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Biomedical subjects

D R Aberle

Publications and source records attributed to D R Aberle.

At least 37 records · Page 2Linked to original sources
PubMed1995

Effects of reduced exposure on computed radiography: comparison of nodule detection accuracy with conventional and asymmetric screen-film radiographs of a chest phantom.

OBJECTIVE: Radiographic exposure has been thought to have little impact on the diagnostic quality of chest computed radiography because of automatic digital control of global optical density. The objectives of this study were to compare images obtained with two different exposures in computed radiography with conventional and asymmetric screen-film images of the chest for the detection of simulated lung nodules by use of receiver operating characteristic analysis and to relate differences in observer performance to parameters of image noise measured for each receptor condition. MATERIALS AND METHODS: At 110 kVp (fixed), exposures for the two screen-film systems were those necessary to achieve adequate optical densities over the lung and mediastinal regions of an anthropomorphic phantom. The two exposures used for the computed radiographs corresponded to the exposure used for the conventional chest screen-film system and an exposure 22% lower. An anthropomorphic phantom constructed of materials matched to the muscle, lung, and bone attenuation of a muscular adult man was used. Soft-tissue-equivalent plastic nodules of various sizes were secured at multiple sites on the phantom to simulate lung nodules. The chest phantom was imaged in 50 configurations with a total of 70 superimposed nodules. The perceptual performances of five radiologists were compared by use of receiver operating characteristic analysis. The signal-to-noise ratio in the mediastinum and the coefficient of variation of noise were measured for all four image conditions by use of a step wedge technique to provide an explanation for differences in diagnostic accuracy. RESULTS: We found no significant differences in the detection of lung nodules between the two screen-film systems or between the conventional screen-film images and the standard-exposure computed radiographs. However, there was a significant decrease in nodule detection on computed radiographs obtained at a reduced exposure; this result was associated with a 21% decrease in the signal-to-noise ratio. CONCLUSION: Our results show that underexposure of computed radiographs decreases the detection of low-contrast objects such as lung nodules. Although consistent global optical density on computed radiographs is achieved over a wide range of exposures, the alterations in signal-to-noise ratio that result from underexposure can reduce the diagnostic quality of computed radiographs.

Adult↗
PubMed1995

Pulmonary thromboembolism: spectrum of findings on CT.

CT has emerged as a potentially important diagnostic technique in pulmonary thromboembolism that can provide direct visualization of the obstructing embolus and its associated vascular and pleuroparenchymal sequelae. Although the role of contrast-enhanced CT in the diagnostic algorithm of pulmonary embolism has not been defined, patients at risk for pulmonary embolism frequently undergo thoracic CT as part of the assessment for other cardiopulmonary conditions. As such, CT may provide the first indication of clinically significant pulmonary embolic disease. This essay reviews the vascular, pleural, and parenchymal features of pulmonary thromboembolism observed on CT scans, describes the limitations of CT, and discusses the imaging features of pulmonary embolism that overlap other clinical conditions.

Adult↗
PubMed1994

Intrathoracic calcifications: radiographic features and differential diagnoses.

Intrathoracic calcifications occur in a wide variety of disorders. Although they are usually harmless sequelae of remote processes, calcifications provide important information for establishing the diagnosis or for evaluating the progression of known disease. They may arise in the pulmonary parenchyma, mediastinum, hilar and mediastinal lymph nodes, pleura, chest wall, or any combination of these structures. The cause of the calcification may be determined by means of the location and pattern of the calcifications within the lung parenchyma and knowledge of the associated clinical features. Calcifications in the thorax are frequently manifestations of previous infectious processes. Less often, they may be due to neoplasms, metabolic disorders, occupational exposure, or previous medical therapy. Large intrathoracid calcifications are usually identified on conventional chest radiographs; detection of smaller calcifications may require use of other imaging modalities, such as dual-energy digital radiography, fluoroscopy, radionuclide scanning, computed tomography (CT), and high-resolution CT.

Calcinosis↗
PubMed1993

Imaging of pulmonary mass lesions with whole-body positron emission tomography and fluorodeoxyglucose.

