High-resolution computer tomography of diffuse infiltrative lung diseases

During a period of 17 months, a total of 101 patients were examined by high resolution computed tomography (HRCT) whose minor focal changes revealed by chest X-ray raised the suspicion of diffuse infiltrative pulmonary disease. The disease of the interstitium was primarily caused by idiopathic pulmonary fibrosis (19%), autoimmune disease (18%), Boeck sarcoidosis (18%) as well as by specific (16%) and aspecific inflammation (12%). HRCT disclosed reticular (61%), nodular (55%), ground-glass opacity-like (48%), emphysematous (33%) and ring-like changes (17%). Also transbronchial excision was performed in 51 patients the results of which were compared to the changes observed during HRCT. Concerning fibrosis and inflammation, HRCT and histological analysis showed identical results in 70%. According to the authors observations, this technique is suitable for detection of fairly fine fibrotic, empysematous and inflammatory signs and for defining the activity of the individual disease as also for the selection of the optimal site of transbronchial excision. HRCT is a useful investigative method both for diagnosing diffuse infiltrative pulmonary disease as well as in following up the effectiveness of treatment.     

Acute interstitial pneumonia: high-resolution CT findings correlated with pathology

OBJECTIVE: The purpose of this study was to evaluate the relation between pathologic phases and high-resolution CT (HRCT) findings in patients with acute interstitial pneumonia (AIP). MATERIALS AND METHODS: Our retrospective review found 14 patients with AIP who were included in this study. Three patients were pathologically diagnosed as having AIP by open lung biopsy, and the other 11 patients were confirmed at autopsy. In eight of the 11 autopsy patients, the postmortem lungs were inflated and fixed by Heitzman's method, and a postmortem HRCT scan was obtained on all 11 autopsy patients. Paying special attention to the disease stage, we selected 27 areas of the lung from antemortem or postmortem HRCT and correlated them with pathologic findings. RESULTS: Nine areas of the lung that showed increased attenuation without traction bronchiectasis were associated with either the exudative (n = 5) or early proliferative (n = 4) phase of AIP. Eleven areas of increased attenuation with traction bronchiectasis were associated with either the proliferative (n = 4) or fibrotic (n = 7) phase of AIP. Honey-combing, observed in one area of the lung, corresponded to restructuring of distal airspaces and dense interstitial fibrosis. Six spared areas, within or adjacent to areas of increased attenuation, showed pathologic findings of the exudative phase. CONCLUSION: HRCT findings were not specific for the pathologic findings in our patients with AIP. Nevertheless, the findings of traction bronchiectasis in areas of increased attenuation suggested the proliferative or fibrotic phase.     

High-resolution CT of the lung in asbestos-exposed subjects. Comparison of low-dose and high-dose HRCT

The lowest possible mAs settings for high-resolution CT (HRCT) were studied on 45 individuals with suspected asbestos-related lung disease. All patients were investigated with 5 to 6 high-dose HRCT images (120 kVp/160 mA/2 s) at 3-cm intervals. At a selected level 4 additional low-dose images were obtained on each patient with lower mAs settings (100 mA/2 s, 80 mA/2 s, 60 mA/2 s, 30 mA/2 s). Thirty-seven subjects out of 45 had HRCT lesions compatible with asbestosis. HRCT images obtained with as low as 60 mA/2 s settings clearly showed pleural tractions and thickenings, parenchymal bands, honeycombing and subpleural curvilinear shadows, whereas in the evaluation of subpleural short lines and ground glass findings 80 mA/2 s were required. The lowest setting, 30 mA/2 s, was sufficient only in detecting and evaluating pleural tractions and thickenings. We conclude that 160 mAs yield good quality HRCT images, with substantial decrease of radiation dose, for the evaluation of asbestos-related lesions.     

