3Lobar AnatomyThere are three lobes in the right lung and two in the leftLobes are divided into anatomic segments; each is supplied by its own bronchus and blood vessels
4Right upper & right middle lobes Lobar Anatomy:Right upper & right middle lobesRULRULRML borders the right atrium and much of the dome of the diaphragm. Indistinct borders of these areas suggest RML pathology.RMLRML
5Lobar Anatomy: Right lower lobe Consolidations of the lower lobes are largely behind the diaphragm dome, hence the diaphragm border will still appear sharp on the PA film.RLLRLL
6Lobar Anatomy: Left upper lobe LULLULLUL borders the left atrium, left ventricle and much of the dome of the diaphragm. Indistinct borders of these areas suggest LUL pathology.
7Lobar Anatomy: Left lower lobe Most of the LLL is posterior to the left border of the heart and the dome of the diaphragm. Distinct borders of these areas with surrounding opacity is seen with LUL consolidations.LLLLLL
8Can you find the source of this patient’s fever and cough?
9Can you find the source of this patient’s fever and cough? Left LowerLobepneumoniaDistinct bordersNote the abnormal opacification of the lower vertebrae in the lateral view. Normally there is less soft tissue around the inferior thoracic vertebrae making them appear darker than the more superior vertebrae. See next slide for comparison.
10On the right is the same radiograph from the previous slide with a normal one for comparison. Normally,inferiorvertebraeappeardarkerNote the general opacification of the lower lobe in the image on the right. Look particularly at the vertebral bodies and posterior border of the heart.
11Lobar AnatomyThe lobes of the lungs are lined by visceral pleura, which normally is not visualized except along the interlobar fissuresFissure anatomy may have many anatomic variations and may not be complete
12On the right there are two fissures, the oblique (major) fissure and the horizontal (minor) fissure. The left lung contains an oblique fissure only.minorminormajor
13It is uncommon to see distinct fissures It is uncommon to see distinct fissures. If opacified there may be thickening of or fluid between the pleura.This patient has congestive heart failure and subsequent subpleural thickening.Can you identify the oblique fissures?
14It is uncommon to see distinct fissures It is uncommon to see distinct fissures. If opacified there may be thickening of or fluid between the pleura.This patient has congestive heart failure and subsequent subpleural thickening.Can you identify the oblique fissures?
15Here there is fluid trapped between the pleura within the fissures.
16Occasionally accessory fissures can be found Occasionally accessory fissures can be found. For example, the azygos fissure, a normal variant, can form during the embryonic migration of the azygos vein through the apical pleura.
17Knowing the normal position of the interlobar fissures helps us diagnose pulmonary volume changes. For example when a lobe collapses the fissure is displaced and seen as a sharp interface between opacified (collapsed) and aerated lung.Can you identify the pleural lining of the collapse lung?
18Can you identify the pleural lining of the collapse lung? Knowing the normal position of the interlobar fissures helps us diagnose pulmonary volume changes. For example when a lobe collapses the fissure is displaced and seen as an interface between two densities (e.g., opacified/collapsed and aerated lung)Can you identify the pleural lining of the collapse lung?scapulaeLeft pulmonary artery:vasculature are pulled inferiorly by the collapsed LLLInferior vertebrae opacified by LLL atelectasisLeft hemidiaphragm becomes indistinct when adjacent to collapsed LLLMajor fissure not normally seen on the PA film because it runs parallel to the radiation beams
21We can use the pleura to identify whether a mass is within the lung parenchyma or in the extrapleural space.Is this mass intrapleural or extrapleural? How can you tell?
22Is this mass intrapleural or extrapleural? How can you tell? We can use the pleura to identify whether a mass is within the lung parenchyma or in the extrapleural space.Is this mass intrapleural or extrapleural? How can you tell?ExtrapleuralThe medial border of the mass is draped by pleura and is distinct where it is adjacent to aerated lung. The lateral border is next to bone and soft tissue of more similar density.
23The pleura is often involved in inflammatory and traumatic insults to the chest. These may result in areas of thickening or distortion of the pleural lining, which may be appreciated in the normally sharp costophrenic & cardiophrenic angles/sulci.Cardiophrenic anglePosterior costophrenic angleLateral costophrenic angleLateral costophrenic angle
24Pleural effusions can be identified by: blunting of the lateral and posterior costophrenic sulci, a meniscus sign, opacification of a hemithorax, and/or fluid in the fissures.Small free-flowing pleural effusions are best identified on the lateral radiograph as this view captures the most dependent region of the thoracic cavity, the posterior costophrenic angles.
