PneumoniaCreated OnMay 4, 2020Last Updated OnMay 4, 2020byadmin You are here: Main Radiology Pneumonia < All Topics Table of Contents Chest radiograph The presence of an infiltrate on plain chest radiograph is considered the gold standard for diagnosing pneumonia when clinical and microbiologic features are supportive. Findings: Lobar Consolidation, Interstitial Infiltrates, and/or Cavitation. Air Bronchogram Characteristic sign of consolidation. The black lines represent patent airways within consolidated lung Consolidation – Right Upper Lobe This image shows consolidation of the right upper lobe which is confined inferiorly by the horizontal fissure. Lobar pneumonia is usually caused by typical organisms – such as Streptococcus pneumoniae Consolidation – Right Middle Lobe The right middle lobe is located below the horizontal fissure which confines the area of consolidation in this image The right middle lobe is also next to the right heart border which is obscured in this image Consolidation – Right Lower Lobe The right lower lobe is located adjacent to the right hemidiaphragm The right heart border is still visible which indicates that the consolidation is not in the middle lobe These images demonstrate examples of the silhouette sign The Silhouette Signs Crisp contour formed by differing densities of normal adjacent structure also known as ‘silhouette’. Loss of contour is positive silhouette sign – indicating disease processes at that area. Thus, silhouette sign can help locate abnormalities in 3D space within the chest 1 – Left heart border – Lingula disease 2 – Hemidiaphragm – Lower lobe lung disease 3 – Paratracheal stripe – Paratracheal disease 4 – Chest wall – Lung, pleural or rib disease 5 – Aortic knuckle – Anterior mediastinal or left upper lobe disease 6 – Paraspinal line – Posterior thorax disease 7 – Right heart border – Middle lobe disease 8 – Density above horizontal fissure – Anterior segment of the right upper lobe (due to formation of a silhouette rather than loss of a silhouette) Consolidation – Right Lower Zone Patchy consolidation in the right lower zone As the consolidation is below the horizontal fissure, we know that it is not in the right upper lobe It is difficult to determine if the consolidation is in the right lower or middle lobe as there is no positive silhouette sign present Consolidation – Multiple Zones Right middle zone consolidation with air bronchogram within. No single well-defined lobe is affected There is also vague consolidation at the left lower zone positive silhouette sign of left hemidiaphragm indicating involvement of the left lower lobe Lingula part of left upper lobe is not involved as the left heart border remains well-defined. Right Middle Zone Pneumonia and Pleural Effusion Right middle zone consolidation with air bronchogram visible. There is an area of opacity due to a parapneumonic effusion (lost of costophrenic angle) – notice that no air bronchogram is...

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