13C-urea breath test in Helicobacter pylori diagnosis and eradication. Correlation to histology, origin of ''false'' results, and influence of food intake

Obliterative or constrictive bronchiolitis is characterized by narrowing of the small airways, due to submucosal and peribronchiolar fibrosis, with chronic obstruction. The vast majority of cases of bronchiolitis obliterans are associated with other diseases and only few cases are idiopathic. We report on the main computed tomography (CT) methods used study obliterative bronchiolitis, the CT findings and the differential diagnosis with other diseases. The dynamic study of alveolar ventilation with CT uses inspiratory and expiratory CT or high-resolution CT (HRCT), spiral dynamic CT or HRCT with advanced image display, ultrafast CT. In abnormal cases HRCT shows direct and indirect signs of small airways disease. The most common (> 80%) sign of obliterative bronchiolitis is the so-called mosaic oligohemia, with low attenuating lobules, caused by air trapping and best seen on expiratory CT, associated with blood flow redistribution to more normal lobules; this finding simulates the ground-glass pattern from infiltrative lung disease. Differential diagnosis is more difficult in the presence of true ground-glass patterns associated with diffuse bronchiolar obstruction and also with mosaic oligohemia due to pulmonary vascular disease and pulmonary emphysema. HRCT can distinguish these diseases and dynamic CT is more sensitive than functional tests in detecting regional abnormalities and air trapping. The combination of HRCT, rapid volumetric scanning and advanced image display is a powerful tool study the normal and abnormal features of bronchiolar function and alveolar ventilation.     

The diagnostic accuracy of high-resolution computed tomography in diffuse infiltrative lung diseases

The purpose of this study was to evaluate the role of high-resolution computed tomography (HRCT) in the clinical diagnosis of diffuse infiltrative lung disease (DILD). Diagnostic accuracy was compared using both chest radiography and HRCT. One hundred thirty-four cases of DILD, representing 21 different diseases, were selected for study, and the disease state was confirmed either histologically or microbiologically. The HRCT images and chest radiographs, available in all cases, were reviewed separately and in random order by 20 physicians who were provided only with information on each patient's age and sex. Overall, a correct first-choice diagnosis was made in 38 percent using radiographs and in 46 percent using HRCT images (p < 0.01). The correct diagnosis was among the top three choices in 49 percent when chest radiographs were used, and in 59 percent when HRCT images were viewed (p < 0.01). The correct first-choice diagnosis increased remarkably when the HRCT was used in usual interstitial pneumonia, sarcoidosis, alveolar proteinosis, bronchiolitis obliterans organizing pneumonia, hypersensitivity pneumonitis, and pulmonary lymphangiomyomatosis. High-resolution computed tomography was confirmed to be superior to conventional radiography in the accurate diagnosis of DILD in clinical practice.     

The hepatopulmonary syndrome: radiologic findings in 10 patients

OBJECTIVE: The purpose of this study was to review the radiologic manifestations of the hepatopulmonary syndrome. MATERIALS AND METHODS: We retrospectively reviewed clinical records, chest radiographs, 99m Tc-macroaggregated albumin (MAA) perfusion lung scans, chest CT scans, and pulmonary angiograms of 10 patients with proven hepatopulmonary syndrome. RESULTS: Chest radiographs showed basilar, medium-sized (1.5-3.0 mm) nodular or reticulonodular opacities in all cases. CT was done in eight cases and showed basilar dilatation of lung vessels with a larger than normal number of visible branches. The vascular basis for these opacities was best appreciated on conventional CT scans of 10-mm sections. No individual arteriovenous malformations were seen on CT scans. High-resolution CT scans showed no evidence of interstitial fibrosis. 99mTc-MAA perfusion lung imaging, done in seven patients, showed pulmonary arteriovenous shunting in five. Contrast echocardiography confirmed intrapulmonary shunting in these five patients. Pulmonary angiography, done in four cases, showed subtle distal vascular dilatation in two and moderate dilatation with early venous filling in two but did not reveal any individual arteriovenous malformations. CONCLUSION: Chest radiographs in hepatopulmonary syndrome usually show bibasilar nodular or reticulonodular opacities. Conventional CT shows that these opacities represent dilated lung vessels. High-resolution CT is useful in excluding pulmonary fibrosis or emphysema as the cause of these opacities. 99mTc-MMA perfusion imaging or contrast echocardiography can be used to confirm intrapulmonary arteriovenous shunting.     

