Risk factors of acute exacerbation of idiopathic pulmonary fibrosis.

BACKGROUND: Although acute exacerbation (AE) of idiopathic pulmonary fibrosis (IPF) is a well known clinical condition, predicting risk factors remain unknown. We evaluated the frequency, risk factors and impact on survival of AE-IPF. METHODS: We retrospectively studied patients diagnosed with IPF based on the criteria of the ATS/ERS consensus statement and followed them for periods of more than 3 years except in dead cases. Initial characteristics including the level of dyspnoea, which was assessed with the modified Medical Research Council (MRC) scale, and decline of forced vital capacity (FVC) defined by at least 10% decline at 6 months, were evaluated as possible risk factors for AE. RESULTS: Seventy-four patients with IPF were studied. One-year, two-year, and three-year incidence of AE were 8.6%, 12.6%, and 23.9%, respectively. Multivariate analysis revealed that higher body mass index (BMI) [hazard ratio (HR), 1.20; 95% confidence interval (CI), 1.03-1.40], higher modified MRC scale [HR, 2.93; 95% CI, 1.46-5.85], and a decline in FVC at 6 mounths [HR, 0.97-2.60 (per mo); 95% CI, 1.01-7.45] were independent risk factors for AE-IPF. The causes of death were assessed to be AE in 20 of 57 expired patients. A stepwise multivariate Cox regression model evaluating AE-IPF, adjusted for %FVC and decline in FVC, demonstrated a statistically significant impact on overall survival [HR, 2.79; 95% CI, 1.59-4.88; p < 0.001]. CONCLUSION: These data suggest that initial high modified MRC scale, high BMI, and decline in FVC at 6 months were significant independent risk factors for AE-IPF. AE was an independent prognostic factor in IPF.

Reproducibility of temporal volume change in CT of lung cancer: comparison of computer software and manual assessment.

The purpose of this study was to investigate the reproducibility of volumetric software evaluation and manual evaluation of tumour growth. Three observers manually evaluated whether tumour volume was increasing, if it was unchanged, or if it had decreased in size in 2 serial CT examinations of 45 solid lung cancers. The tumour volumes were calculated 3 times using volumetric software and were evaluated using the same classifications as for manual evaluation. Both data sets were divided into three groups: growth or reduction with consistency among all three evaluations (group A), growth or reduction with consistency between only two evaluations (group B), and others (group C). The volume variation and relative volume variation were calculated from the median volumes measured by volumetric software. Although all 45 tumours were categorised in group A by volumetric software, only 21 tumours were categorised in group A by manual assessment. The relative volume variation of the manual assessment was 88.5 +/- 76.5%, 20.8 +/- 28.3% and 12.9 +/- 12.8% in group A, B and C, respectively. Significant differences were found between groups A and B (p<0.01) and between groups A and C (p<0.001). Inconsistency is often seen in manual assessment; in contrast, evaluation using volumetric software has good reproducibility, even when the relative change in tumour volume is small.

One-dimensional quantitative evaluation of peripheral lung adenocarcinoma with or without ground-glass opacity on thin-section CT images using profile curves.

The purpose of our investigation was to compare the usefulness of the subjective visual assessment of ground-glass opacity (GGO) with a quantitative method that used a profile curve to determine prognosis. 96 adenocarcinomas were studied. Three diameters ([D1]-[D3]) were defined for estimating the diameter of tumours on the monitor: the distance between two points was measured using software that displays a CT density profile across the tumour. One experienced and one less experienced radiologist independently evaluated the following six parameters: the three diameters [D1]-[D3]; the solid portion of total tumour in the two different ratios ([D2]/[D1], [D3]/[D1]); and the area ratio of GGO for total opacity to subjective visual evaluation. Interobserver agreement between the two radiologists of the diameters (mean bias+/- 1.96 standard deviations) was as follows: [D1], -0.7 +/- 6 mm; [D2], 0.4 +/- 4.4 mm; and [D3], -0.1 +/- 4.2 mm (Bland and Altman's method). Interobserver agreement was fair in evaluating the area ratio of GGO (kappa test, kappa = 0.309). Univariate logistic regression analysis revealed that two ratios ([D2]/[D1], [D3]/[D1]) might be significantly useful in estimating lymph node metastasis (p < 0.026), lymph duct invasion (p < 0.001) and recurrence (p < 0.015). Observation of the area ratio of GGO by an experienced radiologist would be necessary for estimating lymph node metastasis (p = 0.04) and lymph duct invasion (p < 0.001). We concluded that the ratio of solid component to total tumour, which is obtainable in a more objective and simple way using profile curves obtained by software, is a more useful method of estimating prognosis than is visual assessment.

