High-resolution computed tomography features of nonspecific interstitial pneumonia and usual interstitial pneumonia

OBJECTIVE: To assess the accuracy of high-resolution computed tomography (HRCT) in the diagnosis of nonspecific interstitial pneumonia (NSIP). We hypothesized that the computed tomography (CT) features of NSIP could be distinguished from those of usual interstitial pneumonia (UIP). METHODS: The HRCT images of 47 patients with surgical lung biopsy-proven NSIP (n = 25) and UIP (n = 22) were independently reviewed by 2 thoracic radiologists. Predominant imaging patterns, most likely diagnosis, and diagnostic level of confidence were recorded. A confident HRCT diagnosis of NSIP was based on the presence of spatially uniform, bilateral, basal-predominant ground-glass and/or reticular opacities with little if any honeycombing, whereas UIP was confidently diagnosed if a spatially inhomogeneous, bilateral, peripheral, basal-predominant pattern of reticular opacities and honeycombing with little if any ground-glass attenuation was identified. RESULTS: A predominant pattern of ground-glass and/or reticular opacity with minimal to no honeycombing was demonstrated in 48 (96%) of 50 readings in patients with NSIP. Conversely, the presence of honeycombing as a predominant feature had a predictive value of 90% for UIP (P < 0.001). Usual interstitial pneumonia was more likely than NSIP to be subpleural and patchy (P < 0.001). A confident CT diagnosis of NSIP and UIP was correct in 73% and 88% of cases, respectively. The correctness of a CT diagnosis made at intermediate or high confidence was 68% and 88%, respectively. The kappa value for distinction of NSIP from UIP was 0.72. CONCLUSION: In contrast to previous reports, NSIP can be separated from UIP in most cases. The presence of honeycombing as a predominant imaging finding is highly specific for UIP and can be used to differentiate it from NSIP, particularly when the distribution is patchy and subpleural predominant. The presence of predominant ground-glass and reticular opacity is highly characteristic of NSIP, but there is a subset of patients with UIP who have this pattern and may require biopsy for differentiation from NSIP.     

Differential diagnosis between usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP) assessed by high-resolution computed tomography (HRCT)

PURPOSE: The aim of this study was to assess the accuracy of high-resolution CT in the differential diagnosis between UIP and NSIP, and the correlations with histological and functional findings. MATERIALS AND METHODS: Patients underwent thin-collimation spiral CT (1 mm), with 10-mm interval. Pulmonary function was assessed with a pneumotacograph and body plethysmograph connected with a computer for data analysis. Three pathologists, blinded to the clinical and functional data, provided a histological diagnosis based on established criteria reported in the literature. The study group only included patients with a histological diagnosis of either UIP or NSIP. RESULTS: We achieved a correct diagnosis of NSIP in 86.6% of cases (76.4% sensitivity; 84.6% specificity), whereas UIP was correctly diagnosed in 73.3% of cases (84.6% sensitivity; 76.5% specificity). An 80% agreement was achieved between the HRCT and histological findings in the whole case series (73% sensitivity, 87% specificity, p<0.01). CONCLUSIONS: The most important finding of our study was that a ground glass appearance equal to or greater than 15% is highly suggestive of NSIP. Therefore, our results could be useful to confirm a suggested diagnosis of NSIP.     

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.     

Nonspecific interstitial pneumonia versus usual interstitial pneumonia: differences in the density histogram of high-resolution CT

OBJECTIVE: To assess the capability of the density histogram of high-resolution CT (HRCT) in differentiating nonspecific interstitial pneumonia (NSIP) from usual interstitial pneumonia (UIP) without definite honeycombing. METHODS: Twenty-eight NSIP and 32 UIP patients without definite honeycombing on CT were included in this study. We evaluated a CT image at the level of 1 cm above the diaphragm. The pixels of the lung parenchyma were classified into 4 ranges. The fractions of each range of corresponding density were calculated. The skewness (the degree of asymmetry of a distribution) and kurtosis (how sharply peaked a histogram is) were obtained from the density histogram. The mean value and the mode value of the lung attenuation were also measured. RESULTS: The fraction of the range of ground-glass opacity and reticular opacity was greater in NSIP patients (32%, 12%) than in UIP patients (23%, 8%) (P < 0.001). UIP had a larger fraction of the range of normal lung. The density histogram was less skewed (P = 0.01) and had a wider peak (P = 0.02) in NSIP (skewness = 1.2879 +/- 0.5672, kurtosis = 1.2115 +/- 1.9470) than in UIP (skewness = 1.6426 +/- 0.4664, kurtosis = 2.3880 +/- 1.8183). CONCLUSION: The density histogram reflected the differences in the CT features between NSIP and UIP. Therefore, a density histogram may be helpful for differentiating NSIP from UIP without definite honeycombing.     