Regarding Kumar et al. IJROBP 31(3):477-483; 1995

OBJECTIVE: We present a computer-aided diagnostic technique for identifying nodular interstitial lung disease on chest radiographs. The fractal dimension was used as a numerical measure of image texture on digital chest radiographs to distinguish patients with normal lung from those with a diffuse nodular interstitial abnormality. MATERIALS AND METHODS: Twenty digitized chest radiographs were classified as normal (n = 10) or as containing diffuse nodular abnormality (n = 10) on the basis of readings assigned according to the classification of the International Labour Organization. Regions of interest (ROIs) measuring 1.28 cm2 were selected from the intercostal spaces of these radiographs. The fractal dimension of these ROIs was estimated by power spectrum analysis. The cases were not subtle. RESULTS: The fractal dimension provided statistically significant discrimination between normal parenchyma and nodular interstitial lung disease. The area under the receiver operating characteristic curve was 0.90 (+/- 0.02). One operating point provides sensitivity of 88% with a specificity of 80%. CONCLUSION: The fractal dimension can provide a measure of lung parenchymal texture and shows promise as an element of computer-aided diagnosis, characterization, and follow-up of interstitial lung disease.     

Early diagnosis of lentivirus-induced infiltrative lung disease in sheep by high resolution computed tomography

The visna-maedi lentivirus can induce an interstitial pneumonitis in sheep, and provides a convenient example to study natural or experimental lentiviral pathology. We wanted to determine whether high resolution computed tomography (HRCT) is able to detect early morphological changes following lentiviral infection in the lungs. Spontaneously infected adult sheep (n=3) and experimentally infected lambs (n=5) were compared to uninfected controls (n=4). The HRCT scans generally showed abnormal features in infected animals, including: increased parenchymal density; alveolar oedema; thickened interlobular septa; and increased density in peribronchiolar areas. HRCT was more sensitive than chest radiography for the early diagnosis of interstitial pneumonitis, although one sheep with advanced disease and radiographic and histopathological abnormalities had a paradoxically normal scan. One control animal showed minor abnormalities on scanning, which were probably due to the procedure used for anaesthesia. The HRCT observations were confirmed by postmortem histological examination of the lungs. In conclusion, high resolution computed tomography provides a noninvasive means of following the development of lung pathology in a natural ovine model of lentiviral disease.     

Tailored low-dose fluoroscopic voiding cystourethrography for the reevaluation of vesicoureteral reflux in girls

OBJECTIVE: Radionuclide voiding cystography is generally advocated for the reevaluation of proved vesicoureteral reflux. The purpose of this study was to assess the efficacy of tailored low-dose fluoroscopic voiding cystourethrography for this purpose. SUBJECTS AND METHODS: Forty-five girls (2 years 9 months to 19 years 7 months old; mean, 7.4 years) who had proved reflux were examined with tailored low-dose voiding cystourethrography. The technique used a low-dose fluoroscopic system and a computer-based video frame grabber that produced frame-averaged digital video fluoroscopic hard copies. A tailored voiding cystourethrographic protocol was designed to minimize ovarian radiation dose. Digital images were compared with standard 105-mm spot films in a similar group of 25 children. RESULTS: The tailored low-dose fluoroscopic technique produced diagnostically adequate images in all patients that were comparable in quality to standard spot films. The ovarian dose was 1.7-5.2 mrad (0.017-0.052 mGy) with a mean of 2.9 mrad (0.029 mGy). This compared favorably with the lowest reported doses with the radionuclide technique. CONCLUSION: Tailored low-dose fluoroscopic voiding cystourethrography is an attractive and practical alternative to the radionuclide technique in girls with proved vesicoureteral reflux.     