Effect of CT acquisition parameters in the detection of subtle hypoattenuation in acute cerebral infarction: a phantom study.

BACKGROUND AND PURPOSE: We evaluated the effects of varying tube voltage, current per rotation, and section thickness on detectability of 2- and 4-Hounsfield unit (HU) differences on brain CT between normal and ischemic gray matter within 6 hours of ischemia onset, by using a low-contrast phantom. METHODS: The phantom with an attenuation of 36 HU corresponding to normal gray matter contained 2 sets of spheres (34 HU and 32 HU) corresponding to the early CT signs of ischemic brain and complete infarction, respectively. The reproducibility of the CT numbers and the contrast-to-noise ratio (CNR), defined as the CT number difference between the background (36 HU) and the spheres (34 HU or 32 HU) divided by the SD of the background CT number were measured. Five radiologists rated the phantom images for detection of the low-contrast spheres by visual inspection. RESULTS: The CT numbers were reproducible within 1 HU with a tube current of > or =150 mAs at 120 kVp. The CNRs for the 34- and 32-HU spheres were positively correlated with the tube voltage, tube current per rotation, and the section thickness. A CNR of 1.0 was obtained for the 34-HU sphere when scanning was conducted with a section thickness of 10 mm at 120 kVp and 700 mAs, or 135kVp and 450 mAs, respectively. A significant improvement of the accuracy of detection was found with increasing tube current, tube voltage per rotation, and section thickness. CONCLUSION: Our study indicated that the 2-HU hypoattenuation corresponding to the early CT sign of acute ischemic stroke can be detected by using appropriate parameter settings.

Psychophysical analysis of monitor display functions affecting observer diagnostic performance of CT image on liquid crystal display monitors.

The aim of the present study was to propose suitable display functions for CT image representation on liquid crystal display (LCD) monitors by analyzing the characteristics of the monitor's typical display functions using psychophysical analysis. The luminance of the LCD monitor was adjusted to a maximum of 275 cd/m2 and 480 cd/m2. Three types of postcalibrated display functions (i.e., GSDF, CIELAB, and Exponential gamma 2.2) were evaluated. Luminance calculation of a new grayscale test pattern (NGTP) was done for the conversion of the digital driving level (DDL) into the CT value. The psychophysical gradient delta of display functions for the CT value was evaluated and compared via statistical analysis. The delta value of GSDF and CIE decreased exponentially; however, the delta value of Exponential gamma 2.2 showed a convex curve with a peak at a specific point. There was a statistically significant difference among the delta values of the three types of display functions on the 480 cd/m2 maximum via Kruskal Wallis test (P<0.001). The GSDF was suitable for observation of abdominal and lung CT images; however, the display function combined the Exponential gamma 2.2 and the GSDF functions and was ideal for observation of brain CT images by psychophysical analysis.

Pulmonary alveolar microlithiasis: CT and pathologic findings in 10 patients.

BACKGROUND AND AIM: To evaluate CT findings of pulmonary alveolar microlithiasis and correlate the CT with the pathologic findings. METHODS: The study included 10 patients with pathologically proven microlithiasis. Two independent observers evaluated the presence, extent and distribution of the CT findings. CT findings were compared with those at autopsy in two patients and with transbronchial biopsy in eight patients. RESULTS: All patients had a myriad of calcified nodules measuring approximately 1 mm in diameter. Close apposition of the nodules resulted in areas of ground-glass attenuation and consolidation, which were the predominant abnormality on CT in all 10 patients, involving 41% +/- 16.3 (mean +/- SD) and 30% +/- 4.8 of the lung parenchyma, respectively. Calcifications were also seen along interlobular septa, bronchovascular bundles and pleura. Other findings included interlobular septal thickening, thickening of bronchovascular bundles, nodules, and subpleural cysts. There was a solid agreement between the observers for the presence (kappa value; 0.77) and extent (Spearman rank correlation; r = 0.81 to 1.0 p < 0.01) of abnormalities. Autopsy specimens demonstrated microliths in alveolar airspaces and along interlobular septa, bronchovascular bundles and pleura. Subpleural small cysts were shown to represent dilated alveolar ducts. CONCLUSION: Pulmonary microlithiasis is characterised by the presence of numerous small, calcified nodules, calcifications along interlobular septa, bronchovascular bundles and pleura, ground-glass opacities, consolidation, and subpleural cysts. The cysts represent dilated alveolar ducts.

