Fig. 2

Images from 256-slice spiral computed tomography (CT). a-c Standard algorithm-generated images. Width of the lung window, 1000 Hounsfield units (HU); window level, − 700 HU. a At the workstation three-dimensional interface, the left image is an axial maximum intensity projection (MIP) reconstruction with 5-mm slab thickness showing the lower right oblique fissure. The interlobular fissure manifested a band-like pattern and had high density and a clear boundary. No five-line sign was revealed (white arrow). The basic point (small green cross) was set at the middle point of the lower right oblique fissure, coronal (right upper image), and sagittal plane (right lower image) corresponding to the middle point of the axial lower oblique fissures. b In the sagittal position (right lower image), which is the same one as shown in a, and the workspace interface, the reconstructed tangent lines were rotated counter clockwise to a given angle (black arrow) to allow formation of an oblique coronal plane (left image). For the interlobular fissure of this oblique plane, a five-line sign was clearly revealed (white arrow) with a MIP slab thickness of 6 mm. c On the sagittal position, which is the same one as the right lower image shown in b, the angle between the tangent lines and the oblique fissure (arrow) is 31°; the angle between the horizontal line and the oblique fissure (arrowhead) is 53°; and the angle between the tangent lines and the horizontal line (arrow with a fish tail) is 22°. Notice that the minor fissure is imaged as an arc line-like pattern on the sagittal plane