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.     

Nonspecific interstitial pneumonia: correlation between thin-section CT findings and pathologic subgroups in 55 patients

PURPOSE: To characterize thin-section computed tomographic (CT) findings of pathologic subgroups of nonspecific interstitial pneumonia (NIP) in a sizeable number of patients. MATERIALS AND METHODS: The study included 55 cases of pathologically proven NIP. The 55 cases were categorized histologically into four grades: grade 1, interstitial inflammation without fibrosis (n = 6); grade 2, interstitial inflammation predominating over fibrosis (n = 16); grade 3, fibrosis predominating over inflammation (n = 5); and grade 4, fibrosis only (n = 28). Two independent observers evaluated the presence, extent, and distribution of various CT findings. Thin-section CT findings and histologic grades were compared by using the Spearman rank correlation coefficient. Observer agreement was assessed. RESULTS: Areas with ground-glass attenuation and architectural distortion were present in all 55 patients. Traction bronchiectasis and intralobular reticular opacities were seen in 52 and 48 patients, respectively. The extent of traction bronchiectasis (r = 0.68; P <.001) and intralobular reticular opacities (r = 0.35; P <.05) correlated with the histologic grade. Honeycombing was seen in 12 (43%) of 28 patients with grade 4 NIP and in three (11%) of the remaining 27 patients (chi(2) test, P <.001). There was good agreement between the observers for the presence (kappa = 0.7-1.0) and extent (Spearman rank correlation; r = 0.87-0.98; P <.001) of various abnormalities. CONCLUSION: The extent of traction bronchiectasis and intralobular reticulation at thin-section CT correlates with increased fibrosis in NIP. Honeycombing is seen almost exclusively in patients with fibrotic NIP.     

"Crazy paving appearance" on high resolution CT in various diseases.

PURPOSE: The purpose of this work was to demonstrate the variety of causes of crazy-paving appearance (CPA) on high resolution CT (HRCT). METHOD: To identify cases exhibiting CPA (ground-glass opacity with superimposed interlobular septal thickening and intralobular interstitial thickening) on HRCT, we prospectively searched for them over a period of 29 months. RESULTS: We identified 10 cases of CPA on HRCT, including 4 Pneumocystis carinii pneumonia, 1 alveolar proteinosis, 1 usual interstitial pneumonia, 1 pulmonary hemorrhage, 1 acute radiation pneumonitis, 1 adult respiratory distress syndrome, and 1 drug-induced pneumonitis. CONCLUSION: CPA can result from a variety of diseases. When we encounter CPA on HRCT, clinical information is necessary for differentiation of these entities.     

Crazy-paving sign in high-resolution computed tomography in parainfluenza virus pneumonia

The crazy-paving sign is the appearance of a smooth linear pattern superimposed on an area of ground-glass opacity on thin-section computed tomography (CT). A 69-year-old woman was admitted to our hospital for treatment of pneumonia. Thoracic CT showed a crazy-paving sign in the right lung field on admission. She received ceftriaxone and clarithromycin, and the symptoms and infiltration shadow promptly disappeared. Serologic testing revealed a greater than 4-fold increase in the IgG titer for parainfluenza virus I. To our knowledge, there is no previous report of the crazy-paving sign in associated with viral pneumonia in a non-immunocompromised host or with parainfluenza pneumonia.     

Pulmonary involvement of malignant melanoma: thin-section CT findings with pathologic correlation

OBJECTIVES: The purpose of this study was to characterize the thin-section computed tomography (CT) findings of primary and secondary pulmonary malignant melanoma and to correlate them with the histopathologic features. MATERIALS AND METHODS: Patients were identified from a pathologic registration system database through a query for patients with diagnosed primary or secondary pulmonary melanoma who had undergone surgical resection. A total of 19 pulmonary malignant melanomas, including one primary and 18 secondary involvements, from 10 patients were enrolled into this study. The patients consisted of 3 men and 6 women, with a mean age of 55 years (range, 28 to 71 years). Thin-section CT findings evaluated by consensus between two radiologists were compared with the histopathologic specimens. RESULTS: Tumor size ranged from 4 to 62 mm (mean, 19 mm) on thin-section CT images. Four characteristic patterns including solitary or multiple solid nodule, endobronchial lesion, cavitary nodule, and nodule with ground-glass attenuation were disclosed by correlation between thin-section CT and pathologic findings. The most common thin-section CT finding was a solid nodule with a well-defined, smooth margin (n=14). Endobronchial lesions were seen in one primary and one secondary involvement (n=2). Less common CT findings were cavitary nodule (n=1) and nodule with ground-glass attenuation (n=1). CONCLUSION: Primary and secondary pulmonary malignant melanomas show various patterns of involvement on thin-section CT.     

