Chest Radiograph (AP view).
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Kerley lines are thin linear pulmonary opacities seen on the chest radiograph caused by fluid or cellular infiltration into the interstitium of the lungs.
Kerley B lines (red arrows) are thickened interlobular septa visible as 1-2 cm long horizontal linear opacities in the subpleural region, which meet the pleura at right angles. They are typically seen as a ladder up the side of the lungs beginning at the costophrenic angle. These are most readily identified at the costophrenic angles on the PA radiograph and substernal region on lateral radiographs. They represent interlobular lymphatics which have been distended by fluid. They are usually an indication of raised pulmonary venous pressure and interstitial pulmonary oedema (e.g. Left ventricular failure or Mitral stenosis). Other causes include pulmonary fibrosis and lymphangitis carcinomatosa.
Kerley A lines (yellow arrows) are longer lines coursing diagonally toward the hila in the inner half of the lungs. These are caused by distension of anastomotic channels between peripheral and central lymphatics of the lungs.
Kerley B lines are usually observed much more frequently than Kerley A lines. Progression to alveolar oedema may obscure Kerley lines.
Chronic Kerley B lines may be caused by fibrosis and haemosiderin deposition caused by multiple previous episodes of pulmonary oedema.Start Slide Show with PicLens Lite