Fig. 5.  Distributions of (Hounsfield units in parentheses) normally aerated (from −900 to −500; A –C ), poorly aerated (from −500 to −100; D –F ), and atelectatic (from −100 to 100; G –I ) areas in craniocaudal direction (slice 1–100) according to voxel density at inspiration after alveolar recruitment, during one-lung ventilation (OLV) and during two-lung ventilation (TLV) thereafter. Data are summarized in blocks of 10 slices of the dependent lung and presented as means and SDs. They are grouped related to the use of different tidal volumes (V^T) values during OLV (*P < 0.05: 5 vs.  10 ml/kg). ARM = alveolar recruitment maneuver.