Fig. 1.
Magnetic resonance images of a 31-year-old nonpregnant woman in either the supine (A and E), or left-lateral tilt position at 15° (B and F), 30° (C and G), or 45° (D and H) at the L3–L4 disk level (A–D) and the L4–L5 disk level (E–H). (A–D) Neither the aorta (solid arrow) nor inferior vena cava (IVC; outlined arrow) changed in size or shape in any position. Area of the aorta and IVC at each level was 1.4, 2.0 cm2; 1.5, 2.1 cm2; 1.6, 2.4 cm2; and 1.5, 2.4 cm2, respectively. The IVC area at each level was 2.0, 2.1, 2.4, and 2.4 cm2, respectively. (E–H) The size of the IVC changed slightly according to the position. The IVC area at each level was 1.9, 1.4, 1.2, and 1.8 cm2, respectively. Right and left common iliac arteries (dashed arrow), which were divided from the abdominal aorta, were identifiable in any position. Area of the right and left common iliac arteries at each level was 0.7, 0.8 cm2; 0.5, 0.6 cm2; 0.8, 0.7 cm2; and 0.7, 0.7 cm2, respectively. In these axial images, anterior is at the top of the figure and anatomic right is to the left in the figure.