IOTW 12/14/20

65 y/o F p/w fever and hypoxia

  1. Name the structures indicated by labels “A, B, C, D, and E.”
    • A – Diaphragm
    • B – Liver
    • C – Spleen
    • D – Rib with posterior shadowing
    • E – Pleura
  2. What is indicated by label “F”? What type of artifact causes this? What does it signify?
    • B-Lines which are caused by a type of reverberation artifact. This typically signifies thickened or fluid-filled interlobular septa. While occasional B-Lines in the lung bases can sometimes be a normal finding (especially in elderly populations), 3 or more per lung field is usually pathological and consistent with an interstitial syndrome. This can be seen in almost any interstitial process such as pulmonary edema, pneumonia, lung contusions, and masses, for example.
  3. What sign is label “H” and what does it mean?
    • Spine sign. In normal lung, vertebral bodies on ultrasound should terminate at the level of the diaphragm and not be visualized above due to the inability of ultrasound waves to transmit through air. The presence of a fluid collection in the lung, however, will act as an acoustic medium for the transmission of ultrasound waves allowing visualization of the spine above the diaphragm as seen in the images above. This is non-specific for determining the type of fluid collection, as this can be seen with pleural effusions, hemothorax, and even consolidations.
  4. What is indicated by label “G” and what are the two different types?
    • Air bronchograms. They are air-filled areas of the bronchial tree which are visualized in the presence of fluid-filled alveoli which act as an effective acoustic window. There are 2 types of sonographic air bronchograms:
      • Static – These will remain fixed in position during the respiratory cycle. This indicates air trapped in small bronchi caused by complete bronchial obstruction from atelectasis.
      • Dynamic – These will exhibit small movements with respiration indicating partial bronchial obstruction from fluid mixed with air. This finding typically represents pneumonia.
  5. Name four sonographic lung findings that suggest pneumonia as the diagnosis.
    • B-Lines – often seen with small areas of subpleural consolidation. In early stages of pneumonia, only some alveoli will be fluid-filled and can lead to a patch of focal B-Lines.
    • Hepatization – this refers to the solid “liver-like” sonographic appearance of lung as it becomes inflamed and filled with purulent fluid. This can be seen in consolidation or atelectasis.
    • Shred sign – this appears as an irregularity of the pleural interface in the setting of small areas of consolidated lung. These areas abut the pleural surface causing the “shredded” appearance on ultrasound.
    • Dynamic air bronchograms – as discussed in question 4, this finding has been shown to have a 94% specificity and 97% positive predictive value for pneumonia as the cause of the consolidation.
    • Color doppler can also be used which would demonstrate the pulmonary vasculature in areas of consolidation. A concomitant parapneumonic effusion with echogenic debris can suggest empyema.

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