Assessment of complications in patients with lung transplantation with high resolution computerized tomography

INTRODUCTION: High Resolution Computed Tomography (HRCT) has been used by many authors to study the early complications of lung transplantation. Bronchoscopy, transbronchial biopsy and the clinical parameters are the tools of choice to diagnose such complications; HRCT showed excellent sensitivity (100%) and good specificity (93%) especially in detecting bronchial stenoses. We report the preliminary results of HRCT in detecting early/late complications in lung transplant recipients. MATERIAL AND METHODS: Sixteen lung transplant recipients (5 single and 11 double transplants) were examined with HRCT at the Servizio Speciale Diagnostica V of "La Sapienza" University (Rome, Italy). The CT findings were compared with the results of bronchoscopy and respiratory function tests. The patients (8 men and 8 women; age range: 18-57 years, mean: 37.5) had cystic fibrosis (9), emphysema (3), alpha-1-antitrypsin deficiency (1), idiopathic pulmonary fibrosis (2), and bronchiectasis (1). RESULTS AND DISCUSSION: During the follow-up, one patient died of pulmonary edema. CT findings were normal in 3 patients and mild pleural effusion was seen in 2. The other HRCT findings were: bronchial stenosis in 5 cases (which was bilateral in 1) and bronchial dehiscence in 1 patient; four cases of infection (1 CMV, 1 aspecific bacterial pneumonia, 1 Chlamydia psittacea and 1 Aspergillosis) and one of brochiolitis obliterans. A patient was treated for acute and one for chronic rejection. A CMV infection involved only the native lung in a patient. CT is easy to perform and a repeatable and well-tolerated tool with high sensitivity (100%) and good specificity (93%) in the early diagnosis of complications, particularly bronchial stenoses, which complications are often missed at bronchoscopy or clinically silent. CT should be always performed before bronchoscopy because it can provide valuable information for bronchoscopy targeting. CONCLUSIONS: In agreement with other authors we consider HRCT a very useful tool in the early diagnosis of the complications following lung transplantation.     

Influence of clinical and ventilatory parameters on morphology of bronchopulmonary dysplasia

Our aim was to assess multiple factors which contribute to bronchopulmonary dysplasia (BPD) in prematurely born neonates. Specific morphologic features might relate to cumulative oxygen dose, barotrauma, prematurity, infection, and persistent ductus arteriosus (PDA). Seventy-two patients dying from BPD as defined by the histopathologic criteria of Stocker were analyzed retrospectively. Median (range) gestational age was 28 (25-35) weeks, and median survival was 16 (5-386) days. The infants were ventilated for 15 (15-149) days with a mean inspired oxygen fraction (FiO2) of 0.78. The cumulative oxygen dose and mean airway pressures were determined. The presence of neonatal infection, PDA, and interstitial lung emphysema (ILE) was assessed. Baseline lung disease was estimated as proposed by Palta. At autopsy, the degree of hyaline membranes, epithelial cell necrosis, emphysema, atelectasis, interstitial cell proliferation, and lung fibrosis was scored semiquantitatively (0 to 3+). The influence of neonatal infection, PDA, gestational age, survival, oxygen dose, or barotrauma on morphological findings was examined by multivariate analysis. We found "acute" BPD in 22, "reparative" in 34 and long-standing-"healed" in 16 cases. ILE within the first week was associated with interstitial cell proliferation and lung fibrosis in infants surviving more than 28 days. Initial barotrauma contributes to lung fibrosis in infants with BPD.     