Serial high resolution CT in non-specific interstitial pneumonia: prognostic value of the initial pattern.

AIM: To assess the relationship between initial CT pattern and serial changes in CT findings and pulmonary function tests (PFTs) in patients with non-specific interstitial pneumonia (NSIP). MATERIALS AND METHODS: Serial high resolution (HR) CTs and PFTs were retrospectively analyzed in 38 cases of histologically proven NSIP, including 4 with cellular NSIP, 13 with mixed cellular and fibrotic NSIP, and 21 with fibrotic NSIP. The presence and extent of various CT findings were assessed. A fibrosis index (defined as the ratio of the extent of a reticular/honeycomb pattern to the overall extent of abnormal parenchyma) was derived. RESULTS: The predominant CT pattern was reticular/honeycomb in 27 (84%) cases and ground-glass/consolidation in 6 (16%) cases. Between scans, mean disease extent reduced by 5.2%. Disease extent reduced by >10% in 13 (34%) and increased by >10% in 6 (16%) patients. Histopathological subtype of NSIP did not correlate with individual CT pattern, predominant pattern, fibrosis index or serial change in disease extent on CT or PFTs. Response on follow-up CT was associated with fibrosis index, predominant pattern and extent of consolidation on initial CT. CONCLUSION: In NSIP disease, progression on CT correlates with the predominant CT pattern, fibrosis index, and extent of consolidation but not with histopathological subtype. An inflammatory (ground-glass/consolidation) predominant pattern is associated with better outcome in terms of disease extent on HRCT.

Quantification of ground-glass opacity on high-resolution CT of small peripheral adenocarcinoma of the lung: pathologic and prognostic implications.

OBJECTIVE: The purpose of our study was to correlate the high-resolution CT findings of small peripheral adenocarcinoma of the lung with underlying histopathology and to evaluate the prognostic implications of the CT findings. MATERIALS AND METHODS: The high-resolution CT findings of small peripheral adenocarcinoma of the lung in 224 patients were analyzed by two independent observers for location, size, marginal characteristics, and extent of ground-glass opacity and necrosis. The pathologic specimens were reviewed by an experienced lung pathologist. RESULTS: One hundred and thirty-two patients had bronchioloalveolar carcinoma and 92 had adenocarcinoma. The extent of ground-glass opacity was greater in bronchioloalveolar carcinomas (mean +/- SD, 29% +/- 31.6%) than in other adenocarcinomas (8% +/- 13.3%) (p < 0.001). The extent of ground-glass opacity was significantly greater in patients without recurrence (p = 0.020) and those without nodal (p = 0.017) or distant (p = 0.007) metastases than in patients with nodal or distant metastases or in whom the carcinoma had recurred. CONCLUSION: The extent of ground-glass opacity in a nodule is greater in bronchioloalveolar carcinomas than in other adenocarcinomas. Greater extent of ground-glass opacity also correlates with improved prognosis.

Interstitial pneumonia in progressive systemic sclerosis: serial high-resolution CT findings with functional correlation.

