APPROACH TO READING A CHEST RADIOGRAPH Marc Gosselin, MD TERMINOLOGY

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1 APPROACH TO READING A CHEST RADIOGRAPH Marc Gosselin, MD 1. Identify the exam, view and overall technique: penetration of film, amount of rotation 2. The lungs: Aeration, vascular distinctness, and abnormal opacities Ill- defined opacities +/- air bronchograms: consolidation or ground glass Nodules: well or ill-defined, cavitation, calcification Lines (reticular opacities): distribution, architectural distortion Cysts: thin or thick walls, always consider bronchiectasis first 3. Between the lungs: Heart size: cardiac silhouette preferred term Hilum: Enlarged pulmonary arteries or adenopathy usual cause. Mediastinium: Contour abnormalities, widened, identify location 4. Outside the lungs: Pleura: air, fluid, thickening, or nodules (ball under the carpet) Bones: fractures, lytic lesions Soft tissues: asymmetry, mastectomy *Always address both the MORPHOLOGY AND DISTRIBUTION of the disease. TERMINOLOGY Opacity: Consolidation, ground glass, band like, confluent, patchy, diffuse: Do Not use infiltrate Reticular: Usually means interstitial disease - Septal lines (Kerly B lines), curvilinear Nodule (< 3cm): Is it well defined (often interstitial) or ill defined (airspace?). Single or Multiple Mass (> 3cm): Borders, cavitation, calcification and location Volume Loss/Atelectasis: Check for deviation of fissures Extrapulmonary: Outside the lungs, best to use for either pleural, rib or soft tissue processes Lungs/Lung zone: Preferred term to lung fields, i.e. left lower lobe or lung zone

2 Thoracic differential diagnosis: Categorical Organization 1. Multifocal / Focal Ill-defined Opacities (Consolidation) ACUTE SYMPTOMS *Pneumonia (Pus) *Pulmonary Edema (Water) *Pulmonary Hemorrhage (Blood) CHRONIC SYMPTOMS ( ANGIO ) *Alveolar Proteinosis *Neoplasm: Lymphoma Bronchioloalveolar Cell Carcinoma *Granulomatosis: TB / Fungal Alveolar Sarcoidosis *Inflammatory: BOOP Eosinophilic Pneumonia *Old: Chronic Aspiration Lipoid Pneumonia (Hint: Adenopathy makes Lymphoma and Granulomatosis most likely!) 2. Ground Glass Opacities ACUTE SYMPTOMS *Pneumonia: PCP (Acute Subacute), CMV, Resolving bacterial pneumonia *Pulmonary Edema: Non-cardiogenic > Cardiogenic *Pulmonary Hemorrhage CHRONIC SYMPTOMS *Alveolar Proteinosis *Hypersensitivity Pneumonitis: EAA or Drug induced *DIP / RB-ILD (Smoker), UIP, NSIP: Active Alveolitis or Fibrosis Interstitial Lung Disease

3 1. Diffuse Reticular Opacities (Kerley A and B) *Pulmonary Edema: especially Cardiogenic *Lymphangitic Spread of Tumor: Adenocarcinoma or Lymphoma *Interstitial Pneumonia: Viral or Mycoplasma 2. Peripheral Reticular Pattern (Lace-Like Network) *UIP (Usual Interstitial Pneumonia) (AKA Fibrosing Alveolitis) This is most commonly seen secondary to the following: - Idiopathic Pulmonary Fibrosis - Collagen Vascular Disease; Rheumatoid and Scleroderma common - Drugs; ie BCNU, Bleomycin - Asbestosis (Complications: Pulmonary artery HTN, Lung cancer, Active inflammation) 3. Nodular Pattern *Metastasis; any tumor *Granulomatosis Diseases - Sarcoidosis - Tuberculosis - Fungal: Histo, Cocci, Crypto, Blasto - Eosinophilic Granuloma (Ill-defined nodules) *Inhalational Diseases - Subacute to Chronic Hypersensitivity Pneumonitis (Ill-defined nodules) - Silicosis - Coal Workers Pneumoconiosis *Alveolar Microlithiasis Miliary Nodules: TB, Fungal, and Sarcoid. Mets: Thyroid, Melanoma and adenocarcinoma. Alveolar Microlithiasis (Rare)

4 4. Cystic (Central Curvilinear/Reticular) Pattern *Severe Honeycomb Lung (End Stage Fibrosis) *Diffuse or Central Bronchiectasis *EG (Langerhans Cell Histiocytosis) *Lymphangioleiomyomatosis *Tuberous Sclerosis 5. Upper Lobe Diseases (SET PARC) *Sarcoidosis *Silicosis *EG (Smoker) *Extrinsic Allergic Alveolitis (Non-smoker) *TB *Fungal *PCP *Ankylosing Spondylitis / NF1 *Radiation *Cystic Fibrosis 6. Bronchovascular Distribution *Sarcoidosis *Lymphoma *Kaposi s Sarcoma 7. Large Unilateral Pleural Effusion *Malignancy *Infection Usually Empyema *Hemothorax Trauma or Iatrogenic