6-Hydroxycatecholine, a choline-mimicking analogue of the selective neurotoxin, 6-hydroxydopamine

The purpose of this prospective study was to verify whether the percentage area of lung occupied by lowest attenuation values on high-resolution computed tomography (HRCT) scans reflects microscopic emphysema and to compare this quantification with the information yielded by the most widely used pulmonary function tests (PFT). Preoperative HRCT scans were obtained with 1-cm intervals in 38 subjects. With a semiautomatic evaluation procedure, the percentage areas occupied by attenuation values inferior to thresholds ranging from -900 Hounsfield units (HU) to -970 HU were calculated for the lobe or lung to be resected. Emphysema was microscopically quantified by using a computer-based method, measuring the perimeters and interwall distances of alveoli and alveolar ducts. The strongest correlation was found for -950 HU. As a second step, we evaluated possible correlations between PFT and microscopic measurements. Finally, considering the microscopic measurements as a standard, we tried to investigate their relationships with each of the PFT and with the relative area occupied by attenuation values lower than -950 HU for both lungs. This revealed that the diffusing capacity for carbon monoxide associated with HRCT quantification is sufficient to predict microscopic measurements. We concluded that the percentage area of lung occupied by attenuation values lower than -950 HU is a valid index of pulmonary emphysema.     

High-resolution computed tomographic appearance of MALToma of the lung

MALToma of the lung is rare and advances in molecular techniques have only recently allowed accurate diagnostic classification of the previously termed "pseudolymphomas" by demonstrating that many are monoclonal B-cell proliferations of MALT tissue and therefore true low-grade lymphomas. No significant previous contribution was found in the literature regarding the high-resolution CT appearance (HRCT) of these tumours. We describe the high-resolution CT appearances in five cases presenting to our institution from 1994 to 1997. The HRCT scans (1-mm sections at 10- to 15-mm intervals) were performed as the opacities seen radiographically were thought to be part of a diffuse lung process. In one patient a spiral sequence was performed through the main airway. Multifocal, ill-defined nodules containing air bronchograms were seen in four cases and focal lobar consolidation in one case. Interlobular septal thickening, centrilobular micronodules and bronchial wall thickening were seen in two cases. Mediastinal lymphadenopathy and pleural reaction do not appear to be characteristic features. The appearance of multifocal consolidation is similar to that seen in bronchoalveolar cell carcinoma and cryptogenic organising pneumonia.     

Erdheim-Chester disease: a primary macrophage cell disorder

Erdheim-Chester disease (ECD) is a rare focal or systemic infiltrative disorder resulting from xanthogranulomatous tissue deposition. Usually, bone marrow involvement affects long bone metaphyses symmetrically, but it spares the epiphyses. Retroperitoneal space, periaortic area, skin, and brain involvement have been described. Pulmonary involvement is frequent, occurring in 20% of cases. Reported histologic features in the lung include an infiltration of so-called lipid-laden macrophages and granulomatous lesions with fibrosis. Lung function outcome is unpredictable, but terminal respiratory failure is the most frequent cause of death. No effective treatment strategies have been described. We report a new case with lung and bone involvement occurring in a symptomatic woman. Histologic and electron microscopic analysis of the pulmonary infiltrate showed abnormal macrophages devoid of lipids forming nodular granulomas and rendering the previous hypothesis of this disease as a primary lipid storage disorder unlikely. These findings suggest that ECD histogenesis is instead based on a primary macrophage cell disease.     

