HRCT in Diffuse Interstitial Lung Disease Steps in High Resolution CT Diagnosis. Where are the lymphatics? Anatomic distribution

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1 Steps in High Resolution CT Diagnosis Pattern of abnormality Distribution of disease Associated findings Clinical history Tomás Franquet MD What is the diagnosis? Hospital de Sant Pau. Barcelona Secondary Pulmonary Lobule Anatomic structures Centrilobular bronchiole Centrilobular artery Interlobular septum HRCT Basic Pattern of Abnormality Nodular Septal Reticular Cystic Ground-glass opacity Consolidation Courtesy of Harumi Itoh MD, Fukui (Japan) Small Nodules (1-10mm) Perilymphatic Nodules Where are the lymphatics? Anatomic distribution Perilymphatic Along vessels Along bronchi Centrilobular Along pleura Random Interlobar fissures 1

2 Perilymphatic Nodules Sarcoidosis Nodular thickening of 1. Sarcoidosis Bronchi 2. Lymphangitic spread of tumor Vessels 3. Silicosis Interlobar fissures 4. Coalworkers pneumoconiosis Subpleural lung 5. Lymphocytic interstitial pneumonia Perihilar predominance Upper & Mid lung Nodules (Centrilobular) Centrilobular Nodules 1. Hypersensitivity pneumonitis 2. Respiratory Bronchiolitis 3. RB-Interstitial lung disease 4. Silicosis 5. Coalworkers pneumoconiosis Hypersensitivity pneumonitis Small Nodules (Random) Nodules Poorly defined Centrilobular Clusters A few mm from pleura Away from fissures & vessels 2

3 Small Nodules (Random) Septal Pattern Interlobular septal thickening 1. Miliary TB 2. Hematogenous metastases 3. Sarcoidosis 4. Pneumoconiosis (Talcosis, Silicosis) Septal Pattern Pulmonary edema 1. Pulmonary edema 2. Lymphangitic carcinomatosis 3. Lymphoma 4. Lymphocytic interstitial pneumonia Lymphangitic carcinomatosis Lymphangitic carcinomatosis Fromn Webb RW. Thin-section CT of the Seconadry Pulmonary Lobule: The 2004 Fleischner Lecture. Radiology,

4 Reticular Pattern Intralobular lines (intralobular interstitium) Intralobular interstitial thickening Defn: very fine network of lines within visible lobules Caused by: IPF/UIP NSIP H. pneumonitis (chronic) Pulmonary edema ARDS Reticular Pattern Reticular Pattern Niemann-Pick Disease Cystic airspaces Defn:enlarged foci of air-containing lung surrounded by a wall of variable thickness and Honeycombing Defn:cluster or row of small cysts (3-10 mm in Ø) composition1 Typically seen in: IPF/UIP NSIP (fibrotic) H. pneumonitis (chronic) Asbestosis ARDS 4

5 Cystic Lung Disease Pulmonary Langerhans histiocytosis Honeycombing Nodules: smooth, irregular Pulmonary Langerhans histiocytosis Cysts: often bizarre shapes Lymphangioleiomyomatosis Random or diffuse distribution Lymphocytic interstitial pneumonia Upper and midle lung zones Hypersensitivity pneumonitis Relative sparing of lung bases Pulmonary Langerhans histiocytosis Lymphangioleiomyomatosis Muscle proliferation Along airways Along lymphatics Along blood vessels Lymphangioleiomyomatosis Thin walled cysts Diffuse Parenchyma between Journal of Computer Assisted Tomography 2003; 27(4): cysts typically normal 5

6 Ground-glass opacity Defn: Hazy increased attenuation of the lung, but with preservation of bronchial and vascular markings Ground glass opacity Subacute hypersensitivity pneumonitis Nonspecific interstitial pneumonia Collagen vascular disease Lymphocytic interstitial pneumonia Drug reaction Hansell DM et al. Fleischner Society: Glossary of terms for Thoracic Imaging. Radiology 2008 Non-specific Interstitial Pneumonia (NSIP) Crazy-paving pattern Defn :A network of a smooth linear pattern superimposed on an area of ground-glass opacity Crazy-paving pattern (Alveolar proteinosis) Air-space consolidation Defn : Increased attenuation of the lung, caused by filling of air spaces by fluid, cells, or other material Predominant lesion in 4 chronic diseases: Cryptogenic organizing pneumonia Chronic eosinophilic pneumonia Bronchoalveolar cell carcinoma Parenchymal lymphoma 6

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