BACKGROUND: The clinical staging and management of both primary and metastatic lung lesions depends on accurate imaging techniques. Biochemical imaging with positron emission tomography, (PET), and the glucose analog 2-[18F]-fluoro-2-deoxy-D-glucose, (FDG), complements anatomic imaging with conventional radiologic methods. METHODS: A new "whole-body" PET FDG technique that produces two-dimensional, nontomographic and tomographic longitudinal images of the entire body has been developed at UCLA. Sixteen patients with known pulmonary nodules who had undergone thoracic computed tomography (CT) were studied with whole-body PET FDG imaging at the UCLA Medical Center. RESULTS: This PET FDG imaging method identified metabolically active tumor foci in all eight patients with bronchogenic carcinomas, four patients with metastatic lesions to the thorax, and two patients with Hodgkin disease. All diagnoses were confirmed histologically. Additionally, the PET FDG technique detected extrathoracic metastases in 4 of 16 patients. Thoracic CT was not diagnostic of neoplasm in two of the eight patients with bronchogenic carcinomas. In one patient with an ACTH-producing bronchial carcinoid, the lesion ultimately was detected on high-resolution CT but was not metabolically active on PET FDG imaging. CONCLUSIONS: This is the first report of whole-body PET FDG imaging in patients with thoracic lesions. PET FDG imaging accurately detected metabolically active tumor (both intrathoracic and extrathoracic) in patients with bronchogenic carcinoma, pulmonary metastatic disease, and Hodgkin lymphoma. Because lung cancer is characteristically a multisystem disease, this whole-body PET FDG technique has significant implications for treatment planning.

Adenocarcinoma↗
PubMed1993

The effect of irreversible image compression on diagnostic accuracy in thoracic imaging.

RATIONALE AND OBJECTIVES: Digital image compression reduces the storage requirements and network traffic on picture archiving and communications systems. Full-frame bit-allocation (FFBA) is an irreversible image-compression method based on the discrete cosine transform that provides for high compression ratios with a high degree of image fidelity. METHODS: One hundred twenty-two posteroanterior chest radiographs were obtained on patients in an ambulatory patient setting, including 30 cases of interstitial lung disease, 45 images containing combinations of lung nodules (N = 37) or mediastinal masses (N = 39), and 47 normal images containing none of the pathology for which we were testing. The images were digitized (nominal 2 K x 2 K x 12-bit resolution), printed on a 35 x 35-cm hard copy format, and compressed at an approximate compression ratio of 20:1. Observer performance tests were conducted with five radiologists using receiver operating characteristics analysis on digitized uncompressed and compressed hard copy images. RESULTS: There were no significant differences between the two display conditions for the detectability of any of the thoracic abnormalities. CONCLUSIONS: Our preliminary results suggest that irreversible image compression at ratios of 20:1 may be acceptable for use in digital thoracic imaging.

Algorithms↗
PubMed1993

HRCT in acute diffuse lung disease.

The applications of high-resolution computed tomography (HRCT) in the evaluation of acute diffuse lung disease are continually evolving. This review will address the principal morphologic features seen in the acute setting, including ground-glass opacification, air-space consolidation, and bronchial/peribronchial abnormalities. Although not histologically specific, in the appropriate context, these features often reflect an active process that may be amenable to treatment. For each feature, the most common acute diseases exhibiting these features will be reviewed within the context of histologic correlation.

Acute Disease↗
PubMed1992

Performance characteristics and image fidelity of gray-scale monitors.

Gray-scale monitors are an essential element of electronic radiology, and their ability to provide images that are perceived to be identical to those available on conventional or laser-printed film is crucial to success of electronic radiology. Image fidelity is measured in physical characteristics (luminance, dynamic range, distortion, resolution, and noise) and with psychophysical techniques, including receiver operator characteristics analysis with clinical images and testing with contrast-detail patterns to determine threshold contrast. Currently, laser-printed images facilitate greater information transfer than does a gray-scale monitor because of their higher absolute luminance (500 ft-L vs 60 ft-L), greater perceived dynamic range, and better spatial resolution. In the near future, the developments of gray-scale monitors with 150-200 ft-L luminance, a display standard based on just noticeable differences, and algorithms to improve similarities between gray-scale display images and laser-printed images will help increase the acceptability of monitors as a means to make primary diagnoses.

Computer Peripherals↗
PubMed1992

Imaging techniques in the evaluation of pulmonary parenchymal neoplasms.

