Chest X-Ray Interpretation for the Internist Theresa Cuoco, MD Medical University of South Carolina February 22, 2012

Disclaimer: I am NOT a radiologist!

Why do we need to know? To direct care while awaiting an “official read” Low level radiation for the patient Easily available and noninvasive Relatively inexpensive We need to have a basic knowledge of CXR interpretation

Objectives Basics of technique Type of film and the “tions” Identification of structures on a “normal” CXR Alveolar vs interstitial, lobar anatomy, silhouette sign, air bronchograms, and patterns of lung disease The mediastinum, pleura, and heart Systematic approach to interpretation Cases Mediastinum will cover anterior middle and posterior structures Lungs: will cover lobar anatomy, silhouette sign, air bronchograms and patterns of lung disease Also spend some time discussing the pleura Airways, bones and breasts, cardiac and costophrenic diaphragm, edges and extrathoracic, fields lung fields and failure

Technique PA and lateral AP Which is preferred and why? Lateral film – left side of chest against x-ray cassette Decubitus films PA and lateral – x-ray tube is 6 feet from film or detector 1. Less magnification 2. sharper images 3. better inspiratory effort and view of lungs 4. pleural fluid and air easier to see on erect film

Which is which?

The “tions” IdentificaTION InspiraTION PenetraTION RotaTION Identification: make sure its your patient on particular day; male vs female; foreign objects Inspiration: well inspired film you should be able to count 8 ribs…otherwise crowded lung markins, high diaphragms etc EXP film – to detect focal air trapping, may accentuate a PTX Penetration- if not properly penetrated, xray can exaggerate or obliterate important findings…. You should be able to see thoracic vertebrae behind heart Rotation: equal distance from vertebral spines to medical ends of clavicles.

Inspiration vs Expiration Indications for expiratory film – to look for air trapping – In a film that would normally get whiter with expiration, the area would remain inflated and black; also to detect a pneumothorax Any indications for an expiratory film?

Penetration A B Heavy light exposure causes the film to be black (A) Little light exposure causes the film to be white (B)

Rotation

Normal Anatomy A costophrenic angle B left diaphragm C heart D aortic knob E trachea F hilum G carina H stomach bubble J ascending aorta

The Normal Chest X-Ray A gas in splenic flexure B costophrenic angle C heart D descending aorta E trachea F carina G hilum H aortic knob J ascending aorta K right diaphragm The left hilum is slightly higher than the right – this is normal

Alveolar vs Interstitial Alveolar = air sacs Radiolucent Blood, mucous, tumor, or edema in alveoli obscure normal anatomy: “airless lung” Interstitial = vessels, lymphatics, bronchi, and connective tissue Radiodense Interstitial disease: prominent lung markings with aerated lungs Interstitium is essentially branching pulmonary arteries

Lobar Anatomy Anterior Posterior The fissure has to be parallel to the x ray beam for it to be visible on the film – therefore the oblique (major) fissures are not visible on the normal frontal projection

Lobar Anatomy – Lateral Views Right Left

The Silhouette Sign There are 4 basic radiographic densities Gas, fat, soft tissue (water), and metal (bone) Anatomic structures are recognized on x-ray by their density differences Two substances of the same density in direct contact can’t be differentiated Loss of the normal radiologic silhouette (contour) is called the “silhouette sign”

Localizing Lesions Where is the silhouette sign? RML Pneumonia with obscured right heart border Where is the silhouette sign?

Localizing Lesions Right lower lobe infiltrate

Localizing Lesions A Left lingular infiltrate B left lower lobe infiltrate A B

Localizing Lesions A. Right upper lobe infiltrate B left upper lobe patchy infiltrate A B

Localizing Lesions Obscured L heart border = lingula Aortic knob obliterated = left upper lobe Right lung base w heart border seen = right lower lobe Right lung base w heart obscured = right middle lobe Descending aorta obscured = left lower lobe EXCEPTIONS: Pseudosilhouette of diaphragm in underpenetrated film Right heart border my overlap spine Heart obscures anterior left diaphragm on lateral If the heart is positioned slightly to the left, the right heart border may overlap the spine

The Air Bronchogram When lung is consolidated and bronchi contain air, the dense lung delineates the air-filled bronchi Visualization of air in the intrapulmonary bronchi is called the “air bronchogram sign” Abnormal finding Can be seen in: PNA, edema, infarction Chronic lung lesions

NO Air Bronchograms… In pneumonia if bronchi are filled with secretions If cancer obstructs a bronchus Interstitial fibrosis Asthma/emphysema (hyperinflation)

What do you see? Left lung consolidated and collapsed – trachea shifted toward that side; heart shifted left

Lung and Lobar Collapse When a whole lung collapses, the trachea deviates TOWARD the side of collapse (due to volume loss)

