Eosinophilia-myalgia syndrome: findings on chest radiographs in 18 patients.

Findings on chest radiographs of 18 patients with the eosinophilia-myalgia syndrome were compared and correlated with peak eosinophil counts. Nine patients had normal chest radiographs. Of the nine patients with abnormal chest radiographs, three had fine, irregular linear opacities in the lungs (the opacities were most noticeable at the bases); three had similar irregular linear opacities and pleural effusions; and three had pleural effusions and confluent opacities. One patient demonstrated an enlarged heart; no pulmonary edema was seen in this patient or in any others. Although the mean recorded eosinophil cell counts were higher in those patients with abnormal chest radiographs (6,340 vs 5,454/mm3 [6.3 vs 5.4 x 10(9)/L]), the difference was not statistically significant.     

Subtle lung cancers: impact of edge enhancement and gray scale reversal on detection with digitized chest radiographs

The authors studied the impact of edge enhancement and gray scale polarity reversal on the detection of subtle lung cancers. Three experienced readers reviewed 46 biopsy-proved subtle lung cancers and 46 normal controls on chest radiographs that had been digitized into a 1,024 X 1,536-pixel matrix 8 bits deep. Receiver-operating characteristics (ROC) analysis of 1,656 pooled observations indicated that performance was best with the unmodified images (ROC area = 0.83), degraded by moderate enhancement of medium frequencies (ROC area = 0.80), and markedly impaired by severe enhancement of low frequencies (ROC area = 0.69). Gray scale polarity reversal further degraded performance (unenhanced ROC area = 0.74; moderately enhanced ROC area = 0.76; severely enhanced ROC area = 0.76). The authors conclude that edge enhancement and gray scale polarity reversal can impair the detectability of subtle lung cancers on digitized radiographs of medium resolution.     

Effect of monitor luminance and ambient light on observer performance in soft-copy reading of digital chest radiographs

PURPOSE: To examine the combined effects of monitor luminance and ambient light on observer performance for detecting abnormalities in a soft-copy interpretation of digital chest radiographs. MATERIALS AND METHODS: A total of 254 digital chest radiographs were displayed on a high-resolution cathode ray tube monitor at three luminance levels (25, 50, and 100 foot-lamberts) under three ambient light levels (0, 50, and 460 lux). Six chest radiologists reviewed each image in nine modes of combined luminance and ambient light. The observers were allowed to adjust the window width and level of the soft-copy images. The abnormalities included nodule, pneumothorax, and interstitial disease. Observer performance was analyzed in terms of the receiver operating characteristics. The observers reported their subjective level of visual fatigue with each viewing mode. A statistical test was conducted for each of the abnormalities and for fatigue score by using repeated-measures two-way analysis of variance with an interaction. RESULTS: The detection of nodules was the only reading that was affected by the ambient light with a statistically significant difference (P <.05). Otherwise, observer performance for detecting a nodule, pneumothorax, and interstitial disease was not significantly different in the nine-mode comparison. There was no evidence that the luminance of the monitors was related to the ambient light for any of the abnormalities. The fatigue score showed a statistically significant difference due to both the luminance and ambient light. CONCLUSION: When adequate window width and level are applied to soft-copy images, the primary diagnosis with chest radiographs on the monitor is unlikely to be affected under low ambient light and a monitor luminance of 25 foot-lamberts or more.     

Pulmonary embolism findings on chest radiographs and multislice spiral CT

Multislice spiral CT is becoming an increasingly important tool for diagnosing pulmonary embolism. However, in many instances, a chest radiograph is usually performed as a first-line examination. Many parenchymal, vascular, and other ancillary findings may be observed on both imaging modalities with a highly detailed depiction of abnormalities on multislice CT. A comprehensive review of chest radiograph findings is presented with side-by-side correlations of CT images reformatted mainly in the frontal plane.     

Pulmonary blastomycosis: findings on chest radiographs in 63 patients

Posteroanterior and lateral chest radiographs of 63 patients with proved pulmonary blastomycosis were evaluated to determine the most common findings. Included in the analysis were the location of the pulmonary infiltrates, the distribution and parenchymal patterns of disease, and the prevalence of adenopathy, pleural effusions, and/or cavity formation. Blastomycosis pneumonitis involved more than one pulmonary lobe in 21 patients and a single upper lobe in 27 of 63 patients. Forty-eight of the 63 patients had air-space consolidation. In nine of the 63 patients, a pulmonary mass was the major abnormality seen on radiographs. Approximately one fifth of the patients had associated pleural effusions and/or mediastinal or hilar adenopathy. Twenty-three patients (37%) had cavitation within the area of pulmonary consolidation. These findings suggest that blastomycosis should be considered when chest radiographs show air-space infiltrate in the upper lobes or in more than one lobe of the lung, especially when the infiltrate is associated with pleural effusions, cavitation, lymphadenopathy, and/or a paramediastinal mass.     

