Detection of mild emphysema by computed tomography density measurements.

PURPOSE: To assess the ability of a conventional density mask method to detect mild emphysema by high-resolution computed tomography (HRCT); to analyze factors influencing quantification of mild emphysema; and to validate a new algorithm for detection of mild emphysema. MATERIAL AND METHODS: Fifty-five healthy male smokers and 34 never-smokers, 61-62 years of age, were examined. Emphysema was evaluated visually, by the conventional density mask method, and by a new algorithm compensating for the effects of gravity and artifacts due to motion and the reconstruction algorithm. Effects of the reconstruction algorithm, slice thickness, and various threshold levels on the outcome of the density mask area were evaluated. RESULTS: Forty-nine percent of the smokers had mild emphysema. The density mask area was higher the thinner the slice irrespective of the reconstruction algorithm and threshold level. The sharp algorithm resulted in increased density mask area. The new reconstruction algorithm could discriminate between smokers with and those without mild emphysema, whereas the density mask method could not. The diagnostic ability of the new algorithm was dependent on lung level. At about 90% specificity, sensitivity was 65-100% in the apical levels, but low in the rest of the lung. CONCLUSION: The conventional density mask method is inadequate for detecting mild emphysema, while the new algorithm improves the diagnostic ability but is nevertheless still imperfect.

Bronchial mucosal mast cells in asymptomatic smokers relation to structure, lung function and emphysema.

The pathologic mechanisms of chronic obstructive pulmonary disease (COPD) most certainly involves neutrophil granulocytes, cytotoxic T-cells, macophages and mast cells. The aim of this study was to investigate the relation between the number of mast cells in different compartments in bronchial biopsies of central proximal airways to structural changes, lung function tests and emphysema detected by high resolution computed tomography (HRCT). Twenty nine asymptomatic smoking and 16 never-smoking men from a population study were recruited. Central bronchial biopsies were stained to identify mast cells by immunohistochemistry. The number of mast cells in the epithelium, lamina propria and smooth muscle as well as epithelial integrity and thickness of the tenascin and laminin layer were determined. Smokers had increased numbers of mast cells in all compartments (P<0.001). Structural changes were correlated to mast cell numbers with the closest associations to mast cell numbers in the smooth muscle [epithelial integrity (R(S)=-0.48, P=0.008), laminin layer (R(S)=0.63, P=0.0002), tenascin layer (R(S)=0.40, P=0.03)]. Similar correlations between mast cells and lung function tests were seen [functional residual capacity (FRC) (R(S)=0.60, P=0.0006), total lung capacity (TLC) (R(S)=0.44, P=0.02) and residual volume (RV) (R(S)=0.41, P=0.03)]. No correlations could be detected between mast cells and FEV1 or to emphysema. Smoking is associated with an increase of mast cells in all compartments of the bronchial mucosa, including smooth muscle, and this is related to altered airway structure and function.

High-resolution computed tomography in healthy smokers and never-smokers: a 6-year follow-up study of men born in 1933.

PURPOSE: To elucidate whether emphysematous lesions and other high-resolution computed tomography (HRCT) findings considered associated with smoking are part of a progressive process, and to measure the extent to which similar changes are found in never-smokers. MATERIAL AND METHODS: Healthy smokers and never-smokers were recruited from a randomized epidemiological study and investigated with a 6-year interval. Emphysema, parenchymal and subpleural nodules, ground-glass opacities, bronchial alterations, and septal lines were evaluated in 66 subjects (40 smokers, 11 of whom had stopped smoking in the interval, and 26 never-smokers). Lung function was tested. RESULTS: All except emphysematous lesions were present to some extent in never-smokers. Emphysema, parenchymal nodules, and septal lines occurred significantly more in current smokers, and a progression in extent of emphysema, ground-glass opacities, bronchial alterations and septal lines was seen. There was no significant change among those who stopped and never-smokers except for bronchial alterations, which progressed in never-smokers. CONCLUSION: In healthy, elderly never-smokers a low extent of various HRCT findings has to be considered normal. Emphysema, parenchymal nodules, and ground-glass opacities are indicative of smoking-induced disease. Further progress may cease if smoking is stopped.

Influence of the characteristic curve on the clinical image quality of lumbar spine and chest radiographs.