5 Peripheral Wedge-Shaped Consolidation (Mimics PE) 1. -Wegener s Granulomatosis 2. Angio-invasive Aspergillus 3. Cocaine Abuse HILAR ENLARGEMENT 1. Pulmonary Hypertension (Assess main & segmental pulm. arteries) Hyperdynamic (L RT Shunt): ASD, VSD, PDA and Endocardial Cushion Defect. (Assess size of Aortic Arch and left atrium) Obliterative: Chronic PE, Emphysema, Primary Pulmonary Hypertension, Drug-Induced vasculitis, Schistosomiasis Hypoxic: Chronic Bronchitis, Cystic Fibrosis, End Stage Pulmonary Fibrosis, Sleep Apnea and Chronic High Altitude. Pulmonary Venous HTN: Mitral Stenosis, Chronic CHF and Pulmonary Venoocclusive Disease. 2. Hilar Adenopathy Neoplastic: Primary lung Small Cell CA. Metastasis GU, Head &Neck, Breast, Melanoma. Lymphoma, leukemia (CLL) Granulomatosis: Sarcoidosis, TB, Fungal Infectious: Epstein-Barr virus (mononucleosis), AIDS Castleman s Disease MEDIASTINAL MASSES Anterior Mediastinal Mass Lymphoma/Leukemia Germ Cell Tumors: (Teratoma, Seminoma, Embryonal Cell, ChorioCA) Thymic: Thymoma (invasive or encapsulated), Cyst(s), Thymolipoma Thyroid: Goiter, Carcinoma Vascular: Aneurysm of Ascending aorta, Hematoma, Pseudoaneurysm

6 Middle Mediastinal Mass Lymphadenopathy: Neoplastic Primary lung (small cell), lymphoma/leukemia, metastasis (GU, Head & Neck, Breast, melanoma) Non-neoplastic Granulomatosis, EB virus, Castleman s disease Congenital: Bronchogenic cyst, enteric cyst Primary neoplasms: Tracheal, Neurogenic (Vagus N), Esophageal Vascular: Aneurysms, Arch anomalies Posterior Mediastinal Mass * Neurogenic Tumors (Vast Majority) - Nerve Root Tumors: Schwannoma, Neurofibroma - Sympathetic Ganglion Tumors: Neuroblastoma (< 2yo), Ganglioneuroblastoma (2 10yo), Ganglioneuroma (6yo - adult) - Paragangliomas (rare): Pheochromocytoma, chemodectoma. * Vertebral Body Abnormalities: Paraspinous abscess, Tumors * Vascular: Aneurysm descending aorta, Hematoma * Developmental: Enteric/Neurenteric cysts, Bochdalek s Hernia Extramedullary Hematopoiesis (rare) Multiple Cavitary Nodules/Masses *Infectious: Bacterial: Septic emboli / Multiple Abscesses, TB, Nocardia Fungal: Coccidiodomycosis or Aspergillus *Neoplasm: Squamous-cell carcinoma (primary or secondary), Sarcoma. *Vasculitis: Wegener s Granulomatosis, Angiocentric lymphoma, *Trauma: Traumatic lung cyst / hematoma

7 Evaluation of Acquired Heart Disease Small Heart Disease (Restriction or pressure overload) 1. Pericardium: Constrictive Pericarditis 2. Myocardial: Acute MI, Restrictive CM, Hypertrophic CM 3. Valve Disease: Stenosis Large Heart Disease (Myocardial failure or Volume overload) 1. Pericardium: Effusion 2. Myocardium: Dilated CM, Ischemic CM, Right Ventricular Failure 3. Valve Disease: Regurgitation Hints Global enlargement often represents Pericardial or Myocardial disease. Unequal chamber enlargement often secondary to Valve disease. Thin Section CT: Centrilobular Nodules (2 forms) 1. Tree-in-bud Bronchopneumonia, Aspiration, Endobronchial spread of TB, MAI, Asian Panbronchiolitis, ABPA, Cystic fibrosis, Asthma, BOOP. 2. Ill-defined Ground Glass Nodules Hypersensitivity pneumonitis (EAA), NSIP (cellular form), RB-ILD/DIP (smoker), follicular bronchiolitis (Rheumatoid Arthritis, AIDS) (Note: TIB gives thick reticular and ill-defined 3mm nodular opacities on the radiograph that does not extend to the pleural surface. Concurrent bronchial wall thickening is often present.) Mosaic Lung Attenuation 1.Lucent Regions Abnormal (vessels are smaller in these areas) *Small Airways Disease (Air trapping present on expiration): Asthma, Cystic fibrosis, bronchiolitis obliterans. *Pulmonary Artery HTN/Vasculitis Differential Diagnosis: No air trapping 2. Lucent Regions Normal (Vessels same size in all areas): Ground Glass Opacity Differential Diagnosis

