Radiological findings of pulmonary consolidation and collapse

Radiological findings of pulmonary consolidation and collapse

1. CONSOLIDATION AND COLLAPSE Dr. JYOTISH ROY 1 ST YEAR PGT DEPT. OF RADIODIAGNOSIS IPGME&R,KOLKATA

2. AIR-SPACE CONSOLIDATION Air-space consolidation represents replacement of alveolar air by fluid, blood, pus, cells, or other substances. Alveolar consolidation and parenchymal consolidation are synonyms for air-space consolidation

3. Radiographic Findings Radiographic and computed tomography (Ct) abnormalities indicating the presence of air-space consolidation include the following: • Homogeneous opacity obscuring vessels • Air bronchograms •Ill-defined or fluffy opacities • "Air alveolograms " • Patchy opacities • " Acinar " or air-space nodules • Preserved lung volume • Extension to the pleural surface • "CT angiogram" sign

4. Homogeneous Opacity Obscuring vessels : With complete replacement of alveolar air, homogeneous opacification of the lung results. Vessels within the consolidated lung are invisible.

5. Homogeneous Opacity Obscuring vessels

6. AIR BRONCHOGRAM In patients with consolidation, air-filled bronchi are often visible on plain radiographs or CT, appearing lucent compared with opacified lung parenchyma . This finding is termed an air bronchogram AIR BRONCHOGRAM NOT VISIABLE: >central bronchial obstruction, ex- cancer ,mucus >filling the bronchi with blood, ex-pulmonary oedema or haemorhage >bronchopneumonia

7. ILL DEFINED OR FLUFFY OPACITIES Consolidation often results in opacities with ill-defined margins in contrast to the relatively sharp margins of a lung mass. This results from patchy local spread of disease with variable involvement of alveoli at the edges of the pathologic process.

8. ILL DEFINED OR FLUFFY OPACITIES

9. AIR ALVEOLOGRAM >If lung consolidation is not confluent, small focal lucencies representing uninvolved lung may be visible.These have been termed "air alveolograms ," > this is a misnomer as alveoli are too small to see radiographically . > reflect incomplete lung consolidation.

10. PATCHY OPACITIES Variable consolidation in different lung regions patchy areas of increased opacity. Pulnonary vessels may be obscured or poorly defined . Patchy consolidation visible on chest radiographs sometimes appears to be lobular or multilobular on CT ( i.e.involving individual pulmonary lobules). > Some lobules appear abnormally dense while adjacent lobules appear normally aerated.

11. PATCHY OPACITIES

12. ACINAR OR AIR SPACE NODULE > acinar nodule and air-space nodule are used to describe poorly marginated rounded opacities, >5 to 10 mm. in diameter occur due to focal consolidation more easily seen on high-resolution CT (HRCT') than on chest radiographs

13. ACINAR OR AIR SPACE NODULE

14. CT ANGIOGRAM SIGN This sign is present if normal-appearing opacified vessels are visible within the consolidated lung following the infusion of intravenous contrast . Although opacified vessels are sometimes seen within a lung mass, they usually appear compressed or distorted

15. CT ANGIOGRAM SIGN

16. DIFFERENTIAL DIAGNOSIS OF CONSOLIDATION: DIFFUSE OR FOCAL Diffuse consolidation paterns : > perihilar bat-wing consolidation >peripheral subpleural consolidation or reverse bat-wing >diffuse patchy consolidation >diffuse air space nodule >diffuse homogenous consolidation

17. PERIHILAR BAT-WING PATTERN >central consolidation with sparing of the lung periphery > most typical of pulmonary edema also may be seen with pulmonary hemorrhage, pneumonias (including bacteria and atypical pneumonias such as Pmumocystis jiroveci (P. carinii ) pneumonia[PCP) and viral pneumonia), inhalational lung injury. In patients with pulmonary edema perihilar distribution is most often present when rapid accumulation of fluid has occurred. Relative sparing of the lung periphery has been attributed to better lymphatic clearance of edema fluid in this region, although the exact mechanism is unclear.