Conventional PA and lateral chest radiographs continue to be the initial examination of choice to evaluate patients who are suspected of having a pulmonary parenchymal neoplasm. A lung lesion can be characterized as probably benign or malignant based on its radiographic appearance (size, shape, margins, presence of calcification, cavitation or air bronchograms, growth rate). A spiculated or lobulated lesion greater than 3 cm in size that is noncalcified is highly suspicious for malignancy. A lung lesion less than 3 cm in size with smooth borders that appears noncalcified on conventional radiographs should be examined by CT, including densitometry to detect calcification or fat, which indicates benignity. In patients with known lung cancer, CT can help to stage the tumor by indicating hilar or mediastinal involvement, or distant metastases. Currently, MR imaging has a limited role, but can be used as a "problem solving" modality for selected cases in evaluating pulmonary parenchymal neoplasms.

Diagnosis, Differential↗
PubMed1991

High-resolution computed tomography of asbestos-related diseases.

There is growing evidence that HRCT can detect both interstitial and pleural disease in advance of conventional clinical or radiographic studies. Limited HRCT scans are roughly competitive in time and cost with 4-view radiographic examinations. The use of limited HRCT for large-scale screening of asbestos-exposed individuals is controversial. Hopefully this will be resolved as we gain greater understanding of the specificity of HRCT and establish guidelines for standardizing technique and interpretation. At present, limited HRCT scans can supplement the chest radiographic evaluation of subjects in whom there is equivocal parenchymal or pleural disease, unexplained abnormalities on pulmonary function tests, or significant coexisting pleural disease that precludes evaluation of the underlying parenchyma. Interstitial abnormalities on HRCT may be reasonably ascribed to asbestos exposure when there is clear historical documentation of significant, remote dust exposure or concomitant evidence of typical bilateral asbestos-related pleural disease. A subpleural distribution of interstitial abnormality in nondependent lung is important to establish the diagnosis of interstitial fibrosis. Although both unilateral pleural and parenchymal fibroses have been reported, lesions should generally be present bilaterally. In individuals with combined asbestos-cigarette smoke exposure in whom symptoms or functional abnormalities are present, HRCT may play a central role in distinguishing emphysematous lung destruction from the peripheral interstitial changes of asbestosis. Finally, in individuals with significant pleural or parenchymal fibrosis, focal lung masses may not be visible on chest radiographs. In these individuals, CT protocols that sample all regions of the thorax are appropriate.

Asbestosis↗
PubMed1991

Computed tomography of asbestos-related pulmonary parenchymal and pleural diseases.

Computed tomography has acquired an increasingly central role in the evaluation of asbestos-exposed individuals. The advantages of increased contrast resolution and axial image display have extended our ability to interrogate areas of the pulmonary parenchyma and pleura that are inadequately seen on chest radiographs. The additional information to be gained from CT evaluation must be balanced by the additional expense and time required, particularly in view of the large numbers of asbestos-exposed individuals who will undergo screening over the coming decades. Ideally, imaging strategies that include CT should emphasize those problematic situations in which additional information will serve a differential or diagnostic function, alter the management or habits of the individuals, modify the working environment, or improve our understanding of asbestos-induced diseases. The chest radiograph is the mainstay in the imaging evaluation of asbestos-exposed individuals, providing an inexpensive and rapid appraisal of the presence of both focal and diffuse abnormalities of the pleura and lung parenchyma. Conventional (whole-thorax) CT may be an important adjunct in the following situations: (1) to clarify the presence of pleural thickening, particularly in distinguishing pleural disease from normal extrapleural soft tissues; (2) to stage and determine tumor extent in malignant pleural mesothelioma; (3) to identify optimal sites for biopsy of suspicious pleural changes; and (4) to detect and characterize lung cancers or other focal masses that may be obscured by extensive pleural or parenchymal fibrosis. Limited HRCT studies are roughly competitive in time and cost with four-view radiographic examinations. There is growing evidence that HRCT can detect interstitial disease in advance of conventional clinical or radiographic studies. However, the application of limited HRCT for large-scale screening is controversial. This issue will be resolved as we gain greater understanding of the specificity of HRCT and establish guidelines for standardizing the technique and image interpretation. At present, limited HRCT scans can supplement the evaluation of subjects in whom there is equivocal parenchymal or pleural disease on radiographs or unexplained abnormalities on pulmonary function tests. In individuals with significant pleural disease, HRCT can effectively define the presence and extent of interstitial fibrosis. In individuals with combined cigarette smoking-asbestos exposure in whom symptoms or functional abnormalities are present, HRCT may play a central role in distinguishing emphysematous lung destruction from the peripheral interstitial changes of asbestosis.

Asbestosis↗
PubMed1990

Advances in medical imaging.