Cigarette smoking: CT and pathologic findings of associated pulmonary diseases

The health risks associated with cigarette smoking are well known. Cigarette smoking is the most important causative factor in the development of bronchogenic carcinoma. Pulmonary diseases such as chronic bronchitis, centrilobular and panacinar emphysema, respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), and pulmonary Langerhans cell histiocytosis are also related to cigarette smoking. In adenocarcinoma and squamous cell carcinoma, the most common manifestation at computed tomography (CT) is a solitary pulmonary nodule; in small cell carcinoma, hilar and mediastinal adenopathy secondary to metastases; and in large cell carcinoma, a mass with central necrosis or cavitation in the lung periphery. For chronic bronchitis, the most common CT finding is bronchial wall thickening, but this finding is nonspecific. Emphysema, both centrilobular and panacinar associated with alpha-1-antitrypsin deficiency, usually manifests as areas of decreased attenuation and may involve bullous changes. However, centrilobular emphysema more commonly involves the upper lungs, whereas panacinar emphysema more commonly involves the lower lungs. Most patients with RB-ILD have normal high-resolution CT scans; however, abnormalities may be present, the most common of which are areas of ground-glass attenuation. CT appearance of pulmonary Langerhans cell histiocytosis varies depending on the disease stage: In the early stage, typical CT findings include multiple nodules, usually accompanied by cystic spaces with thin, well-defined walls. As the disease progresses, the cystic spaces become more numerous and the number of nodules decreases.     

High-resolution computed tomography sampling for detection of asbestos-related lung disease

RATIONALE AND OBJECTIVES: We determined whether a limited number of high-resolution computed tomography (HRCT) scans will effectively screen for interstitial lung disease (ILD) in a population of individuals exposed to asbestos. METHODS: We retrospectively reviewed the computed tomography studies of 49 patients exposed to asbestos. HRCT in the supine and prone positions had been performed at specifically preselected levels. Two teams of thoracic radiologists evaluated, on separate occasions: (1) all images, (2) prone images only, and (3) a single prone image through the lung bases for the presence of diffuse ILD. RESULTS: A relatively high level of accuracy was obtained with a single prone scan. However, improvement to 95% or better was found when additional prone images were used. CONCLUSION: A screening study for ILD, in this case patients exposed to asbestos, may be performed by preselected prone HRCT images only. The ease and decreased time of performing the procedure make screening relatively large patient groups for ILD more feasible.     

Transmission disequilibrium analysis of a triplet repeat within the hKCa3 gene using family trios with schizophrenia

We evaluated the long-term outcome of farmer's lung (FL) patients and matched control farmers using high-resolution computed tomography (HRCT). The study population consisted of 88 FL patients and 83 control farmers, matched by age, sex, and smoking habits. The mean time after the first diagnosed episode of FL was 14 yr. The great majority, 82%, of the studied subjects were nonsmokers. Clinical studies included HRCT, spirometry, and pulmonary diffusing capacity. Emphysema was found significantly more often (23%) in FL patients than in control farmers (7%) (p = 0.006). The presence of emphysema was 18% in nonsmoking and 44% in smoking FL patients, the respective values being 4% and 20% in control farmers. Patients with recurrent attacks of FL tended to have emphysema more often (p = 0. 08) than patients who had experienced only a single attack. Fibrosis was observed in 17% of the FL patients and in 10% of the control farmers (p = 0.2). Miliary changes were found in 12% of the FL patients compared with 4% of the control farmers (p = 0.07). Both emphysematous and fibrotic but not miliary changes correlated significantly with impaired pulmonary function. In conclusion, farmer's lung disease seems to be associated with an increased risk of developing emphysema.     

Pressor and subpressor angiotensin II administration. Two experimental models of hypertension

BACKGROUND: The neutrophil elastase inhibitor, secretory leucocyte protease inhibitor (SLPI), is a potential therapeutic tool in inflammatory lung diseases such as cystic fibrosis and pulmonary emphysema. The distribution and disappearance in the lung of aerosolised recombinant SLPI (rSLPI) was investigated in healthy humans and in patients with cystic fibrosis or alpha 1-antitrypsin-associated emphysema. METHODS: To distinguish aerosolised rSLPI from endogenous SLPI the recombinant inhibitor was radiolabelled with 99m-technetium (99mTc) pertechnetate. Distribution and disappearance of aerosolised 99mTc-rSLPI in the lungs were studied by gamma radiation imaging. RESULTS: The deposition of 99mTc-rSLPI in normal volunteers was homogeneous in all lung lobes, while in patients with cystic fibrosis or emphysema only well ventilated areas showed deposition of the aerosol. The disappearance rate of 99mTc-rSLPI was biexponential. The half life of the rapid phase was 0.2-2.8 hours, while that of the slow phase was more than 24 hours. CONCLUSIONS: Future aerosol therapy with rSLPI will be most beneficial for well ventilated lung tissue that needs protection against neutrophil derived elastase. It may be more difficult to neutralise the burden of elastase in poorly ventilated, highly inflamed areas as are seen in cystic fibrosis.     