18. PERIHILAR BAT-WING PATTERN

19. Peripheral subpleural consolidation the opposite of a bat-wing pattern (reverse bat-wing pattern) Consolidation is seen adjacent to the chest wall, with sparing of the perihilar regions. > It is most often seen in a patients with a chronic lung disease . > classically associated with eosinophilic lung diseases, particularly eosinophilic pneumonia may also occur with organizing pneumonia, sarcoidosis , radiation pneumonitis , lung contusion, or bronchioloalveolar carcinoma. Peripheral consolidation need not always appear peripheral on the frontal radiograph; it may be peripheral in the anterior or posterior lung and overlie the parahilar regions.

20. Peripheral subpleural consolidation

21. Diffuse patchy consolidation >seen in >pneumonia (bacterial, mycobacterial, fungal, viral , PCP ); >pulmonary edema ; >adult respiratory distress syndrome (ARDS); >pulmonary hemorrhage syndromes; > aspiration; inhalational diseases; eosinophilic diseases; >diffuse bronchioloalveolar carcinoma. >The patchy opacities may correspond to consolidation of lobules, subsegments , or segments

22. Diffuse patchy consolidation

23. Diffuse air-space nodular opacities prominent feature is typical of endobronchial spread of disease seen in patients with endobronchial spread of infection such as tuberculosis (TB) or Mycobacterium avium complex (MAC), bacterial bronchopneumonia , viral pneumonia endobronchial spread of bronchioloalveolar carcinoma, pulmonary haemorrhage , or sometimes aspiration

24. Diffuse air-space nodular opacities

25. Diffuse homogeneous consolidation >most typical in patients with pulmonary edema, ARDS, pulmonary haemorrhage . pneumonias (including viral and PCP), alveolar proteinosis , and extensive atelectasis.

26. DIFFERENTIAL DIAGNOSIS OF FOCAL CONSOLIDATION >lobar consolidation >round or spherical consolidation >segmental or subsegmental consolidation >focal patchy consolidation

27. LOBAR CONSOLIDATION > most typical of pneumonia(including S. pneumoniae , Klebsiella , Legionella, and TB) and abnormalities associated with bronchial obstruction. >occurs because of inter alveolar spread of disease via the pores of Kohn (small holes in the alveolar walls) > spread continues until a fissure or pleural surface is reached. Organisms spread via the pores of Kohn are characterized by thin secretions. > The presence of an incomplete fissure may lead to a lobar pneumonia becoming bilobar (or trilobar )

28. LOBAR CONSOLIDATION interalveolar spread - seen with lymphoma and bronchioloalveolar carcinoma lepidic growth- local interalveolar spread of tumors such as bronchioloalveolar carcinoma, using alveolar walls as a scaffold. Bronchial obstruction with postobstructive pneumonia or atelectasis also commonly results in lobar consolidation Lobar expansion in association with lobar consolidation suggests infection, particularly by Klebsiella or Pneumococcus, TB, bronchial obstruction with postobstructive pneumonia, or consolidation associated with neoplasm

29. LOBAR CONSOLIDATION WITH EXPANSION

30. Round or spherical consolidation >Most typical of bronchioloalveolar carcinoma, lymphoma or lymphoproliferative disease, or round pneumonia. > A round or spherical pneumonia is typical of organisms that spread via the pores of Kohn and canals of lambert and progress to being lobar, such as S. pneumoniae , Klebsiella , Legionella, or TB . > Occurs mostly in children because of poorly form pores of kohn and canals of lambert

31. Round or spherical consolidation

32. Segmental (or subsegmental ) consolidation > a wedge-shaped opacity of more than a few centimeters in size >apex of the wedge pointing toward the hilum . > abnonnality in segmental bronchus or artery. Focal patchy consolidation > typical of pneumonias, endobronchial spread of TB, or endobronchial spread of tumor such as bronchioloalveolar carcinoma >Patchy consolidation is typical of bronchopneumonia. >Pneumonias of( Staphylococcus,Haemophilus , Pseudomonas) are characterized by thick and tenacious secretions and spread via airways rather than the pores of Kohn.