PURPOSE: The aim of our study was to assess the serial high-resolution CT findings and their correlation with the results of pulmonary function tests in patients with progressive systemic sclerosis (PSS) and interstitial pneumonia. METHOD: The study included 40 patients with symptoms or signs of PSS and interstitial pneumonia, who underwent serial high-resolution CT scans (mean follow-up period 39 months). Seventeen patients simultaneously had serial pulmonary function tests (mean follow-up period 40 months). On high-resolution CT, the pattern and extent of parenchymal abnormalities were retrospectively analyzed. Serial changes on high-resolution CT were correlated with the changes of pulmonary function tests. RESULTS: On initial CT, areas of ground-glass opacity (mean +/- SD extent 17.7 +/- 12.3% in all patients), irregular linear opacity (4.4 +/- 4.4% in 36 patients), small nodules (3.9 +/- 12.5% in 28), consolidation (1.9 +/- 4.2% in 13), and honeycombing (1.9 +/- 3.8% in 12) were seen. The total disease extent (p = 0.042) and extents of ground-glass opacity (18.9 +/- 15.5%; p = 0.04) and honeycombing (5.0 +/- 7.2%; p = 0.002) increased significantly on follow-up CT. Both forced vital capacity (from 2.4 +/- 0.4 to 2.0 +/- 0.4 L; p = 0.002) and forced expiratory volume in 1 s (from 2.0 +/- 0.4 to 1.6 +/- 0.3 L; p = 0.013) decreased significantly on follow-up examination. The increase in the extent of honeycombing on CT correlated significantly with the decrease in diffusing capacity for carbon monoxide (r = -0.411, p = 0.049). CONCLUSION: In patients with PSS and interstitial pneumonia, the overall extent of disease and extents of honeycombing and ground-glass opacity increase significantly on follow-up CT. Increase of honeycombing correlates well with decrease of diffusing capacity for carbon monoxide.

Pulmonary involvement in primary Sjögren's syndrome: spectrum of pulmonary abnormalities and computed tomography findings in 60 patients.

The purpose of this study was to describe the high-resolution computed tomography (HRCT) findings of pulmonary involvement in primary Sjögren's syndrome. The study included 60 patients who met the diagnostic criteria for primary Sjögren's syndrome. The authors retrospectively reviewed the presence, extent, and distribution of various HRCT findings. Results showed that the most common HRCT findings were areas with ground-glass attenuation (92%), followed by subpleural small nodules (78%), non-septal linear opacity (75%), interlobular septal thickening (55%), bronchiectasis (38%), and cysts (30%).

Pitfalls in the interpretation of multidetector-row helical CT images at window width and level setting for lung parenchyma.

This article describes pitfalls in the interpretation of multidetector-row helical CT (MDCT) images at the window width and level settings for lung parenchyma. On MDCT, linear artifacts, which look like black and white linear densities and are called "hurricane artifacts," radiate out from objects that have very different densities from their neighbors. For the evaluation of fine parenchymal details, a low table speed/slice collimation should be used. In fact, axial (step and shoot) scanning may be more effective for the evaluation of fine details. Since artifacts from vessels highly enhanced by contrast medium cause data blackout in the surrounding areas at high table speed/slice collimation, pulmonary parenchyma in such situations should be evaluated with unenhanced CT. Although multidetector-row helical CT is a promising tool for the evaluation of lung parenchyma, it is important to identify its shortcomings due to artifacts when interpreting images at the window width and level settings for lung parenchyma and to apply the appropriate methods for eliminating such artifacts.

High-resolution CT using multidetector CT equipment: evaluation of image quality in 11 cadaveric lungs and a phantom.

OBJECTIVE: The aim of this study was to evaluate the image quality and diagnostic efficacy of multidetector high-resolution CT (HRCT) by comparing it with single-detector HRCT and by comparing the noise and artifact of multidetector HRCT images with a phantom. SUBJECTS AND METHODS: Multidetector HRCT with six parameters and single-detector HRCT were performed on cadaveric lungs. The image quality and diagnostic efficacy of multidetector HRCT were evaluated in comparison with those of single-detector HRCT. A phantom was scanned, and image artifact and noise were investigated. RESULTS: . The image quality of multidetector HRCT with axial 1.25 mm x 4i (four images per gantry rotation) mode was equal to that of single-detector HRCT. The image quality of multidetector HRCT with other modes was worse than that on single-detector HRCT. The diagnostic efficacy of multidetector HRCT with high-quality mode (pitch, 3:1) and axial mode was equal to that of single-detector HRCT. The diagnostic efficacy on multidetector HRCT with high-speed mode (pitch, 6:1) was worse than that on single-detector HRCT. In the phantom study, images made in high-speed mode had strong artifacts. Noise in the axial mode was milder than that in high-speed mode but more severe than that in high-quality mode. CONCLUSION: The image quality of axial HRCT with multidetector CT is equal to that on single-detector HRCT. Axial HRCT with multidetector CT is appropriate for evaluating subtle lung abnormalities, but high-speed mode is unsuitable. Using the high-quality mode degrades image quality but is still worthwhile.