Interpretation of chest radiographs in the intensive care unit: a hard- versus soft-copy comparative study

PURPOSE: To compare the reliability of hard- versus soft-copy interpretation of intensive care unit chest radiographs, using a non-specialized standard resolution computer screen. MATERIALS AND METHODS: 104 chest radiographs were included in this study. Three physicians (one radiology resident, one intensive care unit resident and one experienced intensive care unit physician) gave their interpretations on computerized grids. Results were analyzed statistically using ROC curves and Kappa (kappa) index of concordance with experts. RESULTS: Results for reanimation equipment detection are almost independent from the modality (kappa(soft-copy)=0.891+/-0.037, kappa(hard-copy)=0.899+/-0.037). Regarding pathology detection, a global analysis only shows a difference at the limits of significance to the advantage of hard-copy films (kappa(soft)=0.514 +/-0.028, kappa(hard)=0.572+/-0.028). Overall results were significantly better for the radiologist compared to the intensive care unit physicians (kappa(radiologist)=0.751+/-0.048, kappa(intensive-care)=0.405+/-0.048). CONCLUSION: Concerning the task that is studied here, which requires only routine computer equipment, our results suggest that human factors can be more important than material factors.     

Neural networks in radiologic diagnosis. II. Interpretation of neonatal chest radiographs

A neural network (NN) system was trained to choose one or more diagnoses from a list of 12 possible diagnoses, based on 21 radiographic observations made on each of a series of neonatal chest radiographs. Initially, an experienced pediatric radiologist provided both the radiographic observations and ranked differential diagnoses for each of 77 neonatal chest radiographs in the preliminary phase used to train the NN. Subsequently, two pediatric radiologists (one of whom provided the initial training-phase data) independently read a series of 103 neonatal chest radiographs (different from the training set) and compiled a list of radiographic findings and differential diagnoses for each radiograph. The trained NN was then asked to provide a list of differential diagnoses for each case from the radiologists' lists of findings. Agreement between the network and each radiologist independently was greater than between the two radiologists. Both the positive and negative agreement between the network and either radiologist was greater than the inter-radiologist agreements for most of the diagnostic endpoints.     

Thoracic complications of extracorporeal membrane oxygenation: findings on chest radiographs and sonograms.

Neonates treated with extracorporeal membrane oxygenation (ECMO) for respiratory failure have a high frequency of complications related to systemic anticoagulation, ECMO and other life-support lines and catheters, and the antecedent pulmonary disease. Many of these complications involve the thorax and can be defined on chest radiographs or thoracic sonograms. The purpose of this essay is to illustrate the findings of the various thoracic complications of ECMO on chest radiographs and sonograms. This study is based on a review of the medical records and findings on chest radiographs and sonograms of 150 neonates who were treated with ECMO at our institution.     

Receiver-operating-characteristic study of chest radiographs in children: digital hard-copy film vs 2K x 2K soft-copy images.

Two methods are commonly used to visualize digital radiologic imaging data: (1) hard-copy viewing, in which the digital data are used to modulate the intensity of a laser beam that exposes an analog film and (2) soft-copy viewing, in which the digital data are converted to an analog video signal and presented on a CRT monitor. The film method allows new digital imaging systems to be easily integrated into conventional radiologic management and viewing methods. The second method, soft-copy viewing, allows digital imaging data to be managed and viewed electronically in a picture archiving and communication system (PACS). These PACS systems are hypothesized to have improved operational efficiency and enhanced image-analysis capabilities. The quality of soft-copy images is still not widely accepted. This article reports on the results of a large-scale receiver-operating-characteristic study comparing observers' performance in detecting various pediatric chest abnormalities on soft-copy 2048 x 2048K byte displays with their performance with digital laser-printed film from computed radiography. The disease categories studied were pneumothorax, linear atelectasis, air bronchogram, and interstitial disease. The selected data set included 239 images; 77 contained no proved abnormality and 162 contained one or more of the abnormalities mentioned. Seven pediatric radiologists participated in the study, two as judges and five as observers. Our results show no significant difference between viewing images on digital hard copy and soft copy for the detection of pneumothoraces and air bronchograms. A slight performance edge for soft copy was seen for interstitial disease and linear atelectasis. This result indicates that computed chest radiographs in children viewed in a soft-copy PACS environment should result in diagnoses similar to or slightly more accurate than those obtained in a laser-printed film-based environment.     