The "European Guidelines on Quality Criteria for Diagnostic Radiographic Images" do not address the choice of the film characteristic (H&D) curve, which is an important parameter for the description of a radiographic screen-film system. The image contrast of clinical lumbar spine and chest radiographs was altered by digital image processing techniques, simulating images with different H&D curves, both steeper and flatter than the original. The manipulated images were printed on film for evaluation. Seven experienced radiologists evaluated the clinical image quality by analysing the fulfilment of the European Image Criteria (ICS) and by visual grading analysis (VGA) of in total 224 lumbar spine and 360 chest images. A parallel study of the effect of the H&D curve has also been made using a theoretical model. The contrast (DeltaOD) of relevant anatomical details was calculated, using a Monte Carlo simulation-model of the complete imaging system including a 3D voxel phantom of a patient. Correlations between the calculated contrast and the radiologists' assessment by VGA were sought. The results of the radiologists' assessment show that the quality in selected regions of lumbar spine and chest images can be significantly improved by the use of films with a steeper H&D curve compared with the standard latitude film. Significant (p<0.05) correlations were found between the VGA results and the calculations of the contrast of transverse processes and trabecular details in the lumbar spine vertebrae, and with the contrast of blood vessels in the retrocardiac area of the chest.

Value of air trapping in detection of small airways disease in smokers.

PURPOSE: To test the hypothesis that diffuse and/or focal air trapping are sensitive indicators of airflow obstruction in smoker's small airways disease, when age, gender and presence of emphysematous lesions were allowed for. MATERIAL AND METHODS: Fifty-eight smokers and 34 never smokers, recruited from a randomized population study of men born in 1933, were investigated by HRCT and by extended pulmonary function tests, including a sensitive test for small airways disease (N2 slope). Diffuse air trapping was evaluated by calculating a quotient of mean lung density at expiration and inspiration. Focal air trapping was scored visually by consensus. RESULTS: Diffuse air trapping did not differ between non-emphysematous smokers and never smokers. Furthermore, diffuse air trapping correlated well to the quotient between the residual volume and total lung capacity (RV/TLC, p = 0.01) and was consequently higher in emphysematous smokers than in never smokers. Focal air trapping was found as frequently in smokers without emphysema as in never smokers. Smokers with emphysema showed significantly less focal air trapping. Neither the N2 slope nor any of the other lung function variables differed between those with and without focal air trapping among non-emphysematous smokers. CONCLUSION: Neither diffuse nor focal air trapping are sensitive indicators of smoker's small airways disease.

Evaluation of various attenuation corrections in lung SPECT in healthy subjects.

The effect of increasingly more sophisticated attenuation correction methods on image homogeneity has been studied in seven healthy subjects. The subjects underwent computed tomography (CT), single photon emission computed tomography (SPECT) and transmission computed tomography (TCT) of the thorax region in the supine position. Density maps were obtained from the CT and TCT studies. Attenuation corrections were performed using five different methods: (1) uniform correction using only the body contour; (2) TCT based corrections using the average lung density; (3) TCT based corrections using the pixel density; (4) CT based corrections using average lung density; and (5) CT based corrections using the pixel density. The isolated attenuation effects were assessed on quotient images generated by the division of images obtained using various attenuation correction methods divided by the non-uniform attenuation correction based on CT pixel density (reference method). The homogeneity was calculated as the coefficient of variation of the quotient images (CV(att)), showing the isolated attenuation effects. Values of CV(att) were on average 12.8% without attenuation correction, 10.7% with the uniform correction, 8.1% using TCT map using the average lung density value and 4.8% using CT and average lung density corrections. There are considerable inhomogeneities in lung SPECT slices due to the attenuation effect. After attenuation correction the remaining inhomogeneity is considerable and cannot be explained by statistical noise and camera non-uniformity alone.

Lung perfusion scintigraphy prior to lung volume reduction surgery.

PURPOSE: The aim of this study was to evaluate whether lung perfusion scintigraphy (LPS) contributes to the preoperative classification of emphysema heterogeneity in patients undergoing LVRS (lung volume reduction surgery) compared to classification based only on computed tomography (CT). MATERIAL AND METHODS: Forty-five potential candidates for LVRS were examined with CT and LPS. The distribution of emphysema within the lungs was visually classified into three categories: markedly heterogeneous, intermediately heterogeneous, or homogeneous. The results of the two imaging techniques were compared to an objective, CT-based computerized classification of heterogeneity. RESULTS: Visual evaluation of all 90 lungs resulted in 50 correct classifications based on CT, in 40 based on LPS and in 68 correct classifications based on the combination of CT and LPS. The combination was superior to CT alone (p<0.01) in classification of emphysema heterogeneity. There was no significant difference between the evaluations based on either CT or LPS. CONCLUSION: The combined information from CT and LPS are superior in assessing emphysema heterogeneity prior to LVRS.

On visual determination of full inspiration on CT images.