Invasive and noninvasive thymoma: distinctive CT features.

PURPOSE: The purpose of this work was to evaluate the CT features of thymoma and to determine the most helpful findings in differentiating invasive from noninvasive thymoma. METHOD: The CT scans from 27 patients with invasive thymoma and 23 with noninvasive thymoma were independently assessed by two observers without knowledge of their invasiveness. The presence and distribution of various CT findings were independently analyzed. RESULTS: Invasive thymomas were more likely to have lobulated (16/27, 59%) or irregular (6/27, 22%) contours than noninvasive thymomas (8/23, 35% and 1.5/23, 6%, respectively) (p < 0.05). Invasive thymomas had a higher prevalence of low attenuation areas within the tumor (16/27, 60%) than noninvasive thymomas (5/23, 22%) (p < 0.001) as well as foci of calcification (14.5/27, 54% vs. 6/23, 26%; p < 0.01). CONCLUSION: The presence of lobulated or irregular contour, areas of low attenuation, and multifocal calcification is suggestive of invasive thymoma.

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.

Bronchiolitis obliterans with organizing pneumonia versus chronic eosinophilic pneumonia: high-resolution CT findings in 81 patients.

OBJECTIVE: The objective of this research was to compare high-resolution CT findings of bronchiolitis obliterans with organizing pneumonia (BOOP) with those of chronic eosinophilic pneumonia (CEP) and to determine whether high-resolution CT can differentiate the two. MATERIALS AND METHODS: We retrospectively reviewed high-resolution CT scans of 38 patients with BOOP and 43 patients with CEP. Without knowledge of the diagnosis, two radiologists evaluated the frequency and distribution of high-resolution CT findings in both groups of patients and made a diagnosis using a three-point scale of confidence. RESULTS: Nodules, nonseptal linear or reticular opacities, and bronchial dilatation were significantly more common in BOOP than in CEP (31.6% vs. 4.7%, p < 0.005; 44.7% vs. 9.3%, p < 0.001; and 57.9% vs. 25.6%, p < 0.005, respectively). Septal line thickening was more frequent in CEP than in BOOP (72.1% vs. 39.5%, p < 0.005). Peribronchial distribution of consolidation was more frequent in BOOP than in CEP (28.9% vs. 9.3%, p < 0.05). A correct diagnosis was made in 69.7% of cases, and the diagnostician was confident in 21.7%. Interobserver agreement was good (kappa = 0.6). CONCLUSION: Although several of the high-resolution CT findings of BOOP and CEP are different, these diseases are differentiated with confidence in only a small percentage of cases.

Acute respiratory distress syndrome and acute interstitial pneumonia: comparison of thin-section CT findings.

PURPOSE: The purpose of this work was to compare the thin-section CT findings of acute respiratory distress syndrome (ARDS) with those of acute interstitial pneumonia (AIP). METHOD: The thin-section CT scans from 25 patients with ARDS and 25 with AIP were independently assessed by two observers without knowledge of clinical and pathologic data. The presence, extent, and distribution of various CT findings were independently analyzed. RESULTS: Honeycombing was seen more frequently in lobes of patients with AIP (26%) than in lobes with ARDS (8%) (p < 0.001). Compared with patients with ARDS, a greater number of patients with AIP had a predominantly lower lung zone distribution (p < 0.05) and a symmetric distribution (p < 0.05) of the parenchymal abnormalities. CONCLUSION: Patients with AIP have a greater prevalence of honeycombing and are more likely to have a symmetric bilateral distribution and a lower lung zone predominance than patients with ARDS. However, significant overlap exists among the CT findings.

