The aerosol and xenon lung-imaging procedures revealed abnormalities with approximately the same frequency as each other, but more often than any one group of pulmonary function tests, including spirometric data, maximal expiratory more » flow-volume curves, alveolar-arterial oxygen gradient, or indices derived from single-breath nitrogen washout. Perfusion lung imaging was less sensitive than most of the other diagnostic tests evaluated. The results of the radionuclide procedures were compared with each other and with pulmonary function tests and other diagnostic findings to determine their relative sensitivity for detecting evidence of early obstructive airway disease. One hundred subjects answered a respiratory questionnaire and underwent a physical examination, tests of pulmonary function, and three radionuclide lung-imaging procedures. Thus, it is recommended that, for interpretation of scintigraphic images in the assessment of pulmonary embolism, lung pathology associated with isolated xenon retention not be considered a potential cause for large or segmental perfusion defects. In each of these cases, however, the patient was felt actually to have pulmonary embolism. Three segmental perfusion defects were noted in association with isolated xenon retention. Ninety-four of more » these 111 sites showed either normal perfusion or a small, nonsegmental corresponding perfusion defect. Of the 208 individual lung regions with xenon abnormalities, 111 showed isolated washout defects (that is, with normal washin). Ventilation abnormalities were compared with the corresponding perfusion scan results at the same anatomic site. Scintigraphic lung studies were reviewed until 100 cases with abnormal ventilation results were obtained. This study was designed to evaluate the pulmonary blood flow patterns associated with isolated defects on xenon washout images. Xenon-133 washout phase imaging is often used to help determine whether the etiology of a perfusion defect is embolic or due to pulmonary parenchymal pathology, such as chronic obstructive pulmonary disease. Defects ar characteristic irregularities in xenon distribution during inhalation or perfusion studies can be obtained in some patients with disorders of airway tracts or blood vessels such as pulmonary thromboembolism, bronchial carcinoma, and pulmonary sequestration etc. An important problem in the use of xenon isotope in a given patient with cardiovascular or pulmonary disease is detecting regional pathophysiologic conditions of the lungs without any troubles. Recently technical advances such as introduction of new radionuclide preparations, improved imaging devices and computer system concerned with data- procedures, have further enhanced the clinical utility of nuclear medicine. However, these procedures have the disadvantage of complexity and demand the cooperation of the patient. Diagnostic methods like selective pulmonary angiography, bronchography, or bronchospirometry for cardiovascular and pulmonary diseases, which can evaluate regional function of the lungs, were established.
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