The aim of this study was to evaluate the ability of experienced thoracic radiologists to assess full inspiration based on two CT slices, one above and one below the carina, in normal subjects. Ten healthy volunteers were studied. Total lung capacity (TLC) was measured with a body plethysmograph. High-resolution computed tomography (HRCT) was performed in two slices at TLC and at various expired volumes. Mean Hounsfield values (HU) were calculated. Unidentifiable images, stored on a web server, were analysed visually by experienced thoracic radiologists. The results show that the mean lung density at TLC varied by approximately 40 HU between individuals. Within an individual this may correspond to a decrease in lung volume of approximately 25% of TLC. On visual determination of images taken at 65-74% of TLC, more than one-third of the images were assessed as taken at full inspiration; of the images taken at 75-84% of TLC, approximately 50% were assessed as taken at full inspiration. We conclude that visual determination of full inspiration on CT images in normal subjects is highly inaccurate. If quantitative density measurements are to be used in the diagnosis or follow-up of lung disease, thorough control of full inspiration is recommended.

Visual classification of emphysema heterogeneity compared with objective measurements: HRCT vs spiral CT in candidates for lung volume reduction surgery.

The aim of this study was to investigate whether spiral CT is superior to high-resolution computed tomography (HRCT) in evaluating the radiological morphology of emphysema, and whether the combination of both CT techniques improves the evaluation in patients undergoing lung volume reduction surgery (LVRS). The material consisted of HRCT (with 2-mm slice thickness) and spiral CT (with 10-mm slice thickness) of 94 candidates for LVRS. Selected image pairs from these examinations were evaluated. Each image pair consisted of one image from the cranial part of the lung and one image from the caudal part. The degree of emphysema in the two images was calculated by computer. The difference between the images determined the degree of heterogeneity. Five classes of heterogeneity were defined. The study was performed by visual classification of 95 image pairs (spiral CT) and 95 image pairs (HRCT) into one of five different classes of emphysema heterogeneity. This visual classification was compared with the computer-based classification. Spiral CT was superior to HRCT with 47% correct classifications of emphysema heterogeneity compared with 40% for HRCT-based classification ( p<0.05). The combination of the techniques did not improve the evaluation (42%). Spiral CT is superior to HRCT in determining heterogeneity of emphysema visually, and should be included in the pre-operative CT evaluation of LVRS candidates.

Neutrophil-associated activation markers in healthy smokers relates to a fall in DL(CO) and to emphysematous changes on high resolution CT.

Smoking is a risk factor for developing chronic obstructive pulmonary disease (COPD), but there are no good indicators for early identification of subjects who will develop symptomatic COPD. The aim of this study was to investigate inflammatory mechanisms related to changes in lung function and emphysematous changes on high resolution computed tomography (HRCT) in 'healthy' smokers. Subjects were 60-year-old men from a population study. Bronchoscopy was performed in 30 smokers and 18 who had never smoked. Blood tests, lung function measurements and HRCT were carried out in 58 and 34 subjects, respectively. In comparison with never-smokers, smokers had higher levels of myeloperoxidase (MPO), human neutrophil lipocalin (HNL), eosinophil cationic protein (ECP) and lysozyme in blood, higher levels of MPO, interleukin-8 (IL-8) and HNL in bronchial lavage (BL), and of IL-8, HNL and interleukin-lbeta (IL-1beta) in bronchoalveolar lavage (BAL). Smokers also had lower levels of Clara cell protein 16 (CC-16) in blood. HNL in BL and BAL showed strong correlations to other inflammatory markers (MPO, IL-8, IL-1beta). The variations in MPO in BL were explained by variations in HNL (R2 =0.69), while these variations in BAL were explained by variations in HNL and IL-1beta (R2 = 0.76). DL(CO) was the lung function variable most closely related to MPO and IL-8 in BL and BAL and to IL-1beta in BAL. In a multiple regression analysis, MPO, IL-1beta, IL-8 and CC-16 in BL and MPO in BAL contributed to the explanation of variations in DL(CO) to 41% and 22%. respectively, independent of smoking habits. In smokers with emphysematous lesions on HRCT, HNL in BAL correlated to emphysema score (r(s) = 0.71). We conclude that 'healthy' smoking men with a near normal FEV1 show signs of inflammation in the lower airways that are related to a decrease in DL(CO) and to emphysematous lesions on HRCT. This inflammation seems to be the result of both monocyte/macrophage and neutrophil activation.

Interventional treatment of gastrointestinal neuroendocrine tumours.