Pathologic subgroups of nonspecific interstitial pneumonia: differential diagnosis from other idiopathic interstitial pneumonias on high-resolution computed tomography

OBJECTIVE: To determine whether the subtypes of nonspecific interstitial pneumonia (NSIP) could be differentiated from other idiopathic interstitial pneumonias (IIPs) on the basis of findings on high-resolution computed tomography (CT). METHODS: Two observers evaluated the high-resolution CT findings in 90 patients with IIPs. The patients included 36 with NSIP, 11 with usual interstitial pneumonia (UIP), 8 with cryptogenic organizing pneumonia (COP), 10 with acute interstitial pneumonia (AIP), 14 with desquamative interstitial pneumonia (DIP) or respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), and 11 with lymphoid interstitial pneumonia (LIP). The NSIP cases were subdivided into group 1 NSIP (n = 6), group 2 NSIP (n = 15), and group 3 NSIP (n = 15). RESULTS: Observers made a correct diagnosis with a high level of confidence in 65% of NSIP cases, 91% of UIP cases, 44% of COP cases, 40% of AIP cases, 32% of DIP or RB-ILD cases, and 82% of LIP cases. Group 1 NSIP was misdiagnosed as AIP, DIP or RB-ILD, and LIP in 8.3% of patients, respectively. Group 2 NSIP was misdiagnosed as COP in 10% of patients, LIP in 6.7%, AIP in 3.3%, and DIP or RB-ILD in 3.3%. Group 3 NSIP was misdiagnosed as UIP in 6.7% of patients, COP in 6.7%, and DIP or RB-ILD in 3.3%. CONCLUSIONS: In most patients, NSIP can be distinguished from other IIPs based on the findings on high-resolution CT. Only a small percentage of patients with predominantly fibrotic NSIP (group 3 NSIP) show overlap with the high-resolution CT findings of UIP.     

Differentiation of bacterial and non-bacterial community-acquired pneumonia by thin-section computed tomography

Background and objective

The management of community-acquired pneumonia (CAP) depends, in part, on the identification of the causative agents. The objective of this study was to determine the potential of thin-section computed tomography (CT) in differentiating bacterial and non-bacterial pneumonia.

Patients and methods

Thin-section CT studies were prospectively examined in hospitalized CAP patients within 2 days of admission, followed by retrospective assessment by two pulmonary radiologists. Thin-section CT findings on the pneumonias caused by each pathogen were examined, and two types of pneumonias were compared. Using multivariate logistic regression analyses, receiver operating characteristic (ROC) curves were produced.

Results

Among 183 CAP episodes (181 patients, 125 men and 56 women, mean age ± S.D.: 61.1 ± 19.7) examined by thin-section CT, the etiologies of 125 were confirmed (94 bacterial pneumonia and 31 non-bacterial pneumonia). Centrilobular nodules were specific for non-bacterial pneumonia and airspace nodules were specific for bacterial pneumonia (specificities of 89% and 94%, respectively) when located in the outer lung areas. When centrilobular nodules were the principal finding, they were specific but lacked sensitivity for non-bacterial pneumonia (specificity 98% and sensitivity 23%). To distinguish the two types of pneumonias, centrilobular nodules, airspace nodules and lobular shadows were found to be important by multivariate analyses. ROC curve analysis discriminated bacterial pneumonia from non-bacterial pneumonia among patients without underlying lung diseases, yielding an optimal point with sensitivity and specificity of 86% and 79%, respectively, but was less effective when all patients were analyzed together (70% and 84%, respectively).

Conclusion

Thin-section CT examination was applied for the differentiation of bacterial and non-bacterial pneumonias. Though showing some potential, this examination at the present time would not be applicable for patients with underlying lung diseases, severe conditions of pneumonia, or immunocompromised conditions.     