Detection of subtle lung nodules: relative influence of quantum and anatomic noise on chest radiographs

PURPOSE: To assess the relative influence of quantum mottle and structured lung patterns (anatomic noise) on the detection of subtle lung nodules on chest radiographs. MATERIALS AND METHODS: Sixty 8 x 8-cm lung pattern images were extracted from digital chest radiographs in healthy individuals. Sixty quantum mottle images of the same size and quantum noise level were extracted from uniformly exposed digital radiographs. Simulated nodules with various peak contrast-diameter products (CD) that emulated subtle tissue-equivalent lung nodules were numerically superimposed at the center on three-fourths of the images. Printouts were independently viewed and scored by five experienced radiologists. The area under the receiver operating characteristic curve (Az) was estimated as a measure of the detectability of the nodules. RESULTS: At a fixed observer performance level (e.g., Az = 0.8), much smaller and lower-contrast nodules were detected on quantum mottle images (1-mm diameter, CD = 0.01 mm), compared with those on anatomic images (4.5-mm diameter, CD = 0.20 mm). The findings generally agreed with the signal-to-noise ratio calculations based on statistical observer models. CONCLUSION: The detection of subtle lung nodules on chest radiographs is limited by anatomic noise.     

Impact of ambient light and window settings on the detectability of catheters on soft-copy display of chest radiographs at bedside

OBJECTIVE: The aim of this study was to evaluate how ambient light and interactive adjustment of density and contrast affect the detection of catheter fragments when interpreting bedside chest radiographs on soft-copy displays. MATERIALS AND METHODS: A total of 131 catheter fragments were superimposed over 10 bedside chest radiographs obtained with storage phosphor technology. Images were displayed on a clinical intensive care unit viewing station (color cathode-ray tube monitor, 21 inch [53 cm], 1280 x 1024 matrix) and were independently evaluated by five radiologists. The number of catheter fragments per image varied between 12 and 14, with an approximately equal distribution in high- and low-absorption areas. Detectability of catheter fragments was assessed under subdued and bright ambient light conditions with and without interactive adjustment of window width and level. RESULTS: Under subdued light, the detection rate of catheter fragments was significantly higher than under bright light (51.8% vs 56.6%, p < 0.05). Interactive window setting adjustment significantly increased the detection rate from 52.5% to 60.8% (p < 0.05) under subdued light and from 47.9% to 55.6% (p < 0.05) under bright light. With adjustment of window settings, the difference between the detection rates under subdued light (60.8%) and under bright light (55.6%) did not reach statistical significance. CONCLUSION: Detection of catheters on soft-copy display is significantly decreased by bright ambient light, an effect that can be largely compensated for by means of interactive adjustment of window settings.     

The serratus anterior muscle on chest radiographs.

The radiographic appearance of the serratus anterior muscle shadow is analyzed. In frontal and near-frontal views, it produces a "bowling-pin" silhouette. When the muscle is well developed, the medial edge of this silhouette may be superimposed upon the air shadow of the lung in a variety of ways. When it overlies the apex of the lung, it gives rise to the companion shadow; when overlying the midlateral lung edge and costophrenic angle it may mimic pleural and/or extrapleural disease. Recognition of the various possible patterns is important to prevent overdiagnosis of disease, particularly asbestosis.     

Comparison of observer performance on soft-copy reading of digital chest radiographs: high resolution liquid-crystal display monitors versus cathode-ray tube monitors

The purpose of this study is to compare observer performance for detection of abnormalities on chest radiographs with 5-megapixel resolution liquid-crystal displays (LCD) and 5-megapixel resolution cathode-ray tube (CRT) monitors under bright and subdued ambient light conditions. Six radiologists reviewed a total of 254 digital chest radiographs under four different conditions with a combination of two types of monitors (a 5-megapixel resolution LCD and a 5-megapixel resolution CRT monitor) and with two types of ambient light (460 and 50 lux). The abnormalities analyzed were nodules, pneumothorax and interstitial lung disease. For each reader, the detection performance using 5-megapixel LCD and 5-megapixel CRT monitors under bright and subdued ambient light conditions were compared using multi-case and multi-modality ROC analysis. For each type of ambient light, the average detection performance with the two types of monitors was also compared. For each reader, the observer performance of 5-megapixel LCD and 5-megapixel CRT monitors, under both bright and subdued ambient light conditions, showed no significant statistical differences for detecting nodules, pneumothorax and interstitial lung disease. In addition, there was no significant statistical difference in the average performance when the two monitor displays, under both bright and subdued ambient light conditions, were compared.     