Pulmonary alveolar microlithiasis presenting with crazy-paving pattern on high resolution CT

Pulmonary alveolar microlithiasis (PAM) is an uncommon chronic disease characterized by calcifications within the alveoli and a paucity of symptoms in contrast to the imaging findings. We present a 59-year-old woman with a 4-year history of shortness of breath on exertion. Lung auscultation revealed random wheezes and fine and coarse crackles. Pulmonary function tests showed a restrictive pattern. The chest radiograph demonstrated a bilateral symmetric micronodular pattern. High resolution CT scan revealed diffuse ground-glass attenuation with superimposed septal thickening ("crazy-paving" pattern). The patient underwent a lung biopsy, which confirmed the diagnosis of PAM. Our case demonstrates that PAM needs to be considerate in the differential diagnosis of lung lesions that present with crazy-paving pattern on the high resolution CT.     

Nonspecific interstitial pneumonia and usual interstitial pneumonia: comparative appearances at and diagnostic accuracy of thin-section CT.

PURPOSE: To compare the morphologic abnormalities on thin-section computed tomographic (CT) images in a group of patients with histopathologically confirmed nonspecific interstitial pneumonia (NSIP) or usual interstitial pneumonia (UIP) and a clinical presentation of idiopathic pulmonary fibrosis. MATERIALS AND METHODS: Thin-section CT imaging patterns and distribution of disease in 53 patients with histologic diagnoses of NSIP (n = 21) or UIP (n = 32) were quantified retrospectively and independently by four observers. The appearances of NSIP and UIP at CT were compared with univariate and multivariate techniques. RESULTS: The use of thin-section CT proved to have moderate sensitivity (70%), specificity (63%), and accuracy (66%) in the diagnosis of NSIP. An increased proportion of ground-glass attenuation was the cardinal feature of NSIP at CT (odds ratio: 1.04 for each 1% increase in the proportion of ground-glass attenuation). A histologic diagnosis of NSIP was most frequent (in 24 of 35 observations [69%]) when ground-glass attenuation predominated, and was more frequent with mixed (35 of 79 observations [44%]) than with predominantly reticular disease (25 of 98 [26%] observations, P < .005). Logistic regression analysis of the data indicated that misdiagnosis of UIP in patients with NSIP was associated with less ground-glass attenuation (P < .005) at CT and a subpleural disease distribution (P = .02), with the converse being true for UIP cases misdiagnosed as NSIP. CONCLUSION: In patients with a clinical presentation of idiopathic pulmonary fibrosis, the accuracy of thin-section CT in identifying NSIP is considerably higher than previously reported. At CT, NSIP is characterized by more ground-glass attenuation and a finer reticular pattern than is UIP. Nevertheless, considerable overlap in thin-section CT patterns exists between NSIP and UIP.     

Hyperoxia-induced diffuse alveolar damage in pigs: correlation between thin-section CT and histopathologic findings

PURPOSE: To determine whether lung abnormalities at thin-section computed tomography (CT) in experimental hyperoxic lung injury correlate with the pathologic phases of diffuse alveolar damage (DAD). MATERIALS AND METHODS: Eighteen juvenile pigs were exposed to more than 80% oxygen-for 24, 48, 72, 96, or 120 hours-or room air in sealed cages. Their removed lungs were inflated with air infused through the trachea and examined with thin-section CT. Two independent observers, without knowledge of the exposure times, compared 63 areas selected on the CT scans with the corresponding pathologic and histologic findings, which were evaluated independently by two pathologists. RESULTS: CT findings correlated well with histologic findings (rho = 0.86, P <.001), which corresponded to the pathologic phases of DAD. All areas of normal CT attenuation, eight of nine spared regions within areas of opacity, and two of 15 areas of ground-glass opacity corresponded to the early exudative pathologic phase of DAD. All areas that showed traction bronchiolectasis at CT corresponded to the early proliferative pathologic phase. There was good observer agreement regarding the interpretation of CT findings (kappa statistic, >0.60) and histologic results (>/=0.70). CONCLUSION: Thin-section CT findings reflect the pathologic phases of DAD, although the early exudative phase cannot be specifically depicted by thin-section CT. Traction bronchiolectasis on a CT scan suggests progression to the proliferative phase.     