Surface expression and release of soluble forms of CD8 and CD23 in CD40- and IL-4-activated mononuclear cells from patients with Graves'' disease (GD)

OBJECTIVE: This study was performed to assess the usefulness of preoperative thin-section CT alone and in combination with physiologic measurements in emphysema patients being evaluated for lung volume reduction surgery. SUBJECTS AND METHODS: Six 1-mm collimation sections through the chest were obtained in 20 patients being evaluated for lung volume reduction surgery. Extent and severity of emphysema were assessed by visually scoring the images. CT scores ranged from 0 to 144. Inspiratory resistance was measured in 12 of 20 patients and was also used to discriminate between responders (change in forced expiratory volume in 1 sec, > or = 150 ml after surgery) and nonresponders (change in forced expiratory volume in 1 sec, < 150 ml after surgery). RESULTS: Four of 20 patients with mild emphysema as revealed by thin-section CT (scores of < 50) did not improve lung function after lung volume reduction surgery. Eight of the remaining 16 patients with moderate to severe emphysema as revealed by thin-section CT (scores of > 50) underwent inspiratory resistance measurement. Those seven patients whose inspiratory resistance measurement exceeded 8.5 cm H2O/l per second did not respond favorably to lung volume reduction surgery (change in forced expiratory volume in 1 sec, < 150 ml). The remaining five patients whose inspiratory resistance measurement was less than 8.5 cm H2O/l per second responded favorably to lung volume reduction surgery. Thus, only five of the 20 patients showed improvement in forced expiratory volume in 1 sec after surgery. CONCLUSION: Our data suggest that among patients with moderate to severe emphysema who are being examined for lung volume reduction surgery, the combination of radiologic and physiologic assessment is more accurate for predicting a favorable response to lung volume reduction surgery than radiologic assessment alone. However, in patients with chronic obstructive pulmonary disease by the American Thoracic Society criteria, mild emphysema as revealed on thin-section CT virtually precludes further workup because these patients are unlikely to respond favorably to lung volume reduction surgery.     

The assessment of the severity of pulmonary edema by computed tomography. A comparison between high-resolution computed tomography, objective evaluation with density masks and functional tests

The results of high-resolution computed tomography (HRCT) were correlated with those of pulmonary function tests, chest films and CT expiratory density mask values in the evaluation of pulmonary emphysema in 33 symptomatic subjects. Emphysema was quantitated with both subjective and objective measurements. Conventional chest films were useful to diagnose severe emphysema but its actual extent was more reliably evaluated with CT scoring systems. HRCT and density mask correlated well with function tests, but the former method exhibited stronger correlation with carbon monoxide diffusion capacity. The opposite was true for hyperinflation and expiratory obstruction variables. Subjective CT estimates, which are quick and easy to perform, were seen to correspond more specifically to the pathophysiologic derangement and should therefore be used to evaluate the anatomic extent of disease. The functional severity of emphysema correlated only with the overall extent of disease and not with its regional distribution in the upper or lower lungs. Finally, in 4 cases (12.1%) with low CT scores, FEV1 was reduced but diffusion capacity values were normal. In one of these patients HRCT showed signs of bronchiolitis. In fact, small airway disease might be a more critical factor in determining functional impairment than the actual anatomical emphysema.