Quantitative analysis for computed tomography findings of various diffuse lung diseases using volume histogram analysis

OBJECTIVES:: The aim of this study was to achieve the quantitative analysis of the characteristic computed tomography (CT) findings and course of interstitial pneumonia using the volume histogram method. METHODS:: Contrast (CNT), variance (VAR), and entropy (EPY) values from whole-lung volume data were compared between normal lungs and 5 diseases that have characteristic CT findings. Thirteen cases with nonspecific interstitial pneumonia (NSIP) were evaluated before and after treatment. RESULTS:: In cases with thickening of the bronchovascular bundles and interlobular thickening, ground-glass attenuation, airspace consolidation, and honeycombing, the values of VAR and EPY were greater than those in the normal cases (P < 0.05). In the cases with NSIP, the CNT value after treatment was significantly greater and the values of VAR and EPY after treatment were significantly lower than those before treatment (P < 0.05). CONCLUSIONS:: Volume histogram analysis is a promising method for the evaluation of diffuse lung diseases and the effectiveness of treatment.     

High-resolution x-ray computed tomography in lymphoid interstitial pneumonia

Three patients with lymphoid interstitial pneumonia (two HIV 1+ patients with chronic lymphadenopathic syndromes and one with a not-characterized autoimmune disease) have been studied with high-resolution computed tomography (HR-CT). This technique reveals septal lines, small reticulonodular opacities, polyhedral micronodular opacities, "ground-glass" opacities and a dense, subpleural, curved broken line in one patient. The lesions dominate in the bases of the lungs. They are not characteristic for lymphoid interstitial pneumonia. If a patient present with a chronic lymphadenopathic syndrome, the diagnosis of an opportunistic infection should not be automatically made, since the syndrome can be caused by lymphoid interstitial pneumonia.     

Appendiceal diverticulitis: diagnosis and differentiation from usual acute appendicitis using computed tomography

OBJECTIVE: To describe the computed tomographic findings of appendiceal diverticulitis. METHODS: Computed tomography (n = 20) and clinical findings in 23 patients with appendiceal diverticulitis were retrospectively reviewed and compared with those in 23 patients with usual acute appendicitis. RESULTS: Computed tomography visualized the inflamed diverticula (up to 4 per patient) mostly as small (median, 7.5 mm) round cystic outpouchings at the distal appendix with contrast enhancement at the cyst wall in 16 (80%) patients with appendiceal diverticulitis. In 50% of appendiceal diverticulitis patients, computed tomographic diagnosis of accompanying appendicitis was false positive. Appendicolith was rarely observed in the appendiceal diverticulitis group (5% vs 48%, P = 0.002). No significant difference was observed in the clinical findings except for the patient age (median, 45 vs 31 years; P = 0.001). CONCLUSIONS: Most appendiceal diverticulitis can be differentiated from usual acute appendicitis at computed tomography by visualization of the inflamed diverticulum.     

Localized mucinous bronchioloalveolar carcinoma of the lung: thin-section computed tomography and fluorodeoxyglucose positron emission tomography findings

Purpose

The aim of this study was to evaluate thinsection computed tomography (CT) and fluorodeoxyglucose positron emission tomography (FDG-PET) findings of localized pulmonary mucinous bronchioloalveolar carcinomas (BACs).

Methods and materials

From February 2000 to February 2009, there were seven patients with pulmonary localized mucinous BACs that were pathologically confirmed in the surgical specimens. Their CT findings were assessed regarding location, extent (percent) of groundglass opacity (GGO), margin characteristics, and the presence of air-containing spaces and contractive changes. We evaluated the presence of the “angiogram sign” in the patients who underwent enhanced CT. The maximum standardized uptake value (SUVmax) on FDG-PET was measured in four cases.

Results

All tumors were located in the lower lobes. The percentages of GGOs ranged from 0% to 70% (average 20%). The tumor margins were well defined in five cases and ill-defined in two cases. Air-containing spaces were seen in all cases. Evidence of contractive change was seen in two of the seven cases. The angiogram sign was identified in one of five patients who underwent enhanced CT. The SUVmax on FDG-PET ranged from 0.93 to 1.97 (mean 1.53).

