Figure 2a: Graphs show measurements of FLV with MR imaging as a function of GA. MR imaging–based FLV measurements from 30 fetuses with GA of 17–36 weeks. For each fetus, measurements were obtained in duplicate by two observers in the (a) transverse, (b) sagittal, and (c) coronal planes. 
= observer A, 
= observer B. (d) Fitted quadratic functions for three MR imaging planes of measurement differed negligibly.