Vocal tract data from 3D cine-MRI are used together with synchronised acoustics to evaluate a linear regression model for inversion. The first two principal components of vocalic area functions are predicted with correlations 0.99 and 0.97 respectively, from 24 FFT-cepstra measured in the frequency band 0-4 kHz. This best regression model together with the two component representation yields mean absolute errors of 0.37 cm2 in section area and 0.15 cm in vocal tract length.