Conclusion

The imaging features of localized mucinous BACs include solid or partly solid attenuation, the presence of air-containing spaces, lack of contractive changes, and lower lobe predominance. Additionally, the SUVmax is markedly low on FDG-PET.     

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.     

Usual interstitial pneumonia and nonspecific interstitial pneumonia: correlation between CT findings at the site of biopsy with pathological diagnoses

Objectives

The aim of this study was to correlate high-resolution CT (HRCT) findings at the site of biopsy with the whole lung CT and pathologic diagnoses in usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP).

Methods

The study included 35 patients (25 UIP and 10 NSIP) diagnosed both pathologically and clinically. 81 surgical biopsy specimens (54 UIP, and 27 NSIP) and extracted areas corresponding to biopsy sites on HRCT were analyzed. CT interpretations were compared with pathological diagnoses in both extracted images and the whole lung. Concordant and discordant cases in multiple extracted images were divided and analyzed. Then the whole cases were categorized by including or not at least one UIP diagnosis of extracted images and evaluated.

Results

The diagnoses in extracted sites significantly correlated with pathological diagnoses (p = 0.047). There were significant differences in the concordances of extracted images compared with the diagnosis of whole lung and pathology (p = 0.008, 0.003, respectively). All 7 cases that were not concordant were diagnosed as radiological UIP with whole lung CT. The cases with at least one UIP diagnosis of extracted CT images were diagnosed as UIP in pathology more frequently (18 in 25) (p = 0.007).

Conclusions

Radiological UIP in whole CT had more frequently discordant diagnoses from multiple extracted images than NSIP. And there were more cases in pathological UIP that included at least one UIP diagnosis of extracted images compared with pathological NSIP.     

Acute interstitial pneumonia: thin-section CT findings in 36 patients.

PURPOSE: To characterize the computed tomographic (CT) findings of acute interstitial pneumonia and to correlate the pattern and the extent of abnormalities with the time between symptom onset and CT. MATERIALS AND METHODS: The study included 36 patients (20 men, 16 women; age range, 22-83 years; mean age, 61 years) with histopathologically proved acute interstitial pneumonia who were identified retrospectively. The time between symptom onset and CT was 2-90 days (mean, 22 days; median, 17 days). The presence, extent, and distribution of various CT findings were evaluated. Disease duration and extent of each finding were compared by using the Spearman rank correlation coefficient. RESULTS: Areas with ground-glass attenuation, traction bronchiectasis, and architectural distortion were present in all 36 patients. Airspace consolidation was present in 33 patients (92%). The extent of areas of ground-glass attenuation (r = 0.45, P < .01) and the extent of traction bronchiectasis (r = 0.35, P < .05) correlated with disease duration. No other significant correlation was found between the CT findings and disease duration. CONCLUSION: A combination of ground-glass attenuation, airspace consolidation, traction bronchiectasis, and architectural distortion is seen in the majority of patients with acute interstitial pneumonia. The extent of ground-glass attenuation and traction bronchiectasis increases with disease duration.     

Lymphocytic interstitial pneumonia: thin-section CT findings in 22 patients.

PURPOSE: To assess the thin-section computed tomographic (CT) findings of lymphocytic interstitial pneumonia. MATERIALS AND METHODS: The study included 22 patients (five men, 17 women; age range, 24-83 years; mean age, 50 years) with biopsy-proved lymphocytic interstitial pneumonia. The CT scans were obtained by using 1-3-mm collimation and reconstructed by using a high-spatial-frequency algorithm. RESULTS: The predominant abnormalities consisted of areas of ground-glass attenuation and poorly defined centrilobular nodules present in all 22 patients and subpleural small nodules seen in 19 patients. Other common findings included thickening of bronchovascular bundles (n - 19), interlobular septal thickening (n = 18), cystic airspaces (n = 15), and lymph node enlargement (n = 15). Less common findings included large nodules, emphysema, airspace consolidation, bronchiectasis, architectural distortion, honeycombing, and pleural thickening. CONCLUSION: Lymphocytic interstitial pneumonia is characterized by the presence of ground-glass attenuation, poorly defined centrilobular nodules, and thickening of the interstitium along the lymphatic vessels. Lymph node enlargement is more common than previously recognized; it was seen in 68% of patients.