Have you missed Kerley B lines before? What’s your go-to sign for early interstitial edema? Let me know in the comments below.

To the untrained eye, a chest X-ray is a confusing jumble of ribs, vessels, and air. However, the lung is designed to be a vessel of air, appearing dark on an X-ray due to its radiolucency. The interstitium—the complex network of connective tissue that supports the lung's air sacs—is normally invisible. It is only when this network becomes engorged that it betrays its presence. This is where the Kerley B line earns its significance. These lines appear as short, white, horizontal streaks located at the periphery of the lung, typically near the base. They are distinct, usually about one to two centimeters in length, and abut the pleura, the lining of the lung.

In the stark, monochromatic world of the radiograph, the human body reveals its secrets in shades of gray. While radiologists typically hunt for the glaring opacity of a tumor or the distinct fracture of a bone, some of the most critical diagnostic clues lie in the faintest of shadows. Among these subtle indicators are the Kerley lines—specifically, the enigmatic "Kerley B" lines. Named after the Irish radiologist Peter James Kerley, these small, horizontal markings serve as a silent but eloquent storyteller, bridging the gap between visual observation and the physiological reality of heart failure.