Severe acute respiratory syndrome: temporal lung changes at thin-section CT in 30 patients

PURPOSE: To evaluate lung abnormalities on serial thin-section computed tomographic (CT) scans in patients with severe acute respiratory syndrome (SARS) during acute and convalescent periods. MATERIALS AND METHODS: Serial thin-section CT scans in 30 patients (17 men, aged 42.5 years +/- 12.2 [SD]) with SARS were reviewed by two radiologists together for predominant patterns of lung abnormalities: ground-glass opacities, ground-glass opacities with superimposed linear opacities, consolidation, reticular pattern, and mixed pattern (consolidation, ground-glass opacities, and reticular pattern). Scans were classified according to duration in weeks after symptom onset. Longitudinal changes of specific abnormalities were documented in 17 patients with serial scans obtained during 3 weeks. Each lung was divided into three zones; each zone was evaluated for percentage of lung involvement. Summation of scores from all six lung zones provided overall CT score (maximal CT score, 24). RESULTS: Median CT scores increased from 1 in the 1st week to 12.5 in the 2nd week. Ground-glass opacities with or without smooth interlobular septal thickening and consolidation were predominant patterns found during the 1st week. Ground-glass opacities with superimposed irregular reticular opacities, mixed pattern, and reticular opacities were noted from the 2nd week and peaked at or after the 4th week. After the 4th week, 12 (55%) of 22 patients had irregular linear opacities with or without associated ground-glass opacities and CT scores greater than 5; five of these patients had bronchial dilatation. When specific opacities were analyzed in 17 patients, consolidation generally resolved completely (n = 4) or to minimal residual opacities; six (55%) of 11 patients with ground-glass opacities had substantial residual disease (CT scores > 5) on final scans. CONCLUSION: There is a temporal pattern of lung abnormalities at thin-section CT in SARS. Predominant findings at presentation are ground-glass opacities and consolidation. Reticulation is evident after the 2nd week and persists in half of all patients evaluated after 4 weeks. Long-term follow-up is required to determine whether the reticulation represents irreversible fibrosis.     

Exogenous lipoid pneumonia: HRCT, MR, and pathologic findings

The objective of this study was to describe high-resolution CT (HRCT) and MR findings of exogenous lipoid pneumonia and to correlate them with pathologic findings. A retrospective review of the medical records of our institution revealed seven patients with a diagnosis of lipoid pneumonia based on clinical data, chest films, bronchoalveolar lavage, and follow-up. Both HRCT and MR imaging were reviewed by two readers. Pathologic examination of the resected specimen or surgical biopsies were also reviewed in the four available cases. The HRCT findings were pulmonary consolidations (n = 6) with fatty (n = 3) or unspecific but low attenuation values (n = 3), areas of ground-glass opacities (n = 5), septal lines, and centrilobular interstitial thickening (n = 5). In five of the seven cases, a crazy-paving pattern of various spread was also present, either isolated (n = 1) or surrounding a pulmonary consolidation. In two cases traction bronchiectasis and cystic changes consistent with fibrosis were seen. At MR imaging (n = 2) a pulmonary consolidation of high signal intensity on T1-weighted image consistent with lipid content was present in one case. Pathologic examination (n = 4) showed the coexistence of lobules with lesions of various ages, sometimes in contiguous lobules, within the same patient. Recent lesions were those with alveolar fill-in by spumous macrophages and almost normal alveolar walls and septae. In more advanced lesions, lobules were filled in with larger vacuoles often surrounded by inflammatory infiltrates of alveolar walls, bronchiolar walls, and septa. The oldest lesions were characterized by fibrosis and parenchymal distortion around large lipid-containing vacuoles. The HRCT findings reflect pathologic findings in exogenous lipoid pneumonia. Although non-specific, consolidation areas of low attenuation values and crazy-paving pattern are frequently associated in exogenous lipoid pneumonia and are indicative of the diagnosis. Received: 24 July 1998; Revision received: 30 December 1998; Accepted: 1 February 1999     