33. Segmental (or subsegmental ) consolidation

34. Rapidly appearing consolidation (a few hours) : Suggests atelectasis with drowned lung, aspiration, pulmonary edema, pulmonary hemorrhage, infarction, or rapidly progressing pneumonia, particularly in an immunocompromised host. Occasionally a lymphoproliferative neoplasm progresses within hours. Longstanding(chronic) consolidation ( 4 to 6weeks): eosinophilic pneumonia, BOOP, bronchioloalveolar carcinoma, lymphoma, lipoid pneumonia, or some indolent pneumonias such. as fungal infections. Recurrent processes (e.g., recurrent pulmonary edema, pulmonary hemorrhage, or aspiration) may appear to be chronic if radiographs are obtained only during the acute episodes

35. SILHOUETTE SIGN The borders of soft tissue structures such as the mediastinum, hila, and hemidiaphragms are visible on chest radiographs because they are outlined by adjacent air-containing lung. When consolidated lung (or a soft tissue mass) contacts one of these structures, its border becomes invisible or is poorly marginated . This is termed the "silhouette sign.

36. SILHOUETTE SIGNS( FRONTAL RADIOGRAPH) Right superior mediastinum (i.e., superior vena cava[SVC]) =right upper lobe Right heart border = right middle lobe (common) or medial right lower lobe (less common) Right hemidiaphragm =right lower lobe Left superior mediastinum (e.g., aortic arch) = left upper lobe Left heart border= lingular segments of left upper lobe Left hemidiaphragm or descending aorta= left lower lobe Caveat: The diaphragmatic contour seen on the frontal (PA or AP) radiograph represents the dome, or the highest point, of the diaphragm. The diaphragmatic dome is relatively anterior , and lower lobe consolidation may be posterior to it ; in this case, the hemidiaphragm may remain visible.

37. SILHOUETTE SIGNS (LATERAL RADIOGRAPH) >Posterior margin of the heart or posterior left hemidiaphragm =left lower lobe; hiatal hernia may mimic this. >Anterior right hemidiaphragm = right middle lobe >Posterior right hemidiaphragm = right lower lobe

38. The silhouette sign in right upper lobe pneumonia. Consolidation of the right upper lobe obscures ( i.e.silhouettes ) the border of the right superior mediastinum and superior venacava . The upper part of the right hilum is also invisible

39. Anatomic relationships used with the silhouette sign. Obscuration of the borders shown in this diagram are associated with consolidation of the listed lobes. RUL, right upper lobe; RML, right middle lobe; RLL, right lower lobe; LUL, left upper lobe; LLL, left lower lobe.

40. The silhouette sign in right middle lobe pneumonia . On frontal view - Consolidation of the right middle lobe., obscures (silhouettes") the right heart border . In contrast, the left heart border is sharply marginated . 'The right hemidiaphragm appears sharply marginated . The pneumonia is marginated by the minor fissure { arr ow ). : On the lateral view, middle lobe consolidation is visible, marginated above by the minor fissure (large arrows); inferiorly, it is marginated by the major fissure (small arrow)

41. The silhouette sign in right lower lobe pneumonia. : frontal view shows right lower lobe consolidation with obscuration of the diaphragm, right heart border (arrow) remains visible as an edge. On the lateral view, complete right lower lobe consolidation is vis ible, outlined anteriorly by the major fissure (white arrow). The right hemidiaphragm (large blade arrows) is sharply marginated anterior to the consolidated lobe but is invisible posteriorly. posterior left heart border and left hemidiaphragm are sharply marginated (small blade arrow).

42. The left heart border is obscured because of lingular consolidation. 'The left superior mediastinum remains sharply marginated because the medial portions of the anterior and apical segments of the left upper lobe remain aerated

43. The silhouette sign in left lower lobe pneumonia. Frontal view: The left hemidiaphragm is partially obscured by left lower lobe consolidation (arrows). On the lateral view, a portion of the left hemidiaphragm (arrow) also is obscured

44. ATELECTASIS It is used to indicate loss of volume of lung tissue associated with a decrease in the amount of air it contains. It is synonymous with collapse TYPES OF ATELECTASIS Four different types or mechanisms of atelectasis are recognized a) resorption ( obstructive) b) relaxation(passive) c)adhesive d) cicatricial