Evaluation of image quality and spatial resolution of low-dose high-pitch multidetector-row helical high-resolution CT in 11 autopsy lungs and a wire phantom.

PURPOSE: The aim of this study was to evaluate whether low-dose high-pitch (6:1) multidetector-row helical high-resolution CT is appropriate for the evaluation of various pulmonary abnormalities, including faint opacities. METHODS: Eleven autopsy lungs were scanned with a multidetector-row CT scanner using 2.5 mm x 4 beam collimation, effective slice thickness 3 mm, 6:1 pitch, 0.8 second gantry rotation speed, 20 cm Display FOV, high spatial frequency (bone) algorithm, and various radiation doses (120 kVp; 160, 80, 40, 24, and 8 mAs). The image quality of each CT set was assessed as adequate or inadequate for diagnosis by two independent observers. In addition, a wire phantom was scanned with the same parameters in order to describe the MTF curves. RESULTS: There was excellent agreement between the observers for the evaluation of image quality (kappa statistic, 0.84). The ratio of images evaluated as inadequate for 8 mAs and 24 mAs was significantly higher than that for 160, 80, and 40 mAs (p<0.01: chi-square test). MTF curves of both 8 and 24 mAs were significantly inferior to those of 40, 80, and 160 mAs (p<0.0 1, Friedman test), while the MTF curve of 40 mAs was relatively inferior to that of 160 mAs (p<0.05, Friedman test). CONCLUSION: More than 40 mAs in combination with 120 kVp is preferable for the evaluation of details of lung parenchyma by high-pitch. multidetector-row helical high-resolution CT.

Evaluation of compressed lung CT image quality using quantitative analysis.

The goals of this study were (1) to evaluate the quality of compressed lung CT images obtained using high resolution CT (HRCT: 2 mm slice thickness) for degree of compression and conventional CT (10 mm slice thickness) images by using physical and subjective evaluations, and (2) to analyze the distortion of density distribution on lung CT images using histogram analysis for each compression ratio. The coding method was performed according to the Joint Photographic Experts Group (JPEG). We physically evaluated the quality of compressed lung CT images using the peak signal-to-noise ratio (PSNR) as given by the square root of the ratio of the peak value of the gray level squared to the mean square error (dB) and subjectively evaluated the CT images using the mean opinion score (MOS). The acceptable compression ratio for diagnosis was about 1:6 to 1:7 for conventional CT images and about 1:4 to 1:5 for HRCT images as determined by MOS. The PSNR corresponding to acceptable compression ratios was about 50 dB. The difference in density distribution between HRCT and conventional CT was statistically significant (Friedman test: p<0.02) in histogram analysis. Results suggested that, in comparison with conventional CT, a high compression ratio was not suitable for HRCT.

Scintigraphic and MR perfusion imaging in preoperative evaluation for lung volume reduction surgery: pilot study results.

PURPOSE: To compare MR perfusion imaging with perfusion scintigraphy in the evaluation of patients with pulmonary emphysema being considered for lung volume reduction surgery. PATIENTS AND METHODS: Six patients with pulmonary emphysema and two normal individuals were evaluated by MR perfusion imaging, perfusion scintigraphy, and selective bilateral pulmonary angiography. MR images were obtained with an enhanced fast gradient recalled echo with three-dimensional Fourier transformation technique (efgre 3D) (6.3/1.3; flip angle, 30 degrees; field of view, 45-48 cm; matrix, 256 x 160). The presence or absence of perfusion defects in each segment was evaluated by two independent observers. RESULTS: Using angiography as the gold standard, the sensitivity, specificity, and accuracy of MR perfusion imaging in detecting focal perfusion abnormalities were 90%, 87%, and 89%, respectively, while those of perfusion scintigraphy were 71%, 76%, and 71%, respectively. The diagnostic accuracy of MR perfusion imaging was significantly higher than that of scintigraphy (p<0.001, McNemar test). There was good agreement between two observers for MR perfusion imaging (kappa statistic, 0.66) and only moderate agreement for perfusion scintigraphy (kappa statistic, 0.51). CONCLUSION: MR perfusion imaging is superior to perfusion scintigraphy in the evaluation of pulmonary parenchymal perfusion in patients with pulmonary emphysema.

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.