The field of medical imaging, stimulated by advances in digital and communication technologies, has grown tremendously. New imaging techniques that reveal greater anatomical detail are available in most diagnostic radiology departments. We discuss vascular imaging with ultrasound, high-resolution computed tomography of the thorax, magnetic resonance imaging applications, and picture archiving and communication systems. Vascular imaging with ultrasound requires duplex and color flow Doppler, which combine gray-scale ultrasound and the Doppler phenomenon. High-resolution computed tomography modifies conventional computed tomography technology and results in images with higher spatial resolution. Magnetic resonance imaging applications for all areas of the body are being investigated and are replacing older roentgenographic techniques such as computed tomography, arthrography, myelography, and even angiography in a growing number of indications. With these new digital imaging modalities, image management has become an important consideration that can be addressed by picture archiving and communication systems.

Diagnostic Imaging↗
PubMed1990

Current status of digital projectional radiography of the chest.

Thoracic imaging constitutes more than one-third of all medical imaging performed in the United States. Despite the substantial impact of computer technology in other areas of imaging, conventional film-screen acquisition systems still provide the bulk of projectional chest radiography. The successful implementation of digital technology in thoracic imaging requires that the standards of current film-screen methods for both diagnostic accuracy and efficient data management be preserved. This article addresses the technical and clinical aspects of film digitization and storage phosphor technology, which are the two digital acquisition systems in widest application. Scanned projection radiography, which may now be applied to computed radiography systems, is also discussed. Finally, some of the issues surrounding the implementation of picture archiving and communication systems for thoracic imaging are addressed.

Adult↗
PubMed1990

Thoracic manifestations of Wegener granulomatosis: diagnosis and course.

A combination of cytotoxic and corticosteroid therapy has dramatically improved the long-term survival of patients with Wegener granulomatosis. With extended survival, patients now experience diverse cardiopulmonary abnormalities that represent primary or secondary manifestations of the disease or that result from diagnosis and treatment. To evaluate these abnormalities, the authors reviewed the medical histories and chest radiologic findings of 19 patients with the histologic diagnosis of Wegener granulomatosis. In these patients thoracic images demonstrated parenchymal nodules or consolidations with cavitation, diffuse interstitial disease, mediastinal or hilar adenopathy, and isolated stenoses of the larynx or tracheobronchial tree. Intrathoracic relapse occurred in 18 cases; in one-third of these patients, findings at relapse differed from those at initial presentation. Complications from diagnosis or therapy occurred in nine patients. Pulmonary infection was the most frequent complication causing morbidity and was often clinically indistinguishable from the primary disease; it complicated relapse in five patients. The successful radiologic follow-up of patients with Wegener granulomatosis requires a consideration of the varied thoracic manifestations of both the primary disease and the complications of its treatment.

Adult↗
PubMed1990

Lymphangiomyomatosis: CT, chest radiographic, and functional correlations.

Eight patients with the diagnosis of lymphangiomyomatosis were evaluated with computed tomography (CT), chest radiography, and pulmonary function tests to determine the relationship between the extent of disease seen on imaging studies and functional status. Chest radiographic assessment included the subjective determination of disease extent and measurements of lung length and the arc of the right hemidiaphragm. Disease extent on CT scans was scored as a percentage of lung that was abnormal on the basis of visual assessment of the degree of cystic replacement of the lung parenchyma. Significant correlations were observed between CT scores and percentages of predicted forced expiratory volume in 1 second/forced vital capacity (r = -.92, P less than .002) and diffusing capacity of the lungs for carbon monoxide (r = -.80, P less than .017). No significant correlations were observed between subjective chest radiographic scores and pulmonary function tests, although measurements of lung length and percentage of predicted total lung capacity were correlated (r = .76, P less than .045). CT was more accurate than chest radiography in defining the presence and extent of parenchymal cysts and provided for greater morphologic-physiologic correlation. CT, particularly high-resolution CT, may be useful in the diagnosis and longitudinal evaluation of patients with this disease and may be more sensitive than pulmonary function tests in the early stages of lung damage.

Adult↗
PubMed1990

Current use of imaging in the evaluation of primary mediastinal masses.

A wide variety of lesions occur in the mediastinum in patients of every age. Twenty five to 50 percent of these primary mediastinal masses may be malignant, making early diagnosis and therapy crucial. Since most arise from normal structures in the region, localization of lesions to compartments of the mediastinum may assist in diagnosis. This article reviews imaging techniques for lesions originating in the mediastinum.

Arteriovenous Malformations↗