Kazuya Ichikado

PURPOSE: To determine whether idiopathic interstitial pneumonias can be differentiated on the basis of the pattern and distribution of abnormalities at thin-section computed tomography (CT). MATERIALS AND METHODS: Thin-section CT scans in 129 patients with histologically proved idiopathic interstitial pneumonia (35 with usual interstitial pneumonia [UIP], 24 with bronchiolitis obliterans organizing pneumonia [BOOP], 23 with desquamative interstitial pneumonia [DIP], 20 with acute interstitial pneumonia [AIP], and 27 with nonspecific interstitial pneumonia and fibrosis [NIPF]) were independently assessed by two observers without knowledge of clinical or histologic data. The observers recorded the abnormalities, diagnosis, and degree of confidence in their diagnosis. Differential diagnosis was limited to the five types of idiopathic interstitial pneumonia. RESULTS: The two observers made a correct diagnosis, on average, in 74 (57%) cases. On average, the correct diagnosis was made in 25 (71%) cases of UIP, 19 (79%) of BOOP, 14.5 (63%) of DIP, 13 (65%) of AIP, and 2.5 (9%) of NIPF. The two observers made a correct diagnosis with a high degree of confidence in 50 (39%) readings. There was moderate agreement between the observers for the correct diagnosis (k = 0.55) and for the correct diagnosis with a high degree of confidence (k = 0.65). CONCLUSION: Except for NIPF, the various subtypes of idiopathic interstitial pneumonias often have a characteristic appearance that allows differentiation at thin-section CT.

RATIONALE: Patients with a clinicopathological diagnosis of idiopathic pulmonary fibrosis (IPF) may have typical findings of usual interstitial pneumonia (UIP) on computed tomography (CT) or nonspecific or atypical findings, including those often seen in nonspecific interstitial pneumonia. OBJECTIVES: The aims of this study were to revisit the high-resolution CT findings of IPF and to clarify the correlation between the CT findings and mortality. METHODS: The study included 98 patients with a histologic diagnosis of UIP and a clinical diagnosis of IPF. Two observers evaluated the CT findings independently and classified each case into one of the following three categories: (1) definite UIP, (2) consistent with UIP, or (3) suggestive of alternative diagnosis. The correlation between the CT categories and mortality was evaluated using the Kaplan-Meier method and the log-rank test, as well as Cox proportional hazards regression models. MEASUREMENTS AND MAIN RESULTS: Thirty-three of the 98 CT scans were classified as definite UIP, 36 as consistent with UIP, 29 as suggestive of an alternative diagnosis. The mean survival was 45.7, 57.9, and 76.9 months, respectively. There was no significant difference in survival among the three categories (all P > 0.05). Traction bronchiectasis and fibrosis scores were significant predictors of outcome (hazard ratios: 1.30 and 1.10, respectively; 95% confidence intervals: 1.18-14.2 and 1.03-1.19, respectively). CONCLUSIONS: In patients with IPF and UIP pattern on the biopsy, the pattern of abnormality on thin-section CT, whether characteristic of UIP or suggestive of alternative diagnosis, does not influence prognosis. Prognosis is influenced by traction bronchiectasis and fibrosis scores.

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.

PURPOSE: To retrospectively evaluate whether the thin-section computed tomographic (CT) appearance has prognostic value for prediction of mortality, number of ventilator-free days (ie, days without mechanical ventilation), and 28-day risk of barotrauma in patients with a clinically early stage of acute respiratory distress syndrome (ARDS) from diverse causes. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Two independent observers who were blinded to patient outcomes retrospectively evaluated the thin-section CT scans obtained within 7 days after clinical ARDS onset in 26 survivors and 18 nonsurvivors. Of 44 patients, there were 37 men and seven women (mean age +/- standard deviation, 61.8 years +/- 15.6). CT findings were graded on a scale of 1-6 that corresponded with consecutive pathologic phases: score of 1, normal attenuation; score of 2, ground-glass attenuation; score of 3, consolidation; score of 4, ground-glass attenuation associated with traction bronchiolectasis or bronchiectasis; score of 5, consolidation associated with traction bronchiolectasis or bronchiectasis; and score of 6, honeycombing. An overall CT score was obtained by adding the six averaged scores (three zones in each lung). Multivariate regression analysis was used to assess the independent predictive value of the CT score. RESULTS: The area of increased attenuation associated with traction bronchiolectasis or bronchiectasis (P = .002), as well as the overall CT score (P = .002), was smaller in survivors than in nonsurvivors. Results of multivariate regression analysis revealed that CT score was independently associated with mortality (P = .006). A CT score of less than 230 enabled prediction of survival with 73% sensitivity and 75% specificity and was associated with both a greater number of ventilator-free days (P = .018) and a lower incidence of barotrauma (P = .013) within 28 days after ARDS onset. CONCLUSION: Extensive thin-section CT abnormalities indicative of fibroproliferative changes were independently predictive of poor prognosis in patients with a clinically early stage of ARDS.