Effect of dose levels on the diagnostic performance of a selenium-based digital chest system.

RATIONALE AND OBJECTIVES: To evaluate the effect of dose reduction on diagnostic performance by using a digital chest imaging system in which amorphous selenium serves as the x-ray detector. METHODS: Two hundred forty-seven patients were examined with the selenium system. Three sets of images were made in each patient: one set with a standard x-ray dose, one set with 55% of the standard dose, and one set with 35% of the standard dose. All 741 images were read by two radiologists. The diagnostic value of each set of images for detection of pulmonary, mediastinal, and pleural pathology was analyzed with receiver operating characteristic (ROC) methodology by using computed tomography as the reference standard. The authors also assessed the effect of sex, height, and weight of the patients on the diagnostic performance of the readers. RESULTS: The areas under the ROC curves for the detection of various abnormalities at 100%, 55%, and 35% of the standard dose for observer 1, respectively, were pulmonary opacities 0.82, 0.83, 0.84; interstitial disease 0.71, 0.70, 0.72; mediastinal disease 0.81, 0.80, 0.77; and pleural abnormalities 0.71, 0.72, 0.72. There were no statistically significant differences between the two observers. CONCLUSIONS: No statistically significant difference was found between the radiologists' performance in detecting abnormalities with standard x-ray dose images and the performance with images made with 55% and 35% of the standard dose. Sex, height, and weight had no influence on diagnostic performance.

Digital chest imaging using a selenium detector. The impact of hard copy size on observer performance: a computed tomography-controlled study.

RATIONALE AND OBJECTIVES: The authors compare radiologist detection performance under clinical conditions for assessment of the effect of size reduction on the diagnostic performance of digital chest images obtained with a selenium detector. METHODS: Sixty-five patients were examined with the digital system. The images were acquired without an antiscatter grid. Sixty-five posteroanterior life-size images (35 x 43 cm) and sixty-five posteroanterior minified images (56% of life size) were analyzed by three observers for detection of pulmonary, mediastinal, and pleural pathology, using computed tomography as the reference standard. The diagnostic value of life-size and minified images for the detection of these chest abnormalities was analyzed with receiver operating characteristic (ROC) methods. RESULTS: For the detection of the various abnormalities by all radiologists, the areas under the ROC curves with life-size images versus minified images, respectively, were as follows: pulmonary opacities, 0.78 versus 0.78; interstitial disease, 0.74 versus 0.75; mediastinal disease, 0.70 versus 0.72; and pleural abnormalities 0.72 versus 0.67. CONCLUSIONS: There was no statistically significant difference between the radiologists' performance in detecting pulmonary, mediastinal, and pleural pathology with life-size versus that with minified (56% of life size) digital selenium chest radiography.

Postpneumonectomy pulmonary edema. A retrospective analysis of incidence and possible risk factors.

OBJECTIVE: To analyze the incidence of postpneumonectomy pulmonary edema (PPE) and to determine potential risk factors for PPE. MATERIAL AND METHODS: A group of 197 patients was studied retrospectively, and the incidence of PPE was recorded over a 5-year period. Preoperative, perioperative, and postoperative clinical data were collected, and preoperative and postoperative chest radiographs were reviewed. A scoring system was used to distinguish between premanifest and manifest PPE. Postpneumonectomy patients with pulmonary edema, with no clinically evident cause, were considered to have PPE. RESULTS: The incidence of premanifest PPE was 12.2% (n = 24), and that of manifest PPE was 2.5% (n = 5). Mortality in the group of patients who developed manifest PPE was 100%. Two significant perioperative associations were found in the PPE group. One was the administration of fresh frozen plasma (FFP) transfusions (relative risk, 4.3; 95% confidence interval, 1.3 to 14.4 corrected for age and sex), while the other was higher mechanical ventilation pressures during surgery (relative risk, 3.0; 95% confidence interval, 1.2 to 7.3). CONCLUSION: Our data suggest that FFP transfusions form an important risk factor for PPE. The mechanism may be an increased permeability of the pulmonary vessels due to an immunologic reaction after multiple FFP transfusions. The significantly higher mechanical ventilation pressures we found in the PPE group may be explained as an early sign of the development of PPE.

Chest imaging with a selenium detector versus conventional film radiography: a CT-controlled study.

