Imaging features of the linear pattern on X ray
The lines visible on a normal chest radiograph represent the branching pulmonary arteries and veins. These begin centrally and radiate from the hilum toward the periphery of the lung. The linear pattern appears as increased numbers of lines radiating from the central hila bilaterally. In addition, the linear pattern may produce Kerley B lines. These are thin horizontal lines 1 to 2 cm long, extending from the lateral chest wall toward the central lung ( Figures 19-6 and 19-7 ). The most common cause of the linear pattern is congestive heart failure, and to the degree that an interstitial abnormality resembles congestive heart failure, it is more likely to represent the linear pattern of interstitial disease. Novice radiologists should take care not to overdiagnose the linear interstitial pattern. There is a wide variation in the normal appearance of chest radiographs. If one is unsure of whether there is an interstitial abnormality present on a chest radiograph, it is usually best to assume that the examination is normal.