Thoracic imaging in the intensive care unit.
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Catheterization, Central Venous↗
Biomedical subjects
C Chiles
Publications and source records attributed to C Chiles.
A radiographic approach to diffuse lung disease.
The chest radiograph remains the first and foremost imaging modality used in the assessment of patients who have diffuse lung disease. An optimal approach to the radiograph requires an understanding of pulmonary anatomy and pathophysiology of disease. The assessment of the radiograph can be based on an anatomic or a descriptive approach. Associated abnormalities, including pleural effusion, pneumothorax, lymphadenopathy, and so forth, also influence the differential diagnosis. This article presents a basic radiologic approach to diffuse lung diseases.
Diagnosis, Differential↗
Intra-aortic balloon pumps: an update on radiographic recognition.
Intra-aortic balloon pumps increase myocardial perfusion and decrease cardiac afterload in patients with cardiogenic shock and in high-risk patients scheduled for cardiac surgery. Appropriate positioning of the pump can be confirmed in chest radiographs. Familiarity with available catheters helps the physician to recognize overadvancement of the balloon in the ascending aorta or the aortic arch vessels. Because the balloon is long, its position is juxtarenal in most patients.
Female↗
A method for evaluating the bronchial circulation. Preliminary observations.
Due to the small size of the bronchial arteries, the bronchial circulation is difficult to study and remains poorly understood. We have utilized single photon emission computed tomography (SPECT) as a noninvasive means of studying the bronchial circulation. Imaging studies were performed in sheep before and after the introduction of a single pulmonary embolus. Digital bronchial arteriograms demonstrated the dilatation of the bronchial artery which is present on studies one week after embolization. SPECT bronchial perfusion scans reveal a wedge of increased activity that corresponds to a wedge of decreased activity on SPECT pulmonary perfusion images. Axial images available with SPECT provide information about regional alterations of bronchial perfusion not readily apparent on bronchial arteriograms.
Animals↗
Visual skill. Correlation with detection of solitary pulmonary nodules.
A series of visual tests was administered to 65 individuals: 9 Board-certified radiologists, 41 radiology residents, and 15 fourth-year medical students on the senior radiology elective. Results of these visual tests were compared with performance in detection of solitary pulmonary nodules. Among radiology residents or board-certified radiologists, no correlation was found between performance on tests of visual perception and the ability to correctly locate pulmonary nodules. A correlation between visual test scores and nodule detection was evident among medical students. These findings suggest that factors other than skill in visual perception determine a radiologist's ability to correctly identify solitary pulmonary nodules.
Internship and Residency↗
Analysis of the solitary pulmonary nodule by means of digital techniques.
Currently the radiographic determination of the benign or malignant nature of solitary pulmonary nodules relies on growth characteristics determined by comparison radiographs or the detection of calcification in the nodule with either low-peak kilovoltage fluoroscopy or CT of the chest. An alternative approach is analysis of the optical densities within the nodules by means of digital radiography. Two techniques have been described: histogram analysis of chest radiographs digitized with a laser scanner and dual-energy digital radiography. Although both techniques remain experimental, they offer a potential advantage over CT in that a single radiographic exposure is sufficient, thus decreasing the radiation dose to the patient and providing the patient with a less complex work-up.
Calcinosis↗
Pulmonary lymphangiomyomatosis: correlation of CT with radiographic and functional findings.
In 14 patients with biopsy-proved lymphangiomyomatosis, disease extent at computed tomography (CT) was correlated with findings at chest radiography and pulmonary-function testing. The CT scans and chest radiographs were read independently by two chest radiologists. Disease extent was assessed on CT scans by using a visual score (0%-100% involvement of the lung parenchyma) and on radiographs by using an adaptation of the International Labour Office classification of the pneumoconioses. There was good concordance between the two observers for CT and radiographic scores (Kendall tau greater than or equal to .86, P less than .01). A significant but relatively low correlation was present between CT findings and radiographic severity of disease (r = .59, P less than .05). Impairment in gas exchange as assessed with the diffusing capacity correlated better with disease extent seen on CT scans (r = .69) than with chest radiographic findings (r = .59). Three patients had evidence of parenchymal disease on the CT scans but not on the radiographs. In one patient CT findings were negative despite a positive finding on chest radiographs. The authors conclude that CT is superior to chest radiography in the assessment of patients with lymphangiomyomatosis.
Adolescent↗
CT of the pulmonary hilum.
Histologic examination of the lymph nodes is the only 100% accurate method of detecting metastatic disease. Even the pathologist encountering a lymph node cannot predict from the macroscopic appearance whether a lymph node is involved with tumor. Because enlarged lymph nodes may be free of tumor, and nodes of normal size may contain metastases, the accuracy of CT in the detection of hilar involvement by tumor is limited. The primary role of imaging procedures in the preoperative staging of patients with bronchogenic carcinoma is to determine the need for further prethoracotomy assessment. Decisions regarding operability of lung cancer should be based on tissue verification. Recognition of hilar abnormality requires a thorough understanding of normal bronchial and pulmonary vascular anatomy. The administration of intravenous contrast material can facilitate the distinction on a CT scan image of enhancing pulmonary vessels from nonenhancing hilar lymph nodes.