Fissures Formed by 2 visceral pleural layers Demarcate the boundaries of the lobes Shift of fissures is best sign of lobar collapse Can review in detail each of these diagrams of lobar collapse

Which lobes have collapsed? Minor fissure is elevated – RUL partially collapsed Heart has moved to right and silhouette sign of right diaphragm – indicated RLL collapse Minor fissure is elevated – RUL partially collapsed Heart has moved to right and silhouette sign of right diaphragm – indicated RLL collapse

Hilar Displacement The left hilum is normally slightly higher than the right Hilar depression indicates collapse of lower lobe Hilar elevation indicates collapse of upper lobe

Patterns of Lung Disease Pearls Pulmonary markings are more visible in interstitial disease Generalized interstitial markings = linear (reticular) Discrete/focal thickening = nodular Homogeneous or patchy consolidation = alveolar Focal consolidation < 3cm = nodule Focal consolidation > 3cm = mass Heavy calcification generally = benign

What is the pattern? A: Focal/linear B: Diffuse/nodular C: Alveolar C= alveolar filling disease A: Focal/linear B: Diffuse/nodular C: Alveolar

The Mediastinum A = ascending aorta B aortic knob C descending aorta D right heart border E superior vena cava F right tracheal wall G left heart A ascending aorta B aortic knob C descending aorta D right heart G left heart {L left pulmonary artery and R right pulmonary artery – outside the mediastinum} X= retrosternal clear space

The Mediastinum I: Anterior Mediastinum II: Middle Mediastinum Heart Retrosternal clear space 5 T’s II: Middle Mediastinum Esophagus Arch and descending aorta Trachea III: Posterior Mediastinum Paravertebral area Lymph nodes in all 3! Anterior mediastinal compartment – heart and retrosternal clear space – teratoma, thymoma, thyroid, terrible lymphoma, and thoracic aorta Middle mediastinum – esophagus, lymph nodes, arch and descending aorta, trachea Posterior mediastinum is the paravertebral area

The Pleura The posterior costophrenic angle is the deepest and only seen on the lateral film The lateral film is more sensitive for detection of small pleural effusions How much fluid can be seen on a radiograph? Erect PA: 175 mL Erect lateral: 75 mL Decubitus: >5 mL Supine: Several hundred mL Anterior, posterior and lateral costophrenic angles Erect PA = 175 mL Lateral = 75 ml decubitus = >5 mL Supine = several hundred mL

What do you see? Air enters pleural space with each breath but cant escape, increasing intrapleural pressure – increased pressure depresses the diaphragm, collapses the lung, and shifts the mediastinum away Clinical signs: rapid onset respiratory failure, decreased breath sounds, deviated trachea, JVD

The Heart The horizontal width of the heart should be less than ½ the widest internal diameter of the thorax

Left and Right Ventricular Enlargement Left ventricular enlargement Frontal: LHB moves laterally and cardiac apex inferolaterally Lateral: LHB moves inferoposteriorly Right ventricular enlargement Frontal: RHB further right Lateral: Contacts lower half of sternum (instead of lower 3rd)

Cephalization Enlargement of the upper lobe vessels “Vascular redistribution” “Kerley B” lines: interstitial edema thickening the interlobular septa causing short lines perpendicular to the pleural surface

Systematic approach ABCDE ATMLL (“Are There Many Lung Lesions?”) Airway Bones and breasts Cardiac and costophrenic Diaphragm Edges and extrathoracic Fields (lung fields and failure) ATMLL (“Are There Many Lung Lesions?”) Abdomen Thorax – bones and soft tissues Mediastinum Lungs – unilateral and bilateral Airways, bones and breasts, cardiac and costophrenic diaphragm, edges and extrathoracic, fields lung fields and failure

Cases

Young man with cancer Metal nipple markers have been placed Is the lung abnormal: pulmonary nodule below right nipple marker where ribs cross Right shoulder amputated: pulmonary met from osteosarcoma

Young man without symptoms Strange cardiomediastinal shape on left - causes silhouette of left atrium ,pulmonary artery, and aortic arch Lateral shows density in retrosternal clear space

ICU patient with fever, WBC Bilateral dense consolidation with air bronchograms, silhouette signs of diaphragms, blunt right costophrenic angle Dx: Pneumonia 2ndradiograph – several hours later – developed tension PTX with air in pleural space, low right diaphragm, heart shifted to the left.

Two older women with cough Both have alveolar consolidation RUL What forms the sharp lower edges of their lesions? The minor fissure Patient A has right pleural effusion and hilar mass and NO air bronchograms due to central obstruction A= cancer B = PNA

Dyspnea with sudden CP & fever Cardiac silhouette is enlarged; Pulmonary vessels are enlarged with cephalization and mildly indistinct DX – mild left ventricular failure Dx: free air under diaphragms (from perf ulcer) explains sudden chest pain and fever