Neuroendocrine (NE) tumours of the gastrointestinal tract (carcinoids and endocrine pancreatic tumours) are rare diseases. In the presence of liver metastases these patients may suffer from disabling symptoms due to hormone overproduction. Patients with localized disease can be resected for cure and also patients with liver metastases can undergo potentially curative tumour resection. However, long-term follow-up of the latter cases indicates frequent recurrence of tumour. Using close biochemical monitoring of tumour markers combined with newer techniques for tumour visualization, these recurrences can often be diagnosed at an early stage so that repeat surgical procedures can be performed. During the last years very active surgery has been recommended for NE tumours, many of which have a relatively slow growth. Even in patients not amenable to curative liver surgery, debulking can be considered if the main tumour burden can be safely excised. The primary aim of this type of treatment is palliation of hormonal symptoms. An important question is whether the aggressive treatment actually prolongs survival. No prospective studies have been performed. Such studies are hampered by the lack of strict surgical programs running over long periods and the relative rarity of NE tumours. Liver transplantation may be another treatment modality in selected cases.

Emphysematous lesions and lung function in healthy smokers 60 years of age.

We aimed to study the occurrence of emphysematous lesions in symptom free smoking men of about 60 years of age and in a matching group of never-smoking men and the relationship between pulmonary changes at high resolution computed tomography (HRCT) and lung function tests. Our investigation included 57 smoking and 32 never-smoking healthy men from a randomized epidemiological study. HRCT was performed at full inspiration with a 1.5 mm slice thickness and a 3 cm inter-slice distance. Evaluation was made by two radiologists unaware of smoking history. Emphysematous lesions were scored visually. Pulmonary function tests were performed including spirometry and diffusion capacity test (DLCO). Emphysematous changes were demonstrated in 25 of 57 smokers but in only one never-smoker. DLCO/VA was the most sensitive test for early emphysematous lesions. It also correlated with radiographical scoring. Emphysematous lesions were evident in 44% of the healthy symptom free smokers. HRCT may reveal early emphysematous lesions in smokers before clinical symptoms have developed.

Image quality for five modern chest radiography techniques: a modified FROC study with an anthropomorphic chest phantom.

The purpose of the study was to compare the image quality for one conventional and four digital chest radiography techniques. Three storage phosphor systems, one selenium drum system, and one film-screen system were compared using a modified receiver-operating-characteristics method. Simulated pathology was randomly positioned over the parenchymal regions and the mediastinum of an anthropomorphic phantom. Eight observers (four chest radiologists, one specialist in general radiology, one hospital physicist, and two radiographers) evaluated 60 images for each technique. The selenium drum system (Philips, Eindhoven, The Netherlands) rated best for the detection of parenchymal nodules. Together with the storage phosphor system of generation IIIN (Philips/Fuji), the selenium drum system also rated best for detection of thin linear structures. The storage phosphor system of generation V (Fuji) rated best for the detection of mediastinal nodules. The first generation of the storage phosphor system from Agfa (Mortsel, Belgium) rated worst for the detection of parenchymal nodules and thin linear structures. These differences were significant (p < 0.0001). Averaging the results for all test objects, the selenium drum system and the storage phosphor system of generation V were significantly better than the other systems tested. The film/screen system performed significantly better than the first-generation storage phosphor system from Agfa, equal to the generation IIIN storage phosphor system (Philips/Fuji) and significantly worse than the selenium drum system (Philips) and the generation-V storage phosphor system (Fuji). The conclusion is therefore that the image quality of selenium-based digital technique and of the more recent generations of storage phosphor systems is superior to both conventional technique and storage phosphor systems using image plates of older types.

[Spiral computed tomography--solution to diagnostic problems in pulmonary embolism?]. / Spiraldatortomografi--lösningen på lungembolidiagnostikens problem?

Clinical diagnosis of pulmonary embolism is difficult and often dependent on radiological methods. In Sweden scintigraphy has hitherto been the method most commonly used, though all too often it leaves the diagnosis in doubt. Spiral computed tomography, performed during continuous infusion of contrast medium, clearly depicts the pulmonaries arteries, emboli appearing as filling defects. The examination takes less than one minute. Although the method has yet to be fully evaluated, it is already available at most Swedish hospitals. Results presented so far suggest that the technique has great potential, and may become the method of choice in the diagnosis of pulmonary embolism.

Pulmonary edema following intravenous injection of nonionic low-osmolar contrast medium--appearance on HRCT. A case report.