Bronchography↗
Magnetic field modulation of receptor binding.
Although it is widely held that the magnetic fields encountered during magnetic resonance imaging (MRI) and other procedures have no discernible effect on biological systems, we find that at early times of incubation, the amount of binding of the neurotoxin, alpha-bungarotoxin, to nicotinic acetylcholine receptor is significantly reduced in a constant 2.0-T magnetic field. This finding suggests that steady magnetic fields can directly affect the functional activity of biologically important macromolecules, in this particular case a neurotransmitter receptor.
Animals↗
Image optimization in a computed-radiography/photostimulable-phosphor system.
Photostimulable phosphor imaging is an exciting new technology that has several advantages over film/screen radiography, the most important of which is the linearity of the photostimulable phosphor system over a wide exposure latitude. The photostimulable phosphor image is digital, and as such, provides options of how the image is viewed by radiologists. This report discusses the various image-processing parameters available for a photostimulable phosphor system and describes a rational approach for selecting these parameters in portable chest radiography. As photostimulable phosphor imaging becomes more widely implemented, an understanding of the processing parameters will facilitate the production of images that take full advantage of the benefits of these systems.
Humans↗
Chronic multiple pulmonary emboli. Regional response of the bronchial circulation.
In pulmonary embolism, the bronchial circulation can dramatically increase perfusion to the lung and prevent infarction. The physiology of this response is incompletely understood. The authors studied the regional changes in the bronchial circulation in an animal model after multiple chronic pulmonary emboli to the periphery of one lung. The gross anatomy of the bronchial circulation was studied using Batson's solution to produce vascular casts of the pulmonary and bronchial circulations. These casts were prepared in a normal sheep and in a sheep with multiple chronic microemboli in the periphery of one lung. The normal bronchial arteries are visible as threadlike structures covering the surface of the tracheobronchial tree with ramifications extending to the lung periphery. In a sheep with multiple chronic microemboli, the bronchial arteries supply the pulmonary parenchyma deprived of pulmonary arterial flow. The bronchial arteries following pulmonary arterial embolization markedly dilate and are serpentine.
Animals↗
Sarcoidosis: correlation of pulmonary parenchymal pattern at CT with results of pulmonary function tests.
The appearances of the lungs on radiographs and computed tomographic (CT) scans were correlated with degree of uptake on gallium scans and results of pulmonary function tests (PFTs) in 27 patients with sarcoidosis. CT scans were evaluated both qualitatively and quantitatively. Patients were divided into five categories on the basis of the pattern of abnormality at CT: 1 = normal (n = 4); 2 = segmental air-space disease (n = 4); 3 = spherical (alveolar) masslike opacities (n = 4); 4 = multiple, discrete, small nodules (n = 6); and 5 = distortion of parenchymal structures (fibrotic end-stage sarcoidosis) (n = 9). The percentage of the volume judged to be abnormal (CT grade) was correlated with PFT results for each CT and radiographic category. CT grades were also correlated with gallium scanning results and percentage of lymphocytes recovered from bronchoalveolar lavage (BAL). Patients in CT categories 1 and 2 had normal lung function, those in category 3 had mild functional impairment, and those in categories 4 and 5 showed moderate to severe dysfunction. The overall CT grade correlated well with PFT results expressed as a percentage of the predicted value. In five patients, CT scans showed extensive parenchymal disease not seen on radiographs. CT grades did not correlate with the results of gallium scanning or BAL lymphocytes. The authors conclude that patterns of parenchymal sarcoidosis seen at CT correlate with the PFT results and can be used to indicate respiratory impairment.
Airway Obstruction↗
Chronic lung diseases: specific diagnosis by using CT.
We evaluated patterns of abnormal lung parenchyma on CT scans in six specific chronic lung diseases and then applied those findings in the differential diagnosis of these lung parenchymal patterns in 56 subjects. There were 48 patients with chronic lung diseases (43 with histologic proof) consisting of usual interstitial pneumonia (n = 20), sarcoidosis (n = 16), lymphangitic carcinomatosis (n = 7), lymphangioleiomyomatosis (n = 2), drug toxicity (n = 2), and eosinophilic granuloma (n = 1). Including eight CT scans of normal control subjects, 56 CT scans were assessed independently by two readers (R1 and R2). Chest radiographs, most of which were obtained within 1 week of CT examination, were available in 48 of the 56 subjects. CT scans were evaluated for specific parenchymal features including disease distribution, lung distortion, thickening of bronchovascular bundles and polygon walls, bronchiectasis, cysts, and nodules, to determine the association of each abnormal feature with the different diseases. Diagnosis was then made from the overall CT appearance of the lungs and, on a separate occasion, from the appearance of the chest radiograph. The correct diagnosis was made from the CT appearance in 54 of 56 patients (R1) and in 50 of 56 patients (R2). Correct diagnoses were made from the chest radiographs in 42 of 48 patients (R1) and 43 of 48 patients (R2). We have identified features that are reproducible and useful when describing CT scans of patients with chronic lung diseases. Interpretation of the appearance of the lung on CT scans was accurate in diagnosing usual interstitial pneumonia, sarcoidosis, and lymphangitic carcinomatosis.