PURPOSE: To compare radiologist detection performance under clinical conditions for assessment of conventional radiographs and digital chest images obtained with a selenium detector. MATERIALS AND METHODS: One hundred four patients were examined with the digital and conventional systems under near identical technical conditions. The digital images were acquired without an antiscatter grid. Two hundred eight images were analyzed by three radiologists for detection of pulmonary, mediastinal, and pleural abnormalities; computed tomography was used as the reference standard. The diagnostic value of both techniques for the detection of these chest abnormalities was analyzed with receiver operating characteristic (ROC) methods. RESULTS: For detection of the various abnormalities by all radiologists, the areas under the ROC curves with conventional imaging versus digital imaging, respectively, were as follows: pulmonary opacities, 0.81 versus 0.79; interstitial disease, 0.69 versus 0.73; mediastinal disease, 0.79 versus 0.74; and pleural abnormalities, 0.73 versus 0.68. CONCLUSION: There was no statistically significant difference between the radiologists' performance in detecting pulmonary, mediastinal, and pleural abnormalities with conventional radiography versus that with digital selenium chest radiography.

Effects of dose reduction on digital chest imaging using a selenium detector: a study of detecting simulated diffuse interstitial pulmonary disease.

OBJECTIVE: The purpose of this study was to evaluate the effect of dose reduction on the diagnostic performance of a new digital chest imaging system in which amorphous selenium is used as the X-ray detector. Diagnostic performance was assessed for the detection of simulated diffuse interstitial pulmonary disease (DIPD). MATERIALS AND METHODS: DIPD was simulated by superimposing plastic sheets that contained small radiopaque objects (birdseed) on an anthropomorphic chest phantom. We varied the number of sheets from zero to four to simulate the degree of abnormality. We made 80 images with a standard X-ray dose, 80 images with 55% of the standard dose, and 80 images with 35% of the standard dose. Six observers were asked to indicate the presence of DIPD using a five-level scale of confidence. Two hundred forty chest images were then analyzed using receiver operating characteristic (ROC) curves. RESULTS: The area under the ROC curve was 87.2 for all readers with standard-dose imaging (95% confidence interval [CI], 83.7-90.7), 91.7 with 55% of the standard dose (95% CI, 88.8-94.6), and 90.0 with the 35% dose (95% CI, 87.1-92.9). The area under the ROC curve for subtle DIPD (one superimposed sheet) was 75.3 for all readers with standard-dose imaging (95% CI, 67.1-83.5), 79.7 with 55% of the standard dose (95% CI, 71.9-87.5), and 70.3 with the 35% dose (95% CI, 61.7-78.9). For each dose, we observed a gradual improvement of the ROC curves with each additional sheet superimposed on the chest phantom (p < .001). CONCLUSION: We found no significant difference in diagnostic performance among images made with standard X-ray dose, those made with a 55% dose, and those made with a 35% dose (95% CI).

Digital chest imaging with a selenium detector: comparison with conventional radiography for visualization of specific anatomic regions of the chest.

OBJECTIVE: The purpose of this study was to compare a new digital chest radiography system that uses amorphous selenium as the X-ray detector with conventional radiography for the visualization of various anatomic regions of the chest as a first phase of testing image quality. MATERIALS AND METHODS: Six observers analyzed pairs of posteroanterior chest radiographs of 40 patients. One radiograph in each pair was obtained with a conventional chest film changer, and the other was obtained with the digital selenium chest radiography system. Each observer rated the visibility and the radiographic quality of 12 different anatomic regions. RESULTS: The observers rated visualization obtained with the digital system as better than that obtained with the conventional system in four regions (right lower lobe, upper lobes, ribs, and soft tissue), as better than or equal to that obtained with the conventional system in four regions (retrocardiac, retrodiaphragmatic, hilum, and upper mediastinum), and as equal to that obtained with the conventional system in four regions (horizontal fissure, carina, azygoesophageal recess, and thoracic spine). Some observers had a strong preference for the digital images, whereas others showed no preference. The conventional system was not ranked high for any region (2880 observations, p < .01, sign test). CONCLUSION: The digital selenium chest radiography system performs well in a clinical setting, providing visualization of anatomic structures that is better than or at least equal to that provided by standard screen-film images.

Digital chest imaging using a selenium detector. A simulated diffuse interstitial pulmonary disease detection study.

RATIONALE AND OBJECTIVES: To assess the diagnostic performance of a new digital chest imaging system based on a selenium detector in the detection of simulated diffuse interstitial pulmonary disease (DIPD). METHODS: Diffuse interstitial pulmonary disease was simulated by superimposing plastic sheets containing small radio-paque objects (birdseed) on an anthropomorphic chest phantom. the number of sheets was varied from 0 to 4 to simulate the degree of pathology. Eighty conventional radiographs and 80 images with the selenium detector were obtained under comparable conditions. Six observers were asked to indicate the presence of DIPD using a five-level scale of confidence. The total 160 chest images were analyzed using receiver operating characteristic curves. RESULTS: There was no significant difference in detection performance between the conventional and the digital images (95% confidence interval). CONCLUSIONS: None of the observers assessed the diagnostic performance of the digital chest images as significantly different from that of the conventional system. The interobserver differences were higher than the differences between digital and conventional chest images.