25MediastinumMany structures can be identified within the mediastium; we will start with the heart and blood vessels…
35Last one, name the valves… AorticAorticTricuspidMitralTricuspidMitral
36The Vascular Pedicle Found in the superior mediastinum. Right and left margins are normally formed by the superior vena cava and the descending portion of the aortic arch, respectively.A widened vascular pedicle can have several etiologies including elevated intravascular volume, aortic trauma, or pericardial effusion.
38Intravascular volume depletion vs. Intravascular volume elevation
39Intravascular volume depletion vs. Intravascular volume elevation Vascular pedicleVascular pedicleSuperior vena cavaAortaSuperior vena cavaAortaIntravascular volume elevation resulting in an expanded SVC should not be mistaken for hematoma, which would have a less distinct border and more opacified appearance.
40Trauma patient with an aortic transection Note the vascular pedicle’s “fuzzy”, opacified right border.
42What is happening here? Can you follow the heart borders? Looks pretty wide eh?Can you follow the heart borders?
43What is happening here?If you look closely you can make out the superior pericardial borderThe wide vascular pedicle here results from a pericardial effusionThe pacemaker wires roughly outline the right atrium borderThe left heart border can be seen within the effusioneffusioneffusionComparing this with older films can also help make the diagnosis.
44Pulmonary Airways & Vasculature The lungs on the normal chest radiograph are made by pulmonary vessels, the bronchi are normally not seen.This is because:Pulmonary vessels are blood-filled with density similar to water.Bronchi are filled with air and normally have thin walls that do not provide contrast to aerated lungs.
45Pulmonary Airways & Vasculature When lung parenchyma fill with water or inflammatory material:Water-density vessels become less distinct.Air-filled bronchi can be seen as “air bronchograms”.If airways are obstructed (e.g., tumor) they may fill with fluid and no “air bronchograms” will be appreciated.
50What is the source of this man’s chronic cough? Unilateral lung opacification with ipsilateral tracheal shift from the pressure differential helps identify RUL collapseObstructionRULHorizontal fissureTented right hemidiaphragmInferior pulmonary ligament tethering the lobe and tenting the diaphragmRight upper lobe collapse secondary to obstruction of the bronchus by squamous cell carcinoma.
54What is abnormal here? The patient has Sarcoidosis. Lateral border of the SVC is obscured by lymphadenopathyBronchus lumen is obscuredThink about lymphadenopathy when opacities obscure the aortic pulmonary recess (PA) or surrounding the left distal main bronchus (on the lateral)
55Other Mediastinal Structures EsophagusThyroidThymusLymph nodesThese are generally not seen unless there is pathology
56What could be the source of this anterior mediastinal mass?
57What could be the source of this anterior mediastinal mass? Ddx: Lymphoma/leukemia, germ cell tumors (e.g., teratoma), thymic mass (e.g., thymoma, cyst), enlarged thyroid, vascular (e.g., hematoma, aortic aneurysm).This patient has a thymoma.
61In the normal radiograph, the diaphragm is domed with the right side higher than the left (i.e., the heart lying on the left side of the diaphragm may contribute to the lower level).Left diaphragmRight diaphragm
62Elevated intrathoracic pressures (e. g Elevated intrathoracic pressures (e.g., hyperinflation from obstructive lung disease, tension pneumothorax) will flatten the diaphragm.FlatFlattened
65What’s abnormal in these films? Notice the air around the left and right pulmonary arteries.LLL atelectasisThe lucent stripe along the inferior heart border, crossing midline is called a “continuous diaphragm” sign and is indicative of pneumomediastinum.
74What’s abnormal in this film? SplenomegalyGastric air bubble
75What’s abnormal in this film? Gastric air bubble
76What’s abnormal in this film? OuchGastric air bubble
77Which patient needs a chest tube? Gastric air bubble
78Which patient needs a chest tube? PneumothoraxSkin fold lateral borderScapula medial borderTo decide whether a line in the lung represents the scapula, a skin fold or a pneumothorax consider the density difference between the two sides of the line. A pneumothorax will have a sharp line with air density (equal density) on both sides. Skin or scapula will have a line with air on one side and more opaque tissue on the other.Gastric air bubble
80What’s abnormal in this film? NothingThe left lung appears more opacified but it is the result of uneven radiation.The patient is rotated slightly causing the “heel effect”, the relative over exposure of one hemithorax compared to the other caused by uneven radiation. Looking at the relative exposure of the extrathoracic soft tissues can help identify the “heel effect”.
81References:Collins J, Stern EJ. Chest Radiology, the Essentials. Lippincott, Williams & WilkinsDafner RH. Clinical Radiology, the Essentials. 2nd Ed. Lippincott, Williams & WilkinsFreindlich IM, Bragg DG. A Radiologic Approach to Diseases of the Chest. 2nd Ed. Williams & Wilkins