Chronic Disease↗
Pulmonary lymphangioleiomyomatosis: CT findings.
Lymphangioleiomyomatosis, a rare disease occurring in women of childbearing age, is characterized by proliferation of smooth muscle in pulmonary lymphatic channels and mediastinal and abdominal lymph nodes. Chest radiographs typically reveal interstitial disease with normal lung volume. Pneumothorax and pleural effusions may be present. CT scans in eight patients with biopsy-proved pulmonary lymphangioleiomyomatosis were reviewed. The prominent feature of the disease was multiple thin-walled cysts throughout the lungs, best visualized on scans made with 1.5-mm collimation. Mediastinal and/or retrocrural lymphadenopathy, often not appreciated on the chest radiograph, was present in four of eight patients. CT can suggest a diagnosis of lymphangioleiomyomatosis when diagnosis by clinical presentation and chest radiographs is uncertain.
Adult↗
Effects of image processing on nodule detection rates in digitized chest radiographs: ROC study of observer performance.
To evaluate the effects of image processing in digitized chest radiographs when high-resolution images are used, an examination was done in which the detection of pulmonary nodules in unprocessed digitized chest radiographs was compared with that in images that had undergone processing with two methods, adaptive filtration and histogram equalization. The processing techniques have been optimized in previous work to selectively enhance the retrocardiac and subdiaphragmatic areas without significant alteration of detail in the lung. Eight observers were shown 150 test radiographs (50 unprocessed, 50 processed with adaptive filtration, 50 processed with histogram equalization) containing 150 nodules. The results indicate a statistically significant (P less than .03) difference, with highest observer performance in the chest radiographs processed with adaptive filtration (median area under ROC curve = 0.78), compared with unprocessed images (median = 0.68) and chest radiographs processed with histogram equalization (median = 0.62). Performance in the lung was not significantly different. Adaptive filtration applied to selectively enhance underexposed areas of film images may improve nodule detection. Histogram equalization provided no improvement in performance.
Filtration↗
Aortobronchopulmonary fistula complicating aortic aneurysm: diagnosis in four cases.
Aortobronchopulmonary fistula, a fistulous connection between the aorta and lung, is uniformly fatal in untreated cases. However, with early recognition and surgery, the survival rate exceeds 80%. We have had four patients with aortobronchopulmonary fistula, all of which resulted from thoracic aortic aneurysms (two after grafting of thoracic aortic aneurysms, one mycotic, one atherosclerotic). All four patients presented with hemoptysis. All four had a chest radiograph, which in two showed the aneurysm and in three showed airspace disease adjacent to the aorta. The aneurysm was shown by CT in one of two patients and by aortography in two of three patients. Neither CT nor aortography showed the fistula. Aortobronchopulmonary fistula was proved by surgery in two of the patients and by autopsy in the other two. A high index of suspicion is necessary to make the diagnosis of aortobronchopulmonary fistula. The diagnosis should be considered in patients who have minor or major hemoptysis, with either coexisting thoracic aortic aneurysms or history of thoracic aneurysm repair.
Adult↗
The secondary pulmonary lobule: normal and abnormal CT appearances.
The secondary pulmonary lobule is a unit of lung supplied by three to five terminal bronchioles and contained by fibrous septa. High-resolution CT is able to show features of the secondary lobule, including interlobular septa, terminal bronchioles, and pulmonary arteries within a bronchiolovascular bundle. Because interstitial diseases have been shown to affect different components of the secondary lobule, high-resolution CT was used to compare the appearance of the normal secondary lobule with the abnormal secondary lobule in three patients with interstitial diseases primarily affecting lymphatic channels: lymphangitic carcinomatosis, sarcoidosis, and lymphangioleiomyomatosis. In lymphangitic carcinomatosis, the bronchiolovascular bundles and interlobular septa were thicker than those seen in a normal subject. In sarcoidosis, the interlobular septa and bronchiolovascular bundles were also thicker than normal. However, fibrosis caused distortion of the normal polygonal shape of the secondary lobule, not seen in either the normal subject or the patient with lymphangitic carcinomatosis. Lymphangioleiomyomatosis was characterized by multiple cysts within secondary lobules, often obliterating the normal polygonal appearance.
Adult↗
Differentiation of benign from malignant pulmonary nodules with digitized chest radiographs.
To assess whether it is possible to distinguish benign from malignant solitary pulmonary nodules with digital techniques, a retrospective study of 68 patients with proved solitary nodules was performed. The conventional chest radiograph for each patient was digitized to 2,048 X 2,048 X 12 bits, and changes in the optical density within the nodule were analyzed. A number (the corrected gradient number) was then generated that reflected this variation. Striking differences were noted between 26 malignant nodules and 21 calcified granulomas. The technique was then applied to 21 benign nodules that had initially required thoracotomy or further study for diagnosis. In nine of these 21 patients (43%), the corrected gradient number allowed correct classification as a benign lesion.
Diagnosis, Differential↗