Thoracic CT findings of adult T-cell leukemia or lymphoma

OBJECTIVE: The aim of this study was to assess pulmonary CT findings in patients with adult T-cell leukemia or lymphoma. MATERIALS AND METHODS: We retrospectively reviewed CT scans of the lung in 87 patients with adult T-cell leukemia or lymphoma who had undergone chest CT between January 1996 and March 2002 at two institutions. The CT scans were interpreted by two chest radiologists working in consensus. Parenchymal abnormalities (ground-glass attenuation, consolidation, nodules, thickening of bronchovascular bundles, interlobular septal thickening, honeycombing, crazy-paving appearance, and bronchiectasis) were evaluated, as were enlarged lymph nodes, pleural effusion, and pleural thickening. In 46 patients who underwent surgical biopsy or autopsy, CT-pathologic correlation was performed with the actual specimens by a pathologist and two chest radiologists. RESULTS: On the CT scans, abnormal findings were seen in 60 patients (69.0%). CT findings consisted of ground-glass attenuation (n = 37), centrilobular nodules (n = 25), thickening of bronchovascular bundles (n = 22), and consolidation (n = 13). These abnormalities were predominantly seen in the peripheral lung parenchyma (n = 26). Pathologically, these findings corresponded with atypical lymphocyte infiltration along the interstitium and the alveolar spaces. Pleural effusion and enlarged lymph nodes were found in 22 and 27 patients, respectively. CONCLUSION: CT findings in patients with adult T-cell leukemia or lymphoma consisted mainly of ground-glass attenuation, centrilobular nodules, and thickening of the bronchovascular bundles in the peripheral lung. These findings, although nonspecific, are considered suggestive of thoracic involvement in patients with adult T-cell leukemia or lymphoma.     

肺泡微石症的影像学诊断

目的：探讨肺泡微石症的影像学特征。方法;报道肺泡微石症6例,全部病例均行胸部X线检查,2例行常规CT,1例行HRCT。并对全部影像学表现进行了回顾性分析。结果：6例胸片表现为弥漫粟粒样微细结节（2例）。“鱼子样”或“暴风沙样”（2例）、“白肺样”（1例）及高密度“面纱样”改变（1例）,CT可明确肺内微细结节的钙化密度,肺尖部气肿样改变及支气管血管束增粗并呈钙化密度,HRCT则可进一步显示肺野磨砂玻璃样改变,小叶间隔,叶间胸膜及支气管血管束钙化密度与串珠状增厚,小叶中心分布的微细结节与胸膜下蜂窝,结论：肺泡微石症是一种罕见病,其影像学表现具有特征性,影像学检查尤以HRCT检查对该病的诊断有决定性作用。     

Usual interstitial pneumonia and chronic idiopathic interstitial pneumonia: analysis of CT appearance in 92 patients

PURPOSE: To retrospectively analyze computed tomographic (CT) findings of chronic idiopathic interstitial pneumonia (IIP) and to determine which findings are most helpful for distinguishing IIP from usual interstitial pneumonia (UIP) with univariate and multivariate analyses. MATERIALS AND METHODS: Institutional review board approval and informed consent were not required for this retrospective review of patient records and images. Two observers working independently and without knowledge of the diagnosis evaluated the extent and distribution of various thin-section CT findings (ground-glass opacity, consolidation, reticulation, and honeycombing) in 92 patients (51 men, 41 women; mean age, 56 years; age range, 29-81 years) with a histologic diagnosis of UIP (n = 20), cellular nonspecific interstitial pneumonia (NSIP) (n = 16), fibrotic NSIP (n = 16), respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) (n = 11), desquamative interstitial pneumonia (DIP) (n = 15), or lymphoid interstitial pneumonia (LIP) (n = 14). Observers used univariate and multivariate statistical analyses to compare their findings with the extent and distribution of UIP. RESULTS: Observers made the correct diagnosis in 145 (79%) of 184 readings. Multivariate logistic regression analysis showed that the independent findings that distinguished UIP from cellular NSIP were the extent of honeycombing and the most proximal bronchus with traction bronchiectasis (odds ratio, 5.16 and 0.37, respectively); the finding that distinguished UIP from fibrotic NSIP was the extent of honeycombing (odds ratio, 2.10). CT features that distinguished UIP from RB-ILD and DIP included extent of ground-glass opacity (odds ratio, 0.76), thickening of bronchovascular bundles (odds ratio, 1.58), the most proximal bronchus with traction bronchiectasis (odds ratio, 0.22), and the number of segments with traction bronchiectasis (odds ratio, 3.64). CONCLUSION: UIP has a characteristic appearance that usually facilitates distinction from other types of chronic IIPs at thin-section CT. The most useful finding when differentiating UIP from NSIP was the extent of honeycombing.     