45. TYPES OF ATELECTASIS RESORPTION ATELECTASIS >Caused by airway obstruction with resorption of alveolar gas >Occurs within 24 hours >More rapid when breathing pure oxygen >May result in drowned lung with little volume loss >Collateral ventilation may prevent collapse w ith large airway obstruction, airbronchograms are often absent RELAXATION ATELECTASIS Atelectasis due to pleural effusion, pneumothorax, or mass Lung density need not be increase ADHESIVE ATELECTASIS Atelectasis caused by loss of lung surfactant Typical of respiratory distress syndrome of the newborn, acute respiratory distress syndrome, radiation pneumonitis CICATRICIAL ATELECTASIS Atelectasis caused by lung fibrosis

46. RESORPTION(OBSTRUCTIVE) ATELECTASIS > alveolar gas is absorbed by circulating blood and not replaced by inspired air. > Occurs in the presence of airway obstruction >obstructed airway may be the trachea. main bronchus, lobar bronchi or multiple small bronchi or bronchioles. >common after surgery and general anesthesia >airless in 24 hrs of obstruction >occurs more quickly in case of a) breathing pure oxygen b)one way valve endobronchial lesion >drowned lung : rapid transudation of fluid in alveoli and interstitium with out significant volume loss > airbronchogram absent( large airway involvement)

47. RELAXATION AND COMPRESSION ATELECTASIS >Relaxation atelectasis or passive atelectasis: The presence of pneumothorax. pleural effusion, or a mass lesion allows the lung to decrease in volume or relax to its natural size, which is smaller than the thoracic cavity. >compressive atelectasis: it implies a reduction in lung volume beyond its normal relaxed state.

48. RELAXATION AND COMPRESSION ATELECTASIS

49. ADHESIVE ATELECTASIS > Surfactant reduces the surface tension of alveolar fluid and tends to prevent lung collapse as the alveoli decrease in volume with expiration. > Deficiency of surfactant allows alveoli to collapse. so-called adhesive atelectasis. > This is most typical of respiratory distress syndrome of the newborn but is also seen in patients with ARDS, acute radiation pneumonitis, or hypoxemia, and in the postoperative period

50. CICATRICIAL ATELECTASIS > to loss of lung volume occurring in the presence of lung fibrosis. It may be focal, lobar or diffuse, depending on the disease responsible. Findings of fibrosis are typically present

51. CICATRICIAL ATELECTASIS

52. RADIOGRAPHIC FINDINGS OF ATELECTASIS DIRECT SIGNS: >due to lobar volume loss >Displacement of fissures >Crowding of vessels INDIRECT SIGNS: >secondary to volume loss >Diaphragmatic elevation > Mediastinal shift >Compensatory overinflation of normal lung > Hilar displacement >Reorientation of the hilum or bronchi >Approximation of the ribs >Increased lung opacity >Absence of air bronchograms >Shifting granuloma sign

53. lndired Signs Seen With Specific Types of Atelectasis Golden's S sign: right upper lobe atelectasis Juxtaphrenic peak: upper lobe atelectasis Luftsichel sign: upper lobe atelectasis (usually the left upper lobe) Flat waist sign: left lower lobe atelectasis Comet-tail sign: rounded atelectasis

54. ATELECFASIS OF AN ENTIRE LUNG Lung atelectasis usually results from > obstruction of a main bronchus by an endobronchial lesion (or intubation of the opposite main bronchus), > obstruction of small peripheral bronchi by secretions, > large ipsilateral pneumothorax or pleural effusion.

55. Bronchial Obstruction With Lung Collapse > the ipsilateral diaphragm is elevated, >shift of both the upper and lower mediastinum to the side of atelectasis is present the ipsilateral ribs crowding and the lung is increased in density in comparison to the opposite side . Absence of air bronchograms suggests a central obstruction visible air bronchograms suggest peripheral small airway obstruction.

