Chest
I. Basic Concepts:
Over exposed film = dark
Under exposed film = light
Dense objects = white
Little density = black
5 Xray Densities in order of increased brightness: gas, fat, fluid, bone, and metal.
Examples:
heart = lighter bc fluid.
Lung = darker bc air.
Bones = brighter bc calcium.
The closer an object is to the film, the sharper the borders are.
The farther away from the film it is, the more magnified and fuzzy it is.
Basic Views:
1. PA = film against chest and machine at back.
2. AP = film against back and machine at front. (for sicker pts who can't stand)
3. Lateral View = routinely taken with PA view. pt. is in profile view.
4. Decubitus = PA view with pt. lying down. Ex: if R. pleural effusion suspected, order a R. lateral decubitus. pt. will lie on R side.
II. Landmarks:
1. Mediastinum- heart, great vessels, trachea, mainstem bronchi, esophagus, lymph nodes, hilum.
2. Lungs/Pleura
-Right lung (upper, middle, and lower lobes) ---Left lung (upper and lower lobes and lingula)
-Visceral Pleura- thin layer of tissue covering lobes.
3. Chest Wall- ribs, muscle, and fat.
4. Diaphragm- right and left hemi-diaphragm.
Normal Chest Xray:PA and Lateral
III. Systematic Approach:
1. Marker- look for L marker on left chest
2. Inspiration- look for 9 ribs
3. Exposure
4. Rotation- look at clavicles and spine
5. Search Pattern- start at center and work to edges. mediastinum, lungs, chest wall, and diaphragm, and upper abd. Look for signs and problems.
IV. Specific Signs:
1. Silhouette Sign- border between heart and lung is lost due to fluid. ex is pneumonia.
☀right heart border = RML Pneumonia
☀Left heart border = lingula
☀right hemidiaphragm = RLL
☀Left hemidiaphragm = LLL
☀Descending Aorta = LLL
Silhouette sign- pneumonia in RLL obliterates the R. hemidiaphragm.
2. Air Bronchogram Sign- dark branching markings in abnormal white lung. This can be caused by alveoli becoming filled with fluid (pus, blood, or fluid). If this is present, the lesion must be in the lung.
3. Kerly B Sign- small horizontal lines seen in lung periphery. water densities that always extend to the pleura. Seen with increased fluid density in the interlobular septa. Usually caused by pulmonary edema in CHF or lymphatic spread of a tumor seen in lymphangitis carcinomatosis.
4. Snow Ball Sign- determines if a mass or nodule arises from lung or surrounding tissue. If the snow ball appears flattened, it comes from surrounding structure. If it looks like a ball before impact, it comes from lung.
V. Lung Disease Patterns:
1. Interstitial Pattern- innumerable thin white lines. fluid density in interstitium, called reticular pattern or reticulonodular pattern.
2. Air Space Disease- white opacity from fluid in alveoli like pneumonia or a consolidation.
3. Honeycomb Pattern- signifies interstitial lung disease and irreversible scarring seen in fibrosis, alveoli's, asbestosis.
4. Miliary Pattern- lots of pellet size white dots diffusely in both lungs as seen in TB.
IV. Specific Problems based on location:
1. Mediastinum
Aortic Laceration
-occurs in trauma
-blood accumulates at aortic arch
-mediastinal hematoma develops
-mediastinum appears wide
Pneumomediastinum
-mediastinum appears as black air density streaks
Enlarged Cardiac Silhouette
-when hearts largest transverse measurement is greater than half of the width of the chest. This could be caused by cardiomegaly, CHF, cardiomyopathy, or pericardial effusion.
2. Lungs/Pleura
Too White
-Pneumonia- causes a silhouette or air bronchogram sign. TB infection.
-Atelectasis- lung tissue is white (fluid). caused by obstruction, compression, and traction.
-Cavity-thick white soft tissue density with a dark air density center. Causes include abscess, pneumonia, TB, and tumors.
-Pleural Effusion/Hemothorax/Empyema- collection of fluid bw visceral and parietal pleura. costophrenic angle is blunt.
-CHF- vascular redistribution occurs. kerly B lines. peribrochial cuffing. pleural effusions. batwing pattern.
-Chronic Interstitial Lung Disease
-Nodule/Mass-appear as round white fluid density lesions. If less than 3 cm, called nodule. If greater than 3 cm, called mass.
Too Black
-Pneumothorax- air bw visceral and parietal pleura. look for a black crescent over apex of lung.
-Emphysema-overall decrease in lung density (black)
-Pulmonary Embolism-xray looks nl. sometimes see a focal, black, wedge-shaped area. a white shaped area of air space is seen, called Hampton's hump.
3. Chest Wall
-Rib Fracture-look for pneumothorax
-SQ Emphysema-dark air density streaks in the soft tissue. caused by lung laceration, esophageal rupture, tracheal laceration, or skin laceration.
4. Diaphragm
-Rupture-caused by trauma. usually left side. the diaphragm is elevated.
-Hiatus Hernia-gastric funds may appear as fluid density mass or an air fluid level behind the heart in the mediastinum.
Reference: Ouellette, H. and Tetreault, P. (2015). Clinical Radiology Made Ridiculously Simple. Ed. 2
