- “B-Lines” can be seen in patients with pulmonary edema (see attached image below)
- A “B-line” is a reverberation artifact defined by Lichtenstein as having several properties:
1. A comet-tail artifact
2. Arising from the pleural line
3. Well defined
4. Hyperechoic
5. Long (does not fade)
6. Erases A lines
7. Moves with lung sliding
- A large amount of B-lines is pathologic
- These artifacts are also called “comet-tails” due to their appearance
- One or two B-lines can be seen in dependent lung zones in normal lungs
- AIS (Alveolar interstitial syndrome) describes a group of conditions including pulmonary edema, interstitial pneumonia, and pulmonary fibrosis that show similar findings on lung ultrasonography
- The most common presentation of this syndrome is from cardiogenic pulmonary edema and is characterized by B-lines in multiple lung zones
- B lines correspond with interlobular septal thickening on CT scans, which represent pulmonary vascular congestion
Technique
- B-mode is used with the micro-convex (cardiac) probe scanning in at least 8 lung zones
- Quantify the number of B-lines in each zone
- A lung zone is considered to be “positive” when three or more B-lines are present in a longitudinal plane between two ribs
- Two or more regions bilaterally are required to be defined as AIS
- Bilateral diffuse B-lines have a specificity of 95% and a sensitivity of 97% for the diagnosis of pulmonary edema
References
1. Lichtenstein D, Mezie re G, Biderman P, et al. The comet-tail artifact. An ultra- sound sign of alveolar-interstitial syndrome. Am J Respir Crit Care Med 1997; 156(5):1640–6.
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