8 Misconceptions in Chest Radiology General 1. Start with the abnormality on the chest radiograph and then do a review of systems, like an H&P presentation. (Lungs, outside lungs, between lungs) 2. Fat and soft tissues are useful to assess relative penetration of the chest radiograph, not the bones, which are much more dense than the lungs. 3. Echocardiograms, colonoscopy, and pathologists can be wrong. (Rule: Significant differences among clinical, radiology, laboratory tests or pathology require further evaluation and consultation. 4. Infiltrate, aortic knob and lung fields are not useful descriptive terms. (Remember, fields are for cows) 5. Obscuration of the hemi-diaphragms is often secondary to disease in the right middle lobe or lingula, and only rarely the posterior lower lobes. 6. Only 10-15% of pulmonary emboli result in infarct. (The bronchial artery collaterals are present to maintain tissue viability.) 7. Sarcoidosis has an equal incidence with males & females, except in African- Americans (females>males). 8. The azygoesophageal recess does not represent the right medial wall of the aorta. 9. The retrosternal space is often filled in, but with fat or right ventricle, not a mass. (Assess the PA contour closely, if abnormal, then consider the CT) 10. Pneumomediastinum is usually from alveolar rupture, not from the esophagus (even if patient has been vomiting). 11. Most primary lung adenocarcinomas have a characteristic appearance on CT. 12. Low lung volumes often the result of decreased lung compliance, not poor inspiratory effort. Low volumes should suggest underlying lung or abdominal pathology. 13. Lymphadenopathy can be seen on a chest CT scan without IV contrast. 14. Hilar adenopathy is best seen on the lateral projection, even mild enlargement. 15. Widened mediastinum is defined as >25% the width of the thoracic cavity. 16. Rib, Sinus and Lumbar Spine exams often not needed, and have > radiation, often without significant changes in management. 17. Comparison with an adjacent segmental bronchus is a quick way to assess pulmonary arterial size. 18. Atelectasis commonly has air bronchograms, except from post-obstructive etiologies. Cardiac-Vascular 1. The heart size can be assessed on an AP supine chest radiograph. (The 7-10% magnification can be adjusted for on the radiograph) 2. The heart chambers are very well assessed on the lateral view. (Echo is not the only examination to evaluate the heart chambers)

9 3. Heart and diaphragm borders are useful for evaluating only about 10% of the lungs, so try not to rely so much on these areas to evaluate the lungs. 4. Hydrostatic & non-cardiogenic edema can often be differentiated on the CXR. (These are two very different diseases and should not be lumped together) 5. Vascular indistinctness is one of the most sensitive signs of pulmonary edema. 6. Cephalization is not a sign of acute CHF. It means chronic PVH. 7. Radiographic findings of cardiogenic edema do not lag behind clinical symptoms, but rather, the radiograph abnormalities precede the clinical symptoms. 8. Non-cardiogenic edema and ARDS are on a spectrum of severity, depending on how much alveolar epithelium is involved. 9. If the echo reports an abnormality located outside the heart, it is most often normal. 10. Elevated intravascular fluid volume ( fluid up ) does not necessarily mean edema. 11. Relative changes in intravascular volume can often be assessed on the chest radiograph (vascular pedicle). 12. Hydrostatic edema does not commonly manifest as a bat wing appearance on the radiograph. Consolidation usually begins in the lower lobes medially. Pleural 1. A contralateral decubitus view is preferred to assess not only the pleural effusion, but also the obscured part of the lung (Pneumonia vs. atelectasis). 2. Pneumothorax is well seen on an inspiratory view of the chest. 3. Flowing versus loculated pleural effusions often can be seen on a PA & Lateral views (absent smooth meniscus is consistent with loculation) 4. Pleural effusions are first seen on the lateral view posteriorly (basement), not on the PA (first floor). 5. Pneumothorax is expected after tapping a large exudative effusion (The visceral pleura is thickened and is unable to fully expand.) 6. A tension PTX can be diagnosed on the CXR with near certainty (Depressed hemi-diaphragm means supra-atmospheric pressures in pleural space). 7. Pleural and peritoneal enhancement has a very similar differential diagnosis. ICU Radiographs 1. The ETT and Tracheostomy tube do not protect the airway. Aspiration is extremely common, especially if an NG or feeding tube is also present. 2. Aspiration can have a characteristic appearance on radiograph and CT scan. (Tree-in-bud pattern, bronchial wall thickening and dependant distribution) 3. The earliest sign of ARDS improvement on the CXR often is an increase in lung volumes, consistent with improvement of lung compliance. 4. ETT position best assessed with reference to the carina, not the clavicles. 5. The medial clavicular distance from the spinous process best assesses rotation of a radiograph. 6. Subclavian venous catheters should touch the clavicular head. (The artery courses above and around it).

10 Observations 1. Medical students and residents often say, I don t think this is when actually it is the diagnosis or finding. 2. When a question is given as a 50/50 chance, resident/students will be wrong 80% of the time: pick the other choice. (Gosselin s rule) 3. If you like it, you ll learn it; so learn to like it. (Felson)