56. Bronchial Obstruction With Lung Collapse

57. Right Upper Lobe Atelectasis Frontal radiograph >ill defined increase in opacity in the upper thorax >Apparent right mediastinal widening >Silhouetting of the right upper mediastinum >Tracheal shift to the right >Upward bowing and displacement of the minor fissure > Golden's S sign >Elevation of the hilum >Outward rotation of the hilum or bronchus >Right-sided juxtaphrenic peak Lateral radiograph >Upward displacement and bowing of the minor fissure >Anterior displacement and bowing of the upper major fissure

58. Right Upper Lobe Atelectasis

59. Left Upper Lobe Atelectasis Frontal radiograph >Ill-defined increase in opacity in the upper thorax (decreasing with increased collapse) >Silhouetting of the left upper mediastinum >Tracheal shift to the left > Luftsichel sign >Apical cap >Elevation of the hilum >Outward rotation of the hilum or bronchus > Juxtaphrenic peak Lateral radiograph >Anterior bowing and displacement of the major fissure

60. Left Upper Lobe Atelectasis

61. Right Middle Lobe Atelectasis Frontal radiograph >Minor fissure is invisible > in creased lung opacity (decreasing with increased collapse) >Silhouetting of the right heart border Lateral radiograph >Downward bowing and displacement of the minor fissure >Anterior bowing and displacement of the inferior major fissure >Wedge of consolidated lung anchored at the hilum

62. Right Middle Lobe Atelectasis

63. Lower Lobe Atelectasis Frontal radiograph >Major fissure becomes visible (upper portion best seen) >Triangular opacity >Downward bowing of the minor fissure (right lower lobe atelectasis) >Downward displacement of the hilum >Invisibility of the interlobar pulmonary artery >Obscuration of the diaphragm >Shift of the heart >Flat-waist sign (left lower lobe atelectasis) Lateral radiograph >Obscuration of the posterior diaphragm >Posterior bowing of the major fissure (lateral radiograph)

64. RIGHT LOWER LOBE ATELECTASIS

65. Combined Collapse of Right Middle and Lower Lobes occurs in patients with obstruction of the bronchus intermedius . On the frontal and lateral radiographs, both the displaced major and minor fissures may be variably visible, outlining the consolidated lung. On the frontal view, both the right heart border and diaphragm often appear obscured . This appearance may closely mimic that of right lower lobe collapse associated with an elevated hemidiaphragm or subpulmonic pleural effusion.

66. Combined Collapse of Right Middle and Lower Lobes

67. Combined Collapse of Right Middle and Upper Lobes >double lesion sign: most commonly occurs when lung cancer involves the hilum, with invasion of both the upper and middle lobe bronchi while the lower lobe bronchus remains patent; >it may also be seen with multiple isolated bronchial lesions, as in a patient with mucous plugging. >On the frontal radiograph, right upper lobe opacification obscures the right superior mediastinum while right middle lobe opacification obscures the right heart border

68. Combined Collapse of Right Middle and Upper Lobes

69. ROUNDED ATELECTASIS Round or elliptical opacity >Associated with an ipsilateral pleural abnormality >Peripheral in location > Extensive contact with the abnormal pleural surface >Comet-tail sign >Volume loss >Posterior, paravertebral lower lobe in patients with effusion >Atypical appearances when associated with pleural fibrosis >Dense opacification on CT after contrast infusion

70. ROUNDED ATELECTASIS

71. PLATELIKE OR DISCOID ATELECTASIS >Linear areas of atelectasis, > a few millimeters to 1 c.m thick and at least several centimeters in length >commonly occur in patients with decreased depth of breathing or diminished diaphragmatic excursions >they tend to occur at the lung bases, several centimeters above and parallel to the diaphragm . >they cross segmental boundaries. >They may also occur in the medial infrahilar regions. >typically angled upward from the mediastiu m at about a 45-degree angle.

72. PLATELIKE OR DISCOID ATELECTASIS

73. Segmental (or subsegmental ) atelectasis secondary to obstruction of segmental (or subsegmental } bronchi by tumor, mucus, or inflammatory disease wedge-shaped opacities are seen radiating outward :from the hilum or involving the peripheral lungs with the base of the wedge touching the pleural surface.