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HRCTFindings of Lung Disease Abnormal HRCT findings, which have been enumerated over the last 25 years, and their differential diagnosis are reviewed in the subsequent five chapters. These findings can be classified ingeneral terms as:
Combinations and Patterns of HRCT Abnormalities The diagnosis or differential diagnosis ofdiffuse lung disease is often based on the recognition of specific combinationsof HRCT abnormalities, representing specific patterns of disease. For example, ina patient with honeycombing visible on HRCT, idiopathic pulmonary fibrosis maybe a likely diagnosis, but if honeycombing is associated with mosaic perfusionor air trapping, hypersensitivity pneumonitis should be suggested instead. Onthe other hand, mosaic perfusion or air trapping associated with bronchiectasissuggests airways disease. Furthermore, in some patients, ancillaryabnormalities such as lymph node enlargement, mediastinal and cardiacabnormalities, or abnormalities in the upper abdomen may be helpful. Distribution of HRCT Abnormalities When attempting to reach a diagnosis or differential diagnosis of lung disease using HRCT, the predominant distribution of abnormalities must be considered along with their appearance and morphology, and the combination or pattern or abnormal findings present. Although abnormalities in patients with a diffuse lung disease may involve the entire lung to an equal degree, a specific predominance in one or more regions is often discernable. Many lung diseases show specific regional distributions,or a predominance in relation to specific lung structures, a fact that is related to their underlying histology, pathogenesis, and pathophysiology. In different diseases, abnormalitiesmay predominate in relation to: 1. one lung. Many lung diseases are diffuse, and involve both lungs to an equal or nearly equal degree. On the other hand, some diseases may be asymmetrical, predominating in one lung, or may show this finding in some cases. A few lung diseases can be unilateral. 2. the lung in cross section,as displayed on transaxial HRCT images. In different diseases, abnormalities may predominate in (a) the peripheral or subpleural lung, (b) the lung periphery,but with relative sparing of the immediate subpleural regions, or (c) centralor peribronchovascular regions, sparing the supleural lung, or maybe (d)diffuse, equally involving the entire cross section of lung. 3. the upper-, mid-, or lowerlungs. This predominance may be ascertained by comparing the severity of abnormal findings on transaxial scans through the upper-, mid-, and lower lung regions, or by using two-dimensional reconstructions from volumetric imaging. 4. the anterior or posterior lung as seen on transaxial images or sagittal reconstructions. 5. the secondary pulmonary lobuleor lobular structures, being centrilobular, bronchiolar, perilobular, involving the interlobular septa, or lobular. 6. specific lung structures,such as the pleura (visceral or parietal), bronchi, or vascular structures, or a combination of specific lung structures. For example, some patients with nodular lung disease may show a preponderance of nodules in relation to bronchi and peribronchovascular regions, the subpleural lung, and interlobular septa;this combination is termed a lymphatic or perilymphatic distribution. It is typical of sarcoidosis and a few other diseases. It is important to keep in mind that predominance in more than one of the regions described above may be identified in any given case; as when identifying specific HRCT abnormalities, a specific combination of these may be suggestive of a particular diagnosis or differential diagnosis.For example, in a patient with sarcoidosis, a perilymphatic distribution of nodules on HRCT is usually associated with upper-lobe predominance, and the abnormalities may be symmetrical or asymmetrical. Also, significant variations in classical patterns of lung involvement can be seen in individual patients. A specific diagnosis that otherwise seems likely should not be excluded because of an atypical distribution of abnormalities. Clinical Findings Although history and other clinical findings can be of great value in suspecting or diagnosing a specific disease,in clinical practice, many HRCT studies are performed and interpreted with little or no clinical information available. Patients may be referred for HRCT without having seen a local physician or pulmonologist, or prior to their first appointment. However, even in such cases, some basic clinical information useful in diagnosis is often available. Such basic history as whether the patient’s symptoms are acute or chronic, or whether a fever is present, can be helpful. These will be stressed in the subsequent chapters, as specific findings and patterns are reviewed. For example, in a patient with HRCT showing ground-glass opacity as the predominant HRCT abnormality, knowing whether symptoms are acute or chronic can limit an otherwise lengthy and nonspecific differential diagnosis. In a patient with ground-glass opacity and acute symptoms, the most likely diagnoses include pulmonary edema or hemorrhage, atypical pneumonia,aspiration, or diffuse alveolar damage; in a similar patient with progressive or chronic symptoms, the differential diagnosis is long, and includes such diseases as hypersensitivity pneumonitis, nonspecific interstitial pneumonia (NSIP),desquamative interstitial pneumonia (DIP), respiratory bronchiolitis-interstitial lung disease (RB-ILD), lymphoid interstitial pneumonia (LIP), organizing pneumonia (OP), eosinophilic lung disease, alveolar proteinosis, lipoid pneumonia, and invasive pulmonary mucinous adenocarcinoma . From: High-Resolution CT of the Lung 王仁贵：MDCT直接淋巴管造影在弥漫性肺淋巴管瘤病中的诊断价值 |
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来自： 昵称42715024 > 《胸部~华夏》
