discuss the typical CT features of both the systemic and the primary pulmonary vasculitides, drawing a distinction where CT is helpful in differentiating among the various causes.     

Changes in HRCT findings in patients with respiratory bronchiolitis-associated interstitial lung disease after smoking cessation.

High-resolution computed tomography (HRCT) findings in patients with respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) are varied and nonspecific. There is no known report of changes in HRCT findings and respiratory function test results for RB-ILD patients following the cessation of smoking. Five patients with RB-ILD, confirmed by surgical lung biopsy, were retrospectively studied. Each stopped cigarette smoking and did not receive corticosteroid therapy after diagnosis. The clinical symptoms, respiratory function test results and HRCT findings obtained at the final observation were compared with those from the time of diagnosis. Ground-glass opacity and centrilobular nodules corresponding to pathological respiratory bronchiolitis, as well as intralobular fine linear-reticular opacity corresponding to fibrosis involving the subpleural alveolar septa, showed computed tomography-pathological correlations. Both clinical symptoms and the diffusing capacity of the lungs for carbon monoxide improved significantly following smoking cessation, as did ground-glass opacity and centrilobular nodules seen during the initial HRCT examination. Centrilobular nodules and ground-glass opacity, which are the main features of high-resolution computed tomography of respiratory bronchiolitis-associated interstitial lung disease patients and represent pathological respiratory bronchiolitis, can be improved by smoking cessation. The diffusing capacity of the lung for carbon monoxide in respiratory function tests can be also improved.     

Pulmonary abnormalities in ankylosing spondylitis: inspiratory and expiratory high-resolution CT findings in 17 patients

OBJECTIVE: The purpose of this study was to evaluate pulmonary manifestations of ankylosing spondylitis on inspiratory and expiratory high resolution CT. MATERIAL AND METHODS: The study included 17 patients ranging from 40 to 62 years in age. Fifteen patients were male, and 8 were smokers. All patients underwent chest radiography and high-resolution CT. High-resolution CT was obtained using 1 or 2 mm collimation scans at 10-mm intervals at the end of maximal inspiration and at 3 cm intervals at the end of maximal expiration. RESULTS: Pulmonary abnormalities were evident on chest radiography in 2 patients and on CT in 15 patients. The abnormalities on CT included evidence of airway disease in 14 (82%), interstitial abnormalities in 11 (65%), and emphysema in 6 (35%) patients. Airway abnormalities included bronchial wall thickening in 7 (41%), mosaic perfusion in 3 (18%), centrilobular nodules in 3, bronchiolectasis in 2, and air trapping on expiratory CT in 7 (41%) patients. Interstitial abnormalities included parenchymal bands in 7 (41%), intralobular linear opacities (n = 2), and 1 patient each with irregular thickening of interlobular septa, subpleural lines, and honeycombing. CONCLUSION: The majority of patients with ankylosing spondylitis have airway and interstitial abnormalities evident on high-resolution CT. These abnormalities are usually mild and therefore seldom evident on the chest radiograph.     

Imaging of unusual diffuse lung diseases

PURPOSE OF REVIEW: Computed tomography scans are commonly used in imaging lung diseases. As more information accumulates, patterns of rare or new diseases on CT scans are being increasingly reported. Several pulmonary diseases have distinguishing features, which are better delineated on high resolution CT scans than plain chest radiographs. The radiographic features of unusual diffuse lung diseases published in the past two years are described. RECENT FINDINGS: Severe acute respiratory syndrome generally manifests as focal or diffuse bilateral areas of consolidation on chest radiography and reticulation with ground-glass attenuation commonly seen on CT scans. A normal HRCT rules out the diagnosis of Pneumocystis carinii pneumonia while a normal chest radiograph does not. Immunocompromised patients without AIDS, who have CMV pneumonia, generally demonstrate a combination of ground-glass attenuation, air-space consolidation, and small nodules on HRCT. Nodules less than 10 mm in size in immunocompromised patients are highly suggestive of viral infections. Bronchial wall thickening on HRCT associated with cavitating nodules is suggestive of Wegner granulomatosis in the appropriate clinical setting. Small cysts may be seen in a minority of patients with subacute hypersensitivity pneumonitis and centrilobular emphysema in chronic farmer's lung. Reversed halo sign has a high specificity for cryptogenic organizing pneumonia. The triad of ground-glass opacities, ill-defined centrilobular nodules and cysts and focal areas of air trapping is highly suggestive of subacute hypersensitivity pneumonitis. SUMMARY: Familiarizing with radiographic and CT scan patterns may help the clinician to exclude certain diagnoses and narrow the differential diagnosis for others.     

Bronchiolitis obliterans syndrome in lung transplant recipients: correlation of computed tomography findings with bronchiolitis obliterans syndrome stage

The purpose of this study was to correlate the extent of computed tomographic (CT) findings with the severity of respiratory dysfunction in lung transplant recipients with bronchiolitis obliterans syndrome (BOS). Eighty-nine conventional and 61 thin-section CT scans performed in 44 transplant recipients (17 bilateral, 27 single) with BOS were reviewed for mosaic attenuation, degree of bronchial dilation, bronchial thickening, central and peripheral bronchiectasis, mucus plugging, and air trapping. Findings on conventional and thin-section CT scans were correlated with BOS stage for bilateral and single-lung transplant recipients. In bilateral-lung recipients, a significant correlation existed, although weak, between BOS stage and findings of degree of bronchial dilation (P < 0.01), bronchial wall thickening (P = 0.01), peripheral bronchiectasis (P = 0.01), and mosaic attenuation (P = 0.01) on conventional CT; and bronchial wall thickening (P = 0.01) and mosaic attenuation (P = 0.03) on thin-section CT. In single-lung recipients, BOS stage correlated only with the finding of central bronchiectasis (P = 0.02) on conventional CT scans. No correlation was found between the extent of air trapping and BOS stage in either single- or bilateral-lung transplant recipients. CT findings are relatively poor indices of airflow obstruction in lung transplant recipients with BOS, particularly in those with single-lung transplants for emphysema.