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Figure 4: (Left) Images of the Shepp-Logan phantom ($96\times 96$ samples, $288\times 288$ reconstruction matrix) and (right) gradient-echo images of the human brain in vivo (TR/TE  =  500/8 ms, BW 80 Hz/pixel, FA ${30}^{\circ }$, 2 mm slice) reconstructed using zero-padding (zero), the extrapolation method by Constable and Henkelman (comp), and the proposed method with first- and second-order derivatives (TV2). For comparison, reconstructions from fully sampled $288\times 288$ matrices are shown (full). Arrows  =  truncation artifacts.