Evaluation of optical unsharp masking and contrast enhancement of low-scatter chest radiographs

Conventional chest radiography poses a challenging technical problem because of its requirement for simultaneous high-contrast display and wide-latitude recording across the entire image. We developed and evaluated a method of producing chest radiographs by using a tantalum air-interspace grid for highly efficient scatter rejection, wide-latitude X-ray film for recording the low-scatter image, and a LogEtronics printer for optical unsharp masking and contrast enhancement of the recorded image (TWL technique). TWL images can be readily obtained and have excellent contrast and detail across the entire image. In comparison with a conventional technique, the TWL technique provides about a 15% improvement in image contrast in well-penetrated areas and a threefold to tenfold improvement in poorly penetrated areas. A detection study using simulated lung nodules and a chest phantom showed about 10% overall improvement in nodule detection with the TWL technique (51% vs 42%), most of which was due to improvement in detection rates in poorly penetrated areas of the chest (62% vs 26%). In well-penetrated areas, there was a decrease in detection rates (52% vs 44%) using TWL images despite measured improvements in image contrast in these areas. Possibly this was due to the observers' unfamiliarity with the reversed-contrast TWL images. Our results show the TWL technique to be valuable for improving image quality and diagnostic accuracy in chest radiography.     

Comparison of radiologist and CAD performance in the detection of CT-confirmed subtle pulmonary nodules on digital chest radiographs

OBJECTIVES: Detection of subtle pulmonary nodules on digital radiography is a challenging task for radiologists. The aim of this study was to evaluate the performance of a newly approved computer aided detection (CAD) system. MATERIALS AND METHODS: The sensitivity of 3 radiologists and of a CAD system for the detection of pulmonary nodules from 5 to 15 mm in size on digital chest radiography of 117 patients was compared. The reference standard was established by consensus reading of computed tomography scans by 2 experienced radiologists. Computed tomography scans and chest radiographs were performed within 4 weeks. Sixty-six pulmonary nodules from 42 patients, with a mean nodule diameter of 7.5 mm (standard deviation: 2.2 mm), were included in the statistical analysis. Seventy-five of the 117 patients did not have nodules from 5 to 15 mm of size. RESULTS: Two hundred and eighty-eight false-positive detections of the CAD system were found with an average of 2.5 false-positives per image. Sensitivity of the CAD system was 39.4% (95% confidence interval: 11.8%), when compared with 18.2% to 30.3% (95% confidence interval 9.3% to 11.1%) of the 3 radiologists. Substantial agreement for nodule detection ([kappa]N: 0.64-0.73) was found among the 3 radiologists, whereas only moderate agreement was found between the radiologists and the CAD performance ([kappa]N: 0.45-0.52). CONCLUSIONS: The CAD system's diagnostic sensitivity in detecting pulmonary nodules of 5 to 15 mm of size was superior to the 1 of radiologists. The CAD system may be used for assisting the radiologist in the detection of lung nodules on digital chest radiographs.     

Interpreting chest radiographs without visual search.

Ten radiologists were shown a series of 10 normal and 10 abnormal chest films under two viewing conditions: a 0.2-second flash and unlimited viewing time. The results were compared in terms of verbal content, diagnostic accuracy, and level of confidence. The overall accuracy was surprisingly high (70% true positives) considering that no search was possible. Performance improved as expected with free search (97% true positives). These data support the hypothesis that visual search begins with a global response that establishes content, detects gross deviations from normal, and organizes subsequent foveal checking fixations to conduct a detailed examination of ambiguities. The total search strategy then consists of an ordered sequence of interspersed global and checking fixations.     

The suprasternal fossa on chest radiographs in newborns.

Visualization of the suprasternal fossa in the newborn is due to suprasternal retraction. It is seen in 59% of patients with respiratory distress syndrome of the premature prior to intubation, and in 5% of patients with conditions such as pneumonia, meconium aspiration, and transient tachypnea of the newborn. The lower compliance of the lungs in patients with respiratory distress syndrome and increased compliance of the chest wall in premature infants accounts for the higher incidence of accentuation of the fossa. Visualization of the suprasternal fossa can simulate the distended proximal pouch of esophageal atresia. The two can be differentiated in the lateral view where the pretracheal location of the fossa can be appreciated.