Figure 5a. The most common variations in right middle lobe PV draining patterns are shown in volume-rendered posterior views obtained with single-section CT (2-mm collimation, 1-mm reconstruction interval, pitch of 2) before ablation in a 48-year-old woman (a) and a 51-year-old man (c) and obtained with contrast-enhanced multisection CT (four sections, 2.5-mm collimation, 1.25-mm reconstruction interval) before ablation in a 40-year-old man (b). In a, the drainage pathway from the right middle PV to the central portion of the right superior PV is visible; note the independent ostium in a right middle subsegmental vein, which drains into the left atrium (arrowhead). In b, the drainage pathway from the right middle PV to the left atrium via an independent ostium is shown. In c, drainage pathways from the right middle PV to the central portion of the right inferior PV, and from the lingular vein to the central portion of the left inferior PV, are depicted. LI = left inferior, LS = left superior, RI = right inferior, RM = right middle, RS = right superior.