CT-pathologic correlation in small peripheral lung cancers

To evaluate the morphology of small peripheral lung cancers, we studied thin-section CT images of 18 small peripheral lung cancers (14 adenocarcinomas, two squamous-cell carcinomas, one large-cell carcinoma, and one carcinoid) in 17 patients. After surgical resection, specimens were sliced transversely, and the gross morphology and histology were correlated with the appearance of the lesion on preoperative thin-section CT images. CT images showed fine speculations in 78%, a notch in 83%, pleural retraction in 78%, and convergence of peripheral vessels in 83% of the 18 lung cancers. Furthermore, in cases of papillary adenocarcinoma, the lesions had heterogeneous densities (78%) and small cavitations (67%). CT showed a peripheral fluffy zone in most of the well- or moderately differentiated papillary adenocarcinomas. This correlated well with tumor cells lining the alveolar walls, observed in pathologic studies. Comparison of thin-section CT images with pathologic data suggests that the demonstration of the lung-tumor interface and the tumor's internal texture, while not specific for malignant lesions, can make the CT diagnosis of small peripheral lung cancers more accurate.     

Progression of focal pure ground-glass opacity detected by low-dose helical computed tomography screening for lung cancer

OBJECTIVE: To clarify the progression of focal pure ground-glass opacity (pGGO) detected by low-dose helical computed tomography (CT) screening for lung cancer. METHODS: A total of 15,938 low-dose helical CT examinations were performed in 2052 participants in the screening project, and 1566 of them were judged to have yielded abnormal findings requiring further examination. Patients with peripheral nodules exhibiting pGGO at the time of the first thin-section CT examination and confirmed histologically by thin-section CT after follow-up of more than 6 months were enrolled in the current study. Progression was classified based on the follow-up thin-section CT findings. RESULTS: The progression of the 8 cases was classified into 3 types: increasing size (n = 5: bronchioloalveolar carcinoma [BAC]), decreasing size and the appearance of a solid component (n = 2: BAC, n = 1; adenocarcinoma with mixed subtype [Ad], n = 1), and stable size and increasing density (n = 1: BAC). In addition, the decreasing size group was further divided into 2 subtypes: a rapid-decreasing type (Ad: n = 1) and a slow-decreasing type (BAC: n = 1). The mean period between the first thin-section CT and surgery was 18 months (range: 7-38 months). All but one of the follow-up cases of lung cancer were noninvasive whereas the remaining GGO with a solid component was minimally invasive. CONCLUSIONS: The pGGOs of lung cancer nodules do not only increase in size or density, but may also decrease rapidly or slowly with the appearance of solid components. Close follow-up until the appearance of a solid component may be a valid option for the management of pGGO.     

Rheumatoid arthritis-related lung diseases: CT findings

PURPOSE: To evaluate computed tomographic (CT) findings of rheumatoid arthritis-related lung disease and categorize findings according to pathologic features. MATERIALS AND METHODS: CT scans obtained in 63 patients (27 men, 36 women; mean age, 61.7 years +/- 11.2 [SD]; range, 28-81 years) with rheumatoid arthritis were assessed. Mean duration of disease was 7.6 years +/- 9.2. Lung parenchymal abnormalities that included airspace consolidation, ground-glass opacity (GGO), reticulation, honeycombing, nodules, bronchiectasis, and air trapping were assessed retrospectively by two chest radiologists. Final decision was reached with consensus of these radiologists and a third radiologist. Patients were classified according to the predominant CT pattern. One of the chest radiologists and a pulmonary pathologist compared CT findings with pathologic findings in 17 patients. Interobserver agreement between the first two radiologists was assessed. Correlation between CT finding extent score and pulmonary function test results was estimated with Spearman rank correlation coefficient. RESULTS: GGO (57 [90%] patients) and reticulation (62 [98%] patients) were the most common CT features. Four major CT patterns were identified: usual interstitial pneumonia (n = 26), nonspecific interstitial pneumonia (n = 19), bronchiolitis (n = 11), and organizing pneumonia (n = 5). Usual interstitial pneumonia and nonspecific interstitial pneumonia CT patterns overlapped; GGO was more extensive in patients with nonspecific interstitial pneumonia CT pattern (P =.028). In 17 patients who underwent biopsy, CT findings reflected pathologic findings. Exceptions were two patients classified with usual interstitial pneumonia at CT but with nonspecific interstitial pneumonia at pathologic analysis; one patient, with nonspecific interstitial pneumonia at CT but desquamative interstitial pneumonia at pathologic analysis; and one patient, with lymphoid interstitial pneumonia at CT but nonspecific interstitial pneumonia at pathologic analysis. CONCLUSION: Rheumatoid arthritis is associated with four CT patterns: usual interstitial pneumonia, nonspecific interstitial pneumonia, bronchiolitis, and organizing pneumonia. The most common CT features of rheumatoid arthritis-related lung disease were GGO and reticulation.     