Pulmonary edema following i.v. contrast medium injection is a rare adverse reaction. We report on a 71-year-old woman who developed pulmonary edema following i.v. injection of iohexol during spiral CT of the thorax. She developed shortness of breath during the injection, and the first radiographic signs of pulmonary edema were visible on CT images 25 s after the onset of injection. On HRCT images 15 min later, marked edema was demonstrated in both lungs in a mosaic pattern of distribution. After appropriate therapy, the patient recovered without sequelae. A repeat CT 6 days later showed complete normalization.

Stimulable phosphor plates in chest radiology

LANGUAGE="EN">Summary. The stimulable phosphor plate technique has revolutionised radiology with portable equipment. The image quality permits diagnosis under difficult control conditions (ICUs). In order to achieve a signal-to-noise ratio, and therefore a contrast resolution similar to the commonly used film/screen systems, a higher radiation dose is needed. However, overall, with this technique a radiation dose reduction may be achieved as a result of the elimination of the need for retakes. The available stimulable phosphor plate systems, with adequate image processing are reliable, and at least as good as conventional film/screen systems for diagnosis in chest radiography. There are, however, other aspects that make the stimulable phosphor plate technique particularly appealing. Firstly, its reproducibility, which particularly in chest radiography allows images to be obtained with the same grey scale and darkness. Secondly, as this technique permits digital archiving and visualisation of images on screen, images can be rapidly distributed over a network making them available when and where they are needed.

Stimulable phosphor plates in chest radiology.

The stimulable phosphor plate technique has revolutionised radiology with portable equipment. The image quality permits diagnosis under difficult control conditions (ICUs). In order to achieve a signal-to-noise ratio, and therefore a contrast resolution similar to the commonly used film/screen systems, a higher radiation dose is needed. However, overall, with this technique a radiation dose reduction may be achieved as a result of the elimination of the need for retakes. The available stimulable phosphor plate systems, with adequate image processing are reliable, and at least as good as conventional film/screen systems for diagnosis in chest radiography. There are, however, other aspects that make the stimulable phosphor plate technique particularly appealing. Firstly, its reproducibility, which particularly in chest radiography allows images to be obtained with the same grey scale and darkness. Secondly, as this technique permits digital archiving and visualisation of images on screen, images can be rapidly distributed over a network making them available when and where they are needed.

Survival of patients with disseminated midgut carcinoid tumors after aggressive tumor reduction.

Sixty-four consecutive patients with disseminated midgut carcinoids were treated during an 8-year period according to a single clinical protocol aimed at aggressive tumor reduction by surgery alone or with subsequent hepatic artery embolization. All patients had markedly elevated urinary 5-hydroxyindoleacetic acid (5-HIAA) levels (581 +/- 79 micromol/24 h) and hormonal symptoms. Fourteen patients (22%) reached anatomic and biochemical cure by surgery alone. At follow-up, the mean 5-HIAA levels were still normal after 69.0 +/- 6. 2 months; two patients had died from unrelated causes. With the introduction of somatostatin receptor scintigraphy, subclinical disease was diagnosed in 7 of these 14 patients. Forty patients with bilobar hepatic disease underwent embolization in combination with octreotide. In this group, 5-HIAA levels were still reduced by 55% after 71 +/- 11 months of follow-up, and the 5-year survival was 56%, estimated from the total death hazard function. After embolization, two subgroups could be identified with marked differences in their long-term response to treatment. Ten patients were not embolized owing to complicating diseases. The 5-year survival for the entire series was 58%. A significantly increased risk of cardiovascular deaths was seen, which underlines the importance of total survival analysis in a disease with multiple hormonal effects. It is concluded that an active surgical approach must be recommended to patients with the midgut carcinoid syndrome. In patients with bilobar hepatic disease, embolization combined with octreotide treatment markedly reduced the 5-HIAA excretion and suggested a prolonged 5-year survival.

Treatment of liver metastases of carcinoid tumors.

Liver metastases imply a major problem in patients with carcinoid tumors. Patients with localized disease should always undergo resection for cure. Patients with distant metastatic disease can also undergo resection for potential cure or symptom palliation because of the slow growth rate of many carcinoid tumors. In patients with the midgut carcinoid syndrome and bilobar hepatic disease we have performed primary surgery to relieve such symptoms as intestinal obstruction and ischemia, followed by successive embolizations of the hepatic arteries to reduce functional tumor burden in the liver. For optimal palliation, all patients with residual tumor were treated by octreotide. In a consecutive series of 64 patients with the midgut carcinoid syndrome we thus attained a 5-year survival rate of 70%. Fourteen of the patients underwent intentionally curative surgery (e.g., primary surgery followed by liver surgery). Of these patients, none died from their tumor disease during the period of study. The value of adjunctive interferon therapy is currently under evaluation.