结缔组织病胸部病理与X线诊断的相关研究

作者分析了１７例尸检结缔组织病患者的胸部病理改变及有关的临床和Ｘ线诊断，并分析９６例四种常见结缔组织病患者胸片改变。结论：胸部Ｘ线诊断在胸部受累的结缔组织病诊断中具有重要作用；胸片改变的非特异性是临床衰诊的重要原因。     

Transient radiographic progression during initial treatment of pulmonary tuberculosis: CT findings

PURPOSE: A study was undertaken to describe the thin-section CT features of transient radiographic progression during initial treatment of active pulmonary tuberculosis. METHOD: The CT scans of 13 patients who developed transient radiographic progression during initial treatment of pulmonary tuberculosis were evaluated and compared with those of 10 patients with true progression of pulmonary tuberculosis. Two patients underwent transbronchial lung biopsy for pathologic evaluation of new lesion. RESULTS: Eight patients had increased opacity at the site of their original lesion, whereas five had new opacities elsewhere: ipsilateral (n = 3) or contralateral (n = 1) to the original lesion or both (n = 1). Relatively extensive areas of ground-glass attenuation were concomitantly depicted in three of the eight patients with progression in the area of the original lesion. In those with progression ipsilateral or contralateral to the lesion, the character of the new lesions was ground-glass opacity and/or consolidation mainly in the subpleural region. Transbronchial lung biopsy specimens obtained from two patients showed intraluminal organizing exudates and thickened alveolar septa with lymphocyte infiltration, whereas the dominant CT findings of true progression of pulmonary tuberculosis were nodules (n = 8) or centrilobular nodules (n = 7). CONCLUSION: Thin-section CT may be useful to differentiate transient radiographic progression from true progression of pulmonary tuberculosis.     

Diagnostic accuracy of thin-section CT and chest radiography of pediatric interstitial lung disease

OBJECTIVE: We assessed the accuracy of thin-section CT and chest radiography to diagnose pediatric interstitial lung disease. MATERIALS AND METHODS: We identified 20 infants, boys, and girls (age range, 1 month to 14 years) with histopathologic confirmation of interstitial lung disease. Six boys and girls without interstitial lung disease were also included. Two observers independently assessed chest radiograph and CT images. The observers stated the most likely diagnosis and a differential diagnosis. We evaluated individual CT features and their distribution. RESULTS: Observers' diagnoses on CT images were correct (first choice or differential) in 66% of observations versus 45% on chest radiographs (p < 0.025). Correct diagnoses were made on first choice in 61% of CT observations versus 34% on chest radiographs (p < 0.005). Observers were confident (versus uncertain) in 42% of the CT observations versus 18% on chest radiographs; of the confident diagnoses made on CT, 91% were correct. CT interpretations were most accurate in the diagnosis of pulmonary alveolar proteinosis, congenital lymphangiectasia, and idiopathic pulmonary hemosiderosis. All healthy patients examined with CT were correctly identified as such. We noted a distinctive CT pattern in three patients with nonspecific interstitial pneumonitis and one patient with desquamative interstitial pneumonitis; the CT pattern consisted of upper zone predominant honeycombing on a background of ground-glass attenuation. CONCLUSION: A higher proportion of pediatric interstitial lung diseases can be diagnosed on thin-section CT than on chest radiographs. In our study, confident and correct diagnoses were made more frequently with CT than with chest radiographs.